Selective automation and skill transfer in medical robotics: a demonstration on surgical knot-tying.

PubMed

Knoll, Alois; Mayer, Hermann; Staub, Christoph; Bauernschmitt, Robert

2012-12-01

Transferring non-trivial human manipulation skills to robot systems is a challenging task. There have been a number of attempts to design research systems for skill transfer, but the level of the complexity of the actual skills transferable to the robot was rather limited, and delicate operations requiring a high dexterity and long action sequences with many sub-operations were impossible to transfer. A novel approach to human-machine skill transfer for multi-arm robot systems is presented. The methodology capitalizes on the metaphor of 'scaffolded learning', which has gained widespread acceptance in psychology. The main idea is to formalize the superior knowledge of a teacher in a certain way to generate support for a trainee. In our case, the scaffolding is constituted by abstract patterns, which facilitate the structuring and segmentation of information during 'learning by demonstration'. The actual skill generalization is then based on simulating fluid dynamics. The approach has been successfully evaluated in the medical domain for the delicate task of automated knot-tying for suturing with standard surgical instruments and a realistic minimally invasive robotic surgery system. Copyright © 2012 John Wiley & Sons, Ltd.

SAGES Mini Med School: inspiring high school students through exposure to the field of surgery.

PubMed

Rosser, James C; Legare, Timothy B; Jacobs, Charles; Choi, Katherine M; Fleming, Jeffrey P; Nakagiri, Jamie

2018-04-02

The SAGES Mini Med School (SMMS) was designed to expose high school students to the field of surgery through mentoring, knowledge transfer, and hands-on experience with simulation. The objective of this paper is to profile the evolutionary development, performance metrics, and satisfaction queries of this innovative effort. Sixty-one high school students, grades 9-12, took part in the (SMMS) program during the 2015 SAGES Annual Congress. The students completed a surgical skills lab session where they attempted tasks associated with the development of open surgical and laparoscopic skills. The lab included a warm-up with the validated Super Monkey Ball video game, Top Gun Pea Drop task, FLS Peg Transfer task, open knot tying station, and open instrument tie station. The following are the results of the surgical skills lab. For the Super Monkey Ball task, 60 students participated with an average score of 73.0 s (SD = 53.9; range 59.1-87.0; median = 74). Sixty students participated in the Surgeons Knot and Pea Drop tasks with average times of 26.6 s (SD = 19.3; range 21.7-31.6; median = 21.0) and 113.8 s (SD = 65.9; range 96.6-131.0; median = 101.0), respectively. Sixty students participated in the Instrument Tie and 56 students participated in the Peg Transfer stations with average times of 51.7 s (SD = 34.5; range 42.8-60.6; median = 39.5) and 173.1 s (SD = 25.0; range 166.4-179.8; median = 180.0), respectively. 51 (83.6%) agreed that the Mini Med School made them more likely to consider a career in medicine. When asked if the program made them more likely to consider a career in surgery 42 (68.8%) agreed. All 61 respondents (100%) said that they would recommend the program to others. The SMMS program showed that the students had an excellent aptitude for the performance of validated surgical subtasks with high satisfaction, and increased consideration of a career in medicine/surgery. Long-term studies are needed to evaluate the impact on workforce recruitment.

Teaching surgical skills using video internet communication in a resource-limited setting.

PubMed

Autry, Amy M; Knight, Sharon; Lester, Felicia; Dubowitz, Gerald; Byamugisha, Josaphat; Nsubuga, Yosam; Muyingo, Mark; Korn, Abner

2013-07-01

To study the feasibility and acceptability of using video Internet communication to teach and evaluate surgical skills in a low-resource setting. This case-controlled study used video Internet communication for surgical skills teaching and evaluation. We randomized intern physicians rotating in the Obstetrics and Gynecology Department at Mulago Hospital at Makerere University in Kampala, Uganda, to the control arm (usual practice) or intervention arm (three video teaching sessions with University of California, San Francisco faculty). We made preintervention and postintervention videos of all interns tying knots using a small video camera and uploaded the files to a file hosting service that offers cloud storage. A blinded faculty member graded all of the videos. Both groups completed a survey at the end of the study. We randomized 18 interns with complete data for eight in the intervention group and seven in the control group. We found score improvement of 50% or more in six of eight (75%) interns in the intervention group compared with one of seven (14%) in the control group (P=.04). Scores declined in five of the seven (71%) controls but in none in the intervention group. Both intervention and control groups used attendings, colleagues, and the Internet as sources for learning about knot-tying. The control group was less likely to practice knot-tying than the intervention group. The trainees and the instructors felt this method of training was enjoyable and helpful. Remote teaching in low-resource settings, where faculty time is limited and access to visiting faculty is sporadic, is feasible, effective, and well-accepted by both learner and teacher. II.

Validation of Different Combination of Three Reversing Half-Hitches Alternating Posts (RHAPs) Effects on Arthroscopic Knot Integrity.

PubMed

Chong, Alexander Cm; Prohaska, Daniel J; Bye, Brian P

2017-05-01

With arthroscopic techniques being used, the importance of knot tying has been examined. Previous literature has examined the use of reversing half-hitches on alternating posts (RHAPs) on knot security. Separately, there has been research regarding different suture materials commonly used in the operating room. The specific aim of this study was to validate the effect of different stacked half-hitch configuration and different braided suture materials on arthroscopic knot integrity. Three different suture materials tied with five different RHAPs in arthroscopic knots were compared. A single load-to-failure test was performed and the mean ultimate clinical failure load was obtained. Significant knot holding strength improvement was found when one half-hitch was reversed as compared to baseline knot. When two of the half-hitches were reversed, there was a greater improvement with all knots having a mean ultimate clinical failure load greater than 150 newtons (N). Comparison of the suture materials demonstrated a higher mean ultimate clinical failure load when Force Fiber ® was used and at least one half-hitch was reversed. Knots tied with either Force Fiber ® or Orthocord ® showed 0% chance of knot slippage while knots tied with FiberWire ® or braided fishing line had about 10 and 30% knot slippage chances, respectively. A significant effect was observed in regards to both stacked half-hitch configuration and suture materials used on knot loop and knot security. Caution should be used with tying three RHAPs in arthroscopic surgery, particularly with a standard knot pusher and arthroscopic cannulas. The findings of this study indicated the importance of three RHAPs in performing arthroscopic knot tying and provided evidence regarding discrepancies of maximum clinical failure loads observed between orthopaedic surgeons, thereby leading to better surgical outcomes in the future.

The effect of an air knot on surgical knot integrity.

PubMed

Shatkin-Margolis, Abigail; Kow, Nathan; Patonai, Nicolas; Boin, Michael; Muffly, Tyler M

2015-01-01

Surgical trainees may tie air knots, which have a questionable tensile strength and rate of untying. The purpose of this study was to determine the effect of an air knot on knot integrity. The 5 suture materials tested were 0-0 gauge coated polyethylene, polyglyconate, glycolide/lactide, polypropylene, and silk. The suture was tied between 2 hex screws 50 mm on center. The strands were tied using 5 square throws, and the knot tails were cut at 3-mm length. To create a standardized air knot, a round common nail measuring 3 mm in diameter was inserted between throws before tying square throw #3. The suture loop was positioned around the upper and lower hooks of the tensiometer so the location of the knot was roughly equidistant from the hooks. Ultimately, either the loop broke or the knot slipped. At that time, the peak tensile force as well as the outcome of the knot were recorded. A total of 480 knots were tied. The presence of an air knot significantly lowered the tension at knot failure in the glycolide/lactide (P = 0.0003), polypropylene (P = 0.0005), and silk (P = 0.0001) knot configurations. Air knots had the same integrity as surgical knots when coated polyethylene and polyglyconate suture were used. Linear regression was performed and identified both suture material (P < 0.0001) and presence of an air knot (P < 0.0001) to be independently associated with a lower tension at failure. Under laboratory conditions, an air knot may contribute to a lower tensile strength at failure for certain suture materials.

The Effect on Performance Time and Quality of the Knots after Mono or Bimanual Training of Laparoscopic Intracorporeal Knot Tying according to the Gladiator Rule Technique.

PubMed

Asencio, Fernanda de Almeida; Ribeiro, Helizabet Abdala Salomão Ayroza; Romeo, Armando; Wattiez, Arnauld; Ribeiro, Paulo Augusto Galvão Ayroza

2018-05-18

 To assess whether the monomanual or bimanual training of laparoscopic suture following the same technique may interfere with the knots' performance time and/or quality.  A prospective observational study involving 41 resident students of gynecology/obstetrics and general surgery who attended a laparoscopic suture training for 2 days. The participants were divided into two groups. Group A performed the training using exclusively their dominant hand, and group B performed the training using both hands to tie the intracorporeal knot. All participants followed the same technique, called Romeo Gladiator Rule. At the end of the course, the participants were asked to perform three exercises to assess the time it took them to tie the knots, as well as the quality of the knots.  A comparative analysis of the groups showed that there was no statistically significant difference ( p  = 0.334) between them regarding the length of time to tie one knot. However, when the time to tie 10 consecutive knots was compared, group A was faster than group B ( p  = 0.020). A comparison of the knot loosening average, in millimeters, revealed that the knots made by group B loosened less than those made by group A, but there was no statistically significant difference regarding the number of knots that became untied.  This study demonstrated that the knots from group B showed better quality than those from group A, with lower loosening measures and more strength necessary to untie the knots. The study also demonstrated that group A was faster than B when the time to tie ten consecutive knots was compared. Thieme Revinter Publicações Ltda Rio de Janeiro, Brazil.

Is it time for integration of surgical skills simulation into the United Kingdom undergraduate medical curriculum? A perspective from King's College London School of Medicine.

PubMed

Hamaoui, Karim; Sadideen, Hazim; Saadeddin, Munir; Onida, Sarah; Hoey, Andrew W; Rees, John

2013-01-01

Changes in undergraduate medical curricula, combined with reforms in postgraduate education, have training implications for surgical skills acquisition in a climate of reduced clinical exposure. Confidence and prior experience influences the educational impact of learning. Currently there is no basic surgical skills (BSS) programme integrated into undergraduate curricula in the United Kingdom. We explored the role of a dedicated BSS programme for undergraduates in improving confidence and influencing careers in King's College London School of Medicine, and the programme was evaluated. A programme was designed in-line with the established Royal College of Surgeons course. Undergraduates were taught four key skills over four weeks: knot-tying, basic-suturing, tying-at-depth and chest-drain insertion, using low-fidelity bench-top models. A Likert-style questionnaire was designed to determine educational value and influence on career choice. Qualitative data was collected. Only 29% and 42% of students had undertaken previous practice in knot-tying and basic suturing, respectively. 96% agreed that skills exposure prior to starting surgical rotations was essential and felt a dedicated course would augment undergraduate training. There was a significant increase in confidence in the practice and knowledge of all skills taught (p<0.01), with a greater motivation to be actively involved in the surgical firm and theatres. A simple, structured BSS programme can increase the confidence and motivation of students. Early surgical skills targeting is valuable for students entering surgical, related allied, and even traditionally non-surgical specialties such as general practice. Such experience can increase the confidence of future junior doctors and trainees. We advocate the introduction of a BSS programme into United Kingdom undergraduate curricula.

Is it time for integration of surgical skills simulation into the United Kingdom undergraduate medical curriculum? A perspective from King’s College London School of Medicine

PubMed Central

2013-01-01

Purpose: Changes in undergraduate medical curricula, combined with reforms in postgraduate education, have training implications for surgical skills acquisition in a climate of reduced clinical exposure. Confidence and prior experience influences the educational impact of learning. Currently there is no basic surgical skills (BSS) programme integrated into undergraduate curricula in the United Kingdom. We explored the role of a dedicated BSS programme for undergraduates in improving confidence and influencing careers in King’s College London School of Medicine, and the programme was evaluated. Methods: A programme was designed in-line with the established Royal College of Surgeons course. Undergraduates were taught four key skills over four weeks: knot-tying, basic-suturing, tying-at-depth and chest-drain insertion, using low-fidelity bench-top models. A Likert-style questionnaire was designed to determine educational value and influence on career choice. Qualitative data was collected. Results: Only 29% and 42% of students had undertaken previous practice in knot-tying and basic suturing, respectively. 96% agreed that skills exposure prior to starting surgical rotations was essential and felt a dedicated course would augment undergraduate training. There was a significant increase in confidence in the practice and knowledge of all skills taught (p<0.01), with a greater motivation to be actively involved in the surgical firm and theatres. Conclusion: A simple, structured BSS programme can increase the confidence and motivation of students. Early surgical skills targeting is valuable for students entering surgical, related allied, and even traditionally non-surgical specialties such as general practice. Such experience can increase the confidence of future junior doctors and trainees. We advocate the introduction of a BSS programme into United Kingdom undergraduate curricula. PMID:24498471

Tying a molecular knot with optical tweezers

NASA Astrophysics Data System (ADS)

Arai, Yasuharu; Yasuda, Ryohei; Akashi, Ken-Ichirou; Harada, Yoshie; Miyata, Hidetake; Kinosita, Kazuhiko; Itoh, Hiroyasu

1999-06-01

Filamentous structures are abundant in cells. Relatively rigid filaments, such as microtubules and actin, serve as intracellular scaffolds that support movement and force, and their mechanical properties are crucial to their function in the cell. Some aspects of the behaviour of DNA, meanwhile, depend critically on its flexibility-for example, DNA-binding proteins can induce sharp bends in the helix. The mechanical characterization of such filaments has generally been conducted without controlling the filament shape, by the observation of thermal motions or of the response to external forces or flows. Controlled buckling of a microtubule has been reported, but the analysis of the buckled shape was complicated. Here we report the continuous control of the radius of curvature of a molecular strand by tying a knot in it, using optical tweezers to manipulate the strand's ends. We find that actin filaments break at the knot when the knot diameter falls below 0.4µm. The pulling force at breakage is around 1pN, two orders of magnitude smaller than the tensile stress of a straight filament. The flexural rigidity of the filament remained unchanged down to this diameter. We have also knotted a single DNA molecule, opening up the possibility of studying curvature-dependent interactions with associated proteins. We find that the knotted DNA is stronger than actin.

Robot-assisted laparoscopic skills development: formal versus informal training.

PubMed

Benson, Aaron D; Kramer, Brandan A; Boehler, Margaret; Schwind, Cathy J; Schwartz, Bradley F

2010-08-01

The learning curve for robotic surgery is not completely defined, and ideal training components have not yet been identified. We attempted to determine whether skill development would be accelerated with formal, organized instruction in robotic surgical techniques versus informal practice alone. Forty-three medical students naive to robotic surgery were randomized into two groups and tested on three tasks using the robotic platform. Between the testing sessions, the students were given equally timed practice sessions. The formal training group participated in an organized, formal training session with instruction from an attending robotic surgeon, whereas the informal training group participated in an equally timed unstructured practice session with the robot. The results were compared based on technical score and time to completion of each task. There was no difference between groups in prepractice testing for any task. In postpractice testing, there was no difference between groups for the ring transfer tasks. However, for the suture placement and knot-tying task, the technical score of the formal training group was significantly better than that of the informal training group (p < 0.001), yet time to completion was not different. Although formal training may not be necessary for basic skills, formal instruction for more advanced skills, such as suture placement and knot tying, is important in developing skills needed for effective robotic surgery. These findings may be important in formulating potential skills labs or training courses for robotic surgery.

Suturing training in Augmented Reality: gaining proficiency in suturing skills faster.

PubMed

Botden, S M B I; de Hingh, I H J T; Jakimowicz, J J

2009-09-01

Providing informative feedback and setting goals tends to motivate trainees to practice more extensively. Augmented Reality simulators retain the benefit of realistic haptic feedback and additionally generate objective assessment and informative feedback during the training. This study researched the performance curve of the adapted suturing module on the ProMIS Augmented Reality simulator. Eighteen novice participants were pretrained on the MIST-VR to become acquainted with laparoscopy. Subsequently, they practiced 16 knots on the suturing module, of which the assessment scores were recorded to evaluate the gain in laparoscopic suturing skills. The scoring of the assessment method was calculated from the "time spent in the correct area" during the knot tying and the quality of the knot. Both the baseline knot and the knot at the top of the performance curve were assessed by two independent objective observers, by means of a standardized evaluation form, to objectify the gain in suturing skills. There was a statistically significant difference between the scores of the second knot (mean 72.59, standard deviation (SD) 16.28) and the top of the performance curve (mean 95.82, SD 3.05; p < 0.001, paired t-test). The scoring of the objective observers also differed significantly (mean 11.83 and 22.11, respectively; SD 3.37 and 3.89, respectively; p < 0.001) (interobserver reliability Cronbach's alpha = 0.96). The median amount of repetitions to reach the top of the performance curve was eight, which also showed significant differences between both the assessment score (mean 88.14, SD 13.53, p < 0.001) and scoring of the objective observers of the second knot (mean 20.51, SD 4.14; p < 0.001). This adapted suturing module on the ProMIS Augmented Reality laparoscopic simulator is a potent tool for gaining laparoscopic suturing skills.

A cost-effective approach to establishing a surgical skills laboratory.

PubMed

Berg, David A; Milner, Richard E; Fisher, Carol A; Goldberg, Amy J; Dempsey, Daniel T; Grewal, Harsh

2007-11-01

Recent studies comparing inexpensive low-fidelity box trainers to expensive computer-based virtual reality systems demonstrate similar acquisition of surgical skills and transferability to the clinical setting. With new mandates emerging that all surgical residency programs have access to a surgical skills laboratory, we describe our cost-effective approach to teaching basic and advanced open and laparoscopic skills utilizing inexpensive bench models, box trainers, and animate models. Open models (basic skills, bowel anastomosis, vascular anastomosis, trauma skills) and laparoscopic models (basic skills, cholecystectomy, Nissen fundoplication, suturing and knot tying, advanced in vivo skills) are constructed using a combination of materials found in our surgical research laboratories, retail stores, or donated by industry. Expired surgical materials are obtained from our hospital operating room and animal organs from food-processing plants. In vivo models are performed in an approved research facility. Operation, maintenance, and administration of the surgical skills laboratory are coordinated by a salaried manager, and instruction is the responsibility of all surgical faculty from our institution. Overall, the cost analyses of our initial startup costs and operational expenditures over a 3-year period revealed a progressive decrease in yearly cost per resident (2002-2003, $1,151; 2003-2004, $1,049; and 2004-2005, $982). Our approach to surgical skills education can serve as a template for any surgery program with limited financial resources.

Tying Knots in DNA with Holographic Optical Tweezers

NASA Astrophysics Data System (ADS)

Miles, Mervyn; Foster, David; Seddon, Annela; Phillips, David; Carberry, David; Padgett, Miles; Dennis, Mark

It has been demonstrated that holographic optical tweezers can be used to tie a trefoil knot in double-stranded DNA. We have developed an advanced holographic optical tweezers system with several types of intuitive control interfaces. It has been used in a range of research projects including the characterization and assembly of structures. Here the process of tying increasingly complex knots with holographic tweezers will be described. The DNA is of the order of 50 μ m in length and is fluorescently labeled, in order that it can be visualized in the optical microscope of the tweezers system. With a knot was tied, the effect of increasing the persistence length of the DNA by partial methylation of the DNA molecule was investigated. Leverhulme Trust.

Flexor Tendon Repair With Looped Suture: 1 Versus 2 Knots.

PubMed

Gil, Joseph A; Skjong, Christian; Katarincic, Julia A; Got, Christopher

2016-03-01

To assess the strength of flexor tendon repair with looped suture. We hypothesized that, after passing the intact looped suture in the desired repair configuration, splitting the loop and tying 2 independent knots would increase the strength of flexor tendon repair. Thirty-two flexor tendons were harvested and were sharply transected in zone II. The tendons were repaired with a 4-strand core suture repair using 3-0 looped nonabsorbable nylon suture. The harvested tendons were randomly assigned and repaired with either a 1- or a 2-knot construct. The repaired flexor tendons were fixed in a servohydraulic material testing system and were loaded to failure either with uniaxial tension or cyclically. The average force at failure was 43 N for the 1-knot repair and 28 N for the 2-knot repair. The mode of failure of 15 of the flexor tendon repairs that were cyclically loaded to failure was suture pull-out. The average number of cycles and force in cyclic testing that caused failure of flexor tendon repairs was 134 cycles and 31 N for tendons repaired with looped 3-0 suture tied with 1 knot and 94 cycles and 33 N for tendons repaired with looped 3-0 suture tied with 2 knots. Our hypothesis was disproved by the results of this study. This study suggests that, when using looped suture, tying 2 independent knots instead of tying a single knot does not increase the strength of the flexor tendon repair. Copyright © 2016 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

Quiet eye training improves surgical knot tying more than traditional technical training: a randomized controlled study.

PubMed

Causer, Joe; Harvey, Adrian; Snelgrove, Ryan; Arsenault, Gina; Vickers, Joan N

2014-08-01

We examined the effectiveness of technical training (TT) and quiet eye training (QE) on the performance of one-handed square knot tying in surgical residents. Twenty surgical residents were randomly assigned to the 2 groups and completed pretest, training, retention, and transfer tests. Participants wore a mobile eye tracker that simultaneously recorded their gaze and hand movements. Dependent variables were knot tying performance (%), QE duration (%), number of fixations, total movement time (s), and hand movement phase time (s). The QE training group had significantly higher performance scores, a longer QE duration, fewer fixations, faster total knot tying times, and faster movement phase times compared with the TT group. The QE group maintained performance in the transfer test, whereas the TT group significantly decreased performance from retention to transfer. QE training significantly improved learning, retention, and transfer of surgical knot tying compared with a traditional technical approach. Both performance effectiveness (performance outcome) and movement efficiency (hand movement times) were improved using QE modeling, instruction, and feedback. Copyright © 2014 Elsevier Inc. All rights reserved.

Faster acquisition of laparoscopic skills in virtual reality with haptic feedback and 3D vision.

PubMed

Hagelsteen, Kristine; Langegård, Anders; Lantz, Adam; Ekelund, Mikael; Anderberg, Magnus; Bergenfelz, Anders

2017-10-01

The study investigated whether 3D vision and haptic feedback in combination in a virtual reality environment leads to more efficient learning of laparoscopic skills in novices. Twenty novices were allocated to two groups. All completed a training course in the LapSim ® virtual reality trainer consisting of four tasks: 'instrument navigation', 'grasping', 'fine dissection' and 'suturing'. The study group performed with haptic feedback and 3D vision and the control group without. Before and after the LapSim ® course, the participants' metrics were recorded when tying a laparoscopic knot in the 2D video box trainer Simball ® Box. The study group completed the training course in 146 (100-291) minutes compared to 215 (175-489) minutes in the control group (p = .002). The number of attempts to reach proficiency was significantly lower. The study group had significantly faster learning of skills in three out of four individual tasks; instrument navigation, grasping and suturing. Using the Simball ® Box, no difference in laparoscopic knot tying after the LapSim ® course was noted when comparing the groups. Laparoscopic training in virtual reality with 3D vision and haptic feedback made training more time efficient and did not negatively affect later video box-performance in 2D. [Formula: see text].

ProMIS augmented reality training of laparoscopic procedures face validity.

PubMed

Botden, Sanne M B I; Buzink, Sonja N; Schijven, Marlies P; Jakimowicz, Jack J

2008-01-01

Conventional video trainers lack the ability to assess the trainee objectively, but offer modalities that are often missing in virtual reality simulation, such as realistic haptic feedback. The ProMIS augmented reality laparoscopic simulator retains the benefit of a traditional box trainer, by using original laparoscopic instruments and tactile tasks, but additionally generates objective measures of performance. Fifty-five participants performed a "basic skills" and "suturing and knot-tying" task on ProMIS, after which they filled out a questionnaire regarding realism, haptics, and didactic value of the simulator, on a 5-point-Likert scale. The participants were allotted to 2 experience groups: "experienced" (>50 procedures and >5 sutures; N = 27), and "moderately experienced" (<50 procedures and <5 sutures; N = 28). General consensus among all participants, particularly the experienced, was that ProMIS is a useful tool for training (mean: 4.67, SD: 0.48). It was considered very realistic (mean: 4.44, SD: 0.66), with good haptics (mean: 4.10, SD: 0.97) and didactic value (mean 4.10, SD: 0.65). This study established the face validity of the ProMIS augmented reality simulator for "basic skills" and "suturing and knot-tying" tasks. ProMIS was considered a good tool for training in laparoscopic skills for surgical residents and surgeons.

Measuring cognitive load: performance, mental effort and simulation task complexity.

PubMed

Haji, Faizal A; Rojas, David; Childs, Ruth; de Ribaupierre, Sandrine; Dubrowski, Adam

2015-08-01

Interest in applying cognitive load theory in health care simulation is growing. This line of inquiry requires measures that are sensitive to changes in cognitive load arising from different instructional designs. Recently, mental effort ratings and secondary task performance have shown promise as measures of cognitive load in health care simulation. We investigate the sensitivity of these measures to predicted differences in intrinsic load arising from variations in task complexity and learner expertise during simulation-based surgical skills training. We randomly assigned 28 novice medical students to simulation training on a simple or complex surgical knot-tying task. Participants completed 13 practice trials, interspersed with computer-based video instruction. On trials 1, 5, 9 and 13, knot-tying performance was assessed using time and movement efficiency measures, and cognitive load was assessed using subjective rating of mental effort (SRME) and simple reaction time (SRT) on a vibrotactile stimulus-monitoring secondary task. Significant improvements in knot-tying performance (F(1.04,24.95)  = 41.1, p < 0.001 for movements; F(1.04,25.90)  = 49.9, p < 0.001 for time) and reduced cognitive load (F(2.3,58.5)  = 57.7, p < 0.001 for SRME; F(1.8,47.3)  = 10.5, p < 0.001 for SRT) were observed in both groups during training. The simple-task group demonstrated superior knot tying (F(1,24)  = 5.2, p = 0.031 for movements; F(1,24)  = 6.5, p = 0.017 for time) and a faster decline in SRME over the first five trials (F(1,26)  = 6.45, p = 0.017) compared with their peers. Although SRT followed a similar pattern, group differences were not statistically significant. Both secondary task performance and mental effort ratings are sensitive to changes in intrinsic load among novices engaged in simulation-based learning. These measures can be used to track cognitive load during skills training. Mental effort ratings are also sensitive to small differences in intrinsic load arising from variations in the physical complexity of a simulation task. The complementary nature of these subjective and objective measures suggests their combined use is advantageous in simulation instructional design research. © 2015 John Wiley & Sons Ltd.

Comparison of volume, security, and biomechanical strength of square and Aberdeen termination knots tied with 4-0 polyglyconate and used for termination of intradermal closures in canine cadavers.

PubMed

Regier, Penny J; Smeak, Daniel D; Coleman, Kristin; McGilvray, Kirk C

2015-08-01

To compare volumes of square knots and Aberdeen knots in vitro and evaluate security of these knot types when used as buried terminal knots for continuous intradermal wound closures in canine cadavers. Experimental study. 24 surgically closed, full-thickness, 4-cm, epidermal wounds in 4 canine cadavers and 80 knots tied in vitro. Continuous intradermal closures were performed with 4-0 polyglyconate and completed with a buried knot technique. Surgeon (intern or experienced surgeon) and termination knot type (4-throw square knot or 2 + 1 Aberdeen knot; 12 each) were randomly assigned. Closed wounds were excised, and a servohydraulic machine applied tensile load perpendicular to the long axis of the suture line. A load-displacement curve was generated for each sample; maximum load, displacement, stiffness, and mode of construct failure were recorded. Volumes of 2 + 1 Aberdeen (n = 40) and 4-throw square knots (40) tied on a suture board were measured on the basis of a cylindrical model. Aberdeen knots had a mean smaller volume (0.00045 mm(3)) than did square knots (0.003838 mm(3)). Maximum load and displacement did not differ between construct types. Mean stiffness of Aberdeen knot constructs was greater than that of square knots. The 2 + 1 Aberdeen knot had a smaller volume than the 4-throw square knot and was as secure. Although both knots may be reliably used in a clinical setting as the termination knot at the end of a continuous intradermal line, the authors advocate use of the Aberdeen terminal knot on the basis of ease of burying the smaller knot.

The examination assessment of technical competence in vascular surgery.

PubMed

Pandey, V A; Wolfe, J H N; Liapis, C D; Bergqvist, D

2006-09-01

The European Board of Surgery Qualification in Vascular Surgery is a pan-European examination for vascular surgeons who have attained a national certificate of completion of specialist training. A 2-year study was conducted before the introduction of a technical skills assessment in the examination. The study included 30 surgeons: 22 candidates and eight examiners. They were tested on dissection (on a synthetic saphenofemoral junction model), anastomosis (on to anterior tibial artery of a synthetic leg model) and dexterity (a knot-tying simulator with electromagnetic motion analysis). Validated rating scales were used by two independent examiners. Composite knot-tying scores were calculated for the computerized station. The stations were weighted 35, 45 and 20 percent, respectively. Examiners performed better than candidates in the dissection (P<0.001), anastomosis (P=0.002) and dexterity (P=0.005) stations. Participants performed consistently in the examination (dissection versus anastomosis: r=0.79, P<0.001; dexterity versus total operative score: r=-0.73, P<0.001). Interobserver reliability was high (alpha=0.91). No correlation was seen between a candidate's technical skill and oral examination performance or logbook-accredited scores. Current surgical examinations do not address technical competence. This model appears to be a valid assessment of technical skills in an examination setting. The standards are set at a level appropriate for a specialist vascular surgeon. Copyright (c) 2006 British Journal of Surgery Society Ltd.

[Assessment of surgical competence. A Mexican pilot study].

PubMed

Anaya-Prado, Roberto; Ortega-León, Luis Humberto; Ramirez-Solis, Mauro Eduardo; Vázquez-García, José Arturo; Medina-Portillo, Juan Bernardo; Ayala-López, Ernesto Alonso

2012-01-01

Assessment of technical dexterity is currently the weakest issue in surgical evaluation. It is imperative to develop an objective exam that allows us to correct training deficiencies and abilities and to objectively feedback education programs and hospitals. The purpose of this study was to perform a correlation between theoretical knowledge and surgical skills. We performed a national pilot study in in surgeons certifying by the Mexican Board of Surgery in 2010. This was a two-stage study: written exam (stage I) and oral exam (viva voce) to all surgeons approving the written exam (stage II). In stage II we utilized an objective structured assessment of technical skills (OSATS) whose results were correlated with those of the written and oral exams. The assessment involved seven skill stations and a global rating scale to indicate correctly performed or not and a fail/pass exam, respectively. Sixty-two surgeons approved the written exam in two places. We found no statistical difference among skills in open surgery (bowel anastomosis, liver and vascular suture), laparoscopic surgery (grape pilling, cutting a circle and intracorporeal knot tying) and instrument identification. There was a statistically significant difference (p <0.001) when median values were compared between laparoscopic surgery vs. open surgery and the identification of surgical instruments. There was a correlation between theoretical knowledge and surgical skills. When applying an OSATS, we found a positive correlation between theoretical knowledge and surgical skills. This assessment proves to to be valid and reliable for the evaluation of surgical dexterity.

Tensile strength of surgical knots in abdominal wound closure.

PubMed

Fong, Eva D M; Bartlett, Adam S R; Malak, Sharif; Anderson, Iain A

2008-03-01

Abdominal wound dehiscence is a surgical catastrophe that can be attributed to patients or technical factors. The technical properties of the monofilament sutures and knots that are commonly used in abdominal closure are poorly understood. The aim of this study was to compare the tensile strength of monofilament sutures tied with conventional knots. To do this, the knot-holding capacity of four types of knots (square, surgeons', Aberdeen and loop) were tested using three types of gauge 1 monofilament suture, namely nylon, polyglyconate and polydioxanone, using a tensiometer. We found that the knot-holding capacity of the loop knot was between twofold and threefold greater than all the other knots examined. In comparing suture types, polyglyconate had the highest knot-holding capacity for all the knots that were examined and there was no difference in the tensile strength of nylon and polyglyconate tied in a square, surgeons' or Aberdeen knot (P < 0.05). In conclusion, our findings suggest that closure of an abdominal wound would be best commenced with a loop knot, using gauge 1 polyglyconate and finished with either an Aberdeen square or surgeons' knot would be appropriate.

The role of mental rotation and memory scanning on the performance of laparoscopic skills: a study on the effect of camera rotational angle.

PubMed

Conrad, J; Shah, A H; Divino, C M; Schluender, S; Gurland, B; Shlasko, E; Szold, A

2006-03-01

The rotational angle of the laparoscopic image relative to the true horizon has an unknown influence on performance in laparoscopic procedures. This study evaluates the effect of increasing rotational angle on surgical performance. Surgical residents (group 1) (n = 6) and attending surgeons (group 2) (n = 4) were tested on two laparoscopic skills. The tasks consisted of passing a suture through an aperture, and laparoscopic knot tying. These tasks were assessed at 15 degrees intervals between 0 degrees and 90 degrees , on three consecutive repetitions. The participant's performance was evaluated based on the time required to complete the tasks and number of errors incurred. There was an increasing deterioration in suturing performance as the degree of image rotation was increased. Participants showed a statistically significant 20-120% progressive increase in time to completion of the tasks (p = 0.004), with error rates increasing from 10% to 30% (p = 0.04) as the angle increased from 0 degrees to 90 degrees. Knot-tying performance similarly showed a decrease in performance that was evident in the less experienced surgeons (p = 0.02) but with no obvious effect on the advanced laparoscopic surgeons. When evaluated independently and as a group, both novice and experienced laparoscopic surgeons showed significant prolongation to completion of suturing tasks with increased errors as the rotational angle increased. The knot-tying task shows that experienced surgeons may be able to overcome rotational effects to some extent. This is consistent with results from cognitive neuroscience research evaluating the processing of directional information in spatial motor tasks. It appears that these tasks utilize the time-consuming processes of mental rotation and memory scanning. Optimal performance during laparoscopic procedures requires that the rotation of the camera, and thus the image, be kept to a minimum to maintain a stable horizon. New technology that corrects the rotational angle may benefit the surgeon, decrease operating time, and help to prevent adverse outcomes.

Perceptions of the roles of social networking in simulation augmented medical education and training.

PubMed

Martin, Rob; Rojas, David; Cheung, Jeffrey J H; Weber, Bryce; Kapralos, Bill; Dubrowski, Adam

2013-01-01

Simulation-augmented education and training (SAET) is an expensive educational tool that may be facilitated through social networking technologies or Computer Supported Collaborative Learning (CSCL). This study examined the perceptions of medical undergraduates participating in SAET for knot tying skills to identify perceptions and barriers to implementation of social networking technologies within a broader medical education curriculum. The majority of participants (89%) found CSCL aided their learning of the technical skill and identified privacy and accessibility as major barriers to the tools implementation.

Outcomes of a proficiency-based skills curriculum at the beginning of the fourth year for senior medical students entering surgery.

PubMed

Wade, Thomas J; Lorbeer, Karly; Awad, Michael M; Woodhouse, Julie; DeClue, Angela; Brunt, L Michael

2015-10-01

We hypothesized that a proficiency-based curriculum administered early in the fourth year to senior medical students (MS4) would achieve outcomes comparable to a similar program administered during surgical internship. MS4 (n = 18) entering any surgical specialty enrolled in a proficiency-based skills curriculum at the beginning of the fourth year that included suturing/knot-tying, on-call problems, laparoscopic, and other skills (urinary catheter, sterile prep/drape, IV placement, informed consent, electrosurgical use). Assessment was at 4-12 weeks after training by a modified Objective Structured Assessment of Technical Skills (OSATS). Suturing and knot tying tasks were assessed by time and OSATS technical proficiency (TP) scores (1 [novice], 3 [proficient], 5 [expert]). Outcomes were compared with PGY-1 residents who received similar training at the beginning of internship and assessment 4-12 weeks later. Data are presented as mean values ± standard deviation; statistical significance was assessed by Student's t test. Fifteen of 18 MS4 (83%) reached proficiency on all 15 tasks, and 2 others were proficient on all but 1 laparoscopic task. Compared with PGY-1s, MS4 were significantly faster for 3 of 5 suturing and tying tasks and total task time (547 ± 63 vs 637 ± 127 s; P < .05). Mean TP scores were similar for both groups (MS4, 3.4 ± 0.5 vs PGY-1, 3.1 ± .57; P = NS). MS4 OSATS scores were higher for IV placement, informed consent, and urinary catheter placement, but lower for prep and drape and for management of on-call problems. MS4 who participate in a proficiency-based curriculum taught early in the fourth year are able to meet proficiency targets in a high percentage of cases. This approach should better prepare MS4 for surgical internship. Copyright © 2015 Elsevier Inc. All rights reserved.

Prosthetic Aortic Valve Fixation Study: 48 Replacement Valves Analyzed Using Digital Pressure Mapping.

PubMed

Lee, Candice Y; Wong, Joshua K; Ross, Ronald E; Liu, David C; Khabbaz, Kamal R; Martellaro, Angelo J; Gorea, Heather R; Sauer, Jude S; Knight, Peter A

Prostheses attachment is critical in aortic valve replacement surgery, yet reliable prosthetic security remains a challenge. Accurate techniques to analyze prosthetic fixation pressures may enable the use of fewer sutures while reducing the risk of paravalvular leaks (PVL). Customized digital thin film pressure transducers were sutured between aortic annulus models and 21-mm bioprosthetic valves with 15 × 4-mm, 12 × 4-mm, or 9 × 6-mm-wide pledgeted mattress sutures. Simulating open and minimally invasive access, 4 surgeons, blinded to data acquisition, each secured 12 valves using manual knot-tying (hand-tied [HT] or knot-pusher [KP]) or automated titanium fasteners (TFs). Real-time pressure measurements and times were recorded. Two-dimensional (2D) and 3D pressure maps were generated for all valves. Pressures less than 80 mm Hg were considered at risk for PVL. Pressures under each knot (intrasuture) fell less than 80 mm Hg for 12 of 144 manual knots (5/144 HT, 7/144 KP) versus 0 of 288 TF (P < 0.001). Pressures outside adjacent sutures (extrasuture) were less than 80 mm Hg in 10 of 60 HT, zero of 60 KP, and zero of 120 TF sites for 15 × 4-mm valves; 17 of 48 HT, 25 of 48 KP, and 12 of 96 TF for 12 × 4-mm valves; and 15 of 36 HT, 17 of 36 KP, and 9 and 72 TF for 9 × 6-mm valves; P < 0.001 all manual versus TF. Annular areas with pressures less than 80 mm Hg ranged from 0% of the sewing-ring area (all open TF) to 31% (12 × 4 mm, KP). The average time per manual knot, 46 seconds (HT, 31 seconds; KP, 61 seconds), was greater than TF, 14 seconds (P < 0.005). Reduced operative times and PVL risk would fortify the advantages of surgical aortic valve replacement. This research encourages continued exploration of technical factors in optimizing prosthetic valve security.

The Effectiveness of a Simulation-Based Flipped Classroom in the Acquisition of Laparoscopic Suturing Skills in Medical Students-A Pilot Study.

PubMed

Chiu, Hsin-Yi; Kang, Yi-No; Wang, Wei-Lin; Huang, Hung-Chang; Wu, Chien-Chih; Hsu, Wayne; Tong, Yiu-Shun; Wei, Po-Li

To evaluate the effectiveness of a simulation-based flipped classroom in gaining the laparoscopic skills in medical students. An intervention trial. Taipei Medical University Hospital, an academic teaching hospital. Fifty-nine medical students participating in a 1-hour laparoscopic skill training session were randomly assigned to a conventional classroom (n = 29) or a flipped classroom approach (n = 30) based on their registered order. At the end of the session, instructors assessed participants' performance in laparoscopic suturing and intracorporeal knot-tying using the assessment checklist based on a modified Objective Structured Assessment of Technical Skills tool. Students in the flipped group completed more numbers of stitches (mean [M] = 0.47; standard deviation [SD] = 0.507) than those in the conventional group (M = 0.10; SD = 0.310) (mean difference: 0.37; 95% CI: 0.114-582; p = 0.002). Moreover, students in the flipped group also had higher stitch quality scores (M = 7.17; SD = 2.730) than those in the conventional group (M = 5.14; SD = 1.767) (mean difference = 2.03; 95% CI: 0.83-3.228; p = 0.001). Meanwhile, students in the flipped group had higher pass rates for the second throw (p < 0.001), third throw (p = 0.002), appropriate tissue reapproximation without loosening or strangulation (p < 0.001), needle cut from suture under direct visualization (p = 0.004), and needle safely removed under direct visualization (p = 0.018) than those in the conventional group. Comparing with traditional approach, a simulation-based flipped classroom approach may improve laparoscopic intracorporeal knot-tying skill acquisition in medical students. Copyright © 2017 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

Statics and dynamics of DNA knotting

NASA Astrophysics Data System (ADS)

Orlandini, Enzo

2018-02-01

Knots and entanglement in polymers and biopolymers such as DNA and proteins constitute a timely topic that spans various scientific disciplines ranging from physics to chemistry, biology and mathematics. Although in the past many advancements have been made in understanding the equilibrium knotting probability and knot complexity of long polymer chains in solutions, many questions have been addressed in recent years by both experimental and theoretical means—for instance, how the knotting probability depends on the quality of the solvent, the elastic properties of the molecule and its degree of confinement. How knots form, evolve and eventually disappear in a fluctuating chain. Are the equilibrium and non-equilibrium properties of knotted molecules affected by the knot swelling/shrinking dynamics? Moreover, thanks to the great advance in nanotechnology and micromanipulation techniques, nowadays knots can be ‘manually’ tied in a single DNA molecule, followed during their motion along the chains, forced to pass through nanopores, or stretched by external forces or elongational flows. All these experimental approaches allow access to new information on the interplay of topology and polymer physics, and this has opened new perspectives in the field. Here, we provide an overview of the current knowledge of this topic, stressing the main results obtained, including the recent developments in experimental and computational approaches. Since almost all experiments on knotting involve DNA, the review will be mainly focused on the topological properties of this fascinating and biologically relevant molecule.

Analysis of the Structure of Surgical Activity for a Suturing and Knot-Tying Task

PubMed Central

Vedula, S. Swaroop; Malpani, Anand O.; Tao, Lingling; Chen, George; Gao, Yixin; Poddar, Piyush; Ahmidi, Narges; Paxton, Christopher; Vidal, Rene; Khudanpur, Sanjeev; Hager, Gregory D.; Chen, Chi Chiung Grace

2016-01-01

Background Surgical tasks are performed in a sequence of steps, and technical skill evaluation includes assessing task flow efficiency. Our objective was to describe differences in task flow for expert and novice surgeons for a basic surgical task. Methods We used a hierarchical semantic vocabulary to decompose and annotate maneuvers and gestures for 135 instances of a surgeon’s knot performed by 18 surgeons. We compared counts of maneuvers and gestures, and analyzed task flow by skill level. Results Experts used fewer gestures to perform the task (26.29; 95% CI = 25.21 to 27.38 for experts vs. 31.30; 95% CI = 29.05 to 33.55 for novices) and made fewer errors in gestures than novices (1.00; 95% CI = 0.61 to 1.39 vs. 2.84; 95% CI = 2.3 to 3.37). Transitions among maneuvers, and among gestures within each maneuver for expert trials were more predictable than novice trials. Conclusions Activity segments and state flow transitions within a basic surgical task differ by surgical skill level, and can be used to provide targeted feedback to surgical trainees. PMID:26950551

In vitro and in situ characterization of arthroscopic loop security and knot security of braided polyblend sutures: a biomechanical study.

PubMed

Armstrong, Lucas C; Chong, Alexander; Livermore, Ryan W; Prohaska, Daniel J; Doyon, Amanda N; Wooley, Paul H

2015-04-01

We conducted a study to evaluate biomechanical performance during destructive testing of several different suture materials in various arthroscopic knot configurations under both in vitro and in situ conditions. Surgeons of different levels of experience tied the knots. Three different arthroscopic knots (static surgeon's, Weston, Tennessee slider) with 3 reverse half-hitches on alternating posts were tested using Fiberwire, ForceFiber, Orthocord, and Ultrabraid suture materials under both in vitro and in situ (blood plasma at 37°C) conditions. Three surgeons of different experience levels tied the knots on a post 30 mm in circumference. A single load-to-failure test was performed. There were no significant in vitro-in situ differences for Ultrabraid in the different knot configurations or with the different experience levels. Surgeon B (intermediate experience) showed no significant differences between test conditions for any knot configuration or suture material. With Tennessee slider knots, surgeon C (least experience) showed significantly lower clinical failure load under both test conditions and had a higher percentage of complete knot slippage. Surgeon B had no knot slippage with use of Fiberwire. Both the aqueous environment and the surgeon's familiarity with certain knots have an effect on knot security.

In vitro evaluation of square and surgeon's knots in large gauge suture.

PubMed

Gillen, Alex M; Munsterman, Amelia S; Farag, Ramsis; Coleridge, Matthew O D; Hanson, R Reid

2017-02-01

To investigate the strength and size of surgeon's and square knots for starting and ending continuous suture lines using large gauge suture. In vitro mechanical study. Knotted suture. Surgeon's and square knots were tested using 2 and 3 USP polyglactin 910 and 2 USP polydioxanone under linear tension on a universal testing machine. Failure mode and knot holding capacity (KHC) were recorded, and relative knot security (RKS) was calculated as a percentage of KHC. Comparisons were made between number of throws, suture size, suture type, and knot types. Knot volume and weight were assessed by a digital micrometer and balance, respectively. There were no significant differences in KHC (P = .295), RKS (P = .307), volume (P = .128), or weight (P = .310) between square and surgeon's knots at the start or end of suture lines with the same number of throws and suture type. A minimum of 6 throws were required for start knots and 7 throws at end knots to prevent unraveling. Knots tied with 3 polyglactin 910 were strongest (P < .001) and 2 polyglactin 910 produced knots with higher KHC and RKS than 2 polydioxanone (P < .001). No consistent differences were detected between knots types tied with the same suture material; however, number of throws affected KHC and RKS up to 6 throws in start or 7 throws in end knots. The configuration of square and surgeon's knots performed at the end of a continuous line alters their KHC, supporting the use of additional throws for knot security. © 2017 The American College of Veterinary Surgeons.

Effects of Visual Force Feedback on Robot-Assisted Surgical Task Performance

PubMed Central

Reiley, Carol E.; Akinbiyi, Takintope; Burschka, Darius; Chang, David C.; Okamura, Allison M.; Yuh, David D.

2009-01-01

Background Direct haptic (force or tactile) feedback is negligible in current surgical robotic systems. The relevance of haptic feedback in robot-assisted performances of surgical tasks is controversial. We studied the effects of visual force feedback (VFF), a haptic feedback surrogate, on tying surgical knots with fine sutures similar to those used in cardiovascular surgery. Methods Using a modified da Vinci robotic system (Intuitive Surgical, Inc.) equipped with force-sensing instrument tips and real-time VFF overlays in the console image, ten surgeons each tied 10 knots with and 10 knots without VFF. Four surgeons had significant prior da Vinci experience while the remaining six surgeons did not. Performance parameters, including suture breakage and secure knots, peak and standard deviation of applied forces, and completion times using 5-0 silk sutures were recorded. Chi-square and Student’s t-test analyses determined differences between groups. Results Among surgeon subjects with robotic experience, no differences in measured performance parameters were found between robot-assisted knot ties executed with and without VFF. Among surgeons without robotic experience, however, VFF was associated with lower suture breakage rates, peak applied forces, and standard deviations of applied forces. VFF did not impart differences in knot completion times or loose knots for either surgeon group. Conclusions VFF resulted in reduced suture breakage, lower forces, and decreased force inconsistencies among novice robotic surgeons, although elapsed time and knot quality were unaffected. In contrast, VFF did not affect these metrics among experienced da Vinci surgeons. These results suggest that VFF primarily benefits novice robot-assisted surgeons, with diminishing benefits among experienced surgeons. PMID:18179942

The chula knot: a new sliding locking knot with a special property.

PubMed

Kuptniratsaikul, Somsak; Promsang, Trai; Kongrukgreatiyos, Kitiphong

2014-08-01

There are many types of sliding locking knots used in arthroscopic surgery. Each type has its advantages and disadvantages. This technical note describes a new sliding locking knot, the Chula knot. This knot has been used for arthroscopic shoulder surgery in more than 500 cases at our hospital. The Chula knot has a special property in that it can be unfastened and retightened in case of premature locking and unintended loop loosening. This retensioning ability cannot be found in other configurations of arthroscopic knots. The Chula knot also has other benefits: It has high ultimate tensile strength and is easy to tie.

Comparing the tensile strength of square and reversing half-hitch alternating post knots

PubMed Central

Wu, Vincent; Sykes, Edward A.; Mercer, Dale; Hopman, Wilma M.; Tang, Ephraim

2017-01-01

Background Square knots are the gold standard in hand-tie wound closure, but are difficult to reproduce in deep cavities, inadvertently resulting in slipknots. The reversing half-hitch alternating post (RHAP) knot has been suggested as an alternative owing to its nonslip nature and reproducibility in limited spaces. We explored whether the RHAP knot is noninferior to the square knot by assessing tensile strength. Methods We conducted 10 trials for each baseline and knot configuration, using 3–0 silk and 3–0 polyglactin 910 sutures. We compared tensile strength between knot configurations at the point of knot failure between slippage and breakage. Results Maximal failure strength (mean ± SD) in square knots was reached with 4-throw in both silk (30 ± 1.5 N) and polyglactin 910 (39 ± 12 N). For RHAP knots, maximal failure strength was reached at 5-throw for both silk (31 ± 1.5 N) and polyglactin 910 (41 ± 13 N). In both sutures, there were no strength differences between 3-throw square and 4-throw RHAP, between 4-throw square and 5-throw RHAP, or between 5-throw square and 6-throw RHAP knots. Polyglactin 910 sutures, in all knot configurations, were more prone to slippage than silk sutures (p < 0.001). Conclusion The difference in mean tensile strength could be attributed to the proportion of knot slippage versus breakage, which is material-dependent. Future studies can re-evaluate findings in monofilament sutures and objectively assess the reproducibility of square and RHAP knots in deep cavities. Our results indicate that RHAP knots composed of 1 extra throw provide equivalent strength to square knots and may be an alternative when performing hand-ties in limited cavities with either silk or polyglactin 910 sutures. PMID:28327276

Comparing the tensile strength of square and reversing half-hitch alternating post knots.

PubMed

Wu, Vincent; Sykes, Edward A; Mercer, Dale; Hopman, Wilma M; Tang, Ephraim

2017-06-01

Square knots are the gold standard in hand-tie wound closure, but are difficult to reproduce in deep cavities, inadvertently resulting in slipknots. The reversing half-hitch alternating post (RHAP) knot has been suggested as an alternative owing to its nonslip nature and reproducibility in limited spaces. We explored whether the RHAP knot is noninferior to the square knot by assessing tensile strength. We conducted 10 trials for each baseline and knot configuration, using 3-0 silk and 3-0 polyglactin 910 sutures. We compared tensile strength between knot configurations at the point of knot failure between slippage and breakage. Maximal failure strength (mean ± SD) in square knots was reached with 4-throw in both silk (30 ± 1.5 N) and polyglactin 910 (39 ± 12 N). For RHAP knots, maximal failure strength was reached at 5-throw for both silk (31 ± 1.5 N) and polyglactin 910 (41 ± 13 N). In both sutures, there were no strength differences between 3-throw square and 4-throw RHAP, between 4-throw square and 5-throw RHAP, or between 5-throw square and 6-throw RHAP knots. Polyglactin 910 sutures, in all knot configurations, were more prone to slippage than silk sutures ( p < 0.001). The difference in mean tensile strength could be attributed to the proportion of knot slippage versus breakage, which is material-dependent. Future studies can re-evaluate findings in monofilament sutures and objectively assess the reproducibility of square and RHAP knots in deep cavities. Our results indicate that RHAP knots composed of 1 extra throw provide equivalent strength to square knots and may be an alternative when performing hand-ties in limited cavities with either silk or polyglactin 910 sutures.

Backwards Fading to Speed Task Learning

DTIC Science & Technology

2013-09-01

estimates.) Table 1 Finalized Task List Task Domain Task Name Knot Tying Hand Cuff Rappel First Aid Fracture Bleed Map Reading* Resection...materials used. Hand Cuff . There are 10 steps in this task. To complete this task, the learner must manipulate a short length of rope (e.g...Design for Experiment 1 – Step Fade Experiment 1 (Step Fade) Task Type: Knot Tying Task Type: First Aid Task Complexity: Low (1) Hand Cuff (10

A decade of imaging surgeons' brain function (part II): A systematic review of applications for technical and nontechnical skills assessment.

PubMed

Modi, Hemel Narendra; Singh, Harsimrat; Yang, Guang-Zhong; Darzi, Ara; Leff, Daniel Richard

2017-11-01

Functional neuroimaging technologies enable assessment of operator brain function and can deepen our understanding of skills learning, ergonomic optima, and cognitive processes in surgeons. Although there has been a critical mass of data detailing surgeons' brain function, this literature has not been reviewed systematically. A systematic search of original neuroimaging studies assessing surgeons' brain function and published up until November 2016 was conducted using Medline, Embase, and PsycINFO databases. Twenty-seven studies fulfilled the inclusion criteria, including 3 feasibility studies, 14 studies exploring the neural correlates of technical skill acquisition, and the remainder investigating brain function in the context of intraoperative decision-making (n = 1), neurofeedback training (n = 1), robot-assisted technology (n = 5), and surgical teaching (n = 3). Early stages of learning open surgical tasks (knot-tying) are characterized by prefrontal cortical activation, which subsequently attenuates with deliberate practice. However, with complex laparoscopic skills (intracorporeal suturing), prefrontal cortical engagement requires substantial training, and attenuation occurs over a longer time course, after years of refinement. Neurofeedback and interventions that improve neural efficiency may enhance technical performance and skills learning. Imaging surgeons' brain function has identified neural signatures of expertise that might help inform objective assessment and selection processes. Interventions that improve neural efficiency may target skill-specific brain regions and augment surgical performance. Copyright © 2017 Elsevier Inc. All rights reserved.

Evaluation of a novel technique for wound closure using a barbed suture.

PubMed

Murtha, Amy P; Kaplan, Andrew L; Paglia, Michael J; Mills, Benjie B; Feldstein, Michael L; Ruff, Gregory L

2006-05-01

Suture knots present several disadvantages in wound closure, because they are tedious to tie and place ischemic demands on tissue. Bulky knots may be a nidus for infection, and they may extrude through skin weeks after surgery. Needle manipulations during knot-tying predispose the surgeon to glove perforation. A barbed suture was developed that is self-anchoring, requiring no knots or slack management for wound closure. The elimination of knot tying may have advantages over conventional wound closure methods. This prospective, randomized, controlled trial was designed to show that the use of barbed suture in dermal closure of the Pfannenstiel incision during nonemergent cesarean delivery surgery produces scar cosmesis at 5 weeks that is no worse than that observed with conventional closure using 3-0 polydioxanone suture. Cosmesis was assessed by review of postoperative photographs by a blinded, independent plastic surgeon using the modified Hollander cosmesis score. Secondary endpoints included infection, dehiscence, pain, closure time, and other adverse events. The study enrolled 195 patients, of whom 188 were eligible for analysis. Cosmesis scores did not significantly differ between the barbed suture group and the control group. Rates of infection, dehiscence, and other adverse events did not significantly differ between the two groups. Closure time and pain scores were comparable between the groups. The barbed suture represents an innovative option for wound closure. With a cosmesis and safety profile that is similar to that of conventional suture technique, it avoids the drawbacks inherent to suture knots.

Knotless double-row SutureBridge rotator cuff repairs have improved self-reinforcement compared with double-row SutureBridge repairs with tied medial knots: a biomechanical study using an ovine model.

PubMed

Smith, Geoffrey C S; Bouwmeester, Theresia M; Lam, Patrick H

2017-12-01

In double-row SutureBridge (Arthrex, Naples, FL, USA) rotator cuff repairs, increasing tendon load may generate progressively greater compression forces at the repair footprint (self-reinforcement). SutureBridge rotator cuff repairs using tied horizontal mattress sutures medially may limit this effect compared with a knotless construct. Rotator cuff repairs were performed in 9 pairs of ovine shoulders. One group underwent repair with a double-row SutureBridge construct with tied horizontal medial-row mattress sutures. The other group underwent repair in an identical fashion except that medial-row knots were not tied. Footprint contact pressure was measured at 0° and 20° of abduction under loads of 0 to 60 N. Pull-to-failure tests were then performed. In both repair constructs, each 10-N increase in rotator cuff tensile load led to a significant increase in footprint contact pressure (P < .0001). The rate of increase in footprint contact pressure was greater in the knotless construct (P < .00022; ratio, 1.69). The yield point approached the ultimate load to failure more closely in the knotless model than in the knotted construct (P = .00094). There was no difference in stiffness, ultimate failure load, or total energy to failure between the knotless and knotted techniques. In rotator cuff repair with a double-row SutureBridge configuration, self-reinforcement is seen in repairs with and without medial-row knots. Self-reinforcement is greater with the knotless technique. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Crowd-sourced assessment of technical skills: an opportunity for improvement in the assessment of laparoscopic surgical skills.

PubMed

Deal, Shanley B; Lendvay, Thomas S; Haque, Mohamad I; Brand, Timothy; Comstock, Bryan; Warren, Justin; Alseidi, Adnan

2016-02-01

Objective, unbiased assessment of surgical skills remains a challenge in surgical education. We sought to evaluate the feasibility and reliability of Crowd-Sourced Assessment of Technical Skills. Seven volunteer general surgery interns were given time for training and then testing, on laparoscopic peg transfer, precision cutting, and intracorporeal knot-tying. Six faculty experts (FEs) and 203 Amazon.com Mechanical Turk crowd workers (CWs) evaluated 21 deidentified video clips using the Global Objective Assessment of Laparoscopic Skills validated rating instrument. Within 19 hours and 15 minutes we received 662 eligible ratings from 203 CWs and 126 ratings from 6 FEs over 10 days. FE video ratings were of borderline internal consistency (Krippendorff's alpha = .55). FE ratings were highly correlated with CW ratings (Pearson's correlation coefficient = .78, P < .001). We propose the use of Crowd-Sourced Assessment of Technical Skills as a reliable, basic tool to standardize the evaluation of technical skills in general surgery. Copyright © 2016 Elsevier Inc. All rights reserved.

Value of fundamentals of laparoscopic surgery training in a fourth-year medical school advanced surgical skills elective.

PubMed

Edelman, David A; Mattos, Mark A; Bouwman, David L

2012-10-01

Few data are available describing the benefits of initiating fundamentals of laparoscopic surgery (FLS) training during medical school. We hypothesized that an intense 1-month surgical skills elective that included FLS task training for fourth-year medical students (MS4s) would result in performance levels indistinguishable from graduating chief residents (PGY5) who had received clinical skill training and access to self-guided FLS curriculum. From July 2007 through June 2011, 114 MS4s participated in a 1-month advanced surgical skills elective. The curriculum for the elective included cadaver dissections, patient management presentations, and surgical skill training (open surgical skills and basic laparoscopic skills modules performed on FLS trainers and virtual reality laparoscopic simulators). From June 2009 through June 2011, 21 PGY5s graduated who had never received formalized FLS skills training. These residents were tested on FLS by a certified proctor and the results recorded. The performance outcome measure was task completion time. Unpaired Student's t-test was used to compare the performance measures for each group. All PGY5s achieved FLS certification on their first attempt and completed enough cases for graduation. The MS4 group showed significantly better performance than the PGY5 group in the peg transfer and circle cut (P < 0.05). No difference was seen in the knot tying tasks between the two groups (P > 0.05) Incorporating FLS training into a 1 month-long medical school surgery elective enabled MS4s to achieve FLS performance similar to, or better than, the performance achieved by PGY5 surgery residents. We support the integration of FLS skills task training as a standard part of the skills training curriculum for medical students. Copyright © 2012 Elsevier Inc. All rights reserved.

A biomechanical study of laparoscopic 4S-modified Roeder and Weston knot strength in 3-0 polyglactin 910 and 3-0 polydioxanone.

PubMed

Fugazzi, Russell W; Fransson, Boel A; Curran, Katie M; Davis, Howard M; Gay, John M

2013-02-01

To (1) evaluate biomechanical strength of 4 different laparoscopic knots using 2 suture types, and (2) evaluate carotid artery ligature bursting pressure of 2 knots using a single suture type. Biomechanical materials testing. Suture material (3-0 polydioxanone, 3-0 polyglactin 910). Four knot types were tested: 4S-modified Roeder (4SMR) Weston plus 3 square throws (W3S); Weston plus 3 granny throws (W3G); and a 4 square throw knot as a control (control); 24 specimens of each knot type were tied with 3-0 polyglactin 910 and 24 of 3 knot types (4SMR, W3S, control) were tied with 3-0 polydioxanone. Suture loop constructs were tested to 3 mm displacement failure and ultimate failure. Carotid artery ligation bursting pressure was tested using 10 samples each of 4SMR and W3S knots with 3-0 polyglactin 910. The W3S, W3G, and controls were similar. The 4SMR was similar to W3S using 3-0 PDS but the 4SMR had lower load to failure and greater elongation than the Weston using 3-0 polyglactin 910. The 4SMR had a higher slippage rate with 3-0 polyglactin 910. All ligatures withstood supraphysiologic pressures. Surgeons using 3-0 polyglactin 910 should consider using the Weston knot with added throws during laparoscopic procedures. © Copyright 2012 by The American College of Veterinary Surgeons.

Transosseous-equivalent rotator cuff repair: a systematic review on the biomechanical importance of tying the medial row.

PubMed

Mall, Nathan A; Lee, Andrew S; Chahal, Jaskarndip; Van Thiel, Geoffrey S; Romeo, Anthony A; Verma, Nikhil N; Cole, Brian J

2013-02-01

Double-row and transosseous-equivalent repair techniques have shown greater strength and improved healing than single-row techniques. The purpose of this study was to determine whether tying of the medial-row sutures provides added stability during biomechanical testing of a transosseous-equivalent rotator cuff repair. We performed a systematic review of studies directly comparing biomechanical differences. Five studies met the inclusion and exclusion criteria. Of the 5 studies, 4 showed improved biomechanical properties with tying the medial-row anchors before bringing the sutures laterally to the lateral-row anchors, whereas the remaining study showed no difference in contact pressure, mean failure load, or gap formation with a standard suture bridge with knots tied at the medial row compared with knotless repairs. The results of this systematic review and quantitative synthesis indicate that the biomechanical factors ultimate load, stiffness, gap formation, and contact area are significantly improved when medial knots are tied as part of a transosseous-equivalent suture bridge construct compared with knotless constructs. Further studies comparing the clinical healing rates and functional outcomes between medial knotted and knotless repair techniques are needed. This review indicates that biomechanical factors are improved when the medial row of a transosseous-equivalent rotator cuff is tied compared with a knotless repair. However, this has not been definitively proven to translate to improved healing rates clinically. Copyright © 2013 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Performance of basic manipulation and intracorporeal suturing tasks in a robotic surgical system: single- versus dual-monitor views.

PubMed

Shah, Rachit D; Cao, Alex; Golenberg, Lavie; Ellis, R Darin; Auner, Gregory W; Pandya, Abhilash K; Klein, Michael D

2009-04-01

Technical advances in the application of laparoscopic and robotic surgical systems have improved platform usability. The authors hypothesized that using two monitors instead of one would lead to faster performance with fewer errors. All tasks were performed using a surgical robot in a training box. One of the monitors was a standard camera with two preset zoom levels (zoomed in and zoomed out, single-monitor condition). The second monitor provided a static panoramic view of the whole surgical field. The standard camera was static at the zoomed-in level for the dual-monitor condition of the study. The study had two groups of participants: 4 surgeons proficient in both robotic and advanced laparoscopic skills and 10 lay persons (nonsurgeons) who were given adequate time to train and familiarize themselves with the equipment. Running a 50-cm rope was the basic task. Advanced tasks included running a suture through predetermined points and intracorporeal knot tying with 3-0 silk. Trial completion times and errors, categorized into three groups (orientation, precision, and task), were recorded. The trial completion times for all the tasks, basic and advanced, in the two groups were not significantly different. Fewer orientation errors occurred in the nonsurgeon group during knot tying (p=0.03) and in both groups during suturing (p=0.0002) in the dual-monitor arm of the study. Differences in precision and task error were not significant. Using two camera views helps both surgeons and lay persons perform complex tasks with fewer errors. These results may be due to better awareness of the surgical field with regard to the location of the instruments, leading to better field orientation. This display setup has potential for use in complex minimally invasive surgeries such as esophagectomy and gastric bypass. This technique also would be applicable to open microsurgery.

It's a tight record

NASA Astrophysics Data System (ADS)

2018-02-01

How tight can you tie a knot? Researchers at the University of Manchester last year went some way to answering that question when they developed a way of braiding multiple molecular strands, which let them make tighter and more complex knots than ever before (Science 335 159).

Footprint Contact Area and Interface Pressure Comparison Between the Knotless and Knot-Tying Transosseous-Equivalent Technique for Rotator Cuff Repair.

PubMed

Kim, Sung-Jae; Kim, Sung-Hwan; Moon, Hyun-Soo; Chun, Yong-Min

2016-01-01

To quantify and compare the footprint contact area and interface pressure on the greater tuberosity between knotless and knot-tying transosseous-equivalent (TOE) repair using pressure-sensitive film. We used 11 pairs of fresh-frozen cadaveric shoulders (22 specimens), in which rotator cuff tears were created before repair. Each pair was randomized to either conventional medial knot-tying TOE repair (group A) or medial knotless TOE repair using the modified Mason-Allen technique (group B). Pressure-sensitive film was used to quantify the pressurized contact area and interface pressure between the greater tuberosity and supraspinatus tendon. The mean pressurized contact area was 33.2 ± 2.5 mm(2) for group A and 28.4 ± 2.4 mm(2) for group B. There was a significant difference between groups (P = .005). Although the overall contact configuration of both groups was similar and showed an M shape, group A showed a greater pressurized configuration around the medial row. The mean interface pressure was 0.20 ± 0.02 MPa for group A and 0.17 ± 0.02 MPa for group B. There was a significant difference between groups (P = .001). Contrary to our hypothesis, in this time-zero study, medial knotless TOE repair using a modified Mason-Allen suture produced a significantly inferior footprint contact area and interface pressure compared with conventional medial knot-tying TOE repair. Even though we found a statistically significant difference between the 2 repair methods, it is still unknown if this statistical difference seen in our study has any clinical and radiologic significance. Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Conceptual design of a novel multi-DoF manual instrument for laparoscopic surgery.

PubMed

Wang, Xiaofei; Wang, Shuxin; Li, Jianmin; Zhang, Guokai; Wu, Zhiliang

2013-03-01

Laparoscopic surgery is becoming increasingly popular throughout the world. But the conventional instruments used in many surgeries are not flexible enough to be operated. Challenging tasks, such as suturing and knot-tying tasks are difficult to complete using conventional instruments with limited degrees of freedom (DoFs). In the paper, a novel cable-driven multi-DoF manual instrument is presented with a simple structure but strong functionality. The proposed instrument has been developed with a wristlike operation end (OE), a wristlike end effector (EE), and the transmission system. It can be operated intuitively. The orientation and the position of the EE are directly controlled by surgeons due to the one-to-one motion mapping structure. The clamp structure and tension device are reasonably designed. The pitch, yaw, and the open and close motion are actuated by cables. Based on the optimization index Global Condition Index (GCI), four cables are used to actuate the pitch and yaw motions, while other two are used for the open and close motion. The layout of the cables is also determined by the GCI. Experiments carried out with a prototype show that tasks such as suturing and knot-tying can be completed comfortably. Due to the intuitive control and multi-DoFs, surgeons can use the prototype to finish the tasks with ease. The instrument developed herein with intuitive control and dexterity can be used alone or together with a robotic system to accomplish some challenging tasks that are difficult for conventional instruments. Copyright © 2012 John Wiley & Sons, Ltd.

Virtual knotting in proteins and other open curves

NASA Astrophysics Data System (ADS)

Alexander, Keith; Taylor, Alexander; Dennis, Mark

Long filaments naturally knot, from string to long-chain molecules. Knotting in a filament affects its properties, and may be very stable or disappear under slight manipulation. Knotting has been identified in protein backbones for which these mechanical constraints are of fundamental importance to their function, although they are open curves in which knots are not mathematically well defined; knotting can only be identified by closing the ends of the chain. We introduce a new method for resolving knotting in open curves using virtual knots, a wider class of topological objects that do not use a classical closure, capturing the topological ambiguity of open curves. Having analysed all proteins in the Protein Data Bank by this new scheme, we recover and extend previous knotting results, and identify topological interest in some new cases. The statistics of virtual knots in proteins are compared with those of Hamiltonian subchains on cubic lattices, identifying a regime of open curves in which the virtual knotting description is likely to be important. This work was supported by the Leverhulme Trust Programme Grant ``Scientific Properties of Complex Knots'' and the EPSRC.

Proteins analysed as virtual knots

NASA Astrophysics Data System (ADS)

Alexander, Keith; Taylor, Alexander J.; Dennis, Mark R.

2017-02-01

Long, flexible physical filaments are naturally tangled and knotted, from macroscopic string down to long-chain molecules. The existence of knotting in a filament naturally affects its configuration and properties, and may be very stable or disappear rapidly under manipulation and interaction. Knotting has been previously identified in protein backbone chains, for which these mechanical constraints are of fundamental importance to their molecular functionality, despite their being open curves in which the knots are not mathematically well defined; knotting can only be identified by closing the termini of the chain somehow. We introduce a new method for resolving knotting in open curves using virtual knots, which are a wider class of topological objects that do not require a classical closure and so naturally capture the topological ambiguity inherent in open curves. We describe the results of analysing proteins in the Protein Data Bank by this new scheme, recovering and extending previous knotting results, and identifying topological interest in some new cases. The statistics of virtual knots in protein chains are compared with those of open random walks and Hamiltonian subchains on cubic lattices, identifying a regime of open curves in which the virtual knotting description is likely to be important.

Proteins analysed as virtual knots

PubMed Central

Alexander, Keith; Taylor, Alexander J.; Dennis, Mark R.

2017-01-01

Long, flexible physical filaments are naturally tangled and knotted, from macroscopic string down to long-chain molecules. The existence of knotting in a filament naturally affects its configuration and properties, and may be very stable or disappear rapidly under manipulation and interaction. Knotting has been previously identified in protein backbone chains, for which these mechanical constraints are of fundamental importance to their molecular functionality, despite their being open curves in which the knots are not mathematically well defined; knotting can only be identified by closing the termini of the chain somehow. We introduce a new method for resolving knotting in open curves using virtual knots, which are a wider class of topological objects that do not require a classical closure and so naturally capture the topological ambiguity inherent in open curves. We describe the results of analysing proteins in the Protein Data Bank by this new scheme, recovering and extending previous knotting results, and identifying topological interest in some new cases. The statistics of virtual knots in protein chains are compared with those of open random walks and Hamiltonian subchains on cubic lattices, identifying a regime of open curves in which the virtual knotting description is likely to be important. PMID:28205562

Automated robot-assisted surgical skill evaluation: Predictive analytics approach.

PubMed

Fard, Mahtab J; Ameri, Sattar; Darin Ellis, R; Chinnam, Ratna B; Pandya, Abhilash K; Klein, Michael D

2018-02-01

Surgical skill assessment has predominantly been a subjective task. Recently, technological advances such as robot-assisted surgery have created great opportunities for objective surgical evaluation. In this paper, we introduce a predictive framework for objective skill assessment based on movement trajectory data. Our aim is to build a classification framework to automatically evaluate the performance of surgeons with different levels of expertise. Eight global movement features are extracted from movement trajectory data captured by a da Vinci robot for surgeons with two levels of expertise - novice and expert. Three classification methods - k-nearest neighbours, logistic regression and support vector machines - are applied. The result shows that the proposed framework can classify surgeons' expertise as novice or expert with an accuracy of 82.3% for knot tying and 89.9% for a suturing task. This study demonstrates and evaluates the ability of machine learning methods to automatically classify expert and novice surgeons using global movement features. Copyright © 2017 John Wiley & Sons, Ltd.

Rabbit tissue model (RTM) harvesting technique.

PubMed

Medina, Marelyn

2002-01-01

A method for creating a tissue model using a female rabbit for laparoscopic simulation exercises is described. The specimen is called a Rabbit Tissue Model (RTM). Dissection techniques are described for transforming the rabbit carcass into a small, compact unit that can be used for multiple training sessions. Preservation is accomplished by using saline and refrigeration. Only the animal trunk is used, with the rest of the animal carcass being discarded. Practice exercises are provided for using the preserved organs. Basic surgical skills, such as dissection, suturing, and knot tying, can be practiced on this model. In addition, the RTM can be used with any pelvic trainer that permits placement of larger practice specimens within its confines.

Comparing the da Vinci si single console and dual console in teaching novice surgeons suturing techniques.

PubMed

Crusco, Salvatore; Jackson, Tiffany; Advincula, Arnold

2014-01-01

Robot-assisted laparoscopic surgery is often taught with the surgical mentor at the surgeon console and the trainee at the patient's bedside. The da Vinci dual console (Intuitive Surgical, Sunnyvale, California) allows a surgical mentor to teach with both the mentor and the trainee working at a surgeon console simultaneously. The purpose of this study is to evaluate the effectiveness of the dual console versus the single console for teaching medical students robotic tasks. Forty novice medical students were randomized to either the da Vinci single-console or dual-console group and were taught 4 knot-tying techniques by a surgical mentor. The students were timed while performing the tasks. No statistically significant differences in mean task times were observed between the single- and dual-console groups: interrupted stitch with a 2-handed knot (300 seconds for single vs 294 seconds for dual, P=.59), interrupted stitch with a 1-handed knot (198 seconds for single vs 212 seconds for dual, P=.88), figure-of-8 stitch with a 2-handed knot (261 seconds for single vs 219 seconds for dual, P=.20), and figure-of-8 stitch with a 1-handed knot (200 seconds for single vs 199 seconds for dual, P=.53). No significant difference was observed in performance time when teaching knot-tying techniques to medical students using the da Vinci dual console compared with the single console. More research needs to be performed on the utility of the da Vinci dual console in surgical training.

Comparing the da Vinci Si Single Console and Dual Console in Teaching Novice Surgeons Suturing Techniques

PubMed Central

Jackson, Tiffany; Advincula, Arnold

2014-01-01

Background and Objectives: Robot-assisted laparoscopic surgery is often taught with the surgical mentor at the surgeon console and the trainee at the patient's bedside. The da Vinci dual console (Intuitive Surgical, Sunnyvale, California) allows a surgical mentor to teach with both the mentor and the trainee working at a surgeon console simultaneously. The purpose of this study is to evaluate the effectiveness of the dual console versus the single console for teaching medical students robotic tasks. Methods: Forty novice medical students were randomized to either the da Vinci single-console or dual-console group and were taught 4 knot-tying techniques by a surgical mentor. The students were timed while performing the tasks. Results: No statistically significant differences in mean task times were observed between the single- and dual-console groups: interrupted stitch with a 2-handed knot (300 seconds for single vs 294 seconds for dual, P = .59), interrupted stitch with a 1-handed knot (198 seconds for single vs 212 seconds for dual, P = .88), figure-of-8 stitch with a 2-handed knot (261 seconds for single vs 219 seconds for dual, P = .20), and figure-of-8 stitch with a 1-handed knot (200 seconds for single vs 199 seconds for dual, P = .53). Conclusion: No significant difference was observed in performance time when teaching knot-tying techniques to medical students using the da Vinci dual console compared with the single console. More research needs to be performed on the utility of the da Vinci dual console in surgical training. PMID:25392618

Arthroscopic repair of a type II SLAP lesion using a single corkscrew anchor.

PubMed

Kartus, Jüri; Perko, Mark

2002-03-01

The use of a double-looped 5-mm Corkscrew anchor (Arthrex, Naples, FL) enables the surgeon to use a single anchor to perform a secure fixation of both the anterior labrum as well as the biceps insertion in a type II SLAP lesion. The technique involves tying 1 knot through the anterior portal and a second knot through the posterior portal.

Proficiency training on a virtual reality robotic surgical skills curriculum.

PubMed

Bric, Justin; Connolly, Michael; Kastenmeier, Andrew; Goldblatt, Matthew; Gould, Jon C

2014-12-01

The clinical application of robotic surgery is increasing. The skills necessary to perform robotic surgery are unique from those required in open and laparoscopic surgery. A validated laparoscopic surgical skills curriculum (Fundamentals of Laparoscopic Surgery or FLS™) has transformed the way surgeons acquire laparoscopic skills. There is a need for a similar skills training and assessment tool for robotic surgery. Our research group previously developed and validated a robotic training curriculum in a virtual reality (VR) simulator. We hypothesized that novice robotic surgeons could achieve proficiency levels defined by more experienced robotic surgeons on the VR robotic curriculum, and that this would result in improved performance on the actual daVinci Surgical System™. 25 medical students with no prior robotic surgery experience were recruited. Prior to VR training, subjects performed 2 FLS tasks 3 times each (Peg Transfer, Intracorporeal Knot Tying) using the daVinci Surgical System™ docked to a video trainer box. Task performance for the FLS tasks was scored objectively. Subjects then practiced on the VR simulator (daVinci Skills Simulator) until proficiency levels on all 5 tasks were achieved before completing a post-training assessment of the 2 FLS tasks on the daVinci Surgical System™ in the video trainer box. All subjects to complete the study (1 dropped out) reached proficiency levels on all VR tasks in an average of 71 (± 21.7) attempts, accumulating 164.3 (± 55.7) minutes of console training time. There was a significant improvement in performance on the robotic FLS tasks following completion of the VR training curriculum. Novice robotic surgeons are able to attain proficiency levels on a VR simulator. This leads to improved performance in the daVinci surgical platform on simulated tasks. Training to proficiency on a VR robotic surgery simulator is an efficient and viable method for acquiring robotic surgical skills.

Multimedia article. The keys to the new laparoscopic world Thumbs up! knot and Tornado knot.

PubMed

Uchida, K; Haruta, N; Okajima, M; Matsuda, M; Yamamoto, M

2005-06-01

Most laparoscopic surgeons feel some anxiety when performing intracorporeal knotting with conventional techniques [1, 2]. Two factors contribute to this anxiety. The first is the necessity of recognizing three dimensions on a two-dimensional monitor. The conventional intracorporeal knotting techniques make loops by twisting the thread with a second pair of forceps. This necessitates cooperative movement of both hands, with the added difficulties of depth perception. Regular touch confirmations reduce problems with depth perception. However, touch confirmation is more complicated in laparoscopic surgery than in laparotomy. The second problem is that tied loops can come loose and escape the instruments, especially with hard thread. This is not only stressful but also increases operation time.

Pierced Lasso Proteins

NASA Astrophysics Data System (ADS)

Jennings, Patricia

Entanglement and knots are naturally occurring, where, in the microscopic world, knots in DNA and homopolymers are well characterized. The most complex knots are observed in proteins which are harder to investigate, as proteins are heteropolymers composed of a combination of 20 different amino acids with different individual biophysical properties. As new-knotted topologies and new proteins containing knots continue to be discovered and characterized, the investigation of knots in proteins has gained intense interest. Thus far, the principle focus has been on the evolutionary origin of tying a knot, with questions of how a protein chain `self-ties' into a knot, what the mechanism(s) are that contribute to threading, and the biological relevance and functional implication of a knotted topology in vivo gaining the most insight. Efforts to study the fully untied and unfolded chain indicate that the knot is highly stable, remaining intact in the unfolded state orders of magnitude longer than first anticipated. The persistence of ``stable'' knots in the unfolded state, together with the challenge of defining an unfolded and untied chain from an unfolded and knotted chain, complicates the study of fully untied protein in vitro. Our discovery of a new class of knotted proteins, the Pierced Lassos (PL) loop topology, simplifies the knotting approach. While PLs are not easily recognizable by the naked eye, they have now been identified in many proteins in the PDB through the use of computation tools. PL topologies are diverse proteins found in all kingdoms of life, performing a large variety of biological responses such as cell signaling, immune responses, transporters and inhibitors (http://lassoprot.cent.uw.edu.pl/). Many of these PL topologies are secreted proteins, extracellular proteins, as well as, redox sensors, enzymes and metal and co-factor binding proteins; all of which provide a favorable environment for the formation of the disulphide bridge. In the PL topologies, the threaded topology is formed by a covalent loop where part of the polypeptide chain is threaded through, forming what we term a PL. The advantage of a PL topology for fundamental studies, compared to other knotted proteins, is that the threaded topology can easily be manipulated to yield an unknotted state. Exploiting the oxidative state of the cysteines, the building blocks that form the disulphide bridge generating the covalent loop, through altering the chemical environment, and thereby controlling the formation of the covalent loop, easily generates unknotted protein. The biological advantage, we have found, is that the PL can exert allosteric control through this on/off mechanism in a target protein. Most significantly, as the disulphide bridge acts as an on/off switch in knotting, the biophysical investigation of PL topologies can provide a new tool to steer folding and function in proteins, as disulphide bridges are commonly used in protein engineering and therapeutics.

[Simulated used of the "grasping tie" as in esophago-jejunostomy after total gastrectomy].

PubMed

Picardi, Nicola

2003-01-01

Simulated test of effectiveness of the original tool grasping tie--technically already illustrated in a former paper listed in bibliography--for fixing a spongy rubber tube simulating an oesophagus on a circular stapler head axis, by tightening over it a nylon ribbon slip-knot (the tie). After connecting the head to the stapler anvil through an other spongy rubber tube simulating a jejunal loop, and the firing of the stapler, it is demonstrated the correct circular anastomosis achievable.

Shoulder abduction diminishes self-reinforcement in transosseous-equivalent rotator cuff repair in both knotted and knotless techniques.

PubMed

Smith, Geoffrey C S; Lam, Patrick H

2018-06-20

The self-reinforcement mechanism after double row suturebridge rotator cuff repair generates increasing compressive forces at the tendon footprint with increasing tendon load. Passive range of motion is usually allowed after rotator cuff repair. The mechanism of self-reinforcement could be adversely affected by shoulder abduction. Rotator cuff tears were created ex vivo in nine pairs of ovine shoulders. Two different repair techniques were used. One group was repaired using a double row 'suturebridge' construct with tied horizontal medial row mattress sutures (Knotted repair group). The other group was repaired identically except that medial row knots were not tied (Knotless repair group). Footprint compression was measured at varying amounts of abduction and under tendon loads of 0, 10, 20, 30, 40, 50 and 60N. The rate of increase of contact pressure (degree of self-reinforcement) was calculated for each abduction angle. Abduction diminishes footprint contact pressure in both knotted and knotless double row suturebridge constructs. Progressive abduction from 0 to 40 abduction in the knotless group and 0-30 in the knotted group results in a decrease in self-reinforcement. Abduction beyond this does not cause a further decrease in self-reinforcement. There was no difference in the rate of increase of footprint contact pressure at each angle of abduction when comparing the knotted and knotless groups. In the post-operative period, high tendon load combined with minimal abduction would be expected to generate the greatest amount of footprint compression which may improve tendon healing. Therefore, to maximize footprint compression the use of abduction pillows should be avoided while early isometric strengthening should be used.

Peer video review and feedback improve performance in basic surgical skills.

PubMed

Vaughn, Carolyn J; Kim, Edward; O'Sullivan, Patricia; Huang, Emily; Lin, Matthew Y C; Wyles, Susannah; Palmer, Barnard J A; Pierce, Jonathan L; Chern, Hueylan

2016-02-01

Incorporation of home-video assessments allows flexibility in feedback but requires faculty time. Peer feedback (PF) may provide additional benefits while avoiding these constraints. Twenty-four surgical interns completed a 12-week skills curriculum with home-video assignments focused on knot tying and suturing. Interns were randomized into 2 groups: PF or faculty feedback (FF). Peers and faculty provided feedback on home videos with checklists, global rating, and comments. Learners' skills were assessed at baseline, during, and at the conclusion of the curriculum. Performance of the 2 groups as rated by experts was compared. FF and PF were compared. Both groups improved from baseline, and the highest rated scores were seen on their home-video assessments. The PF group performed better at the final assessment than the FF group (effect size, .84). When using a checklist, there was no significant difference between scores given by peers and faculty. The PF group performed better at the final assessment, suggesting reviewing and analyzing another's performance may improve one's own performance. With checklists as guidance, peers can serve as raters comparable to faculty. Copyright © 2016 Elsevier Inc. All rights reserved.

Sociality influences cultural complexity.

PubMed

Muthukrishna, Michael; Shulman, Ben W; Vasilescu, Vlad; Henrich, Joseph

2014-01-07

Archaeological and ethnohistorical evidence suggests a link between a population's size and structure, and the diversity or sophistication of its toolkits or technologies. Addressing these patterns, several evolutionary models predict that both the size and social interconnectedness of populations can contribute to the complexity of its cultural repertoire. Some models also predict that a sudden loss of sociality or of population will result in subsequent losses of useful skills/technologies. Here, we test these predictions with two experiments that permit learners to access either one or five models (teachers). Experiment 1 demonstrates that naive participants who could observe five models, integrate this information and generate increasingly effective skills (using an image editing tool) over 10 laboratory generations, whereas those with access to only one model show no improvement. Experiment 2, which began with a generation of trained experts, shows how learners with access to only one model lose skills (in knot-tying) more rapidly than those with access to five models. In the final generation of both experiments, all participants with access to five models demonstrate superior skills to those with access to only one model. These results support theoretical predictions linking sociality to cumulative cultural evolution.

Sociality influences cultural complexity

PubMed Central

Muthukrishna, Michael; Shulman, Ben W.; Vasilescu, Vlad; Henrich, Joseph

2014-01-01

Archaeological and ethnohistorical evidence suggests a link between a population's size and structure, and the diversity or sophistication of its toolkits or technologies. Addressing these patterns, several evolutionary models predict that both the size and social interconnectedness of populations can contribute to the complexity of its cultural repertoire. Some models also predict that a sudden loss of sociality or of population will result in subsequent losses of useful skills/technologies. Here, we test these predictions with two experiments that permit learners to access either one or five models (teachers). Experiment 1 demonstrates that naive participants who could observe five models, integrate this information and generate increasingly effective skills (using an image editing tool) over 10 laboratory generations, whereas those with access to only one model show no improvement. Experiment 2, which began with a generation of trained experts, shows how learners with access to only one model lose skills (in knot-tying) more rapidly than those with access to five models. In the final generation of both experiments, all participants with access to five models demonstrate superior skills to those with access to only one model. These results support theoretical predictions linking sociality to cumulative cultural evolution. PMID:24225461

Comparison of ultrasonic suture welding and traditional knot tying in a rabbit rotator cuff repair model.

PubMed

Nho, Shane J; Cole, Brian J; Mazzocca, Augustus D; Williams, James M; Romeo, Anthony A; Bush-Joseph, Charles A; Bach, Bernard R; Hallab, Nadim J

2006-01-01

The purpose of this study is to evaluate ultrasonic suture welding of monofilament suture in an animal model of rotator cuff repair with biomechanical and histologic analyses. We randomly assigned 46 shoulders in 23 rabbits to 1 of 3 treatment groups: sham-operated (n = 15), knotted (n = 15), and welded (n = 16). Supraspinatus defects were surgically created and acutely repaired with suture anchors loaded with either No. 2-0 Ethibond for knotted group or No. 2-0 nylon for welded shoulders. Eighteen weeks postoperatively, all animals were killed, and the shoulders underwent either biomechanical testing or histologic analysis. The maximum stress of the sham-operated group (20.6 N/mm2) was significantly greater than that of both the knotted (10.2 N/mm2) and welded (8.3 N/mm2) groups (P < .05), but no differences were observed between the knotted and welded groups. Although some histologic changes were noted, none was considered to be significant to distinguish either group.

Training Laparoscopic Skills at Home: Residents' Opinion of a New Portable Tablet Box Trainer.

PubMed

van der Aa, Jessica E; Schreuder, Henk W R

2016-04-01

To determine residents' opinion about a new portable box trainer, to see if they would be interested in using this for training at home, and to give an overview of the box trainers that could be used at home. An expert opinion study was performed among 27 gynecology residents to determine the value of the portable box trainer in training their laparoscopic skills and the value of using it at home. Their opinions were scored on a 5-point Likert scale. Gynecology residents very much appreciated the portable box trainer in its design, size, visualization, light source, ability to record, and instruments (all median 4). They felt that the portable box trainer would be effective in training laparoscopic skills in general; in training hand-eye coordination, 3D perception, and tying knots (all median 4); and especially in training basic skills (median 5). Almost all residents would use the portable box trainer if they had one at home (median 5). The literature supports the hypothesis that training laparoscopic skills at home using a box trainer may be effective in acquiring and maintaining laparoscopic skills. Training laparoscopic skills at home using a portable box trainer may be of added value in the laparoscopic training of surgical residents. Residents feel positive about using the new portable box trainer that is presented and appreciate the possibility of training at home. © The Author(s) 2015.

Knot Security of 5 Metric (USP 2) Sutures: Influence of Knotting Technique, Suture Material, and Incubation Time for 14 and 28 Days in Phosphate Buffered Saline and Inflamed Equine Peritoneal Fluid.

PubMed

Sanders, Ruth E; Kearney, Clodagh M; Buckley, Conor T; Jenner, Florien; Brama, Pieter A

2015-08-01

To evaluate knot security for 3 knot types created in 3 commonly used 5 metric suture materials incubated in physiological and pathological fluids. In vitro mechanical study. Knotted suture loops (n = 5/group). Loops of 3 different suture materials (glycolide/lactide copolymer; polyglactin 910; polydioxanone) were created around a 20 mm rod using 3 knot types (square [SQ], surgeon's [SK], and triple knot [TK]) and were tested to failure in distraction (6 mm/min) after tying (day 0) and after being incubated for 14 and 28 days in phosphate buffered saline (PBS) or inflamed peritoneal fluid. Failure load (N) and mode were recorded and compared. For polydioxanone, significant differences in force to knot failure were found between SQ and SK/TK but not between SK and TK. The force required to break all constructs increased after incubation in phosphate buffered saline (PBS). With glycolide/lactide copolymer no differences in force to knot failure were observed. With polyglactin 910, a significant difference between SQ and TK was observed, which was not seen between the other knot types. Incubation in inflamed peritoneal fluid caused a larger and more rapid decrease in force required to cause knot failure than incubation in PBS. Mechanical properties of suture materials have significant effects on knot security. For polydioxanone, SQ is insufficient to create a secure knot. Additional wraps above a SK confer extra stability in some materials, but this increase may not be clinically relevant or justifiable. Glycolide/lactide copolymer had excellent knot security. © Copyright 2015 by The American College of Veterinary Surgeons.

On the Construction and Dynamics of Knotted Fields

NASA Astrophysics Data System (ADS)

Kedia, Hridesh

Representing a physical field in terms of its field lines has often enabled a deeper understanding of complex physical phenomena, from Faraday's law of magnetic induction, to the Helmholtz laws of vortex motion, to the free energy density of liquid crystals in terms of the distortions of the lines of the director field. At the same time, the application of ideas from topology--the study of properties that are invariant under continuous deformations--has led to robust insights into the nature of complex physical systems from defects in crystal structures, to the earth's magnetic field, to topological conservation laws. The study of knotted fields, physical fields in which the field lines encode knots, emerges naturally from the application of topological ideas to the investigation of the physical phenomena best understood in terms of the lines of a field. A knot--a closed loop tangled with itself which can not be untangled without cutting the loop--is the simplest topologically non-trivial object constructed from a line. Remarkably, knots in the vortex (magnetic field) lines of a dissipationless fluid (plasma), persist forever as they are transported by the flow, stretching and rotating as they evolve. Moreover, deeply entwined with the topology-preserving dynamics of dissipationless fluids and plasmas, is an additional conserved quantity--helicity, a measure of the average linking of the vortex (magnetic field) lines in a fluid (plasma)--which has had far-reaching consequences for fluids and plasmas. Inspired by the persistence of knots in dissipationless flows, and their far-reaching physical consequences, we seek to understand the interplay between the dynamics of a field and the topology of its field lines in a variety of systems. While it is easy to tie a knot in a shoelace, tying a knot in the the lines of a space-filling field requires contorting the lines everywhere to match the knotted region. The challenge of analytically constructing knotted field configurations has impeded a deeper understanding of the interplay between topology and dynamics in fluids and plasmas. We begin by analytically constructing knotted field configurations which encode a desired knot in the lines of the field, and show that their helicity can be tuned independently of the encoded knot. The nonlinear nature of the physical systems in which these knotted field configurations arise, makes their analytical study challenging. We ask if a linear theory such as electromagnetism can allow knotted field configurations to persist with time. We find analytical expressions for an infinite family of knotted solutions to Maxwell's equations in vacuum and elucidate their connections to dissipationless flows. We present a design rule for constructing such persistently knotted electromagnetic fields, which could possibly be used to transfer knottedness to matter such as quantum fluids and plasmas. An important consequence of the persistence of knots in classical dissipationless flows is the existence of an additional conserved quantity, helicity, which has had far-reaching implications. To understand the existence of analogous conserved quantities, we ask if superfluids, which flow without dissipation just like classical dissipationless flows, have an additional conserved quantity akin to helicity. We address this question using an analytical approach based on defining the particle relabeling symmetry--the symmetry underlying helicity conservation--in superfluids, and find that an analogous conserved quantity exists but vanishes identically owing to the intrinsic geometry of complex scalar fields. Furthermore, to address the question of a ``classical limit'' of superfluid vortices which recovers classical helicity conservation, we perform numerical simulations of \\emph{bundles} of superfluid vortices, and find behavior akin to classical viscous flows.

Measuring cognitive load during simulation-based psychomotor skills training: sensitivity of secondary-task performance and subjective ratings.

PubMed

Haji, Faizal A; Khan, Rabia; Regehr, Glenn; Drake, James; de Ribaupierre, Sandrine; Dubrowski, Adam

2015-12-01

As interest in applying cognitive load theory (CLT) to the study and design of pedagogic and technological approaches in healthcare simulation grows, suitable measures of cognitive load (CL) are needed. Here, we report a two-phased study investigating the sensitivity of subjective ratings of mental effort (SRME) and secondary-task performance (signal detection rate, SDR and recognition reaction time, RRT) as measures of CL. In phase 1 of the study, novice learners and expert surgeons attempted a visual-monitoring task under two conditions: single-task (monitoring a virtual patient's heart-rate) and dual-task (tying surgical knots on a bench-top simulator while monitoring the virtual patient's heart-rate). Novices demonstrated higher mental effort and inferior secondary-task performance on the dual-task compared to experts (RRT 1.76 vs. 0.73, p = 0.012; SDR 0.27 vs. 0.97, p < 0.001; SRME 7.75 vs. 2.80, p < 0.001). Similarly, secondary task performance deteriorated from baseline to dual-task among novices (RRT 0.63 vs. 1.76 s, p < 0.006 and SDR 1.00 vs. 0.27, p < 0.001), but not experts (RRT 0.63 vs. 0.73 s, p = 0.124 and SDR 1.00 vs. 0.97, p = 0.178). In phase 2, novices practiced surgical knot-tying on the bench top simulator during consecutive dual-task trials. A significant increase in SDR (F(9,63) = 6.63, p < 0.001, f = 0.97) and decrease in SRME (F(9,63) = 9.39, p < 0.001, f = 1.04) was observed during simulation training, while RRT did not change significantly (F(9,63) = 1.18, p < 0.32, f = 0.41). The results suggest subjective ratings and dual-task performance can be used to track changes in CL among novices, particularly in early phases of simulation-based skills training. The implications for measuring CL in simulation instructional design research are discussed.

Transfer of training in the development of intracorporeal suturing skill in medical student novices: a prospective randomized trial.

PubMed

Muresan, Claude; Lee, Tommy H; Seagull, Jacob; Park, Adrian E

2010-10-01

To help optimize the use of limited resources in trainee education, we developed a prospective randomized trial to determine the most effective means of teaching laparoscopic suturing to novices. Forty-one medical students received rudimentary instruction in intracorporeal suturing, then were pretested on a pig enterotomy model. They then were posttested after completion of 1 of 4 training arms: laparoscopic suturing, laparoscopic drills, open suturing, and virtual reality (VR) drills. Tests were scored for speed, accuracy, knot quality, and mental workload (National Aeronautics and Space Administration [NASA] Task Load Index). Paired t tests were used. Task time was improved in all groups except the VR group. Knot quality improved only in the open or laparoscopic suturing groups. Mental workload improved only for those practicing on a physical laparoscopic trainer. For novice trainees, the efficacy of VR training is questionable. In contrast, the other training methods had benefits in terms of time, quality, and perceived workload. Copyright © 2010 Elsevier Inc. All rights reserved.

Evaluation of Surgical Devices Using an Artificial Pediatric Thoracic Model: A Comparison Between Robot-Assisted Thoracoscopic Suturing Versus Conventional Video-Assisted Thoracoscopic Suturing.

PubMed

Takazawa, Shinya; Ishimaru, Tetsuya; Harada, Kanako; Deie, Kyoichi; Hinoki, Akinari; Uchida, Hiroo; Sugita, Naohiko; Mitsuishi, Mamoru; Iwanaka, Tadashi; Fujishiro, Jun

2018-05-01

Pediatric robot-assisted surgery is increasingly being performed, but it is difficult to perform this procedure in infants. A pediatric thoracoscopic model of a 1-year-old patient was developed in our previous study, and this model was used to evaluate the use of a surgical robot for infant surgery. Eight pediatric surgeons performed an intracorporeal suturing and knot-tying task using the da Vinci Xi Robotic Surgical System. The task completion time, number of needle manipulations, and force applied during suturing of the robot-assisted thoracoscopic surgery (RATS) group were compared with those of the video-assisted thoracoscopic surgery (VATS) group whose data had been collected from the same 8 surgeons in our previous study. The RATS group showed a significantly shorter completion time than the VATS group in the knot-tying phase (P = .016) and in the total phase (P = .0078). The RATS group showed a significantly smaller number of manipulations than the VATS group in the total phase (P = .039). The RATS group showed a significantly smaller pushing force index than the VATS group in the suturing phase (P = .031), knot-tying phase (P = .031), and in the total phase (P = .031). A seventh rib in the model was dislocated in all RATS group cases. The da Vinci Surgical System might be useful in infants because of fast movement and small pushing force. However, the robotic 8 mm instruments were too large for use in the thoracic cavity of the 1-year-old infant.

Minilaparoscopic varicocelectomy with preservation of testicular artery and lymphatic vessels by using intracorporeal knot-tying technique: five-year experience.

PubMed

Chung, Shiu-Dong; Wu, Chia-Chang; Lin, Victor Chia-Hsiang; Ho, Chen-Hsun; Yang, Stephen Shei Dei; Tsai, Yao-Chou

2011-08-01

In this study we present our experience using minilaparoscopic intracorporeal knot tying to ligate internal spermatic veins (ISV) while sparing the spermatic artery and lymphatics. Minilaparoscopic varicocelectomies were performed in 87 patients between January 2004 and January 2009. All varicoceles were detected clinically according to the World Health Organization (WHO) classification and confirmed by scrotal color Doppler ultrasonography. The surgical indications were scrotal symptoms in 71, infertility in 16, and both conditions in 2. Three 3.5 mm minilaparoscopic ports were used for the operation. The ISVs were dissected and then ligated with intracorporeal knot-tying. The testicular artery and lymphatic vessels were carefully preserved to minimize procedure-related complications. Unilateral laparoscopic varicocelectomy was performed in 21 (24.2%) patients and bilateral in 66 (75.8%). Mean operative time was 71.1 ± 29.2 and 46.8 ± 12.6 min for bilateral and unilateral varicocelectomies, respectively. All patients were discharged within 24 h after surgery. Neither immediate major nor late procedure-related complications were noted. Of the 71 patients with scrotal symptoms, the symptoms completely subsided in 55 (77.5%) and partially subsided in 10 (14.1%). Only one (1.2%) recurrent varicocele was detected within a mean follow-up of 21 months (range = 3-42). Neither hydrocele formation nor testicular atrophy was found during the follow-up period. Our 5-year experience revealed that minilaparoscopic varicocelectomy with sparing of artery and lymphatic vessels could safely and effectively ligate all spermatic veins and preserve spermatic arteries and lymphatic channels without leading to a high varicocele persistence or recurrence.

Relative humidity sensor based on a few-mode microfiber knot resonator by mitigating group index difference

NASA Astrophysics Data System (ADS)

Anh Le, Duy Duong; Lee, Seungmin; Han, Young-Geun

2017-04-01

A few-mode microfiber knot resonator (FM-MKR) incorporating a polyvinyl alcohol (PVA) is investigated for measurement of relative humidity (RH). Two modes, such as HE11 and HE12, are excited and interfered in a nonadiabatically tapered structure of the single-mode fiber (SMF). After making a tie with the few-mode microfiber, the FM-MKR is fabricated. In the FM-MKR, two modes, such as HE11 and HE12, must be circulated within the optical knot and cross-coupled independently with a phase delay. By optimizing the diameter of the microfiber, the difference of group effective refractive indices between two modes is dramatically suppressed resulting in the improvement of RH sensitivity of the proposed FM-MKR.

KymoKnot: A web server and software package to identify and locate knots in trajectories of linear or circular polymers.

PubMed

Tubiana, Luca; Polles, Guido; Orlandini, Enzo; Micheletti, Cristian

2018-06-07

The KymoKnot software package and web server identifies and locates physical knots or proper knots in a series of polymer conformations. It is mainly intended as an analysis tool for trajectories of linear or circular polymers, but it can be used on single instances too, e.g. protein structures in PDB format. A key element of the software package is the so-called minimally interfering chain closure algorithm that is used to detect physical knots in open chains and to locate the knotted region in both open and closed chains. The web server offers a user-friendly graphical interface that identifies the knot type and highlights the knotted region on each frame of the trajectory, which the user can visualize interactively from various viewpoints. The dynamical evolution of the knotted region along the chain contour is presented as a kymograph. All data can be downloaded in text format. The KymoKnot package is licensed under the BSD 3-Clause licence. The server is publicly available at http://kymoknot.sissa.it/kymoknot/interactive.php .

Development and Evaluation of a Remedial Reading Workbook for Navy Training.

DTIC Science & Technology

1979-12-01

quirements (1973) and the Bluejackets’ Manual, 20th Edition (1978). The workbook is based on established remedial reading principles and many of the exercises...knot is just a little over one mile an hour; or a knot in a rope; hitches and bends in a line LASH To tie up with a line (or wire). Le , inq is what you...long i. (Exercise 5 - silent vowel is circled) 1 - saior, 2 b* 3 - peoce, 4 - rescul 5 - ste_, 6 - fantag 7 - inbc&d, 8 - issu, 9 - le , 10 - rel e, 11

Medical Students Teaching Medical Students Surgical Skills: The Benefits of Peer-Assisted Learning.

PubMed

Bennett, Samuel Robert; Morris, Simon Rhys; Mirza, Salman

2018-04-10

Teaching surgical skills is a labor intensive process, requiring a high tutor to student ratio for optimal success, and teaching for undergraduate students by consultant surgeons is not always feasible. A surgical skills course was developed, with the aim of assessing the effectiveness of undergraduate surgical peer-assisted learning. Five surgical skills courses were conducted looking at eight domains in surgery, led by foundation year doctors and senior medical students, with a tutor to student ratio of 1:4. Precourse and postcourse questionnaires (Likert scales 0-10) were completed. Mean scores were compared precourse and postcourse. Surgical skills courses took place within clinical skills rooms in the Queen Elizabeth Hospital Birmingham (UK). Seventy students (59 medical, 2 dental, and 9 physician associate students) from a range of academic institutions across the UK completed the course. There was an overall increase in mean scores across all eight domains. Mean improvement score precourse and postcourse in WHO surgical safety checklist (+3.94), scrubbing (+2.99), gowning/gloving (+3.34), knot tying (+5.53), interrupted sutures (+5.89), continuous sutures (+6.53), vertical mattress sutures (+6.46), and local anesthesia (+3.73). Peer-assisted learning is an effective and feasible method for teaching surgical skills in a controlled environment, subsequently improving confidence among healthcare undergraduates. Such teaching may provide the basis for feasibly mass-producing surgical skills courses for healthcare students. Copyright © 2018 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

Virtual Reality and Computer-Enhanced Training Devices Equally Improve Laparoscopic Surgical Skill in Novices

PubMed Central

Kanumuri, Prathima; Ganai, Sabha; Wohaibi, Eyad M.; Bush, Ronald W.; Grow, Daniel R.

2008-01-01

Background: The study aim was to compare the effectiveness of virtual reality and computer-enhanced video-scopic training devices for training novice surgeons in complex laparoscopic skills. Methods: Third-year medical students received instruction on laparoscopic intracorporeal suturing and knot tying and then underwent a pretraining assessment of the task using a live porcine model. Students were then randomized to objectives-based training on either the virtual reality (n=8) or computer-enhanced (n=8) training devices for 4 weeks, after which the assessment was repeated. Results: Posttraining performance had improved compared with pretraining performance in both task completion rate (94% versus 18%; P<0.001*) and time [181±58 (SD) versus 292±24*]. Performance of the 2 groups was comparable before and after training. Of the subjects, 88% thought that haptic cues were important in simulators. Both groups agreed that their respective training systems were effective teaching tools, but computer-enhanced device trainees were more likely to rate their training as representative of reality (P<0.01). Conclusions: Training on virtual reality and computer-enhanced devices had equivalent effects on skills improvement in novices. Despite the perception that haptic feedback is important in laparoscopic simulation training, its absence in the virtual reality device did not impede acquisition of skill. PMID:18765042

A Guided Tour of Light Beams; From lasers to optical knots

NASA Astrophysics Data System (ADS)

Simon, David S.

2016-11-01

From science fiction death rays to supermarket scanners, lasers have become deeply embedded in our daily lives and our culture. But in recent decades the standard laser beam has evolved into an array of more specialized light beams with a variety of strange and counterintuitive properties. Some of them have the ability to reconstruct themselves after disruption by an obstacle, while others can bend in complicated shapes or rotate like a corkscrew. These unusual optical effects open new and exciting possibilities for science and technology. For example, they make possible microscopic tractor beams that pull objects toward the source of the light, and they allow the trapping and manipulation of individual molecules to construct specially-tailored nanostructures for engineering or medical use. It has even been found that beams of light can produce lines of darkness that can be tied in knots. This book is an introductory survey of these specialized light beams and their scientific applications, at a level suitable for undergraduates with a basic knowledge of optics and quantum mechanics. It provides a unified treatment of the subject, collecting together in textbook form for the first time many topics currently found only in the original research literature.

Arthroscopic Repair of Ankle Instability With All-Soft Knotless Anchors.

PubMed

Pereira, Hélder; Vuurberg, Gwen; Gomes, Nuno; Oliveira, Joaquim Miguel; Ripoll, Pedro L; Reis, Rui Luís; Espregueira-Mendes, João; Niek van Dijk, C

2016-02-01

In recent years, arthroscopic and arthroscopically assisted techniques have been increasingly used to reconstruct the lateral ligaments of the ankle. Besides permitting the treatment of several comorbidities, arthroscopic techniques are envisioned to lower the amount of surgical aggression and to improve the assessment of anatomic structures. We describe our surgical technique for arthroscopic, two-portal ankle ligament repair using an all-soft knotless anchor, which is made exclusively of suture material. This technique avoids the need for classic knot-tying methods. Thus it diminishes the chance of knot migration caused by pendulum movements. Moreover, it avoids some complications that have been related to the use of metallic anchors and some currently available biomaterials. It also prevents prominent knots, which have been described as a possible cause of secondary complaints.

Bringing the skills laboratory home: an affordable webcam-based personal trainer for developing laparoscopic skills.

PubMed

Kobayashi, Sow Alfred; Jamshidi, Ramin; O'Sullivan, Patricia; Palmer, Barnard; Hirose, Shinjiro; Stewart, Lygia; Kim, Edward Hyung

2011-01-01

The purpose of this work was to develop a more flexible system of laparoscopic surgery training with demonstrated effectiveness and construct validity. A personal, portable, durable laparoscopic trainer can be designed at low cost. The evaluation of expert surgeons on this device will reveal technical superiority over novices. With practice, novice surgeons can improve their performance significantly as measured by scores derived from performing skills with this training device. Prospective trial with observation and intervention components. The first aspect was observational comparison of novice and expert performance. The second was a prospective static-group comparison with pretest/posttest single-sample design. Tertiary-care academic medical center with affiliated general surgery residency. A total of 21 junior surgical residents and 5 experienced operators. Performance was assessed by the 5 tasks in the McGill Inanimate System for Training and Evaluation of Laparoscopic Skills (MISTELS): pegboard transfer, pattern cutting, placement of ligating loop, extracorporeal knotting, and intracorporeal knotting. Each task was assessed for accuracy and speed. Expert surgeons scored significantly higher than novices on total score and 4 of the 5 MISTELS tasks (peg transfer, pattern cut, extracorporeal knot, and intracorporeal knot). After 4 months of home-based training, the novices improved in total score and 3 of the 5 tasks (peg transfer, pattern cut, and extracorporeal knot). A low-cost personal laparoscopic training device can be built by individual residents. With their use, residents can significantly improve performance in important surgical skills. Evaluation of the system supports its validity. Copyright © 2011 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

Suspension string: a new method of aortic valvuloplasty for aortic insufficiency and ventricular septal defect.

PubMed

Huang, Zhixiong

2006-09-01

In a 4-year-old boy with ventricular septal defect, severe aortic insufficiency, and mild infundibular stenosis, a new method was used to reconstruct the prolapsed aortic cusp. Two ends of a pledged stitch were passed through the aorta at each side of the right, noncoronary commissure and then through another pledget, and were then tied repeatedly in a row. The length of the row of knots was equal to that of the free edge of left coronary or noncoronary leaflet. The remainder of the stitch was passed through a pledget and then the aortic wall at each side of the left and right coronary commissure to the extraaortic wall pledget and were tied. A suspension string was formed by the row of knots and supported by a Teflon (Dupont Teflon, Wilmington, DE) felt pledget sandwich at each of two commissures. The free margin of the prolapsed cusp was attached to the suspension string by a continuous suture. The concomitant anomalies were corrected. The result was satisfactory.

Voluntary autonomous simulator based training in minimally invasive surgery, residents' compliance and reflection.

PubMed

van Empel, Pieter J; Verdam, Mathilde G E; Strypet, Magnus; van Rijssen, Lennart B; Huirne, Judith A; Scheele, Fedde; Bonjer, H Jaap; Meijerink, W Jeroen

2012-01-01

Knot tying and suturing skills in minimally invasive surgery (MIS) differ markedly from those in open surgery. Appropriate MIS training is mandatory before implementation into practice. The Advanced Suturing Course (ASC) is a structured simulator based training course that includes a 6-week autonomous training period at home on a traditional laparoscopic box trainer. Previous research did not demonstrate a significant progress in laparoscopic skills after this training period. This study aims to identify factors determining autonomous training on a laparoscopic box trainer at home. Residents (n = 97) attending 1 of 7 ASC courses between January 2009 and June 2011 were consecutively included. After 6 weeks of autonomous, training a questionnaire was completed. A random subgroup of 30 residents was requested to keep a time log. All residents received an online survey after attending the ASC. We performed outcome comparison to examine the accuracy of individual responses. Out of 97 residents, the main motives for noncompliant autonomous training included a lack of (training) time after working hours (n = 80, 83.3%), preferred practice time during working hours (n = 76, 31.6%), or another surgical interest than MIS (n = 79, 15.2%). Previously set training goals would encourage autonomous training according to 27.8% (n = 18) of residents. Thirty participants submitted a time log and reported an average 76.5-minute weekly training time. All residents confirmed that autonomous home practice on a laparoscopic box trainer is valuable. Autonomous practice should be structured and inclusive of adequate and sufficient feedback points. A minimally required practice time should be set. An obligatory assessment, including corresponding consequence should be conducted. Compliance herewith may result in increased voluntary (autonomous) simulator based (laparoscopic) training by residents. Copyright © 2012 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

Demonstration of Ice-Free Cathodic Protection Systems for Water Storage Tanks at Fort Drum: Final Report on Project AR-F-318 for FY05

DTIC Science & Technology

2007-06-01

and immovable with fingers. Body side rivet base and outside rivet burr should be flat against the material. Bent rivets will fail under stress ...such as using knots, tying around sharp edges, etc.) and maximum permitted free fall distance. Also, to be stressed are the importance of inspections...limitations; e. Application limits; f. Proper hook -up, anchoring and tie-off techniques, including the proper dee-ring or other attachment point to use on

A randomized control trial to evaluate the importance of pre-training basic laparoscopic psychomotor skills upon the learning curve of laparoscopic intra-corporeal knot tying.

PubMed

Molinas, Carlos Roger; Binda, Maria Mercedes; Sisa, Cesar Manuel; Campo, Rudi

2017-01-01

Training of basic laparoscopic psychomotor skills improves the acquisition of more advanced laparoscopic tasks, such as laparoscopic intra-corporeal knot tying (LICK). This randomized controlled trial was designed to evaluate whether pre-training of basic skills, as laparoscopic camera navigation (LCN), hand-eye coordination (HEC), and bimanual coordination (BMC), and the combination of the three of them, has any beneficial effect upon the learning curve of LICK. The study was carried out in a private center in Asunción, Paraguay, by 80 medical students without any experience in surgery. Four laparoscopic tasks were performed in the ENCILAP model (LCN, HEC, BMC, and LICK). Participants were allocated to 5 groups (G1-G5). The study was structured in 5 phases. In phase 1, they underwent a base-line test ( T 1 ) for all tasks (1 repetition of each task in consecutive order). In phase 2, participants underwent different training programs (30 consecutive repetitions) for basic tasks according to the group they belong to (G1: none; G2: LCN; G3: HEC; G4: BMC; and G5: LCN, HEC, and BMC). In phase 3, they were tested again ( T 2 ) in the same manner than at T 1 . In phase 4, they underwent a standardized training program for LICK (30 consecutive repetitions). In phase 5, they were tested again ( T 3 ) in the same manner than at T 1 and T 2 . At each repetition, scoring was based on the time taken for task completion system. The scores were plotted and non-linear regression models were used to fit the learning curves to one- and two-phase exponential decay models for each participant (individual curves) and for each group (group curves). The LICK group learning curves fitted better to the two-phase exponential decay model. From these curves, the starting points ( Y 0), the point after HEC training/before LICK training ( Y 1), the Plateau, and the rate constants ( K ) were calculated. All groups, except for G4, started from a similar point ( Y 0). At Y 1, G5 scored already better than the others (G1 p  = .004; G2 p  = .04; G3 p  < .0001; G4 NS). Although all groups reached a similar Plateau, G5 has a quicker learning than the others, demonstrated by a higher K (G1 p  < 0.0001; G2 p  < 0.0001; G3 p  < 0.0001; and G4 p  < 0.0001). Our data confirms that training improves laparoscopic skills and demonstrates that pre-training of all basic skills (i.e., LCN, HEC, and BMC) shortens the LICK learning curve.

Fishing. Unit 1, Colorado Division of Wildlife.

ERIC Educational Resources Information Center

Hetzel, George K.; Smith, Dwight R.

This booklet on fishing is part of a series developed to encourage youth to pursue outdoor projects. Fish anatomy, equipment, casting techniques, knot and leader tying, hooks, fishing areas, cleaning and cooking fish, types of bait, lures, and regulations are discussed and illustrated. Suggested activities and field trips are listed. (MR)

Use of Collapsible Box Trainer as a Module for Resident Education

PubMed Central

Caban, Angel M.; Guido, Christopher; Silver, Michele; Rossidis, George; Sarosi, George

2013-01-01

Background and Objectives: We sought to determine whether training with a simple collapsible mobile box trainer leads to improved performance of fundamental laparoscopic skills (FLSs) during a 6-month interval versus validated laparoscopic box trainers and virtual-reality trainers, only accessible at a simulation training center. Methods: With institutional review board approval, 20 first- and second-year general surgery residents were randomized to scheduled training sessions in a surgical simulation laboratory or training in the use of a portable, collapsible Train Anywhere Skill Kit (TASKit) (Ethicon Endo-Surgery Cincinnati, OH, USA) trainer. Training was geared toward the FLS set for a skill assessment examination at a 6-month interval. Results: The residents who trained with the TASKit performed the peg-transfer, pattern-cut exercise, Endoloop, and intracorporeal knot-tying FLS tasks statistically more efficiently during their 6-month assessment versus their initial evaluation as compared with the group randomized to the simulation laboratory training. Conclusions: Using a simple collapsible mobile box trainer such as the TASKit can be a cost-effective method of training and preparing residents for FLS tasks considering the current cost associated with virtual and high-definition surgical trainers. This mode of surgical training allows residents to practice in their own time by removing barriers associated with simulation centers. PMID:24018083

KnotProt: a database of proteins with knots and slipknots

PubMed Central

Jamroz, Michal; Niemyska, Wanda; Rawdon, Eric J.; Stasiak, Andrzej; Millett, Kenneth C.; Sułkowski, Piotr; Sulkowska, Joanna I.

2015-01-01

The protein topology database KnotProt, http://knotprot.cent.uw.edu.pl/, collects information about protein structures with open polypeptide chains forming knots or slipknots. The knotting complexity of the cataloged proteins is presented in the form of a matrix diagram that shows users the knot type of the entire polypeptide chain and of each of its subchains. The pattern visible in the matrix gives the knotting fingerprint of a given protein and permits users to determine, for example, the minimal length of the knotted regions (knot's core size) or the depth of a knot, i.e. how many amino acids can be removed from either end of the cataloged protein structure before converting it from a knot to a different type of knot. In addition, the database presents extensive information about the biological functions, families and fold types of proteins with non-trivial knotting. As an additional feature, the KnotProt database enables users to submit protein or polymer chains and generate their knotting fingerprints. PMID:25361973

The Sex Difference in Basic Surgical Skills Learning: A Comparative Study.

PubMed

Lou, Zheng; Yan, Fei-Hu; Zhao, Zhi-Qing; Zhang, Wei; Shui, Xian-Qi; Liu, Jia; Zhuo, Dong-Lan; Li, Li; Yu, En-da

2016-01-01

Very little is known of sex-related differences among medical students in the acquisition of basic surgical skills at an undergraduate level. The aim of this study was to investigate the sex differences in basic surgical skills learning and the possible explanations for sex disparities within basic surgical skills education. A didactic description of 10 surgical skills was performed, including knot tying, basic suture I, basic suture II, sterile technique, preoperative preparation, phlebotomy, debridement, laparotomy, cecectomy, and small bowel resection with hand-sewn anastomosis. The students were rated on a 100-point scale for each basic surgical skill. Later during the same semester all the students took the final theoretical examination. A total of 342 (male = 317 and female = 25) medical students participated in a single skills laboratory as part of their third-year medical student clerkship. The mean scores for each of the 10 surgical skills were higher in female group. The difference in sterile technique, preoperative preparation, cecectomy, and small bowel resection with hand-sewn anastomosis reached the significant level. Compared with male medical students, the mean theory examination score was significantly higher in female medical students. Approximately 76% of the (19 of 25) female students expressed their interest in pursuing a surgical career, whereas only 65.5% (207 of 317) male students wanted to be surgical professionals (p = 0.381). Female medical students completed basic surgical skills training more efficiently and passed the theoretical examination with significantly higher scores than male medical students. In the future, studies should be done in other classes in our institution and perhaps other schools to see if these findings are reliable or valid or just a reflection of this 1 sample. Copyright © 2016 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

Children's Literature--Passage to the Sea.

ERIC Educational Resources Information Center

Bagnall, Norma

Focusing on books that use the sea as their theme, this booklet provides guidelines for teachers on how to integrate marine-related children's literature into the classroom. The first section of the booklet presents brief synopses of eight sea-related books while the second section contains 39 learning center activities, including knot tying,…

Credit Squeeze Exposes Weaknesses in Investments

ERIC Educational Resources Information Center

Blumenstyk, Goldie; Field, Kelly

2008-01-01

This article reports that the credit crisis tying global financing systems into knots has left hundreds of colleges scrambling for cash to pay their bills and to cover the spiking interest on their debts. While it is still unclear to what extent the federal government's new $700-billion bailout package will help unwind the credit tangle, the…

IDRA Newsletter. Volume 44, No. 8

ERIC Educational Resources Information Center

Goodman, Christie L., Ed.

2017-01-01

Each edition of the IDRA Newsletter strives to provide many different perspectives on the issues in education topics discussed and to define its significance in the state and national dialogue. This issue focuses on Culture of Poverty Myths and includes: (1) Tying the Knot Between School Finance Policy and Serving All Students (David G. Hinojosa);…

Physical and functional comparison of Coated VICRYL* Plus Antibacterial Suture (coated polyglactin 910 suture with triclosan) with Coated VICRYL* Suture (coated polyglactin 910 suture).

PubMed

Storch, Mark; Scalzo, Howard; Van Lue, Stephen; Jacinto, Gabriel

2002-01-01

The goal of this study was to compare the physical and functional properties of coated polyglactin 910 suture with and without triclosan by human assessment and instrument-based measurements. Surgeons specializing in general, orthopedic, plastic, or gynecologic surgery evaluated the suture materials in an in vivo porcine model with regard to (1) ease of passage through tissue, (2) first-throw knot holding, (3) knot tie-down smoothness, (4) knot security, (5) surgical handling, and (6) overall evaluation. Breaking strength retention was determined at 14, 21, 28, and 35 days post-implantation in rats using a tensile strength measurement device. The absorption rate was determined in rats by histopathology at 7, 28, 56, 63, 70, and 77 days post-implantation. The tactile smoothness and tie-down behavior of both wet and dry sutures were evaluated by product characterization technicians. The scores for surgeons' evaluation of suture material were favorable and similar for both sutures. Surgeons could not reliably make a distinction in handling between the two sutures. Breaking strength retention was the same for both sutures, ranging from 79% on day 14 to 5% on day 35. Both sutures were essentially absorbed at 70 days post-implantation. Product characterization assessment of the two sutures found them to be indistinguishable. The addition of triclosan to coated polyglactin 910 sutures did not affect physical handling properties or performance characteristics based on the testing and evaluations performed.

Can video games be used to predict or improve laparoscopic skills?

PubMed

Rosenberg, Bradley H; Landsittel, Douglas; Averch, Timothy D

2005-04-01

Performance of laparoscopic surgery requires adequate hand-eye coordination. Video games are an effective way to judge one's hand-eye coordination, and practicing these games may improve one's skills. Our goal was to see if there is a correlation between skill in video games and skill in laparoscopy. Also, we hoped to demonstrate that practicing video games can improve one's laparoscopic skills. Eleven medical students (nine male, two female) volunteered to participate. On day 1, each student played three commercially available video games (Top Spin, XSN Sports; Project Gotham Racing 2, Bizarre Creations; and Amped 2, XSN Sports) for 30 minutes on an X-box (Microsoft, Seattle, WA) and was judged both objectively and subjectively. Next, the students performed four laparoscopic tasks (object transfer, tracing a figure-of-eight, suture placement, and knot-tying) in a swine model and were assessed for time to complete the task, number of errors committed, and hand-eye coordination. The students were then randomized to control (group A) or "training" (i.e., video game practicing; group B) arms. Two weeks later, all students repeated the laparoscopic skills laboratory and were reassessed. Spearman correlation coefficients demonstrated a significant relation between many of the parameters, particularly time to complete each task and hand-eye coordination at the different games. There was a weaker association between video game performance and both laparoscopic errors committed and hand-eye coordination. Group B subjects did not improve significantly over those in group A in any measure (P >0.05 for all). Video game aptitude appears to predict the level of laparoscopic skill in the novice surgeon. In this study, practicing video games did not improve one's laparoscopic skill significantly, but a larger study with more practice time could prove games to be helpful.

The Basic Surgical Skills Course in Sub-Saharan Africa: An Observational Study of Effectiveness.

PubMed

Fergusson, Stuart J; Sedgwick, David M; Ntakiyiruta, Georges; Ntirenganya, Faustin

2018-04-01

The Basic Surgical Skills (BSS) course is a common component of postgraduate surgical training programmes in sub-Saharan Africa, but was originally designed in a UK context, and its efficacy and relevance have not been formally assessed in Africa. An observational study was carried out during a BSS course delivered to early-stage surgical trainees from Rwanda and the Democratic Republic of the Congo. Technical skill in a basic wound closure task was assessed in a formal Objective Structured Assessment of Technical Skills (OSAT) before and after course completion. Participants completed a pre-course questionnaire documenting existing surgical experience and self-perceived confidence levels in surgical skills which were to be taught during the course. Participants repeated confidence ratings and completed course evaluation following course delivery. A cohort of 17 participants had completed a pre-course median of 150 Caesarean sections as primary operator. Performance on the OSAT improved from a mean of 10.5/17 pre-course to 14.2/17 post-course (mean of paired differences 3.7, p < 0.001). Improvements were seen in 15/17 components of wound closure. Pre-course, only 47% of candidates were forming hand-tied knots correctly and 38% were appropriately crossing hands with each throw, improving to 88 and 76%, respectively, following the course (p = 0.01 for both components). Confidence levels improved significantly in all technical skills taught, and the course was assessed as highly relevant by trainees. The Basic Surgical Skills course is effective in improving the basic surgical technique of surgical trainees from sub-Saharan Africa and their confidence in key technical skills.

KnotProt: a database of proteins with knots and slipknots.

PubMed

Jamroz, Michal; Niemyska, Wanda; Rawdon, Eric J; Stasiak, Andrzej; Millett, Kenneth C; Sułkowski, Piotr; Sulkowska, Joanna I

2015-01-01

The protein topology database KnotProt, http://knotprot.cent.uw.edu.pl/, collects information about protein structures with open polypeptide chains forming knots or slipknots. The knotting complexity of the cataloged proteins is presented in the form of a matrix diagram that shows users the knot type of the entire polypeptide chain and of each of its subchains. The pattern visible in the matrix gives the knotting fingerprint of a given protein and permits users to determine, for example, the minimal length of the knotted regions (knot's core size) or the depth of a knot, i.e. how many amino acids can be removed from either end of the cataloged protein structure before converting it from a knot to a different type of knot. In addition, the database presents extensive information about the biological functions, families and fold types of proteins with non-trivial knotting. As an additional feature, the KnotProt database enables users to submit protein or polymer chains and generate their knotting fingerprints. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

Physical Experience Leads to Enhanced Object Perception in Parietal Cortex: Insights from Knot Tying

ERIC Educational Resources Information Center

Cross, Emily S.; Cohen, Nichola Rice; de C. Hamilton, Antonia F.; Ramsey, Richard; Wolford, George; Grafton, Scott T.

2012-01-01

What does it mean to "know" what an object is? Viewing objects from different categories (e.g., tools vs. animals) engages distinct brain regions, but it is unclear whether these differences reflect object categories themselves or the tendency to interact differently with objects from different categories (grasping tools, not animals). Here we…

Topological and metric properties of linear and circular DNA chains in nano-slits and nano-channels

NASA Astrophysics Data System (ADS)

Orlandini, Enzo; Micheletti, Cristian

2014-03-01

Motivated by recent advancements in single DNA molecule experiments, based on nanofluidic devices, we investigate numerically the metric and topological properties of a modelof open and circular DNA chains confined inside nano-slits and nano-channles. The results reveal an interesting characterization of the metric crossover behaviour in terms of the abundance, type and length of occuring knots. In particular we find that the knotting probability is nonmonotonic for increasing confinement and can be largely enhanced or suppressed, compared to the bulk case, by simply varying the slit or channel trasversal dimension. The observed knot population consists of knots that are far simpler than for DNA chains in spherical (i.e. cavities or capsids) confinement. These results suggest that nanoslits and nanochannels can be properly designed to produce open DNA chains hosting simple knots or to sieve DNA rings according to their knotted state. Finally we discuss the implications that the presence of knots may have on the dynamical properties of confined DNA chains such as chain elongation, injection/ejection processes and entanglement relaxation. We acknowledge financial support from the Italian ministry of education, grant PRIN 2010HXAW77.

Extended score interval in the assessment of basic surgical skills.

PubMed

Acosta, Stefan; Sevonius, Dan; Beckman, Anders

2015-01-01

The Basic Surgical Skills course uses an assessment score interval of 0-3. An extended score interval, 1-6, was proposed by the Swedish steering committee of the course. The aim of this study was to analyze the trainee scores in the current 0-3 scored version compared to a proposed 1-6 scored version. Sixteen participants, seven females and nine males, were evaluated in the current and proposed assessment forms by instructors, observers, and learners themselves during the first and second day. In each assessment form, 17 tasks were assessed. The inter-rater reliability between the current and the proposed score sheets were evaluated with intraclass correlation (ICC) with 95% confidence intervals (CI). The distribution of scores for 'knot tying' at the last time point and 'bowel anastomosis side to side' given by the instructors in the current assessment form showed that the highest score was given in 31 and 62%, respectively. No ceiling effects were found in the proposed assessment form. The overall ICC between the current and proposed score sheets after assessment by the instructors increased from 0.38 (95% CI 0.77-0.78) on Day 1 to 0.83 (95% CI 0.51-0.94) on Day 2. A clear ceiling effect of scores was demonstrated in the current assessment form, questioning its validity. The proposed score sheet provides more accurate scores and seems to be a better feedback instrument for learning technical surgical skills in the Basic Surgical Skills course.

Extended score interval in the assessment of basic surgical skills.

PubMed

Acosta, Stefan; Sevonius, Dan; Beckman, Anders

2015-01-01

Introduction The Basic Surgical Skills course uses an assessment score interval of 0-3. An extended score interval, 1-6, was proposed by the Swedish steering committee of the course. The aim of this study was to analyze the trainee scores in the current 0-3 scored version compared to a proposed 1-6 scored version. Methods Sixteen participants, seven females and nine males, were evaluated in the current and proposed assessment forms by instructors, observers, and learners themselves during the first and second day. In each assessment form, 17 tasks were assessed. The inter-rater reliability between the current and the proposed score sheets were evaluated with intraclass correlation (ICC) with 95% confidence intervals (CI). Results The distribution of scores for 'knot tying' at the last time point and 'bowel anastomosis side to side' given by the instructors in the current assessment form showed that the highest score was given in 31 and 62%, respectively. No ceiling effects were found in the proposed assessment form. The overall ICC between the current and proposed score sheets after assessment by the instructors increased from 0.38 (95% CI 0.77-0.78) on Day 1 to 0.83 (95% CI 0.51-0.94) on Day 2. Discussion A clear ceiling effect of scores was demonstrated in the current assessment form, questioning its validity. The proposed score sheet provides more accurate scores and seems to be a better feedback instrument for learning technical surgical skills in the Basic Surgical Skills course.

Usefulness of virtual reality in assessment of medical student laparoscopic skill.

PubMed

Matzke, Josh; Ziegler, Craig; Martin, Kevin; Crawford, Stuart; Sutton, Erica

2017-05-01

This study evaluates if undergraduate medical trainees' laparoscopic skills acquisition could be assessed using a virtual reality (VR) simulator and how the resultant metrics correlate with performance of Fundamentals of Laparoscopic Surgery (FLS) tasks. Our hypothesis is that the VR simulator metrics will correlate with passing results in a competency-based curriculum (FLS). Twenty-eight fourth-year medical students applying for surgical residency were recruited to participate in a VR training curriculum comprised of camera navigation, hand eye coordination, and FLS tasks: circle cutting (CC), ligating loop (LL), peg transfer (PT), and intracorporeal knot tying (IKT). Students were given 8 wk to achieve proficiency goals, after which they were observed performing FLS tasks. The ability of the VR simulator to detect penalties in each of the FLS tasks and correlations of time taken to complete tasks are reported. Twenty-five students trained in all components of the curriculum. All students were proficient in camera navigation and hand eye coordination tasks. Proficiency was achieved in CC, LL, PT, and IKT by 21, 19, 23, and one student, respectively. VR simulation showed high specificity for predicting zero penalties on the observed CC, LL, and PT tasks (80%, 75%, and 80%, respectively). VR can be used to assess medical student's acquisition of laparoscopic skills. The absence of penalties in the simulator reasonably predicts the absence of penalties in all FLS skills, except IKT. The skills acquired by trainees can be used in residency for further monitoring of progress toward proficiency. Copyright © 2016 Elsevier Inc. All rights reserved.

Turning Points in Qualitative Research: Tying Knots in a Handkerchief. Crossroads in Qualitative Inquiry Series.

ERIC Educational Resources Information Center

Lincoln, Yvonna S., Ed.; Denzin, Norman K., Ed.

The chapters of this volume traces the changes in the discipline of qualitative inquiry over the last five decades. The collection serves as a textbook for training scholars in the history and trajectory of qualitative research. The chapters of part 1, The Revolution of Representation: Feminist and Race/Ethnic Studies Discourses, are: (1) Situated…

Transfer of laparoscopic radical prostatectomy skills from bench model to animal model: a prospective, single-blind, randomized, controlled study.

PubMed

Sabbagh, Robert; Chatterjee, Suman; Chawla, Arun; Hoogenes, Jen; Kapoor, Anil; Matsumoto, Edward D

2012-05-01

Learning laparoscopic urethrovesical anastomosis is a crucial step in laparoscopic radical prostatectomy. Previously we noted that practice on a low fidelity urethrovesical model was more effective for trainees than basic suturing drills on a foam pad when learning laparoscopic urethrovesical anastomosis skills. We evaluated learner transfer of skills, specifically whether skills learned on the urethrovesical model would transfer to a high fidelity, live animal model. A total of 28 senior residents, fellows and staff surgeons in urology, general surgery and gynecology were randomized to 2 hours of laparoscopic urethrovesical anastomosis training on a urethrovesical model (group 1) or to basic laparoscopic suturing and knot tying on foam pads (group 2). All participants then performed timed laparoscopic urethrovesical anastomosis on anesthetized female pigs. A blinded urologist scored subject videotaped performance using checklist, global rating scale and end product rating scores. Group 1 was significantly more adept than group 2 at the laparoscopic urethrovesical anastomosis pig task when measured by the checklist, global rating scale and end product rating (each p <0.05). Time to completion was similar in the 2 groups. No statistically significant difference was noted in global rating scale and checklist scores for laparoscopic urethrovesical anastomosis performed on the urethrovesical model vs the pig. Training on a urethrovesical model is superior to training with basic laparoscopic suturing on a foam pad for performing laparoscopic urethrovesical anastomosis skills on an anesthetized female pig. Skills learned on a urethrovesical model transfer to a high fidelity, live animal model. Copyright © 2012 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Deep Gate Recurrent Neural Network

DTIC Science & Technology

2016-11-22

Schmidhuber. A system for robotic heart surgery that learns to tie knots using recurrent neural networks. In IEEE International Conference on...tasks, such as Machine Translation (Bahdanau et al. (2015)) or Robot Reinforcement Learning (Bakker (2001)). The main idea behind these networks is to...and J. Peters. Reinforcement learning in robotics : A survey. The International Journal of Robotics Research, 32:1238–1274, 2013. ISSN 0278-3649. doi

Evaluation of a Surgery-Based Adjunct Course for Senior Medical Students Entering Surgical Residencies.

PubMed

Green, Courtney A; Vaughn, Carolyn J; Wyles, Susannah M; O'Sullivan, Patricia S; Kim, Edward H; Chern, Hueylan

2016-01-01

Preparatory courses for senior medical students aim to ease the transition from medical school to residency. We designed a novel adjunct curriculum to enhance students' readiness for surgical internship. This study addresses the feasibility and outcomes of this course. A curriculum was designed based on ACGME surgical milestones. Students participated in 8 (3h) sessions held over 4 weeks as an adjunct to a well-established intern preparatory course. Course activities involved interactive simulation cases to emphasize care of surgical patients, and skills sessions focused on knot tying and suturing, which were reinforced with home video assignments. Students rated confidence on 14 management skills using a 5-point Likert scale (5 = high confidence). Faculty graded students' technical performance using a global scale (0-10) for 5 suturing exercises. Comparisons between precourse and postcourse data collected for all measures were made using t-tests (α = 0.05). A total of 11 students entering 4 different surgical fields participated. Overall confidence in patient management improved from 2.41 to 3.89 (standard deviation = 0.49, 0.35; p < 0.05). Students' scores on all 5 suturing tasks increased (p < 0.05). We developed a surgery-specific component to the existing preparatory course at our institution. Students demonstrated increased confidence in ward management skills and increased technical scores in all exercises. Although only 3 sessions were dedicated to technical skills, improvements may highlight the benefit of home video assignments. This course serves as a specialty-specific model for schools with existing preparatory courses. Our curriculum highlights skills specific for surgical residency, while maximizing resources. Copyright © 2016 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

Core Concepts: Orthopedic Intern Curriculum Boot Camp.

PubMed

Seeley, Mark A; Kazarian, Erick; King, Brandon; Biermann, Janet S; Carpenter, James E; Caird, Michelle S; Irwin, Todd A

2016-01-01

Orthopedic surgical interns must gain a broad array of clinical skills in a short time. However, recent changes in health care have limited resident-patient exposures. With the reported success of simulation training in the surgical literature, the American Board of Orthopaedic Surgery (ABOS) and Residency Review Committee for Orthopaedic Surgery have required that surgical simulation training be a component of the intern curricula in orthopedic surgical residencies. This study examined the short-term effectiveness of an orthopedic "intern boot camp" covering 7 of 17 simulation training concept modules published by the ABOS. Eight orthopedic post-graduate year 1 (PGY-1) residents (study group) completed a structured 3-month curriculum and were compared with 7 post-graduate year 2 (PGY-2) residents (comparison group) who had just completed their orthopedic surgical internship. Seven core skills were assessed using both task-specific and global rating scales. The PGY-1 residents demonstrated a statistically significant improvement in all 7 modules with respect to their task-specific pre-test scores: sterile technique (P=.001), wound closure (P<.001), knot tying (P=.017), casting and splinting (P<.001), arthrocentesis (P=.01), basics of internal fixation (P<.001), and compartment syndrome evaluation (P=.004). After the camp, PGY-1 and -2 scores in task-specific measures were not significantly different. A 3-month simulation-based boot camp instituted early in orthopedic internship elevated a variety of clinical skills to levels exhibited by PGY-2 residents. Copyright 2016, SLACK Incorporated.

Expert videotape analysis and critiquing benefit laparoscopic skills training of urologists.

PubMed

Nakada, Stephen Y; Hedican, Sean P; Bishoff, Jay T; Shichman, Steven J; Wolf, J Stuart

2004-01-01

Teaching laparoscopic skills has become the focus of the latest generation of hands-on laparoscopic courses. Thirty-four practicing urologists, ages 31 to 61 years (mean, 46.6 years) with laparoscopic experience (range, 0 to 200, mean, 27.6 cases), 32 of whom had taken prior American Urological Association (AUA) laparoscopy courses, participated in an AUA-sponsored hands-on laparoscopic skills course over a 2-day period in August 2002 or March 2003. They all took a knowledge assessment examination and performed standardized tasks (rope passing, ring placement, and laparoscopic suturing and knot tying) at the beginning and the end of the course with a videotape analysis and critique. Prior to the repeat-skills assessment, each participant was individually critiqued and instructed based on a videotape review of their initial performance. The urologists also participated in a porcine laboratory and a pelvic trainer session totaling 6 hours between skills assessments. None of the participants had performed significant laparoscopic suturing prior to the course. Using Wilcoxon's signed rank test, the participants improved from a mean of 119.32 seconds to 98.36 seconds with the rope pass (P = 0.0001), and with the ring placement from a mean of 9.70/minute to 12.09/minute (P = 0.0001). All participants had significantly fewer false passes (mean, 9.35 compared with 5.21) during repeat skills assessments (P = 0.0001). Participants improved from 0.54 sutures/minute to 1.22 sutures/ minute following the video critique and practice (P = 0.0001). Degree of laparoscopic experience (number of cases), age of the urologist, and precourse knowledge (examination score) had no significant bearing on results in the initial skills assessment or in the improvement of task time (Spearman correlation coefficients). Urologists with some laparoscopic experience (mean 27.6 cases) can improve laparoscopic skills using mentored videotape analysis and experience gained from a 2-day hands-on course. Prior knowledge, degree of experience, and urologist age had no significant bearing on performance in this setting.

Knoto-ID: a tool to study the entanglement of open protein chains using the concept of knotoids.

PubMed

Dorier, Julien; Goundaroulis, Dimos; Benedetti, Fabrizio; Stasiak, Andrzej

2018-05-02

The backbone of most proteins forms an open curve. To study their entanglement, a common strategy consists in searching for the presence of knots in their backbones using topological invariants. However, this approach requires to close the curve into a loop, which alters the geometry of curve. Knoto-ID allows evaluating the entanglement of open curves without the need to close them, using the recent concept of knotoids which is a generalization of the classical knot theory to open curves. Knoto-ID can analyse the global topology of the full chain as well as the local topology by exhaustively studying all subchains or only determining the knotted core. Knoto-ID permits to localize topologically non-trivial protein folds that are not detected by informatics tools detecting knotted protein folds. Knoto-ID is written in C ++ and includes R (www.R-project.org) scripts to generate plots of projections maps, fingerprint matrices and disk matrices. Knoto-ID is distributed under the GNU General Public License (GPL), version 2 or any later version and is available at https://github.com/sib-swiss/Knoto-ID. A binary distribution for Mac OS X, Linux and Windows with detailed user guide and examples can be obtained from https://www.vital-it.ch/software/Knoto-ID. julien.dorier@sib.swiss.

Proceedings of the EMU Conference on Foreign Languages for Business and the Professions (Dearborn, Michigan, April 5-7, 1984). Part II: Program Overviews and Components.

ERIC Educational Resources Information Center

Voght, Geoffrey M., Ed.

Part II of the proceedings includes nine presentations. They are: "Business and Foreign Language Tie the Knot at Nazareth College: A Four Year Program Model" (Octave G. Naulleau); "For an Actual Education in International Management" (Alain Eclache and Georges Labet); "A Foreign Language Program for Majors in Hotel and Restaurant Management:…

[TECHNIQUES IN MITRAL VALVE REPAIR VIA A MINIMALLY INVASIVE APPROACH].

PubMed

Ito, Toshiaki

2016-03-01

In mitral valve repair via a minimally invasive approach, resection of the leaflet is technically demanding compared with that in the standard approach. For resection and suture repair of the posterior leaflet, premarking of incision lines is recommended for precise resection. As an alternative to resection and suture, the leaflet-folding technique is also recommended. For correction of prolapse of the anterior leaflet, neochordae placement with the loop technique is easy to perform. Premeasurement with transesophageal echocardiography or intraoperative measurement using a replica of artificial chordae is useful to determine the appropriate length of the loops. Fine-tuning of the length of neochordae is possible by adding a secondary fixation point on the leaflet if the loop is too long. If the loop is too short, a CV5 Gore-Tex suture can be passed through the loop and loosely tied several times to stack the knots, with subsequent fixation to the edge of the leaflet. Finally, skill in the mitral valve replacement technique is necessary as a back-up for surgeons who perform minimally invasive mitral valve repair.

Clinical results of hamstring autografts in anterior cruciate ligament reconstruction: a comparison of femoral knot/press-fit fixation and interference screw fixation.

PubMed

Ho, Wei-Pin; Lee, Chian-Her; Huang, Chang-Hung; Chen, Chih-Hwa; Chuang, Tai-Yuan

2014-07-01

To compare the clinical outcomes of femoral knot/press-fit anterior cruciate ligament (ACL) reconstruction with conventional techniques using femoral interference screws. Among patients who underwent arthroscopic ACL reconstruction with hamstring autografts, 73 were treated with either a femoral knot/press-fit technique (40 patients, group A) or femoral interference screw fixation (33 patients, group B). The clinical results of the 2 groups were retrospectively compared. The inclusion criteria were primary ACL reconstruction in active patients. The exclusion criteria were fractures, multiligamentous injuries, patients undergoing revision, or patients with contralateral ACL-deficient knees. In the femoral knot/press-fit technique, semitendinosus and gracilis tendons were prepared as 2 loops with knots. After passage through a bottleneck femoral tunnel, the grafts were fixed with a press-fit method (grafts' knots were stuck in the bottleneck of the femoral tunnel). A tie with Mersilene tape (Ethicon, Somerville, NJ) over a bone bridge for each tendon loop and an additional bioabsorbable interference screw were used for tibial fixation. The mean follow-up period was 38 months (range, 24 to 61 months). A significant improvement in knee function and symptoms was reported in most patients, as shown by improved Tegner scores, Lysholm knee scores, and International Knee Documentation Committee assessments (P < .01). The results of instrumented laxity testing, thigh muscle assessment, and radiologic assessment were clearly improved when compared with the preoperative status (P < .01). No statistically significant difference in outcomes could be observed between group A and group B (P = not significant). In this nonrandomized study, femoral knot/press-fit ACL reconstruction did not appear to provide increased anterior instability compared with that of conventional femoral interference screw ACL reconstruction. Favorable outcomes with regard to knee stability and patient satisfaction were achieved in most of our ACL-reconstructed patients using femoral knot/press-fit fixation with hamstring tendon autograft. Level IV, therapeutic case series. Copyright © 2014 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Topological semimetals carrying arbitrary Hopf numbers: Fermi surface topologies of a Hopf link, Solomon's knot, trefoil knot, and other linked nodal varieties

NASA Astrophysics Data System (ADS)

Ezawa, Motohiko

2017-07-01

We propose a type of Hopf semimetal indexed by a pair of numbers (p ,q ) , where the Hopf number is given by p q . The Fermi surface is given by a preimage of the Hopf map, which consists of loops nontrivially linked for a nonzero Hopf number. The Fermi surface forms a torus link, whose examples are a Hopf link indexed by (1 ,1 ) , Solomon's knot (2 ,1 ) , a double Hopf link (2 ,2 ) , and a double trefoil knot (3 ,2 ) . We may choose p or q to be a half integer, where the Fermi surface is a torus knot, such as a trefoil knot (3 /2 ,1 ) . It is even possible to make the Hopf number an arbitrary rational number, where a semimetal whose Fermi surface forms open strings is generated.

Are there p-adic knot invariants?

NASA Astrophysics Data System (ADS)

Morozov, A. Yu.

2016-04-01

We suggest using the Hall-Littlewood version of the Rosso-Jones formula to define the germs of p-adic HOMFLY-PT polynomials for torus knots [ m, n] as coefficients of superpolynomials in a q-expansion. In this form, they have at least the [ m, n] ↔ [ n, m] topological invariance. This opens a new possibility to interpret superpolynomials as p-adic deformations of HOMFLY polynomials and poses a question of generalizing to other knot families, which is a substantial problem for several branches of modern theory.

Evaluating Robotic Surgical Skills Performance Under Distractive Environment Using Objective and Subjective Measures.

PubMed

Suh, Irene H; LaGrange, Chad A; Oleynikov, Dmitry; Siu, Ka-Chun

2016-02-01

Distractions are recognized as a significant factor affecting performance in safety critical domains. Although operating rooms are generally full of distractions, the effect of distractions on robot-assisted surgical (RAS) performance is unclear. Our aim was to investigate the effect of distractions on RAS performance using both objective and subjective measures. Fifteen participants performed a knot-tying task using the da Vinci Surgical System and were exposed to 3 distractions: (1) passive distraction entailed listening to noise with a constant heart rate, (2) active distraction included listening to noise and acknowledging a change of random heart rate from 60 to 120 bpm, and (3) interactive distraction consisted of answering math questions. The objective kinematics of the surgical instrument tips were used to evaluate performance. Electromyography (EMG) of the forearm and hand muscles of the participants were collected. The median EMG frequency (EMG(fmed)) and the EMG envelope (EMG(env)) were analyzed. NASA Task Load Index and Fundamentals of Laparoscopic Surgery score were used to evaluate the subjective performance. One-way repeated analysis of variance was applied to examine the effects of distraction on skills performance. Spearman's correlations were conducted to compare objective and subjective measures. Significant distraction effect was found for all objective kinematics measures (P < .05). There were significant distraction effects for EMG measures (EMG(env), P < .004; EMG(fmed), P = .031). Significant distraction effects were also found for subjective measurements. Distraction impairs surgical skills performance and increases muscle work. Understanding how the surgeons cope with distractions is important in developing surgical education. © The Author(s) 2015.

Synthesizing a Trefoil Knotted Block Copolymer via Ring-Expansion Strategy

DOE PAGES

Cao, Pengfei; Rong, Li-Han; Mangadlao, Joey; ...

2017-02-07

We synthesized a synthetic trefoil knotted poly(e-caprolatone) block-poly(L-lactide) (TK-PLA-b-PCL) via a ring expansion strategy from a trefoil knotted tin (Sn) initiator. Ring closing reaction between the bis-copper(I) templated phenanthro line complex and dibutyldimethoxytin results in a templated trefoil knotted initiator. Furthermore, the bis-copper(I) templated trefoil knotted poly(L-lactide) (TK-PLA) can be synthesized by ring-opening polymerization of L-lactide monomer, and decomplexation reaction of the templated TK-PLA will result in a geniune TK-PLA without constraint from the copper template. Subsequent insertion of e caprolactone in the bis-copper(I) templated TK-PLA forms the templated trefoil knotted block copolymer, i.e., TK-PLA-b-PCL, and the copper-free TK-PLA-b-PCL canmore » be obtained by decomplexation reaction. Finally, both TK-PLA and TK-PLA-b-PCL are analyzed by the 1 H NMR, FT-IR, UV-vis, DLS, and GPC.« less

UMass at TREC WEB 2014: Entity Query Feature Expansion using Knowledge Base Links

DTIC Science & Technology

2014-11-01

bears 270 sun tzu 274 golf instruction 291 sangre de cristo mountains 263 evidence for evolution 300 how to find the mean 262 balding cure 280 view my...internet history 294 flowering plants (b) Worst Query Title 264 tribe formerly living in alabama 295 how to tie a windsor knot 283 hayrides in pa 252...work we leverage the rich semantic knowledge available through these links to understand relevance of documents for a query. We fo- cus on the ad hoc

Stable elastic knots with no self-contact

NASA Astrophysics Data System (ADS)

Moulton, Derek E.; Grandgeorge, Paul; Neukirch, Sébastien

2018-07-01

We study an elastic rod bent into an open trefoil knot and clamped at both ends. The question we consider is whether there are stable configurations for which there are no points of self-contact. This idea can be fairly easily replicated with a thin strip of paper, but is more difficult or even impossible with a flexible wire. We search for such configurations within the space of three tuning parameters related to the degrees of freedom in a simple experiment. Mathematically, we show, both within standard Kirchhoff theory as well within an elastic strip theory, that stable and contact-free knotted configurations can be found, and we classify the corresponding parametric regions. Numerical results are complemented with an asymptotic analysis that demonstrates the presence of knots near the doubly-covered ring. In the case of the strip model, quantitative experiments of the region of good knots are also provided to validate the theory.

Expert Videotape Analysis and Critiquing Benefit Laparoscopic Skills Training of Urologists

PubMed Central

Hedican, Sean P.; Bishoff, Jay T.; Shichman, Steven J.; Wolf, J. Stuart

2004-01-01

Introduction: Teaching laparoscopic skills has become the focus of the latest generation of hands-on laparoscopic courses. Methods: Thirty-four practicing urologists, ages 31 to 61 years (mean, 46.6 years) with laparoscopic experience (range, 0 to 200, mean, 27.6 cases), 32 of whom had taken prior American Urological Association (AUA) laparoscopy courses, participated in an AUA-sponsored hands-on laparoscopic skills course over a 2-day period in August 2002 or March 2003. They all took a knowledge assessment examination and performed standardized tasks (rope passing, ring placement, and laparoscopic suturing and knot tying) at the beginning and the end of the course with a videotape analysis and critique. Prior to the repeat-skills assessment, each participant was individually critiqued and instructed based on a videotape review of their initial performance. The urologists also participated in a porcine laboratory and a pelvic trainer session totaling 6 hours between skills assessments. None of the participants had performed significant laparoscopic suturing prior to the course. Results: Using Wilcoxon's signed rank test, the participants improved from a mean of 119.32 seconds to 98.36 seconds with the rope pass (P= 0.0001), and with the ring placement from a mean of 9.70/minute to 12.09/minute (P=0.0001). All participants had significantly fewer false passes (mean, 9.35 compared with 5.21) during repeat skills assessments (P=0.0001). Participants improved from 0.54 sutures/minute to 1.22 sutures/ minute following the video critique and practice (P=0.0001). Degree of laparoscopic experience (number of cases), age of the urologist, and precourse knowledge (examination score) had no significant bearing on results in the initial skills assessment or in the improvement of task time (Spearman correlation coefficients). Conclusion: Urologists with some laparoscopic experience (mean 27.6 cases) can improve laparoscopic skills using mentored videotape analysis and experience gained from a 2-day hands-on course. Prior knowledge, degree of experience, and urologist age had no significant bearing on performance in this setting. PMID:15119667

"Circadian cortical compensation": a longitudinal study of brain function during technical and cognitive skills in acutely sleep-deprived surgical residents.

PubMed

Leff, Daniel Richard; Orihuela-Espina, Felipe; Athanasiou, Thanos; Karimyan, Vahe; Elwell, Clare; Wong, John; Yang, Guang-Zhong; Darzi, Ara W

2010-12-01

To test the hypothesis that fatigue-induced performance decline in surgical residents is associated with changes in brain function as detected by functional near-infrared spectroscopy. Surgical residents (n = 7) participated in a prospective study involving 2-hourly objective measurements of neurocognitive skill (arithmetic calculations using Nintendo "brain training"), technical performance (surgical knot tying on a trainer, and monitoring time taken, path length and number of movements), and introspective fatigue (questionnaire-based) across 10 hours of acute sleep deprivation (10:00 PM to 8:00 PM. Simultaneously, changes in cortical oxyhemoglobin (HbO₂), deoxyhemoglobin (HHb), and total hemoglobin (HbT), inferring prefrontal function, were recorded by using functional near-infrared spectroscopy. Arithmetic performance remained stable despite increasing levels of subject fatigue (time: P = 0.07, errors: P = 0.70, efficiency: P = 0.58). Technical skill improved between the first (10:00 PM and the second (12:00 AM sessions (P < 0.05) and stabilized thereafter (12:00 AM to 8:00 AM. Greater activation was required to complete cognitive versus technical drills. Stimulus type (0: cognitive, 1: technical) was found to be an independent predictor of changes in cortical excitation (HbO₂: P < 0.01, HHb: P < 0.05, HbT: P < 0.01). Cortical responses to the cognitive task increased over the course of the simulated night shift. In addition, "time interval" was observed to be an independent predictor of cortical hemodynamic change (HbO₂: P < 0.01, HbT: P < 0.01). Neurocognitive tasks may tax the sleep-deprived resident more than well-learned technical skills. Performing cognitive skills at night, such as decision making, may depend upon enhanced prefrontal recruitment indicative of a focused attentional strategy and/or compensation to sleep deprivation. Further work should focus on determining whether errors in performance are associated with attentional lapses and failure of cortical compensation.

The impact of goal setting and goal orientation on performance during a clerkship surgical skills training program.

PubMed

Gardner, Aimee K; Diesen, Diana L; Hogg, Deborah; Huerta, Sergio

2016-02-01

The purpose of this study was to integrate relevant goal-setting theory and to identify if trainees' goal orientations have an impact on the assigned goals-performance relationship. Trainees attended 1 of the 3 goal-training activities (do your best, performance, or learning goals) for knot tying (KT) and camera navigation (CN) during the 3rd-year clerkship rotation. Questionnaires and pretests and/or post-tests were completed. One twenty-seven 3rd-year medical students (age: 25 ± 2.6; 54% women) participated in the training program. Pretraining to post-training performance changes were significant for all groups on both tasks (P < .01), but the increase was significantly greater (P < .01) for the learning goals group (do your best: KTΔ = 2.14, CNΔ = 1.69; performance: KTΔ = 2.49, CNΔ = 2.24; learning: KTΔ = 3.04 CNΔ = 2.76). Correlations between goal orientations and improvement were examined, revealing a unique role of goal orientation for performance improvement. These data indicate that consideration of goal type and trainee goal orientation must be considered during curriculum development to maximize educational value. Copyright © 2016 Elsevier Inc. All rights reserved.

Laparoscopic Suturing as a Barrier to Broader Adoption of Laparoscopic Surgery.

PubMed

Lim, Sangtaeck; Ghosh, Sudip; Niklewski, Paul; Roy, Sanjoy

2017-01-01

Laparoscopic surgery is increasingly replacing the open procedure because of its many patient-related benefits that are well aligned with policies and programs that seek to optimize health system performance. However, widespread adoption of laparoscopic surgery has been slow, in part, because of the complexity of laparoscopic suturing. The objective of this study was to review the clinical and economic impacts of laparoscopic suturing in key procedures and to assess its role as a barrier to the broader adoption of laparoscopic surgery. A medical literature search of MEDLINE, EMBASE, and BIOSIS from January 2010 through June 2016 identified 47 relevant articles. Laparoscopic suturing and intracorporeal knot tying may result in extended surgical time, complications, and surgeon errors, while improving patient quality of life through improved cosmesis, diet toleration, and better bowel movements. Despite advancement in surgical techniques and the availability of newer surgical tools, the complexity of laparoscopic suturing continues to be a barrier to greater adoption of MIS. The results of the study underscore the need for development of proficiency in laparoscopic suturing, which may help improve patient outcomes and reduce healthcare costs.

A Novel Technique of Posterolateral Suturing in Thoracoscopic Diaphragmatic Hernia Repair

PubMed Central

Boo, Yoon Jung; Rohleder, Stephan; Muensterer, Oliver J.

2017-01-01

Background  Closure of the posterolateral defect in some cases of congenital diaphragmatic hernia (CDH) can be difficult. Percutaneous transcostal suturing is often helpful to create a complete, watertight closure of the diaphragm. A challenge with the technique is passing the needle out the same tract that it entered so that no skin is caught when the knots are laid down into the subcutaneous tissue. This report describes a novel technique using a Tuohy needle to percutaneously suture the posterolateral defect during thoracoscopic repair of CDH. Case  We report a case of a 6-week-old infant who presented with a CDH and ipsilateral intrathoracic kidney that was repaired using thoracoscopic approach. The posterolateral part of the defect was repaired by percutaneous transcostal suturing and extracorporeal knot tying. To assure correct placement of the sutures and knots, a Tuohy needle was used to guide the suture around the rib and out through the same subcutaneous tract. The total operative time was 145 minutes and there were no perioperative complications. The patient was followed up for 3 months, during which there was no recurrence. Conclusion  Our percutaneous Tuohy technique for closure of the posterolateral part of CDH enables a secure, rapid, and tensionless repair. PMID:28804698

A Novel Technique of Posterolateral Suturing in Thoracoscopic Diaphragmatic Hernia Repair.

PubMed

Boo, Yoon Jung; Rohleder, Stephan; Muensterer, Oliver J

2017-01-01

Background  Closure of the posterolateral defect in some cases of congenital diaphragmatic hernia (CDH) can be difficult. Percutaneous transcostal suturing is often helpful to create a complete, watertight closure of the diaphragm. A challenge with the technique is passing the needle out the same tract that it entered so that no skin is caught when the knots are laid down into the subcutaneous tissue. This report describes a novel technique using a Tuohy needle to percutaneously suture the posterolateral defect during thoracoscopic repair of CDH. Case  We report a case of a 6-week-old infant who presented with a CDH and ipsilateral intrathoracic kidney that was repaired using thoracoscopic approach. The posterolateral part of the defect was repaired by percutaneous transcostal suturing and extracorporeal knot tying. To assure correct placement of the sutures and knots, a Tuohy needle was used to guide the suture around the rib and out through the same subcutaneous tract. The total operative time was 145 minutes and there were no perioperative complications. The patient was followed up for 3 months, during which there was no recurrence. Conclusion  Our percutaneous Tuohy technique for closure of the posterolateral part of CDH enables a secure, rapid, and tensionless repair.

Surgical skill acquisition with self-directed practice using computer-based video training.

PubMed

Jowett, Nathan; LeBlanc, Vicki; Xeroulis, George; MacRae, Helen; Dubrowski, Adam

2007-02-01

Computer-based video training (CBVT) provides flexible opportunities for surgical trainees to learn fundamental technical skills, but may be ineffective in self-directed practice settings because of poor trainee self-assessment. This study examined whether CBVT is effective in a self-directed learning environment among novice trainees. Thirty novice trainees used CBVT to learn the 1-handed square knot while self-assessing their proficiency every 3 minutes. On reaching self-assessed skill proficiency, trainees were randomized to either cease practice or to complete additional practice. Performance was evaluated with computer and expert-based measures during practice and on pretests, posttests, and 1-week retention tests. Analyses revealed performance improvements for both groups (all P < .05), but no differences between the 2 groups (all P > .05) on all tests. CBVT for the 1-handed square knot is effective in a self-directed learning environment among novices. This lends support to the implementation of self-directed digital media-based learning within surgical curricula.

The temporal outcomes of open versus arthroscopic knotted and knotless rotator cuff repair over 5 years

PubMed Central

Lucena, Thomas R; Lam, Patrick H; Millar, Neal L

2015-01-01

Background The present study aimed to determine how repair technique influenced structural and clinical outcomes at 5 years post-surgery. Methods Three cohorts of patients had repair of a symptomatic rotator cuff tear using (i) an open double-row mattress repair technique (n = 25); (ii) arthroscopic single-row simple suture knotted technique (n = 25); or (iii) arthroscopic single-row inverted mattress knotless technique (n = 36) by one surgeon. Standardized patient- and examiner-determined outcomes were obtained pre-operatively and postoperatively with a validated protocol, ultrasound were also performed at the same time. Results Retear occurred more often after open repair (48%) at 5 years than after arthroscopic knotted (33%) and arthroscopic knotless (26%) repair. Retear was associated with increasing age, pre-operative tear size and weaker pre-operative and 5 years postoperative cuff strength. Between 2 years and 5 years, the open repair group experienced an increase in the frequency of pain during activity, as well as in the difficulty experienced and the severity of pain during overhead activities (p < 0.05) and, at 5 years, also experienced more difficulty with overhead activities, compared to the arthroscopic knotless repair group. Conclusions At 5-year follow-up, arthroscopic rotator cuff repair techniques resulted in fewer retears and better outcomes compared to an open double-row technique. PMID:27582985

Kinematics of Parsec-scale Jets of Gamma-Ray Blazars at 43 GHz within the VLBA-BU-BLAZAR Program

NASA Astrophysics Data System (ADS)

Jorstad, Svetlana G.; Marscher, Alan P.; Morozova, Daria A.; Troitsky, Ivan S.; Agudo, Iván; Casadio, Carolina; Foord, Adi; Gómez, José L.; MacDonald, Nicholas R.; Molina, Sol N.; Lähteenmäki, Anne; Tammi, Joni; Tornikoski, Merja

2017-09-01

We analyze the parsec-scale jet kinematics from 2007 June to 2013 January of a sample of γ-ray bright blazars monitored roughly monthly with the Very Long Baseline Array at 43 GHz. In a total of 1929 images, we measure apparent speeds of 252 emission knots in 21 quasars, 12 BL Lacertae objects (BLLacs), and 3 radio galaxies, ranging from 0.02c to 78c; 21% of the knots are quasi-stationary. Approximately one-third of the moving knots execute non-ballistic motions, with the quasars exhibiting acceleration along the jet within 5 pc (projected) of the core, and knots in BLLacs tending to decelerate near the core. Using the apparent speeds of the components and the timescales of variability from their light curves, we derive the physical parameters of 120 superluminal knots, including variability Doppler factors, Lorentz factors, and viewing angles. We estimate the half-opening angle of each jet based on the projected opening angle and scatter of intrinsic viewing angles of knots. We determine characteristic values of the physical parameters for each jet and active galactic nucleus class based on the range of values obtained for individual features. We calculate the intrinsic brightness temperatures of the cores, {T}{{b},{int}}{core}, at all epochs, finding that the radio galaxies usually maintain equipartition conditions in the cores, while ˜30% of {T}{{b},{int}}{core} measurements in the quasars and BLLacs deviate from equipartition values by a factor >10. This probably occurs during transient events connected with active states. In the Appendix, we briefly describe the behavior of each blazar during the period analyzed.

HOMFLY for twist knots and exclusive Racah matrices in representation [333

NASA Astrophysics Data System (ADS)

Morozov, A.

2018-03-01

Next step is reported in the program of Racah matrices extraction from the differential expansion of HOMFLY polynomials for twist knots: from the double-column rectangular representations R = [ rr ] to a triple-column and triple-hook R = [ 333 ]. The main new phenomenon is the deviation of the particular coefficient f[ 332 ][ 21 ] from the corresponding skew dimension, what opens a way to further generalizations.

Attitude Differences and Task Performance for Black and White Naval Recruits in Problem-Solving Groups of Differing Size and Racial Composition.

DTIC Science & Technology

A field study was made in which 288 black and white naval personnel (224 recruits and 64 squad leaders) in groups of varying size and racial composition performed two problem-solving tasks (knot tying and ship-routing). Black and white leaders, subordinates and group types (25% black tetrads, 75% black tetrads, racially balanced dyads and tetrads) were compared in measures of self - esteem , duration of speech, locus of control, job and general satisfaction, Bales IPA behavior, and performance on the tasks.

Augmented reality telementoring (ART) platform: a randomized controlled trial to assess the efficacy of a new surgical education technology.

PubMed

Vera, Angelina M; Russo, Michael; Mohsin, Adnan; Tsuda, Shawn

2014-12-01

Laparoscopic skills training has evolved over recent years. However, conveying a mentor's directions using conventional methods, without realistic on-screen visual cues, can be difficult and confusing. To facilitate laparoscopic skill transference, an augmented reality telementoring (ART) platform was designed to overlay the instruments of a mentor onto the trainee's laparoscopic monitor. The aim of this study was to compare the effectiveness of this new teaching modality to traditional methods in novices performing an intracorporeal suturing task. Nineteen pre-medical and medical students were randomized into traditional mentoring (n = 9) and ART (n = 10) groups for a laparoscopic suturing and knot-tying task. Subjects received either traditional mentoring or ART for 1 h on the validated fundamentals of laparoscopic surgery intracorporeal suturing task. Tasks for suturing were recorded and scored for time and errors. Results were analyzed using means, standard deviation, power regression analysis, correlation coefficient, analysis of variance, and student's t test. Using Wright's cumulative average model (Y = aX (b)) the learning curve slope was significantly steeper, demonstrating faster skill acquisition, for the ART group (b = -0.567, r (2) = 0.92) than the control group (b = -0.453, r (2) = 0.74). At the end of 10 repetitions or 1 h of practice, the ART group was faster versus traditional (mean 167.4 vs. 242.4 s, p = 0.014). The ART group also had fewer fails (8) than the traditional group (13). The ART Platform may be a more effective training technique in teaching laparoscopic skills to novices compared to traditional methods. ART conferred a shorter learning curve, which was more pronounced in the first 4 trials. ART reduced the number of failed attempts and resulted in faster suture times by the end of the training session. ART may be a more effective training tool in laparoscopic surgical training for complex tasks than traditional methods.

Smart Sensor-Based Motion Detection System for Hand Movement Training in Open Surgery.

PubMed

Sun, Xinyao; Byrns, Simon; Cheng, Irene; Zheng, Bin; Basu, Anup

2017-02-01

We introduce a smart sensor-based motion detection technique for objective measurement and assessment of surgical dexterity among users at different experience levels. The goal is to allow trainees to evaluate their performance based on a reference model shared through communication technology, e.g., the Internet, without the physical presence of an evaluating surgeon. While in the current implementation we used a Leap Motion Controller to obtain motion data for analysis, our technique can be applied to motion data captured by other smart sensors, e.g., OptiTrack. To differentiate motions captured from different participants, measurement and assessment in our approach are achieved using two strategies: (1) low level descriptive statistical analysis, and (2) Hidden Markov Model (HMM) classification. Based on our surgical knot tying task experiment, we can conclude that finger motions generated from users with different surgical dexterity, e.g., expert and novice performers, display differences in path length, number of movements and task completion time. In order to validate the discriminatory ability of HMM for classifying different movement patterns, a non-surgical task was included in our analysis. Experimental results demonstrate that our approach had 100 % accuracy in discriminating between expert and novice performances. Our proposed motion analysis technique applied to open surgical procedures is a promising step towards the development of objective computer-assisted assessment and training systems.

Evaluation of longitudinal joint tie bar system.

DOT National Transportation Integrated Search

2011-09-01

"An adequate longitudinal joint tie bar system is essential in the overall performance of concrete pavement. Excessive : longitudinal joint openings are believed to be caused by either inadequate tie bar size or spacing or improper tie bar : installa...

Development and validation of a sensor- and expert model-based training system for laparoscopic surgery: the iSurgeon.

PubMed

Kowalewski, Karl-Friedrich; Hendrie, Jonathan D; Schmidt, Mona W; Garrow, Carly R; Bruckner, Thomas; Proctor, Tanja; Paul, Sai; Adigüzel, Davud; Bodenstedt, Sebastian; Erben, Andreas; Kenngott, Hannes; Erben, Young; Speidel, Stefanie; Müller-Stich, Beat P; Nickel, Felix

2017-05-01

Training and assessment outside of the operating room is crucial for minimally invasive surgery due to steep learning curves. Thus, we have developed and validated the sensor- and expert model-based laparoscopic training system, the iSurgeon. Participants of different experience levels (novice, intermediate, expert) performed four standardized laparoscopic knots. Instruments and surgeons' joint motions were tracked with an NDI Polaris camera and Microsoft Kinect v1. With frame-by-frame image analysis, the key steps of suturing and knot tying were identified and registered with motion data. Construct validity, concurrent validity, and test-retest reliability were analyzed. The Objective Structured Assessment of Technical Skills (OSATS) was used as the gold standard for concurrent validity. The system showed construct validity by discrimination between experience levels by parameters such as time (novice = 442.9 ± 238.5 s; intermediate = 190.1 ± 50.3 s; expert = 115.1 ± 29.1 s; p < 0.001), total path length (novice = 18,817 ± 10318 mm; intermediate = 9995 ± 3286 mm; expert = 7265 ± 2232 mm; p < 0.001), average speed (novice = 42.9 ± 8.3 mm/s; intermediate = 52.7 ± 11.2 mm/s; expert = 63.6 ± 12.9 mm/s; p < 0.001), angular path (novice = 20,573 ± 12,611°; intermediate = 8652 ± 2692°; expert = 5654 ± 1746°; p < 0.001), number of movements (novice = 2197 ± 1405; intermediate = 987 ± 367; expert = 743 ± 238; p < 0.001), number of movements per second (novice = 5.0 ± 1.4; intermediate = 5.2 ± 1.5; expert = 6.6 ± 1.6; p = 0.025), and joint angle range (for different axes and joints all p < 0.001). Concurrent validity of OSATS and iSurgeon parameters was established. Test-retest reliability was given for 7 out of 8 parameters. The key steps "wrapping the thread around the instrument" and "needle positioning" were most difficult to learn. Validity and reliability of the self-developed sensor-and expert model-based laparoscopic training system "iSurgeon" were established. Using multiple parameters proved more reliable than single metric parameters. Wrapping of the needle around the thread and needle positioning were identified as difficult key steps for laparoscopic suturing and knot tying. The iSurgeon could generate automated real-time feedback based on expert models which may result in shorter learning curves for laparoscopic tasks. Our next steps will be the implementation and evaluation of full procedural training in an experimental model.

The comparison of two methods to manufacture fused biconical tapered optical fiber coupler

NASA Astrophysics Data System (ADS)

Wang, Yue; Liu, Hairong

2009-08-01

Optical fiber coupler is a directional coupler which is crucial component for optical fiber communication systems. The fused biconical taper is the most important method in facture of optical fiber coupler, with many advantages of low excess loss, precise coupling ratio, good consistency and stability. In this paper we have introduced a new method to manufacture optical fiber coupler. And more over the new manufacture process has been compared with the traditional manufacture method. In the traditional crafts, two optical fibers are parallel placed, and then use the method of tie a knot of the two optical fibers. In the new process, a new program of fiber placement is introduced. Two optical fibers are parallel placed in the middle of the fixture, and then in order to make the bare part of the optical fiber close as much as possible, the new plan using high temperature resistant material bind the both end of the fiber which are not removing the cladding. After many contrast tests, we can see that adopt the improved method of fiber placement, during the process of fiber pulling, the variation of optical power in the directional arm and the coupler arm are more smooth and steady. But the excess loss (EL) generated in the process of pulling is a bit higher than the traditional method of tie a knot. The tests show that the new method of optical fiber placement is feasible in the actual projects for the manufacture of coupler with low coupling ratio, but for the control of the EL still need further studying.

Visuospatial abilities and fine motor experiences influence acquisition and maintenance of fundamentals of laparoscopic surgery (FLS) task performance.

PubMed

Harrington, Cuan M; Dicker, Patrick; Traynor, Oscar; Kavanagh, Dara O

2018-05-18

Minimally invasive surgery poses a unique learning curve due to the requirement for non-intuitive psychomotor skills. The fundamentals of laparoscopic surgery (FLS) program trains and certifies residents in such skills. However, innate predictors of FLS performance and maintenance remain to be described. This single-centre observational study aimed to assess for candidate factors influencing the acquisition and maintenance of FLS performance amongst a surgically naïve cohort. Laparoscopically naïve medical students were recruited from pre-clinical university grades. Participants completed five visuospatial/psychomotor tests and a questionnaire surveying non-surgical experiences and personality traits. Individuals completed baseline assessments of FLS standard tasks followed by an intensive training course over week one and two on inanimate box trainers. A post-training assessment was performed in week three to evaluate acquisition. Participants were withdrawn from exposure and retested at four 1-month intervals to assess maintenance requirements. Forty-nine participants enrolled with 35 (71.4%) and 33 (67.3%) completing acquisition and maintenance phases, respectively. Mean age of participants was 19.3 (± 1.2) years with 68.6% female predominance. Participants demonstrated significant improvements in all five tasks during the acquisition (p < 0.05) period and maintenance of skills with task exposure at 1-month intervals. Significant predictors of skill acquisition included: card rotations for intracorporeal knot (p = 0.027) and combined tasks (p = 0.028) and cube comparisons for extracorporeal knot (p = 0.040). During skill maintenance: Card rotations predicted performance across all tasks (p < 0.05), Cube comparisons for tasks 1/2/4/5 (p < 0.05), PicSOR for peg transfer (p = 0.017) and grooved pegboard for peg transfer (p = 0.023) and ligating-loop (p = 0.038) tasks. Musical instrument experience demonstrated associations with skill acquisition in peg transfer (p = 0.042) and intracorporeal knot (p = 0.034) while video gaming predicted performance in these tasks (p < 0.05) during the maintenance phase. A sporting background or competitive personality did not influence skill performance. Multiple visuospatial abilities and non-surgical experiences positively influenced FLS performance during skill acquisition and/or maintenance. Further consideration to these individual factors may facilitate selection of more technically adaptable surgical residents.

Construct Validity of Fresh Frozen Human Cadaver as a Training Model in Minimal Access Surgery

PubMed Central

Macafee, David; Pranesh, Nagarajan; Horgan, Alan F.

2012-01-01

Background: The construct validity of fresh human cadaver as a training tool has not been established previously. The aims of this study were to investigate the construct validity of fresh frozen human cadaver as a method of training in minimal access surgery and determine if novices can be rapidly trained using this model to a safe level of performance. Methods: Junior surgical trainees, novices (<3 laparoscopic procedure performed) in laparoscopic surgery, performed 10 repetitions of a set of structured laparoscopic tasks on fresh frozen cadavers. Expert laparoscopists (>100 laparoscopic procedures) performed 3 repetitions of identical tasks. Performances were scored using a validated, objective Global Operative Assessment of Laparoscopic Skills scale. Scores for 3 consecutive repetitions were compared between experts and novices to determine construct validity. Furthermore, to determine if the novices reached a safe level, a trimmed mean of the experts score was used to define a benchmark. Mann-Whitney U test was used for construct validity analysis and 1-sample t test to compare performances of the novice group with the benchmark safe score. Results: Ten novices and 2 experts were recruited. Four out of 5 tasks (nondominant to dominant hand transfer; simulated appendicectomy; intracorporeal and extracorporeal knot tying) showed construct validity. Novices’ scores became comparable to benchmark scores between the eighth and tenth repetition. Conclusion: Minimal access surgical training using fresh frozen human cadavers appears to have construct validity. The laparoscopic skills of novices can be accelerated through to a safe level within 8 to 10 repetitions. PMID:23318058

Laparoscopic Suturing as a Barrier to Broader Adoption of Laparoscopic Surgery

PubMed Central

Ghosh, Sudip; Niklewski, Paul; Roy, Sanjoy

2017-01-01

Background: Laparoscopic surgery is increasingly replacing the open procedure because of its many patient-related benefits that are well aligned with policies and programs that seek to optimize health system performance. However, widespread adoption of laparoscopic surgery has been slow, in part, because of the complexity of laparoscopic suturing. The objective of this study was to review the clinical and economic impacts of laparoscopic suturing in key procedures and to assess its role as a barrier to the broader adoption of laparoscopic surgery. Database: A medical literature search of MEDLINE, EMBASE, and BIOSIS from January 2010 through June 2016 identified 47 relevant articles. Conclusion: Laparoscopic suturing and intracorporeal knot tying may result in extended surgical time, complications, and surgeon errors, while improving patient quality of life through improved cosmesis, diet toleration, and better bowel movements. Despite advancement in surgical techniques and the availability of newer surgical tools, the complexity of laparoscopic suturing continues to be a barrier to greater adoption of MIS. The results of the study underscore the need for development of proficiency in laparoscopic suturing, which may help improve patient outcomes and reduce healthcare costs. PMID:28694682

Arthroscopic repair of the posterior root of the medial meniscus using knotless suture anchor: A technical note.

PubMed

Eun, Sang Soo; Lee, Sang Ho; Sabal, Luigi Andrew

2016-08-01

There are numerous methods for repairing posterior root tears of the medial meniscus (PRTMM). Repair techniques using suture anchors through a high posteromedial portal have been reported. The present study found that using a knotless suture anchor instead of suture anchor seemed easier and faster because it avoided passing the sutures through the meniscus and tying a knot in a small space. This study describes a knotless suture anchor technique through a high posteromedial portal, and its clinical results. Copyright © 2016 Elsevier B.V. All rights reserved.

A Net of Friends: Investigating Friendship by Integrating Attachment Theory and Social Network Analysis.

PubMed

Gillath, Omri; Karantzas, Gery C; Selcuk, Emre

2017-11-01

The current article focuses on attachment style-an individual difference widely studied in the field of close relationships-and its application to the study of social networks. Specifically, we investigated whether attachment style predicts perception and management of social networks. In Study 1, we examined the associations of attachment style with perceptions of network tie strength and multiplexity. In Studies 2a and 2b, we investigated the association between attachment style and network management skills (initiating, maintaining, and dissolving ties) and whether network management skills mediated the associations of attachment style with network tie strength and multiplexity. In Study 3, experimentally enhancing attachment security made people more likely to initiate and less likely to dissolve social ties (for the latter, especially among those high on avoidance or anxiety). As for maintenance, security priming also increased maintenance; however, mainly among people high on attachment anxiety or low on attachment avoidance.

Parent-Implemented Behavioral Skills Training of Social Skills

ERIC Educational Resources Information Center

Dogan, Rebecca K.; King, Melissa L.; Fischetti, Anthony T.; Lake, Candice M.; Mathews, Therese L.; Warzak, William J.

2017-01-01

Impairment in social skills is a primary feature of Autism Spectrum Disorders (ASDs). Research indicates that social skills are intimately tied to social development and negative social consequences can persist if specific social behaviors are not acquired. The present study evaluated the effects of behavioral skills training (BST) on teaching…

Topological vortices in gauge models of graphene

NASA Astrophysics Data System (ADS)

Zhang, Xin-Hui; Li, Xueqin; Hao, Jin-Bo

2018-06-01

Graphene-like structure possessing the topological vortices and knots, and the magnetic flux of the vortices configuration quantized, are proposed in this paper. The topological charges of the vortices are characterized by Hopf indices and Brower degrees. The Abelian background field action (BF action) is a topological invariant for the knot family, which is just the total sum of all the self-linking numbers and all the linking numbers. Flux quantization opens the possibility of having Aharonov-Bohm-type effects in graphene without external electromagnetic field.

The impact of heat stress on operative performance and cognitive function during simulated laparoscopic operative tasks.

PubMed

Berg, Regan J; Inaba, Kenji; Sullivan, Maura; Okoye, Obi; Siboni, Stefano; Minneti, Michael; Teixeira, Pedro G; Demetriades, Demetrios

2015-01-01

Increasing ambient temperature to prevent intraoperative patient hypothermia remains widely advocated despite unconvincing evidence of efficacy. Heat stress is associated with decreased cognitive and psychomotor performance across multiple tasks but remains unexamined in an operative context. We assessed the impact of increased ambient temperature on laparoscopic operative performance and surgeon cognitive stress. Forty-two performance measures were obtained from 21 surgery trainees participating in the counter-balanced, within-subjects study protocol. Operative performance was evaluated with adaptations of the validated, peg-transfer, and intracorporeal knot-tying tasks from the Fundamentals of Laparoscopic Surgery program. Participants trained to proficiency before enrollment. Task performance was measured at two ambient temperatures, 19 and 26°C (66 and 79°F). Participants were randomly counterbalanced to initial hot or cold exposure before crossing over to the alternate environment. Cognitive stress was measured using the validated Surgical Task Load Index (SURG-TLX). No differences in performance of the peg-transfer and intracorporeal knot-tying tasks were seen across ambient conditions. Assessed via use of the six bipolar scales of the SURG-TLX, we found differences in task workload between the hot and cold conditions in the areas of physical demands (hot 10 [3-12], cold 5 [2.5-9], P = .013) and distractions (hot 8 [3.5-15.5], cold 3 [1.5-5.5], P = .001). Participant perception of distraction remained greater in the hot condition on full scoring of the SURG-TLX. Increasing ambient temperature to levels advocated for prevention of intraoperative hypothermia does not greatly decrease technical performance in short operative tasks. Surgeons, however, do report increased perceptions of distraction and physical demand. The impact of these findings on performance and outcomes during longer operative procedures remains unclear. Copyright © 2015 Elsevier Inc. All rights reserved.

[Application of inner figure-of-eight suture to laparoscopic colorectal surgery].

PubMed

Chen, Jianjun; Zhong, Ming

2018-03-25

Regardless of laparoscopic or open colorectal surgeries, intestinal anastomosis is usually an important operative procedure. Even if stapler is widely used in different intestinal surgery nowadays, hand sewn suture is an indispensable procedure in clinical practice, meanwhile after stapled anastomosis, additional hand sewn suture is usually performed to ensure the safety of anastomosis. The inner figure-of-eight suture is a single layer suture technique which has been widely used in skin, tendon, rectus and uterus for quick and secure approximation. We describe our innovative application of inner figure-of-eight suture technique for intestinal anastomosis and/or reinforcement after stapled anastomosis in laparoscopic colorectal surgery. Main steps of inner figure-of-eight suture for intestinal anastomosis on posterior wall are as follows: (1) At 4 mm from cut edge of bowel, needle enters vertically from one side and courses mucosa-serosa-opposite serosa-mucosa in parallel to the entry point. (2) The needle is brought back to first entry side of bowel at 45 degree to enter the mucosa 5 mm below the first entry point and out on opposite side mucosa horizontally. (3) Both lose ends of the suture are pulled to approximate bowel edges and knots are tied on mucosal surface, in which suture line presents figure-of-eight on mucosal surface and two parallel suture lines are seen on serosal surface. When inner figure-of-eight suture is performed on anterior wall, the procedure is similar, but needle passes from serosa-mucosa-opposite mucosa-serosa and repeated to complete the inner figure-8 suture and knots are tied on serosa. The final look is two parallel sutures at 0.5 mm in between and the figure-of-eight remains inside the lumen. We did not deliberately try to invert the bowel edges, and if anastomosis is not satisfactory at final examination, simple interrupted seromuscular suture can be carried out. From 2015 till now, we have successfully completed inner figure-of-eight sutures in 38 cases receiving intestinal anastomosis reinforcement procedure and in 24 cases receiving hand sewn anastomosis. Comparison study revealed inner figure-of-eight suture presented shorter anastomotic time and less medical cost without anastomotic leakage, stump leakage or bleeding. No anastomotic stenosis was found at enteroscopy examination during follow up. We think that inner figure-of-eight suture possesses safe and simple advantages and is a manual suture technique worthy of promotion.

A modified laryngeal tie-forward procedure using metallic implants for treatment of dorsal displacement of the soft palate in horses.

PubMed

Rossignol, Fabrice; Ouachée, Emilie; Boening, Karl Josef

2012-08-01

To describe a modified laryngeal tie-forward procedure (LTFP) using metallic implants. Retrospective case series. Twenty-seven horses (including 24 race horses) with dorsal displacement of the soft palate (DDSP) or palatal instability (PI) diagnosed using high-speed treadmill endoscopy (n = 15), history and resting examination (n = 8), or dynamic endoscopy over ground (n = 4). All horses underwent the modified LTFP. Modifications of the surgical procedure consisted in the use of 3 metallic stents called Suture Button(TM) through which the sutures are threaded and in a tying technique that involved a single knot connecting left and right suture loops (versus tying each separately). Lateral radiographs were taken 24 hours after surgery. Follow-up was obtained by telephone communication with trainers or owners. Surgery was performed without complications on all horses. The 3 metallic buttons were clearly visible on the postoperative radiographic examination. No evidence of suture breakage was observed 24 hours postoperatively based on radiographs. In other aspects, this technique is not very different from that originally described by Ducharme et al; it is an innovation that could offer some advantages to the surgeons and increase suture resistance to pullout from the thyroid cartilage. Our technique was used without complication in a small group of horses and return to performance may be similar to the original technique. © Copyright 2012 by The American College of Veterinary Surgeons.

An original use in low colo-rectal anastomosis of the new surgical device "grasping tie".

PubMed

Picardi, Nicola

2005-01-01

The grasping tie is an original and mechanical tool, conceived and planned to be used in digestive surgery to do the equivalent of a purse string. Its use is conceived to make easier the mechanical anastomosis in the more difficult situations as the oesophago-jejunal or the very low colo-rectal ones, as in the example of the presented paper. A thin ribbon of nylon will be progressively tightened as a one-way running knot upon the tract of the gut, either directly or about the axis of a circular stapler. Once completed the stapler suture it will be completely extracted together with the muscle-mucosal rings, so that nothing of the ribbon remains in the patient. The use of the grasping tie is also advantageous in quickly closing the gut above and below a tumour, to a safer manipulation and to reduce the contamination of the operative field. An original and useful use of the grasping tie is demonstrated in the present paper for the surgical treatment of a low rectal cancer with preservation of the anus. Its use is that to close the distal stump of the rectum below the tumour, to take away from the pelvis the proximal stump with the tumour, and then to proceed to the mechanical anastomosis in a now wide operatory field, introducing in the anus an enteral dilator and preparing on it the definitive purse string, as illustrated.

The American College of Surgeons/Association of Program Directors in Surgery National Skills Curriculum: adoption rate, challenges and strategies for effective implementation into surgical residency programs.

PubMed

Korndorffer, James R; Arora, Sonal; Sevdalis, Nick; Paige, John; McClusky, David A; Stefanidis, Dimitris

2013-07-01

The American College of Surgeons/Association of Program Directors in Surgery (ACS/APDS) National Skills Curriculum is a 3-phase program targeting technical and nontechnical skills development. Few data exist regarding the adoption of this curriculum by surgical residencies. This study attempted to determine the rate of uptake and identify implementation enablers/barriers. A web-based survey was developed by an international expert panel of surgical educators (5 surgeons and 1 psychologist). After piloting, the survey was sent to all general surgery program directors via email link. Descriptive statistics were used to determine the residency program characteristics and perceptions of the curriculum. Implementation rates for each phase and module were calculated. Adoption barriers were identified quantitatively and qualitatively using free text responses. Standardized qualitative methodology of emergent theme analysis was used to identify strategies for success and details of support required for implementation. Of the 238 program directors approached, 117 (49%) responded to the survey. Twenty-one percent (25/117) were unaware of the ACS/APDS curriculum. Implementation rates for were 36% for phase I, 19% for phase II, and 16% for phase III. The most common modules adopted were the suturing, knot-tying, and chest tube modules of phase I. Over 50% of respondents identified lack of faculty protected time, limited personnel, significant costs, and resident work-hour restrictions as major obstacles to implementation. Strategies for effective uptake included faculty incentives, adequate funding, administrative support, and dedicated time and resources. Despite the availability of a comprehensive curriculum, its diffusion into general surgery residency programs remains low. Obstacles related to successful implementation include personnel, learner, and administrative issues. Addressing these issues may improve the adoption rate of the curriculum. Copyright © 2013 Mosby, Inc. All rights reserved.

A Vascular Anastomosis Simulation Can Provide a Safe and Effective Environment for Resident Skills Development.

PubMed

Heelan Gladden, Alicia A; Conzen, Kendra D; Benge, Michael J; Gralla, Jane; Kennealey, Peter T

2018-04-09

Vascular anastomoses are complex surgical procedures, performed in time-sensitive circumstances, making intraoperative teaching more challenging. We sought to evaluate whether a vascular anastomosis simulation was effective in developing resident skills. General surgery residents participated in a vascular anastomosis simulation for 1 to 2hours during their transplant rotation. An attending transplant surgeon at the University of Colorado guided the resident through end-to-end and end-to-side anastomoses using bovine carotid artery (Artegraft). The residents completed a presimulation and postsimulation survey which quantitated their confidence. They also completed the MiSSES scale, which assessed the validity of the simulation. Twenty residents participated in the simulation and completed the surveys. The residents reported increased understanding in how to set up an end-to-end anastomosis and an end-to-side anastomosis (p = 0.001 and p = 0.009, respectively). They reported increased ability to suture, forehand and backhand with a Castro-Viejo needle driver (both p < 0.001). The residents reported increased ability to manipulate the needle (p = 0.006), and increased ability to manipulate tissue without causing trauma (p = 0.021). They reported increased confidence in tying a surgical knot with 6-0 Prolene and in operating while wearing loupes (p = 0.002, and p < 0.001, respectively). Overall, the residents reported increased confidence when asked to perform part of a vascular anastomosis in the operating room (p < 0.001). Seventeen residents completed the MiSSES scale with median scores of "somewhat agree" to "strongly agree" on all domains of the scale. The use of a simple, inexpensive vascular anastomosis simulation is an effective and safe environment to improve residents' surgical skills and the residents felt that the simulation was valid. Copyright © 2018 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

The value of haptic feedback in conventional and robot-assisted minimal invasive surgery and virtual reality training: a current review.

PubMed

van der Meijden, O A J; Schijven, M P

2009-06-01

Virtual reality (VR) as surgical training tool has become a state-of-the-art technique in training and teaching skills for minimally invasive surgery (MIS). Although intuitively appealing, the true benefits of haptic (VR training) platforms are unknown. Many questions about haptic feedback in the different areas of surgical skills (training) need to be answered before adding costly haptic feedback in VR simulation for MIS training. This study was designed to review the current status and value of haptic feedback in conventional and robot-assisted MIS and training by using virtual reality simulation. A systematic review of the literature was undertaken using PubMed and MEDLINE. The following search terms were used: Haptic feedback OR Haptics OR Force feedback AND/OR Minimal Invasive Surgery AND/OR Minimal Access Surgery AND/OR Robotics AND/OR Robotic Surgery AND/OR Endoscopic Surgery AND/OR Virtual Reality AND/OR Simulation OR Surgical Training/Education. The results were assessed according to level of evidence as reflected by the Oxford Centre of Evidence-based Medicine Levels of Evidence. In the current literature, no firm consensus exists on the importance of haptic feedback in performing minimally invasive surgery. Although the majority of the results show positive assessment of the benefits of force feedback, results are ambivalent and not unanimous on the subject. Benefits are least disputed when related to surgery using robotics, because there is no haptic feedback in currently used robotics. The addition of haptics is believed to reduce surgical errors resulting from a lack of it, especially in knot tying. Little research has been performed in the area of robot-assisted endoscopic surgical training, but results seem promising. Concerning VR training, results indicate that haptic feedback is important during the early phase of psychomotor skill acquisition.

Relationships: The Critical Ties That Bind Professionals.

ERIC Educational Resources Information Center

Roper, Larry

2002-01-01

This article proposes that the success of student affairs professionals is more closely tied to their ability to construct and manage essential relationships during their careers than any other activity. The author discusses essential principles and skills in developing and managing professional relationships. (GCP)

Modified loop technique in three dogs with mitral regurgitation.

PubMed

Aoki, Takuma; Fujii, Yoko; Sunahara, Hiroshi; Takano, Hiroshi; Wakao, Yoshito

2013-01-31

Mitral valvuloplasty (MVP) is used in dogs with refractory mitral regurgitation (MR); however, it is difficult to tie the artificial chord, i.e., the expanded polytetrafluoroethylene suture, at the planned height of the mitral valve, because of the slippery nature of the knot. The loop technique has resolved these difficulties in humans. Premanufactured loops (length, 8.0-15.0 mm with 1.0-mm increments) were used in the new modified loop technique. In the current study, cardiac murmurs disappeared, and the MR markedly improved or completely disappeared approximately 3 months after surgery in 3 dogs. Therefore, this new technique might be effective in dogs.

Performance evaluation of stereo endoscopic imaging system incorporating TFT-LCD.

PubMed

Song, C-G; Park, S-K

2005-01-01

This paper presents a 3D endoscopic video system designed to improve visualization and enhance the ability of the surgeon to perform delicate endoscopic surgery. In a comparison of the polarized and electric shutter-type stereo imaging systems, the former was found to be superior in terms of both accuracy and speed for knot-tying and for the loop pass test. The results of our experiments show that the proposed 3D endoscopic system has a sufficiently wide viewing angle and zone for multi-viewing, and that it provides better image quality and more stable optical performance compared with the electric shutter-type.

Impact of continuous training through distributed practice for acquisition of minimally invasive surgical skills.

PubMed

Nakata, Bruce Negrello; Cavalini, Worens; Bonin, Eduardo A; Salvalaggio, Paolo R; Loureiro, Marcelo P

2017-10-01

Minimally invasive surgery (MIS) requires the mastery of manual skills and a specific training is required. Apart from residencies and fellowships in MIS, other learning opportunities utilize massive training, mainly with use of simulators in short courses. A long-term postgraduate course represents an opportunity to learn through training using distributed practice. The objective of this study is to assess the use of distributed practice for acquisition of basic minimally invasive skills in surgeons who participated in a long-term MIS postgraduate course. A prospective, longitudinal and quantitative study was conducted among surgeons who attended a 1-year postgraduate course of MIS in Brazil, from 2012 to 2014. They were tested through five different exercises in box trainers (peg-transfer, passing, cutting, intracorporeal knot, and suture) in the first (t0), fourth (t1) and last, eighth, (t2) meetings of this course. The time and penalties of each exercise were collected for each participant. Participant skills were assessed based on time and accuracy on a previously tested score. Fifty-seven surgeons (participants) from three consecutive groups participated in this study. There was a significant improvement in scores in all exercises. The average increase in scores between t0 and t2 was 88% for peg-transfer, 174% for passing, 149% for cutting, 130% for intracorporeal knot, and 120% for suture (p < 0.001 for all exercises). Learning through distributed practice is effective and should be integrated into a MIS postgraduate course curriculum for acquisition of core skills.

29 CFR 1915.71 - Scaffolds or staging.

Code of Federal Regulations, 2011 CFR

2011-07-01

... large, loose or dead knots. It shall also be free from dry rot, large checks, worm holes or other... welding, burning, riveting or open flame work shall be performed on any staging suspended by means of... sections of extension trestle ladders shall be so spread that when in an open position the spread of the...

29 CFR 1915.71 - Scaffolds or staging.

Code of Federal Regulations, 2014 CFR

2014-07-01

... large, loose or dead knots. It shall also be free from dry rot, large checks, worm holes or other... welding, burning, riveting or open flame work shall be performed on any staging suspended by means of... sections of extension trestle ladders shall be so spread that when in an open position the spread of the...

29 CFR 1915.71 - Scaffolds or staging.

Code of Federal Regulations, 2012 CFR

2012-07-01

... large, loose or dead knots. It shall also be free from dry rot, large checks, worm holes or other... welding, burning, riveting or open flame work shall be performed on any staging suspended by means of... sections of extension trestle ladders shall be so spread that when in an open position the spread of the...

29 CFR 1915.71 - Scaffolds or staging.

Code of Federal Regulations, 2013 CFR

2013-07-01

... large, loose or dead knots. It shall also be free from dry rot, large checks, worm holes or other... welding, burning, riveting or open flame work shall be performed on any staging suspended by means of... sections of extension trestle ladders shall be so spread that when in an open position the spread of the...

Typical Intellectual Engagement as a Byproduct of Openness, Learning Approaches, and Self-Assessed Intelligence

ERIC Educational Resources Information Center

Arteche, Adriane; Chamorro-Premuzic, Tomas; Ackerman, Phillip; Furnham, Adrian

2009-01-01

Students (n = 328) from US and UK universities completed four self-report measures related to intellectual competence: typical intellectual engagement (TIE), openness to experience, self-assessed intelligence (SAI), and learning approaches. Confirmatory data reduction was used to examine the structure of TIE and supported five major factors:…

14 CFR 25.233 - Directional stability and control.

Code of Federal Regulations, 2011 CFR

2011-01-01

... piloting skill or alertness, in power-off landings at normal landing speed, without using brakes or engine... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Flight Ground and Water Handling... that the wind velocity need not exceed 25 knots at any speed at which the airplane may be expected to...

14 CFR 25.233 - Directional stability and control.

Code of Federal Regulations, 2012 CFR

2012-01-01

... piloting skill or alertness, in power-off landings at normal landing speed, without using brakes or engine... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Flight Ground and Water Handling... that the wind velocity need not exceed 25 knots at any speed at which the airplane may be expected to...

14 CFR 25.233 - Directional stability and control.

Code of Federal Regulations, 2014 CFR

2014-01-01

... piloting skill or alertness, in power-off landings at normal landing speed, without using brakes or engine... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Flight Ground and Water Handling... that the wind velocity need not exceed 25 knots at any speed at which the airplane may be expected to...

14 CFR 25.233 - Directional stability and control.

Code of Federal Regulations, 2013 CFR

2013-01-01

... piloting skill or alertness, in power-off landings at normal landing speed, without using brakes or engine... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Flight Ground and Water Handling... that the wind velocity need not exceed 25 knots at any speed at which the airplane may be expected to...

Interminable Knots: Hostages to Toxic Stories

ERIC Educational Resources Information Center

Sagan, Olivia

2011-01-01

This paper presents one case study from a five-year psychosocial exploration of the auto/biographic activity of a small group of mental health service users. Each individual voluntarily took part in a weekly basic expressive literacy course in which they were encouraged to improve their writing skills. Biographic narrative interviews which…

76 FR 18589 - Self-Regulatory Organizations; The NASDAQ Stock Market LLC; Notice of Filing of Proposed Rule...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-04

...) of that Rule. This tie-breaker resolves price disputes based on minimizing order imbalances. In other... Opening Cross, the system will choose that price which minimizes the order imbalance remaining if the... opening cross. NASDAQ initially adopted the imbalance-based tie-breaker based upon its successful use in...

Tracking the Integration of Library Skills in the Curriculum.

ERIC Educational Resources Information Center

Gill, Suzanne L.

2003-01-01

Describes the use of IMSeries software, a relational database capable of implementing curriculum design, in an elementary school. Topics include Big6 research skills; tracking the scope and sequence of curriculum; tying library skills to curricular disciplines; information literacy; and examples of a lesson unit and assessment strategy. (LRW)

Developing the Effective Teaching Skills of Teacher Candidates during Early Field Experiences

ERIC Educational Resources Information Center

Welsh, Kelly A.; Schaffer, Connie

2017-01-01

This study examined the development of effective teaching skills in teacher candidates in the context of early field experiences directly tied to a pedagogical course. Evidence from faculty instructors, mentor teachers, and teacher candidates suggests secondary education candidates were able to develop effective teaching skills related to…

Development and validation of a laparoscopic hysterectomy cuff closure simulation model for surgical training.

PubMed

Tunitsky-Bitton, Elena; Propst, Katie; Muffly, Tyler

2016-03-01

The number of robotically assisted hysterectomies is increasing, and therefore, the opportunities for trainees to become competent in performing traditional laparoscopic hysterectomy are decreasing. Simulation-based training is ideal for filling this gap in training. The objective of the study was to design a surgical model for training in laparoscopic vaginal cuff closure and to present evidence of its validity and reliability as an assessment and training tool. Participants included gynecology staff and trainees at 2 tertiary care centers. Experienced surgeons were also recruited at the combined International Urogynecologic Association and American Urogynecologic Society scientific meeting. Participants included 19 experts and 21 trainees. All participants were recorded using the laparoscopic hysterectomy cuff closure simulation model. The model was constructed using the an advanced uterine manipulation system with a sacrocolopexy tip/vaginal stent, a vaginal cuff constructed from neoprene material and lined with a swimsuit material (nylon and spandex) secured to the vaginal stent with a plastic cable tie. The uterine manipulation system was attached to the fundamentals of laparoscopic surgery laparoscopic training box trainer using a metal bracket. Performance was evaluated using the Global Operative Assessment of Laparoscopic Skills scale. In addition, needle handling, knot tying, and incorporation of epithelial edge were also evaluated. The Student t test was used to compare the scores and the operating times between the groups. Intrarater reliability between the scores by the 2 masked experts was measured using the interclass correlation coefficient. Total and annual experience with laparoscopic suturing and specifically vaginal cuff closure varied greatly among the participants. For the construct validity, the participants in the expert group received significantly higher scores in each of the domains of the Global Operative Assessment of Laparoscopic Skills Scale and for each of the 3 added items than did the trainees. The median total Global Operative Assessment of Laparoscopic Skills Scale score (maximum 20) for the experts was 18.8 (range, 11-20), whereas the median total Global Operative Assessment of Laparoscopic Skills Scale score for the trainees was 10 (range, 8-18) (P = .001). The overall score that included the 3 new domains (maximum 35) was 33 (range, 18-35) for the experts and 17.5 (range, 14-31.5) for trainees (P = .001). For the face validity testing, the majority of the study participants (32 [85%]) agreed or strongly agreed that the model is realistic and all participants agreed or strongly agreed that the model appears to be useful for improving technique required for this task. For the interrater reliability, the scores assigned by each observer had an interclass correlation coefficient of 0.8 (95% confidence interval, 0.7-0.93). This model is easily constructed and has an acceptable cost. We have demonstrated evidence of construct validity. This is a valuable education tool that can serve to improve skills, which are essential to the gynecological surgeon but are often lacking in residency training because of national changes in practice patterns. Copyright © 2016 Elsevier Inc. All rights reserved.

14 CFR 29.173 - Static longitudinal stability.

Code of Federal Regulations, 2011 CFR

2011-01-01

... of the control is necessary to obtain an airspeed less than the trim speed, and a forward movement of the control is necessary to obtain an airspeed more than the trim speed. (b) Throughout the full range... maintain airspeed within ±5 knots of the desired trim airspeed without exceptional piloting skill or...

14 CFR 27.173 - Static longitudinal stability.

Code of Federal Regulations, 2011 CFR

2011-01-01

... control is necessary to obtain an airspeed less than the trim speed, and a forward movement of the control is necessary to obtain an airspeed more than the trim speed. (b) Throughout the full range of... within ±5 knots of the desired trim airspeed without exceptional piloting skill or alertness. [Amdt. 27...

A Technology Integration Education (TIE) Model: Millennial Preservice Teachers' Motivations about Technological, Pedagogical, and Content Knowledge (TPACK) Competencies

ERIC Educational Resources Information Center

Holland, Denise D.; Piper, Randy T.

2014-01-01

Nobel laureates Schultz (1971) and Becker (1964, 1993) reinvigorated the analysis of education investments. Human capital investments that improve cognitive skills for elementary and secondary students have important economic implications. An interdisciplinary, 12-construct technology integration education (TIE) model was developed. The sample…

How university students with reading difficulties are supported in achieving their goals.

PubMed

Stack-Cutler, Holly L; Parrila, Rauno K; Jokisaari, Markku; Nurmi, Jari-Erik

2015-01-01

We examine (a) what social ties university students with a history of reading difficulty (RD) report assisting them to achieve their goals, (b) outlets available for developing social ties, (c) resources mobilized within these relationships, and (d) the impact of social ties' status on academic achievement. Participants were 107 university students with RD who were currently completing or had recently completed a university degree. Results showed that university students with RD named friends, parents, and significant others (e.g., boy/girlfriend, spouse) as social ties most often. Personal social ties were developed through social media networking sites and within close relationships, and institutional social ties through academic centers and university general services, among others. Resources mobilized among personal and institutional social ties included emotional and social support, advice and planning, writing and studying help, and goal setting. Institutional social ties also afforded job search assistance, accommodations, skill development, financial support, and mental health services. Finally, the status of employed, but not student, social ties explained academic achievement. © Hammill Institute on Disabilities 2013.

Spacer grid assembly and locking mechanism

DOEpatents

Snyder, Jr., Harold J.; Veca, Anthony R.; Donck, Harry A.

1982-01-01

A spacer grid assembly is disclosed for retaining a plurality of fuel rods in substantially parallel spaced relation, the spacer grids being formed with rhombic openings defining contact means for engaging from one to four fuel rods arranged in each opening, the spacer grids being of symmetric configuration with their rhombic openings being asymmetrically offset to permit inversion and relative rotation of the similar spacer grids for improved support of the fuel rods. An improved locking mechanism includes tie bars having chordal surfaces to facilitate their installation in slotted circular openings of the spacer grids, the tie rods being rotatable into locking engagement with the slotted openings.

Alumni Networks--"An Untapped Potential to Gain and Retain Highly-Skilled Workers?"

ERIC Educational Resources Information Center

David, Alexandra; Coenen, Frans

2014-01-01

In times of increasing skills shortage, regions and particularly non-core regions, need to attract highly-skilled workers. It is better for these regions to (re)attract highly-skilled workers that gained knowledge and contacts elsewhere and because they once lived in the region for study have already ties to the university region than trying to…

State Initiatives on Industry-Based Skill Standards and Credentials.

ERIC Educational Resources Information Center

Ganzglass, Evelyn; Simon, Martin

A study examined state initiatives for industry-based skill standards and credentials. Officials in 19 states were interviewed, case studies of programs in 3 states (Georgia, Pennsylvania, and Texas) were conducted, and focus group discussions were held with 25 individuals. State skill standards were generally found to be tied to broader efforts…

Establishing and Enriching School-Community Ties in Small Schools. Small Schools Network Information Exchange Number 6.

ERIC Educational Resources Information Center

Regional Laboratory for Educational Improvement of the Northeast & Islands, Andover, MA.

This information packet contains 14 articles reprinted from various books and journals. Establishing and enriching school-community ties in small schools is the theme for this "Information Exchange Packet," the sixth in a series developed for Small Schools Network members. The articles and their authors are: "Skills in Building Support for…

Slavery in America: A Thematic Unit Appropriate for Adult Literacy Classrooms. Teacher to Teacher.

ERIC Educational Resources Information Center

White, Lisa

This thematic unit is designed for adult literacy students with at least a third grade reading level. Objectives are tied closely to skills needed for the General Educational Development tests and include computer and workplace skills. Equipped for the Future (EFF) roles and skills are also integrated into the plans. Best practice teaching…

Suture slippage in knotless suture anchors resulting in subacromial-subdeltoid bursitis.

PubMed

Hayeri, Mohammad Reza; Keefe, Daniel T; Chang, Eric Y

2016-05-01

Rotator cuff repair using a suture bridge and knotless suture anchors is a relatively new, but increasingly used technique. The suture bridge technique creates an anatomically similar and more secure rotator cuff repair compared with conventional arthroscopic techniques and the use of knotless anchors eliminates the challenges associated with knot tying during arthroscopic surgery. However, previous in vitro biomechanical tests have shown that the hold of the suture in a knotless suture anchor is far lower than the pullout strength of the anchor from bone. Up until now slippage has been a theoretical concern. We present a prospectively diagnosed case of in vivo suture loosening after rotator cuff repair using a knotless bridge technique resulting in subacromial-subdeltoid bursitis.

Two-phase pressure drop reduction BWR assembly design

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dix, G.E.; Crowther, R.L.; Colby, M.J.

1992-05-12

This patent describes a boiling water reactor having discrete bundles of fuel rods confined within channel enclosed fuel assemblies, an improvement to a fuel bundle assembly for placement in the reactor. It comprises a fuel channel having vertically extending walls forming a continuous channel around a fuel assembly volume, the channel being open at the bottom end for engagement to a lower tie plate and open at the upper end for engagement to an upper tie plate; rods for placement within the chamber, each the rod containing fissile material for producing nuclear reaction when in the presence of sufficient moderatedmore » neutron flux; a lower tie plate for supporting the bundle of rods within the channel, the lower tie plate for supporting the bundle of rods within the channel, the lower tie plate joining the bottom of the channel to close the bottom end of the channel, the lower tie plate providing defined apertures for the inflow of water in the channel between the rods for the generating of steam during the nuclear reaction; the plurality of fuel rods extending from the lower tie plate wherein a single phase region of the water in the bundle is defined to an upward portion of the bundle wherein a two phase region of the water and steam in the bundle is defined during nuclear steam generating reaction in the fuel bundle.« less

Reconstructive transoral laser microsurgery for posterior glottic web with stenosis.

PubMed

Atallah, Ihab; Manjunath, M Krishniah; Omari, Ahmad Al; Righini, Christian Adrien; Castellanos, Paul F

2017-03-01

To demonstrate that reconstructive transoral laser microsurgical (R-TLM) techniques can be used for the treatment of symptomatic laryngeal posterior glottic web-based stenosis (PGWS) in a large cohort of patients utilizing a postcricoid mucosal advancement flap (PCMAF). Retrospective cohort review. A consecutive series of patients with PGWS who underwent R-TLM using a PCMAF were reviewed for outcomes. After laser excision of the PGWS scar and mobilization of fixed cricoarytenoid joints, a PCMAF was raised using microinstruments and a scanning free-beam CO 2 laser. The flap was advanced and attached over the scar bed using a technique with multiple novel features that make it easy to adopt. Fifty-two patients were treated. Of the cases, 42.3% had a tracheostomy at presentation with grade II to IV PGWS, and 46% of cases had grade III to IV PGWS. In all cases, R-TLM was the only treatment approach. No open reconstructions were performed. No airway stents were used. Patients without tracheostomy, regardless of the grade of stenosis, did not require a tracheostomy to undergo this operation. All tracheostomy patients were successfully decannulated. All patients without a tracheostomy had significant improvement of their respiratory symptoms on the Dyspnea Index (mean Δ = 14.75, P value <.01). RTLM using the PCMAF is a feasible, safe, and effective alternative to open approaches for airway reconstruction for PGWS. This novel transoral technique includes a much simpler endoscopic suturing alternative to knot tying among other new features. It is reproducible and reliable for laryngologists familiar with laryngeal microsurgery. 4. Laryngoscope, 127:685-690, 2017. © 2016 The American Laryngological, Rhinological and Otological Society, Inc.

Perceptions of national wealth and skill influence pay expectations: replicating global hierarchy on a microscale.

PubMed

Maitner, Angela T; DeCoster, Jamie

2015-01-01

In highly multicultural societies, the economic status hierarchy may come to mimic the hierarchy of global wealth, reinforcing social inequality by tying pay scales to national wealth. We investigated how nationality influences expectations of payment in the UAE. Participants reported how much they expected people to be paid and how much skill they were perceived to have by nationality. They also reported their perceptions of the national wealth of different countries. Participants generally expected Westerners to be paid more than Arabs, who would be paid more than Sub-Saharan Africans and Asians. Expectations about payment in private sector employment were driven by both actual and stereotyped differences in national wealth and skill, with non-Gulf Cooperation Council Arabs most likely to see national wealth as a factor explaining the economic hierarchy. These results suggest that people expect payment to be tied to national wealth, reflecting the global hierarchy on a microscale.

Tying knots: an activity theory analysis of student learning goals in clinical education.

PubMed

Larsen, Douglas P; Wesevich, Austin; Lichtenfeld, Jana; Artino, Antony R; Brydges, Ryan; Varpio, Lara

2017-07-01

Learning goal programmes are often created to help students develop self-regulated learning skills; however, these programmes do not necessarily consider the social contexts surrounding learning goals or how they fit into daily educational practice. We investigated a high-frequency learning goal programme in which students generated and shared weekly learning goals with their clinical teams in core Year 3 clerkships. Our study explores: (i) how learning goals were incorporated into the clinical work, and (ii) the factors that influenced the use of students' learning goals in work-based learning. We conducted semi-structured interviews with 14 students and 14 supervisors (attending physicians and residents) sampled from all participating core clerkships. Interviews were coded for emerging themes. Using cultural historical activity theory and knotworking as theoretical lenses, we developed a model of the factors that influenced students' learning goal usage in a work-based learning context. Students and supervisors often faced the challenge of reconciling contradictions that arose when the desired outcomes of student skill development, grading and patient care were not aligned. Learning goals could function as tools for developing new ways of acting that overcame those contradictions by facilitating collaborative effort between students and their supervisors. However, for new collaborations to take place, both students and supervisors had to engage with the goals, and the necessary patients needed to be present. When any one part of the system did not converge around the learning goals, the impact of the learning goals programme was limited. Learning goals are potentially powerful tools to mediate interactions between students, supervisors and patients, and to reconcile contradictions in work-based learning environments. Learning goals provide a means to develop not only learners, but also learning systems. © 2017 John Wiley & Sons Ltd and The Association for the Study of Medical Education.

It's the Economy, Stupid! Re-Thinking Learning and Skills.

ERIC Educational Resources Information Center

Hughes, Chris

In England, vocational education and training (VET) does not exist as an institutionalized system as in Europe, where specialist institutions are tied to vocational qualifications, the labor market, and long-term objectives. Education has purposes other than to provide a skilled work force for the economy. However, the relationship between…

Good Workers for Good Jobs: Improving Education and Workforce Systems in the US. National Poverty Center Working Paper Series #12-20

ERIC Educational Resources Information Center

Holzer, Harry J.

2012-01-01

Stagnant earnings and growing inequality in the US labor market reflect both a slowdown in the growth of worker skills and the growing matching of good-paying jobs to skilled workers. Improving the ties between colleges, workforce institutions, and employers would help more workers gain the needed skills. Evaluation evidence shows that training…

"We Were Slow; It Was Challenging" and "It Was Hard Not to Make Knots": Crocheting as a Literacy Event in a Second Grade Classroom Community

ERIC Educational Resources Information Center

Kneller, Sarah A.; Boyd, Maureen P.

2008-01-01

This paper describes a "crazy about crocheting class" and shows how crocheting became a literacy event that promoted student empowerment and classroom community while engaging second grade students in authentic literacy practices. We document how crocheting evolved from a classroom management activity that also encouraged fine motor skills to a…

TIE: an ability test of emotional intelligence.

PubMed

Śmieja, Magdalena; Orzechowski, Jarosław; Stolarski, Maciej S

2014-01-01

The Test of Emotional Intelligence (TIE) is a new ability scale based on a theoretical model that defines emotional intelligence as a set of skills responsible for the processing of emotion-relevant information. Participants are provided with descriptions of emotional problems, and asked to indicate which emotion is most probable in a given situation, or to suggest the most appropriate action. Scoring is based on the judgments of experts: professional psychotherapists, trainers, and HR specialists. The validation study showed that the TIE is a reliable and valid test, suitable for both scientific research and individual assessment. Its internal consistency measures were as high as .88. In line with theoretical model of emotional intelligence, the results of the TIE shared about 10% of common variance with a general intelligence test, and were independent of major personality dimensions.

Knotting fingerprints resolve knot complexity and knotting pathways in ideal knots.

PubMed

Hyde, David A B; Henrich, Joshua; Rawdon, Eric J; Millett, Kenneth C

2015-09-09

We use disk matrices to define knotting fingerprints that provide fine-grained insights into the local knotting structure of ideal knots. These knots have been found to have spatial properties that highly correlate with those of interesting macromolecules. From this fine structure and an analysis of the associated planar graph, one can define a measure of knot complexity using the number of independent unknotting pathways from the global knot type as the knot is trimmed progressively to a short arc unknot. A specialization of the Cheeger constant provides a measure of constraint on these independent unknotting pathways. Furthermore, the structure of the knotting fingerprint supports a comparison of the tight knot pathways to the unconstrained unknotting pathways of comparable length.

In Vitro Evaluation of the Size, Knot Holding Capacity, and Knot Security of the Forwarder Knot Compared to Square and Surgeon's Knots Using Large Gauge Suture.

PubMed

Gillen, Alex M; Munsterman, Amelia S; Hanson, R Reid

2016-11-01

To investigate the strength, size, and holding capacity of the self-locking forwarder knot compared to surgeon's and square knots using large gauge suture. In vitro mechanical study. Knotted suture. Forwarder, surgeon's, and square knots were tested on a universal testing machine under linear tension using 2 and 3 USP polyglactin 910 and 2 USP polydioxanone. Knot holding capacity (KHC) and mode of failure were recorded and relative knot security (RKS) was calculated as a percentage of KHC. Knot volume and weight were assessed by digital micrometer and balance, respectively. ANOVA and post hoc testing were used tocompare strength between number of throws, suture, suture size, and knot type. P<.05 was considered significant. Forwarder knots had a higher KHC and RKS than surgeon's or square knots for all suture types and number of throws. No forwarder knots unraveled, but a proportion of square and surgeon's knots with <6 throws did unravel. Forwarder knots had a smaller volume and weight than surgeon's and square knots with equal number of throws. The forwarder knot of 4 throws using 3 USP polyglactin 910 had the highest KHC, RKS, and the smallest size and weight. Forwarder knots may be an alternative for commencing continuous patterns in large gauge suture, without sacrificing knot integrity, but further in vivo and ex vivo testing is required to assess the effects of this sliding knot on tissue perfusion before clinical application. © Copyright 2016 by The American College of Veterinary Surgeons.

Proof of Concept Study: Investigating Force Metrics of an Intracorporeal Suturing Knot Task.

PubMed

Wee, Justin; Azzie, Georges; Drake, James; Gerstle, J Ted

2018-06-19

Mastering proper force manipulation in minimally invasive surgery can take many hours of practice and training. Improper force control can lead to necrosis, infection, and scarring. A force-sensing skin (FSS) has been developed, which measures forces at the distal end of minimal access surgeries' (MAS) instruments without altering the instrument's structural integrity or the surgical workflow, and acts as a minimally disruptive add-on to any MAS instrument. A proof of concept study was conducted using a FSS-equipped 5 mm straight-tip needle holder. Participants (n = 19: 3 novices, 11 fellows, and 5 staff surgeons) performed one intracorporeal suturing knot task (ISKT). Using participant task video footage, each participant's two puncture forces (each wall of the Penrose drain) and three knot tightening forces were measured. Force metrics from the three expertise groups were compared using analysis of variance (ANOVA) and Tukey's honest significance test with statistical significance assessed at P < .05. Preliminary ISKT force metric data showed differences between novices and more experienced fellows and surgeons. Of the five stages of the ISKT evaluated, the first puncture force of the Penrose drain seemed to best reflect the difference in skill among participants. The study demonstrated ISKT knot tightening and puncture force ranges across three expertise levels (novices, surgical fellows, and staff surgeons) of 0.586 to 6.089 newtons (N) and 0.852 to 2.915 N, respectively. The investigation of force metrics is important for the implementation of future force feedback systems as it can provide real-time information to surgeons in training and the operating theater.

PA-566, A Root-knot Nematode Resistant, Pimento-type Pepper

USDA-ARS?s Scientific Manuscript database

The Agricultural Research Service of the U.S. Department of Agriculture has released a new, open-pollinated, breeding line of a pimento-type pepper (Capsicum annuum) designated PA-566. The new breeding line is the product of a recurrent backcross breeding procedure to incorporate the dominant N roo...

Where Does Handwriting Fit in? Strategies to Support Academic Achievement

ERIC Educational Resources Information Center

Cahill, Susan M.

2009-01-01

In today's environment of high-stakes testing, handwriting is a skill that is often overlooked in order to focus on other areas of the curriculum. However, research indicates that handwriting is tied to academic achievement, especially composition and literacy skills. This article provides strategies that can be used to support students with…

[Will inpatient care still be financeable? Effects of the minimum wage to operators].

PubMed

Meyer, Dirk

2010-11-01

Due to demographic and social developments nursing service will continueto be a growth industry in the long run. The requirement for this is the political volition of a sufficient funding. A minimum wage in nursing service tends to increase prices of the offered services. Stated justifications for a minimum wage are wage dumping protection (inter alia against the background of the upcoming opening of the single market in 2011) as well as raising rivals' costs. Protection is focused on the 266,000 non-skilled workers in basic care owing to the strong tightening of the labour market for caregivers. Operative minimum wages will lead to adjustments by optimising operations, intensification of work, and rationalisation of workflow by increased employment of capital as well as technical substitution of relatively expensive non-skilled workers. In addition there will be increased pressure on prices for nursing services and private co-payments. There will be an increased supply and demand for illegal services. Suppliers who had been tied to collective contracts so far will achieve a relative advantage in competition.

A Systematic Determination of Skill and Simulator Requirements for Airline Transport Pilot Certification.

DTIC Science & Technology

1985-03-01

scene contents should provide the needed information simultaneously in each perspec- tive as prioritized. For the others, the requirement is that...turn the airplane using nosewheel steering until lineup is accomplished. Minimize side loads. (3) Apply forward elevator pressure to ensure positive... simultaneously advancing the power toward the computed takeoff setting. Set final takeoff thrust by approxi- mately 60 knots. (6) As the airplane accelerates, keep

The European Academy laparoscopic “Suturing Training and Testing’’ (SUTT) significantly improves surgeons’ performance

PubMed Central

Sleiman, Z.; Tanos, V.; Van Belle, Y.; Carvalho, J.L.; Campo, R.

2015-01-01

The efficiency of suturing training and testing (SUTT) model by laparoscopy was evaluated, measuring the suturingskill acquisition of trainee gynecologists at the beginning and at the end of a teaching course. During a workshop organized by the European Academy of Gynecological Surgery (EAGS), 25 participants with three different experience levels in laparoscopy (minor, intermediate and major) performed the 4 exercises of the SUTT model (Ex 1: both hands stitching and continuous suturing, Ex 2: right hand stitching and intracorporeal knotting, Ex 3: left hand stitching and intracorporeal knotting, Ex 4: dominant hand stitching, tissue approximation and intracorporeal knotting). The time needed to perform the exercises is recorded for each trainee and group and statistical analysis used to note the differences. Overall, all trainees achieved significant improvement in suturing time (p < 0.005) as measured before and after completion of the training. Similar significantly improved suturing time differences (p < 0.005) were noted among the groups of trainees with different laparoscopic experience. In conclusion a short well-guided training course, using the SUTT model, improves significantly surgeon’s laparoscopic suturing ability, independently of the level of experience in laparoscopic surgery. Key words: Endoscopy, laparoscopic suturing, psychomotor skills, surgery, teaching, training suturing model. PMID:26977264

TIE: An Ability Test of Emotional Intelligence

PubMed Central

Śmieja, Magdalena; Orzechowski, Jarosław; Stolarski, Maciej S.

2014-01-01

The Test of Emotional Intelligence (TIE) is a new ability scale based on a theoretical model that defines emotional intelligence as a set of skills responsible for the processing of emotion-relevant information. Participants are provided with descriptions of emotional problems, and asked to indicate which emotion is most probable in a given situation, or to suggest the most appropriate action. Scoring is based on the judgments of experts: professional psychotherapists, trainers, and HR specialists. The validation study showed that the TIE is a reliable and valid test, suitable for both scientific research and individual assessment. Its internal consistency measures were as high as .88. In line with theoretical model of emotional intelligence, the results of the TIE shared about 10% of common variance with a general intelligence test, and were independent of major personality dimensions. PMID:25072656

In-vivo assessment of barbed suturing thread with regard to tissue reaction and material absorption in a rat model.

PubMed

Petrut, Bogdan; Hogea, Maximiliam; Fetica, Bogdan; Kozan, Andrei; Feflea, Dragos; Sererman, Gabriel; Goezen, Ali Serdar; Rassweiler, Jens

2013-01-01

The laparoscopic approach in urological surgery demands a high degree of skill in intracorporeal suturing and knot tying. In an effort to reduce the amount of time required to perform a suture, new materials have been developed that through selfanchorage distribute tension more evenly across the suture and also eliminate the need of knot tying. The goal of this study was to assess the in vivo tissue response to a novel material (V-Loc tm; Covidien) in comparison to established materials (Vicryl, PDS II), in the case of bladder suturing, in a rat model. The study included 48 male Wistar rats. All underwent a median abdominal incision, with a 1cm cystotomy, followed by a running suture. The suture material used was either V-Loc absorbable self anchoring thread, Vicryl threaded absorbable suture or monofilament absorbable suture. The abdominal cavity and the bladder suture were macroscopically evaluated at the rats' scheduled death at 3 and 6 weeks. The bladder wall was microscopically assessed by a pathologist, with regard to tissue reaction and suture material degradation. All rats survived the procedure, with the abdominal scar fully healed at week 2. There were no signs of infection or lithiasis during the observation. Macroscopically, at 3 weeks, the suture material was recognizable and visible in all cases, with special mention that the V-Loc thread was considerably more rigid, retaining its shape almost entirely, and provoked more adhesion of the surrounding tissue. At 6 weeks, the suture was indistinguishable in the bladder wall in the case of monofilament absorbable material, barely visible in the case of Vicryl, while the aspect of the V-Loc suture resembled the one at 3 weeks, with the material still clearly visible in the bladder wall, shape almost entirely maintained, and surrounding tissue adherence. Microscopically, at 3 weeks and 6 weeks, all bladder walls examined had regained their structure. At 3 weeks, the monofilament absorbable suture showed intense tissue reaction, with the material already in phagocytosis; at 6 weeks, no clear evidence of leftover material was observed. At 3 weeks, the Vicryl material showed moderate tissue reaction, with phagocytosis initiated between the strands of the material; at 6 weeks, the material was almost entirely absorbed, but with a clear leftover tissue reaction. In the case of the V-Loc suture, due to the hardness of the thread, the material itself could not be cut for analysis with the bladder wall, and the examination could only involve the bladder wall and marks of the thread. Thus, the tissue reaction was minimal, as was the presence of phagocytes at the suture site. The material showed little, if any, signs of absorption after 6 weeks. The materials tested all proved equally effective in suturing the bladder wall in a rat model. However, the novel barbed thread proved a consistently low in-vivo absorption rate, while maintaining its rigidity over time. More research is needed to assess the possible clinical implications of these findings.

In-vivo assessment of barbed suturing thread with regard to tissue reaction and material absorption in a rat model

PubMed Central

PETRUT, BOGDAN; HOGEA, MAXIMILIAM; FETICA, BOGDAN; KOZAN, ANDREI; FEFLEA, DRAGOS; SERERMAN, GABRIEL; GOEZEN, ALI SERDAR; RASSWEILER, JENS

2013-01-01

Aim The laparoscopic approach in urological surgery demands a high degree of skill in intracorporeal suturing and knot tying. In an effort to reduce the amount of time required to perform a suture, new materials have been developed that through selfanchorage distribute tension more evenly across the suture and also eliminate the need of knot tying. The goal of this study was to assess the in vivo tissue response to a novel material (V-Loc tm; Covidien) in comparison to established materials (Vicryl, PDS II), in the case of bladder suturing, in a rat model. Methods The study included 48 male Wistar rats. All underwent a median abdominal incision, with a 1cm cystotomy, followed by a running suture. The suture material used was either V-Loc absorbable self anchoring thread, Vicryl threaded absorbable suture or monofilament absorbable suture. The abdominal cavity and the bladder suture were macroscopically evaluated at the rats’ scheduled death at 3 and 6 weeks. The bladder wall was microscopically assessed by a pathologist, with regard to tissue reaction and suture material degradation. Results All rats survived the procedure, with the abdominal scar fully healed at week 2. There were no signs of infection or lithiasis during the observation. Macroscopically, at 3 weeks, the suture material was recognizable and visible in all cases, with special mention that the V-Loc thread was considerably more rigid, retaining its shape almost entirely, and provoked more adhesion of the surrounding tissue. At 6 weeks, the suture was indistinguishable in the bladder wall in the case of monofilament absorbable material, barely visible in the case of Vicryl, while the aspect of the V-Loc suture resembled the one at 3 weeks, with the material still clearly visible in the bladder wall, shape almost entirely maintained, and surrounding tissue adherence. Microscopically, at 3 weeks and 6 weeks, all bladder walls examined had regained their structure. At 3 weeks, the monofilament absorbable suture showed intense tissue reaction, with the material already in phagocytosis; at 6 weeks, no clear evidence of leftover material was observed. At 3 weeks, the Vicryl material showed moderate tissue reaction, with phagocytosis initiated between the strands of the material; at 6 weeks, the material was almost entirely absorbed, but with a clear leftover tissue reaction. In the case of the V-Loc suture, due to the hardness of the thread, the material itself could not be cut for analysis with the bladder wall, and the examination could only involve the bladder wall and marks of the thread. Thus, the tissue reaction was minimal, as was the presence of phagocytes at the suture site. The material showed little, if any, signs of absorption after 6 weeks. Conclusion The materials tested all proved equally effective in suturing the bladder wall in a rat model. However, the novel barbed thread proved a consistently low in-vivo absorption rate, while maintaining its rigidity over time. More research is needed to assess the possible clinical implications of these findings. PMID:26527981

Knotting probability of self-avoiding polygons under a topological constraint.

PubMed

Uehara, Erica; Deguchi, Tetsuo

2017-09-07

We define the knotting probability of a knot K by the probability for a random polygon or self-avoiding polygon (SAP) of N segments having the knot type K. We show fundamental and generic properties of the knotting probability particularly its dependence on the excluded volume. We investigate them for the SAP consisting of hard cylindrical segments of unit length and radius r ex . For various prime and composite knots, we numerically show that a compact formula describes the knotting probabilities for the cylindrical SAP as a function of segment number N and radius r ex . It connects the small-N to the large-N behavior and even to lattice knots in the case of large values of radius. As the excluded volume increases, the maximum of the knotting probability decreases for prime knots except for the trefoil knot. If it is large, the trefoil knot and its descendants are dominant among the nontrivial knots in the SAP. From the factorization property of the knotting probability, we derive a sum rule among the estimates of a fitting parameter for all prime knots, which suggests the local knot picture and the dominance of the trefoil knot in the case of large excluded volumes. Here we remark that the cylindrical SAP gives a model of circular DNA which is negatively charged and semiflexible, where radius r ex corresponds to the screening length.

Knotting probability of self-avoiding polygons under a topological constraint

NASA Astrophysics Data System (ADS)

Uehara, Erica; Deguchi, Tetsuo

2017-09-01

We define the knotting probability of a knot K by the probability for a random polygon or self-avoiding polygon (SAP) of N segments having the knot type K. We show fundamental and generic properties of the knotting probability particularly its dependence on the excluded volume. We investigate them for the SAP consisting of hard cylindrical segments of unit length and radius rex. For various prime and composite knots, we numerically show that a compact formula describes the knotting probabilities for the cylindrical SAP as a function of segment number N and radius rex. It connects the small-N to the large-N behavior and even to lattice knots in the case of large values of radius. As the excluded volume increases, the maximum of the knotting probability decreases for prime knots except for the trefoil knot. If it is large, the trefoil knot and its descendants are dominant among the nontrivial knots in the SAP. From the factorization property of the knotting probability, we derive a sum rule among the estimates of a fitting parameter for all prime knots, which suggests the local knot picture and the dominance of the trefoil knot in the case of large excluded volumes. Here we remark that the cylindrical SAP gives a model of circular DNA which is negatively charged and semiflexible, where radius rex corresponds to the screening length.

Let’s Tie the Knot: Marriage of Complement and Adaptive Immunity in Pathogen Evasion, for Better or Worse

PubMed Central

Bennett, Kaila M.; Rooijakkers, Suzan H. M.; Gorham, Ronald D.

2017-01-01

The complement system is typically regarded as an effector arm of innate immunity, leading to recognition and killing of microbial invaders in body fluids. Consequently, pathogens have engaged in an arms race, evolving molecules that can interfere with proper complement responses. However, complement is no longer viewed as an isolated system, and links with other immune mechanisms are continually being discovered. Complement forms an important bridge between innate and adaptive immunity. While its roles in innate immunity are well-documented, its function in adaptive immunity is less characterized. Therefore, it is no surprise that the field of pathogenic complement evasion has focused on blockade of innate effector functions, while potential inhibition of adaptive immune responses (via complement) has been overlooked to a certain extent. In this review, we highlight past and recent developments on the involvement of complement in the adaptive immune response. We discuss the mechanisms by which complement aids in lymphocyte stimulation and regulation, as well as in antigen presentation. In addition, we discuss microbial complement evasion strategies, and highlight specific examples in the context of adaptive immune responses. These emerging ties between complement and adaptive immunity provide a catalyst for future discovery in not only the field of adaptive immune evasion but in elucidating new roles of complement. PMID:28197139

Let's Tie the Knot: Marriage of Complement and Adaptive Immunity in Pathogen Evasion, for Better or Worse.

PubMed

Bennett, Kaila M; Rooijakkers, Suzan H M; Gorham, Ronald D

2017-01-01

The complement system is typically regarded as an effector arm of innate immunity, leading to recognition and killing of microbial invaders in body fluids. Consequently, pathogens have engaged in an arms race, evolving molecules that can interfere with proper complement responses. However, complement is no longer viewed as an isolated system, and links with other immune mechanisms are continually being discovered. Complement forms an important bridge between innate and adaptive immunity. While its roles in innate immunity are well-documented, its function in adaptive immunity is less characterized. Therefore, it is no surprise that the field of pathogenic complement evasion has focused on blockade of innate effector functions, while potential inhibition of adaptive immune responses (via complement) has been overlooked to a certain extent. In this review, we highlight past and recent developments on the involvement of complement in the adaptive immune response. We discuss the mechanisms by which complement aids in lymphocyte stimulation and regulation, as well as in antigen presentation. In addition, we discuss microbial complement evasion strategies, and highlight specific examples in the context of adaptive immune responses. These emerging ties between complement and adaptive immunity provide a catalyst for future discovery in not only the field of adaptive immune evasion but in elucidating new roles of complement.

Factors Affecting Success for Women in Skilled Blue Collar Jobs.

ERIC Educational Resources Information Center

Walshok, Mary Lindenstein

Women's success in nontraditional blue collar jobs in the skilled trades or crafts appears to be tied to three separate but interrelated issues which are a function of differences in social background and shift in the structure of employment and economic opportunities for women, according to qualitative data gathered in in-depth interviews of more…

Perceptions of national wealth and skill influence pay expectations: replicating global hierarchy on a microscale

PubMed Central

Maitner, Angela T.; DeCoster, Jamie

2015-01-01

In highly multicultural societies, the economic status hierarchy may come to mimic the hierarchy of global wealth, reinforcing social inequality by tying pay scales to national wealth. We investigated how nationality influences expectations of payment in the UAE. Participants reported how much they expected people to be paid and how much skill they were perceived to have by nationality. They also reported their perceptions of the national wealth of different countries. Participants generally expected Westerners to be paid more than Arabs, who would be paid more than Sub-Saharan Africans and Asians. Expectations about payment in private sector employment were driven by both actual and stereotyped differences in national wealth and skill, with non-Gulf Cooperation Council Arabs most likely to see national wealth as a factor explaining the economic hierarchy. These results suggest that people expect payment to be tied to national wealth, reflecting the global hierarchy on a microscale. PMID:26074852

Pruning Cottonwood

Treesearch

R. L. Johnson

1959-01-01

Planting cottonwood trees can be a profitable investment, but to get the most for their money land-owners should consider the possibilities of pruning. At present, there are wide differentials in the stumpage value of cottonwood stands, primarily because of variation in log quality. By restricting knots to the inner core, artificial pruning of small open-grown trees...

78 FR 73457 - Airworthiness Directives; the Boeing Company Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-06

... frequency eddy current inspections for cracking of the tension tie at BS 760 or 780, as applicable, and do... ties, including doing an open-hole high frequency eddy current inspection for cracks, as applicable...) and paragraph (i) of this AD, but not as AMOCs for the high frequency eddy current inspections...

Atomic resolution of structural changes in elastic crystals of copper(II) acetylacetonate

NASA Astrophysics Data System (ADS)

Worthy, Anna; Grosjean, Arnaud; Pfrunder, Michael C.; Xu, Yanan; Yan, Cheng; Edwards, Grant; Clegg, Jack K.; McMurtrie, John C.

2018-01-01

Single crystals are typically brittle, inelastic materials. Such mechanical responses limit their use in practical applications, particularly in flexible electronics and optical devices. Here we describe single crystals of a well-known coordination compound—copper(II) acetylacetonate—that are flexible enough to be reversibly tied into a knot. Mechanical measurements indicate that the crystals exhibit an elasticity similar to that of soft materials such as nylon, and thus display properties normally associated with both hard and soft matter. Using microfocused synchrotron radiation, we mapped the changes in crystal structure that occur on bending, and determined the mechanism that allows this flexibility with atomic precision. We show that, under strain, the molecules in the crystal reversibly rotate, and thus reorganize to allow the mechanical compression and expansion required for elasticity and still maintain the integrity of the crystal structure.

A novel robotic platform for single-port abdominal surgery

NASA Astrophysics Data System (ADS)

Singh, Satwinder; Cheung, Jo L. K.; Sreedhar, Biji; Hoa, Xuyen Dai; Ng, Hoi Pang; Yeung, Chung Kwong

2018-03-01

In this paper, a novel robot-assisted platform for single-port minimally invasive surgery is presented. A miniaturized seven degrees of freedom (dof) fully internalized in-vivo actuated robotic arm is designed. Due to in-vivo actuation, the system has a smaller footprint and can generate 20 N of gripping force. The complete work envelop of the robotic arms is 252 mm × 192 mm × 322 m. With the assistance of the cannula-swivel system, the robotic arms can also be re-positioned and have multi-quadrant reachability without any additional incision. Surgical tasks, such as lifting, gripping suturing and knot tying that are commonly used in a standard surgical procedure, were performed to verify the dexterity of the robotic arms. A single-port trans-abdominal cholecystectomy in a porcine model was successfully performed to further validate its functionality.

The Role of Direct and Visual Force Feedback in Suturing Using a 7-DOF Dual-Arm Teleoperated System.

PubMed

Talasaz, Ali; Trejos, Ana Luisa; Patel, Rajni V

2017-01-01

The lack of haptic feedback in robotics-assisted surgery can result in tissue damage or accidental tool-tissue hits. This paper focuses on exploring the effect of haptic feedback via direct force reflection and visual presentation of force magnitudes on performance during suturing in robotics-assisted minimally invasive surgery (RAMIS). For this purpose, a haptics-enabled dual-arm master-slave teleoperation system capable of measuring tool-tissue interaction forces in all seven Degrees-of-Freedom (DOFs) was used. Two suturing tasks, tissue puncturing and knot-tightening, were chosen to assess user skills when suturing on phantom tissue. Sixteen subjects participated in the trials and their performance was evaluated from various points of view: force consistency, number of accidental hits with tissue, amount of tissue damage, quality of the suture knot, and the time required to accomplish the task. According to the results, visual force feedback was not very useful during the tissue puncturing task as different users needed different amounts of force depending on the penetration of the needle into the tissue. Direct force feedback, however, was more useful for this task to apply less force and to minimize the amount of damage to the tissue. Statistical results also reveal that both visual and direct force feedback were required for effective knot tightening: direct force feedback could reduce the number of accidental hits with the tissue and also the amount of tissue damage, while visual force feedback could help to securely tighten the suture knots and maintain force consistency among different trials/users. These results provide evidence of the importance of 7-DOF force reflection when performing complex tasks in a RAMIS setting.

Initiatives: The Escher Dilemma; Lowering the Bar or Helium Pole; Phillippe le Basquette (Fill the Basket); Concentration Point; Who Done It?/the Lie Game; A Missing Piece; Mindfulness Meditation; Untying Knots: Bending on Teamwork; Triangle Tag for Church Groups.

ERIC Educational Resources Information Center

Butler, Steve; Gass, Mike; Schoel, Jim; Murphy, Morgan; Murray, Mark; White, Will; Loggers, Otto; Renaker, Paul

1999-01-01

Describes nine group problem-solving and communication initiatives used in adventure- and experiential-education settings. Includes target group, group size, time and space requirements, activity level, props, instructions, and tips for post-activity group reflection and processing. Activities emphasize teamwork, communication skills, and a…

In Search of Functional Advantages of Knots in Proteins.

PubMed

Dabrowski-Tumanski, Pawel; Stasiak, Andrzej; Sulkowska, Joanna I

2016-01-01

We analysed the structure of deeply knotted proteins representing three unrelated families of knotted proteins. We looked at the correlation between positions of knotted cores in these proteins and such local structural characteristics as the number of intra-chain contacts, structural stability and solvent accessibility. We observed that the knotted cores and especially their borders showed strong enrichment in the number of contacts. These regions showed also increased thermal stability, whereas their solvent accessibility was decreased. Interestingly, the active sites within these knotted proteins preferentially located in the regions with increased number of contacts that also have increased thermal stability and decreased solvent accessibility. Our results suggest that knotting of polypeptide chains provides a favourable environment for the active sites observed in knotted proteins. Some knotted proteins have homologues without a knot. Interestingly, these unknotted homologues form local entanglements that retain structural characteristics of the knotted cores.

Tongue-Tied: The Lives of Multilingual Children in Public Education

ERIC Educational Resources Information Center

Santa Ana, Otto

2004-01-01

Tongue-Tied is an anthology that gives voice to millions of people who, on a daily basis, are denied the opportunity to speak in their own language. First-person accounts by Amy Tan, Sherman Alexie, Bell Hooks, Richard Rodriguez, Maxine Hong Kingston, and many other authors open windows into the lives of linguistic minority students and their…

Quantifying technical skills during open operations using video-based motion analysis.

PubMed

Glarner, Carly E; Hu, Yue-Yung; Chen, Chia-Hsiung; Radwin, Robert G; Zhao, Qianqian; Craven, Mark W; Wiegmann, Douglas A; Pugh, Carla M; Carty, Matthew J; Greenberg, Caprice C

2014-09-01

Objective quantification of technical operative skills in surgery remains poorly defined, although the delivery of and training in these skills is essential to the profession of surgery. Attempts to measure hand kinematics to quantify operative performance primarily have relied on electromagnetic sensors attached to the surgeon's hand or instrument. We sought to determine whether a similar motion analysis could be performed with a marker-less, video-based review, allowing for a scalable approach to performance evaluation. We recorded six reduction mammoplasty operations-a plastic surgery procedure in which the attending and resident surgeons operate in parallel. Segments representative of surgical tasks were identified with Multimedia Video Task Analysis software. Video digital processing was used to extract and analyze the spatiotemporal characteristics of hand movement. Attending plastic surgeons appear to use their nondominant hand more than residents when cutting with the scalpel, suggesting more use of countertraction. While suturing, attendings were more ambidextrous, with smaller differences in movement between their dominant and nondominant hands than residents. Attendings also seem to have more conservation of movement when performing instrument tying than residents, as demonstrated by less nondominant hand displacement. These observations were consistent within procedures and between the different attending plastic surgeons evaluated in this fashion. Video motion analysis can be used to provide objective measurement of technical skills without the need for sensors or markers. Such data could be valuable in better understanding the acquisition and degradation of operative skills, providing enhanced feedback to shorten the learning curve. Copyright © 2014 Mosby, Inc. All rights reserved.

Parity in knot theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manturov, Vassily O

2010-06-29

In this work we study knot theories with a parity property for crossings: every crossing is declared to be even or odd according to a certain preassigned rule. If this rule satisfies a set of simple axioms related to the Reidemeister moves, then certain simple invariants solving the minimality problem can be defined, and invariant maps on the set of knots can be constructed. The most important example of a knot theory with parity is the theory of virtual knots. Using the parity property arising from Gauss diagrams we show that even a gross simplification of the theory of virtualmore » knots, namely, the theory of free knots, admits simple and highly nontrivial invariants. This gives a solution to a problem of Turaev, who conjectured that all free knots are trivial. In this work we show that free knots are generally not invertible, and provide invariants which detect the invertibility of free knots. The passage to ordinary virtual knots allows us to strengthen known invariants (such as the Kauffman bracket) using parity considerations. We also discuss other examples of knot theories with parity. Bibliography: 27 items.« less

A knotted complex scalar field for any knot

NASA Astrophysics Data System (ADS)

Bode, Benjamin; Dennis, Mark

Three-dimensional field configurations where a privileged defect line is knotted or linked have experienced an upsurge in interest, with examples including fluid mechanics, quantum wavefunctions, optics, liquid crystals and skyrmions. We describe a constructive algorithm to write down complex scalar functions of three-dimensional real space with knotted nodal lines, using trigonometric parametrizations of braids. The construction is most natural for the family of lemniscate knots which generalizes the torus knot and figure-8 knot, but generalizes to any knot or link. The specific forms of these functions allow various topological quantities associated with the field to be chosen, such as the helicity of a knotted flow field. We will describe some applications to physical systems such as those listed above. This work was supported by the Leverhulme Trust Programme Grant ''Scientific Properties of Complex Knots''.

Weaving Knotted Vector Fields with Tunable Helicity.

PubMed

Kedia, Hridesh; Foster, David; Dennis, Mark R; Irvine, William T M

2016-12-30

We present a general construction of divergence-free knotted vector fields from complex scalar fields, whose closed field lines encode many kinds of knots and links, including torus knots, their cables, the figure-8 knot, and its generalizations. As finite-energy physical fields, they represent initial states for fields such as the magnetic field in a plasma, or the vorticity field in a fluid. We give a systematic procedure for calculating the vector potential, starting from complex scalar functions with knotted zero filaments, thus enabling an explicit computation of the helicity of these knotted fields. The construction can be used to generate isolated knotted flux tubes, filled by knots encoded in the lines of the vector field. Lastly, we give examples of manifestly knotted vector fields with vanishing helicity. Our results provide building blocks for analytical models and simulations alike.

Evaluation of 5 knots and 2 suture materials for arthroscopic rotator cuff repair: very strong sutures can still slip.

PubMed

Abbi, Gaurav; Espinoza, Luis; Odell, Timothy; Mahar, Andrew; Pedowitz, Robert

2006-01-01

To compare a standard suture material with a newer material using multiple arthroscopic knot configurations and to evaluate the biomechanical performance of a new sliding-locking knot compared with 4 surgical standards. Controlled laboratory study. Five knots were evaluated (Weston, Tennessee, Duncan, SMC, and the new San Diego knot) using 2 suture materials, No. 2 Ethibond (Ethicon, Somerville, NJ) or No. 2 Fiberwire (Arthrex, Naples, FL). Eight samples were tested for each knot-suture configuration. Samples were pretensioned to 10 N and then loaded from 10 to 45 N for 1,000 cycles. Intact knots were loaded to failure. Fiberwire had significantly higher load-to-failure (276 +/- 24 N) compared with Ethibond (111 +/- 13 N) (P < .001), although there was no significant difference as a function of knot configuration. Of the 40 Fiberwire knots, 3 failed by early slippage during cyclic loading and 8 slipped at very low tension during load-to-failure. None of the Ethibond knots and none of the San Diego knots failed by early slippage. Surface characteristics and suture construction affect the tendency for knot slippage. Surgeons should understand the impact of handling characteristics, frictional properties, and ultimate failure load when selecting suture materials and knots for arthroscopic repair.

Optical vortex knots in tightly-focused light beams

NASA Astrophysics Data System (ADS)

Dennis, Mark; Sugic, Danica

Optical vortices, that is, zero lines of complex amplitude in a propagating light field, can be knotted or linked in a controlled way. This was demonstrated previously in experiments where a computer-controlled hologram determined the amplitude of paraxial laser light, meaning the longitudinal extent of the knot was several orders of magnitude larger than its width. We describe what happens to these optical knots when the transverse width of the beam, and hence the knot, is reduced. Outside the paraxial regime, the field's polarization becomes highly inhomogeneous, and knotted structures occur in a variety of polarization singularities. We propose experiments realising these knotted polarization structures in tightly-focused beams, which should yield optical knots of unit aspect ratio, of several optical wavelengths in size, which could be suitable for embedding knotted defect structures in liquid crystals, Bose-Einstein condensates and photopolymers. This work was supported by the Leverhulme Trust Programme Grant ''Scientific Properties of Complex Knots''.

Spontaneous knotting of an agitated string.

PubMed

Raymer, Dorian M; Smith, Douglas E

2007-10-16

It is well known that a jostled string tends to become knotted; yet the factors governing the "spontaneous" formation of various knots are unclear. We performed experiments in which a string was tumbled inside a box and found that complex knots often form within seconds. We used mathematical knot theory to analyze the knots. Above a critical string length, the probability P of knotting at first increased sharply with length but then saturated below 100%. This behavior differs from that of mathematical self-avoiding random walks, where P has been proven to approach 100%. Finite agitation time and jamming of the string due to its stiffness result in lower probability, but P approaches 100% with long, flexible strings. We analyzed the knots by calculating their Jones polynomials via computer analysis of digital photos of the string. Remarkably, almost all were identified as prime knots: 120 different types, having minimum crossing numbers up to 11, were observed in 3,415 trials. All prime knots with up to seven crossings were observed. The relative probability of forming a knot decreased exponentially with minimum crossing number and Möbius energy, mathematical measures of knot complexity. Based on the observation that long, stiff strings tend to form a coiled structure when confined, we propose a simple model to describe the knot formation based on random "braid moves" of the string end. Our model can qualitatively account for the observed distribution of knots and dependence on agitation time and string length.

The B1 Protein Guides the Biosynthesis of a Lasso Peptide

NASA Astrophysics Data System (ADS)

Zhu, Shaozhou; Fage, Christopher D.; Hegemann, Julian D.; Mielcarek, Andreas; Yan, Dushan; Linne, Uwe; Marahiel, Mohamed A.

2016-10-01

Lasso peptides are a class of ribosomally synthesized and post-translationally modified peptides (RiPPs) with a unique lariat knot-like fold that endows them with extraordinary stability and biologically relevant activity. However, the biosynthetic mechanism of these fascinating molecules remains largely speculative. Generally, two enzymes (B for processing and C for cyclization) are required to assemble the unusual knot-like structure. Several subsets of lasso peptide gene clusters feature a “split” B protein on separate open reading frames (B1 and B2), suggesting distinct functions for the B protein in lasso peptide biosynthesis. Herein, we provide new insights into the role of the RiPP recognition element (RRE) PadeB1, characterizing its capacity to bind the paeninodin leader peptide and deliver its peptide substrate to PadeB2 for processing.

LONG-TERM MONITORING OF THE DYNAMICS AND PARTICLE ACCELERATION OF KNOTS IN THE JET OF CENTAURUS A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goodger, J. L.; Hardcastle, M. J.; Croston, J. H., E-mail: j.l.goodger@herts.ac.u, E-mail: m.j.hardcastle@herts.ac.u, E-mail: J.Croston@soton.ac.u

2010-01-01

We present new and archival multi-frequency radio and X-ray data for Centaurus A obtained over almost 20 years at the Very Large Array and with Chandra, with which we measure the X-ray and radio spectral indices of jet knots, flux density variations in the jet knots, polarization variations, and proper motions. We compare the observed properties with current knot formation models and particle acceleration mechanisms. We rule out impulsive particle acceleration as a formation mechanism for all of the knots as we detect the same population of knots in all of the observations, and we find no evidence of extrememore » variability in the X-ray knots. We find that the most likely mechanism for all the stationary knots is a collision resulting in a local shock followed by a steady state of prolonged, stable particle acceleration, and X-ray synchrotron emission. In this scenario, the X-ray-only knots have radio counterparts that are too faint to be detected, while the radio-only knots are due to weak shocks where no particles are accelerated to X-ray emitting energies. Although the base knots are prime candidates for reconfinement shocks, the presence of a moving knot in this vicinity and the fact that there are two base knots are hard to explain in this model. We detect apparent motion in three knots; however, their velocities and locations provide no conclusive evidence for or against a faster moving 'spine' within the jet. The radio-only knots, both stationary and moving, may be due to compression of the fluid.« less

Molecular Knots

PubMed Central

Fielden, Stephen D. P.; Woltering, Steffen L.

2017-01-01

Abstract The first synthetic molecular trefoil knot was prepared in the late 1980s. However, it is only in the last few years that more complex small‐molecule knot topologies have been realized through chemical synthesis. The steric restrictions imposed on molecular strands by knotting can impart significant physical and chemical properties, including chirality, strong and selective ion binding, and catalytic activity. As the number and complexity of accessible molecular knot topologies increases, it will become increasingly useful for chemists to adopt the knot terminology employed by other disciplines. Here we give an overview of synthetic strategies towards molecular knots and outline the principles of knot, braid, and tangle theory appropriate to chemistry and molecular structure. PMID:28477423

Thin walled channel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crowther, R.L.; Johansson, E.B.

1988-06-07

A fuel assembly is described comprising fuel rods positioned in a spaced array by upper and lower tie-plates, an open ended flow channel surrounding the array for conducting coolant upward about the fuel rods, the open ended channel having a polygon shaped cross section with flat side sections connected between the corner sections; means separate from the channel connecting the upper and lower tie-plates together and maintaining the fuel rods in spaced array independent of the flow channel, improvement in the flow channel comprising: four corners having a first thickness; four sides having a second and reduced thickness from themore » corner thickness, the sides welded to the corner sections.« less

An unusual case of murder-suicide: The importance of studying knots.

PubMed

D'Ovidio, Cristian; Rosato, Enrica; Carnevale, Aldo

2017-01-01

An atypical murder-suicide that involved a married couple over 80 years of age was investigated at the Institute of Legal Medicine of the University of Chieti-Pescara and is presented and discussed here. The whole story allows us to confront the difficulties involved in the discovery of a dead body in water when the circumstantial evidence does not allow any unique interpretation of the facts. The atypical and misleading element appeared to be how the body of the man was tied, with the interpretation inclined towards a homicidal manner of death. It was only by combining the contributions of each of the findings that emerged during the course of the autopsy with the circumstantial evidence from the site inspection that it was possible to reach resolution of this case, which was then identified as a murder-suicide. Copyright © 2016 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

Variation in pin knot frequency in black walnut lumber cut from a small provenance/progeny test

Treesearch

Peter Y. S. Chen; Robert E. Bodkin; J. W. Van Sambeek

1995-01-01

This small study examined the frequency of knots (> 1 growth ring), pin knots (latent or suppressed buds), and pin knot clusters in 414 black walnut (Juglans nigra L.) lumber from 42 logs. 18 to 21 cm dbh, cut from a 14-year-old provenance/progeny test. Two boards from opposite sides of each log were analyzed for number of knots, pin knots, and...

ooi: OpenStack OCCI interface

NASA Astrophysics Data System (ADS)

López García, Álvaro; Fernández del Castillo, Enol; Orviz Fernández, Pablo

In this document we present an implementation of the Open Grid Forum's Open Cloud Computing Interface (OCCI) for OpenStack, namely ooi (Openstack occi interface, 2015) [1]. OCCI is an open standard for management tasks over cloud resources, focused on interoperability, portability and integration. ooi aims to implement this open interface for the OpenStack cloud middleware, promoting interoperability with other OCCI-enabled cloud management frameworks and infrastructures. ooi focuses on being non-invasive with a vanilla OpenStack installation, not tied to a particular OpenStack release version.

An integrated 3D log processing optimization system for small sawmills in central Appalachia

Treesearch

Wenshu Lin; Jingxin Wang

2013-01-01

An integrated 3D log processing optimization system was developed to perform 3D log generation, opening face determination, headrig log sawing simulation, fl itch edging and trimming simulation, cant resawing, and lumber grading. A circular cross-section model, together with 3D modeling techniques, was used to reconstruct 3D virtual logs. Internal log defects (knots)...

Virtual reality in surgical education.

PubMed

Ota, D; Loftin, B; Saito, T; Lea, R; Keller, J

1995-03-01

Virtual reality (VR) is an emerging technology that can teach surgeons new procedures and can determine their level of competence before they operate on patients. Also VR allows the trainee to return to the same procedure or task several times later as a refresher course. Laparoscopic surgery is a new operative technique which requires the surgeon to observe the operation on a video-monitor and requires the acquisition of new skills. VR simulation could duplicate the operative field and thereby enhance training and reduce the need for expensive animal training models. Our preliminary experience has shown that we have the technology to model tissues and laparoscopic instruments and to develop in real time a VR learning environment for surgeons. Another basic need is to measure competence. Surgical training is an apprenticeship requiring close supervision and 5-7 years of training. Technical competence is judged by the mentor and has always been subjective. If VR surgical simulators are to play an important role in the future, quantitative measurement of competence would have to be part of the system. Because surgical competence is "vague" and is characterized by such terms as "too long, too short" or "too close, too far," it is possible that the principles of fuzzy logic could be used to measure competence in a VR surgical simulator. Because a surgical procedure consists of a series of tasks and each task is a series of steps, we will plan to create two important tasks in a VR simulator and validate their use. These tasks consist of laparoscopic knot tying and laparoscopic suturing. Our hypothesis is that VR in combination with fuzzy logic can educate surgeons and determine when they are competent to perform these procedures on patients.

Validity evidence for the Fundamentals of Laparoscopic Surgery (FLS) program as an assessment tool: a systematic review.

PubMed

Zendejas, Benjamin; Ruparel, Raaj K; Cook, David A

2016-02-01

The Fundamentals of Laparoscopic Surgery (FLS) program uses five simulation stations (peg transfer, precision cutting, loop ligation, and suturing with extracorporeal and intracorporeal knot tying) to teach and assess laparoscopic surgery skills. We sought to summarize evidence regarding the validity of scores from the FLS assessment. We systematically searched for studies evaluating the FLS as an assessment tool (last search update February 26, 2013). We classified validity evidence using the currently standard validity framework (content, response process, internal structure, relations with other variables, and consequences). From a pool of 11,628 studies, we identified 23 studies reporting validity evidence for FLS scores. Studies involved residents (n = 19), practicing physicians (n = 17), and medical students (n = 8), in specialties of general (n = 17), gynecologic (n = 4), urologic (n = 1), and veterinary (n = 1) surgery. Evidence was most common in the form of relations with other variables (n = 22, most often expert-novice differences). Only three studies reported internal structure evidence (inter-rater or inter-station reliability), two studies reported content evidence (i.e., derivation of assessment elements), and three studies reported consequences evidence (definition of pass/fail thresholds). Evidence nearly always supported the validity of FLS total scores. However, the loop ligation task lacks discriminatory ability. Validity evidence confirms expected relations with other variables and acceptable inter-rater reliability, but other validity evidence is sparse. Given the high-stakes use of this assessment (required for board eligibility), we suggest that more validity evidence is required, especially to support its content (selection of tasks and scoring rubric) and the consequences (favorable and unfavorable impact) of assessment.

Quantum knots and the number of knot mosaics

NASA Astrophysics Data System (ADS)

Oh, Seungsang; Hong, Kyungpyo; Lee, Ho; Lee, Hwa Jeong

2015-03-01

Lomonaco and Kauffman developed a knot mosaic system to introduce a precise and workable definition of a quantum knot system. This definition is intended to represent an actual physical quantum system. A knot -mosaic is an matrix of mosaic tiles ( through depicted in the introduction) representing a knot or a link by adjoining properly that is called suitably connected. is the total number of all knot -mosaics. This value indicates the dimension of the Hilbert space of these quantum knot system. is already found for by the authors. In this paper, we construct an algorithm producing the precise value of for that uses recurrence relations of state matrices that turn out to be remarkably efficient to count knot mosaics. where matrices and are defined by for , with matrices and . Here denotes the sum of all entries of a matrix . For , means the identity matrix of size.

Robotic artificial chordal replacement for repair of mitral valve prolapse.

PubMed

Brunsting, Louis A; Rankin, J Scott; Braly, Kimberly C; Binford, Robert S

2009-07-01

Artificial chordal replacement (ACR) has emerged as a superior method of mitral valve repair with excellent early and late efficacy. It is also ideal to combine with robotic techniques for correction of mitral prolapse, and this article presents a current method of robotic Gore-Tex ACR. Patients with isolated posterior leaflet prolapse are approached with the fourth-generation DaVinci robotic system and endoaortic balloon occlusion. A pledgetted anchor stitch is placed in a papillary muscle, and a 2-o Gore-Tex suture is passed through the anchor pledget. After full annuloplasty ring placement, the Gore-Tex suture is woven into the prolapsing segment and positioned temporarily with robotic forceps. Chordal length is then "adjusted" by lengthening or shortening the temporary knot over 1-cm increments as the valve is tested by injection of cold saline into the ventricle. After achieving good leaflet position and valve competence, the chord is tied permanently. The "adjustable" ACR procedure preserves leaflet surface area and produces a competent valve in the majority of patients. Postoperative transesophageal echo shows a large surface area of coaptation. Patient recovery is facilitated by the minimally invasive approach, while long-term stability of similar open ACR techniques have been excellent with a 2% to 3% failure rate over 10 years of follow-up. Robotic Gore-Tex ACR without leaflet resection is a reproducible procedure that simplifies mitral repair for prolapse. The outcomes observed in early robotic applications have been excellent. It is suggested that most patients with simple prolapse might validly be approached in this manner.

How securely is the testicular artery occluded in the spermatic cord by using a ligature?

PubMed

Rijkenhuizen, A B M; Sommerauer, S; Fasching, M; Velde, K; Peham, C

2013-09-01

There are no studies on the ideal ligature technique for the spermatic cord. To compare the maximal resistance pressure in the testicular artery and the maximal tensile forces to produce failure of 2 different ligature techniques used for ligation of the equine spermatic cord. The capabilities of 2 types of ligatures, single knot loop and double knot loop, were assessed using a pressure-resistance test in testicular arteries and with an in vitro mechanical evaluation of the tensile strength by single cycle-to-failure testing. In the pressure-resistance test, the mean ± s.d. peak force at failure of the single knot loop was 354.4 ± 91.7 mmHg and for the double knot loop 303.2 ± 62.0 mmHg. There was no significant difference between the maximal load to failure of the single knot loop and double knot loop technique. The pressure needed for rupture was significantly higher (P = 0.001) than for leakage. The maximal tensile force at failure of the single knot loop was significantly higher than the double knot loop (P = 0.028). There was no significant difference in load elongation properties to failure between the single knot loop and double knot loop. Although no significant differences were obtained in the pressure-resistance test, the single knot loop sustained significantly greater load to failure than the double knot loop in single cycle-to-failure testing. Based on these findings, it would appear that the performance of the single knot loop should be superior to the double knot loop. Both ligature techniques are able to withstand the normal physiological intravascular pressure. The single knot loop has the greater breaking strength of the 2 ligatures tested and is less time consuming to perform and may therefore have advantages during equine castration. © 2012 EVJ Ltd.

Knotted fields and explicit fibrations for lemniscate knots

NASA Astrophysics Data System (ADS)

Bode, B.; Dennis, M. R.; Foster, D.; King, R. P.

2017-06-01

We give an explicit construction of complex maps whose nodal lines have the form of lemniscate knots. We review the properties of lemniscate knots, defined as closures of braids where all strands follow the same transverse (1, ℓ) Lissajous figure, and are therefore a subfamily of spiral knots generalizing the torus knots. We then prove that such maps exist and are in fact fibrations with appropriate choices of parameters. We describe how this may be useful in physics for creating knotted fields, in quantum mechanics, optics and generalizing to rational maps with application to the Skyrme-Faddeev model. We also prove how this construction extends to maps with weakly isolated singularities.

Knotting probability of a shaken ball-chain.

PubMed

Hickford, J; Jones, R; du Pont, S Courrech; Eggers, J

2006-11-01

We study the formation of knots on a macroscopic ball chain, which is shaken on a horizontal plate at 12 times the acceleration of gravity. We find that above a certain critical length, the knotting probability is independent of chain length, while the time to shake out a knot increases rapidly with chain length. The probability of finding a knot after a certain time is the result of the balance of these two processes. In particular, the knotting probability tends to a constant for long chains.

Quantifying the impact of weak, strong, and super ties in scientific careers

PubMed Central

Petersen, Alexander Michael

2015-01-01

Scientists are frequently faced with the important decision to start or terminate a creative partnership. This process can be influenced by strategic motivations, as early career researchers are pursuers, whereas senior researchers are typically attractors, of new collaborative opportunities. Focusing on the longitudinal aspects of scientific collaboration, we analyzed 473 collaboration profiles using an egocentric perspective that accounts for researcher-specific characteristics and provides insight into a range of topics, from career achievement and sustainability to team dynamics and efficiency. From more than 166,000 collaboration records, we quantify the frequency distributions of collaboration duration and tie strength, showing that collaboration networks are dominated by weak ties characterized by high turnover rates. We use analytic extreme value thresholds to identify a new class of indispensable super ties, the strongest of which commonly exhibit >50% publication overlap with the central scientist. The prevalence of super ties suggests that they arise from career strategies based upon cost, risk, and reward sharing and complementary skill matching. We then use a combination of descriptive and panel regression methods to compare the subset of publications coauthored with a super tie to the subset without one, controlling for pertinent features such as career age, prestige, team size, and prior group experience. We find that super ties contribute to above-average productivity and a 17% citation increase per publication, thus identifying these partnerships—the analog of life partners—as a major factor in science career development. PMID:26261301

Preliminary evaluation of the SimPORTAL major vessel injury (MVI) repair model.

PubMed

Veneziano, Domenico; Poniatowski, Lauren H; Reihsen, Troy E; Sweet, Robert M

2016-04-01

Major vessel injury (MVI) is a dangerous complication associated with laparoscopic surgery that leads, if not properly handled, to blood loss, conversion to open surgery, and eventually death. In this paper, we describe the preliminary evaluation of the SimPORTAL MVI model, created with the goal of simulating an intra-corporeal injury to a large vessel. For this study, we created MVI models for 17 residents (PGY 1-4). Each resident was asked to perform an intracorporeal knot on a penrose drain within a maximum time limit of 6 min (in accordance with European basic laparoscopic urological skills rules) and then to subsequently repair a vessel injury on the MVI model, which was perfused with synthetic blood, within a maximum blood loss of 3 L. During the vessel repair, low lights and pulse sounds were used to simulate the operating room environment. All participants filled out a survey pre- and post-task to score various aspects of the model. We successfully created a model that simulates a critical surgical event. None of the participants reported having previous experience repairing a MVI. Six participants were able to perform the intracorporeal knot, and 12 residents (70.5%) were able to repair the MVI model under the given time and blood loss limits. Eleven participants agreed that the MVI model behaves like a real vessel, and six felt to be capable of performing the task prior to attempting it. Sixteen participants thought that the MVI model should be part of laparoscopic curriculums during residency. The SimPORTAL MVI model is a feasible low-cost model that would be well appreciated as a part of laparoscopic curriculum for residents. Minor improvements, including pressure measurement in the vessel for task assessment, will be made in the future, and further studies are necessary to definitively validate this model.

A numerical model for the Serpens radio jet

NASA Astrophysics Data System (ADS)

Raga, A. C.; Curiel, S.; Rodríguez, L. F.; Cantó, J.

2000-12-01

The Serpens (``triple source'') radio continuum jet shows a series of aligned knots with ~ 1-2'' angular separations, forming a curved structure circumscribed within a cone of ~ 10o full opening angle. We present a high resolution, 3D numerical simulation of a jet with variable ejection direction and velocity with parameters appropriate for the Serpens jet, from which we obtain predictions of 3.6 cm radio continuum maps. We find that the general morphology of the radio emission, and the time evolution of the successive knots, qualitatively agree with 3.6 cm VLA observations of the Serpens radio jet. Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) and with the participation of ISAS and NASA. Members of the Consortium on the ISOPHOT Serendipity Survey (CISS) are MPIA Heidelberg, ESA ISO SOC Villafranca, AIP Potsdam, IPAC Pasadena, Imperial College London.

All in a Knot of One Another's Labours: Self-Determination, Network Organising and Learning

ERIC Educational Resources Information Center

Pedler, Mike

2012-01-01

This essay is about how to learn to organise to tackle the intractable and most difficult problems of organisations and societies. It opens with a discussion of the nature of such problems, which are the spur for Revans' action learning and the focus of some recent thinking on leadership. Action learning works on the basis of peer relationships…

Sampling large random knots in a confined space

NASA Astrophysics Data System (ADS)

Arsuaga, J.; Blackstone, T.; Diao, Y.; Hinson, K.; Karadayi, E.; Saito, M.

2007-09-01

DNA knots formed under extreme conditions of condensation, as in bacteriophage P4, are difficult to analyze experimentally and theoretically. In this paper, we propose to use the uniform random polygon model as a supplementary method to the existing methods for generating random knots in confinement. The uniform random polygon model allows us to sample knots with large crossing numbers and also to generate large diagrammatically prime knot diagrams. We show numerically that uniform random polygons sample knots with large minimum crossing numbers and certain complicated knot invariants (as those observed experimentally). We do this in terms of the knot determinants or colorings. Our numerical results suggest that the average determinant of a uniform random polygon of n vertices grows faster than O(e^{n^2}) . We also investigate the complexity of prime knot diagrams. We show rigorously that the probability that a randomly selected 2D uniform random polygon of n vertices is almost diagrammatically prime goes to 1 as n goes to infinity. Furthermore, the average number of crossings in such a diagram is at the order of O(n2). Therefore, the two-dimensional uniform random polygons offer an effective way in sampling large (prime) knots, which can be useful in various applications.

Scaling behavior of knotted random polygons and self-avoiding polygons: Topological swelling with enhanced exponent.

PubMed

Uehara, Erica; Deguchi, Tetsuo

2017-12-07

We show that the average size of self-avoiding polygons (SAPs) with a fixed knot is much larger than that of no topological constraint if the excluded volume is small and the number of segments is large. We call it topological swelling. We argue an "enhancement" of the scaling exponent for random polygons with a fixed knot. We study them systematically through SAP consisting of hard cylindrical segments with various different values of the radius of segments. Here we mean by the average size the mean-square radius of gyration. Furthermore, we show numerically that the topological balance length of a composite knot is given by the sum of those of all constituent prime knots. Here we define the topological balance length of a knot by such a number of segments that topological entropic repulsions are balanced with the knot complexity in the average size. The additivity suggests the local knot picture.

Constructing a polynomial whose nodal set is the three-twist knot 52

NASA Astrophysics Data System (ADS)

Dennis, Mark R.; Bode, Benjamin

2017-06-01

We describe a procedure that creates an explicit complex-valued polynomial function of three-dimensional space, whose nodal lines are the three-twist knot 52. The construction generalizes a similar approach for lemniscate knots: a braid representation is engineered from finite Fourier series and then considered as the nodal set of a certain complex polynomial which depends on an additional parameter. For sufficiently small values of this parameter, the nodal lines form the three-twist knot. Further mathematical properties of this map are explored, including the relationship of the phase critical points with the Morse-Novikov number, which is nonzero as this knot is not fibred. We also find analogous functions for other simple knots and links. The particular function we find, and the general procedure, should be useful for designing knotted fields of particular knot types in various physical systems.

Scaling behavior of knotted random polygons and self-avoiding polygons: Topological swelling with enhanced exponent

NASA Astrophysics Data System (ADS)

Uehara, Erica; Deguchi, Tetsuo

2017-12-01

We show that the average size of self-avoiding polygons (SAPs) with a fixed knot is much larger than that of no topological constraint if the excluded volume is small and the number of segments is large. We call it topological swelling. We argue an "enhancement" of the scaling exponent for random polygons with a fixed knot. We study them systematically through SAP consisting of hard cylindrical segments with various different values of the radius of segments. Here we mean by the average size the mean-square radius of gyration. Furthermore, we show numerically that the topological balance length of a composite knot is given by the sum of those of all constituent prime knots. Here we define the topological balance length of a knot by such a number of segments that topological entropic repulsions are balanced with the knot complexity in the average size. The additivity suggests the local knot picture.

The Arabidopsis RING-Type E3 Ligase TEAR1 Controls Leaf Development by Targeting the TIE1 Transcriptional Repressor for Degradation[OPEN

PubMed Central

Zhang, Jinzhe; Wei, Baoye; Yuan, Rongrong; Yu, Hao

2017-01-01

The developmental plasticity of leaf size and shape is important for leaf function and plant survival. However, the mechanisms by which plants form diverse leaves in response to environmental conditions are not well understood. Here, we identified TIE1-ASSOCIATED RING-TYPE E3 LIGASE1 (TEAR1) and found that it regulates leaf development by promoting the degradation of TCP INTERACTOR-CONTAINING EAR MOTIF PROTEIN1 (TIE1), an important repressor of CINCINNATA (CIN)-like TEOSINTE BRANCHED1/CYCLOIDEA/PCF (TCP) transcription factors, which are key for leaf development. TEAR1 contains a typical C3H2C3-type RING domain and has E3 ligase activity. We show that TEAR1 interacts with the TCP repressor TIE1, which is ubiquitinated in vivo and degraded by the 26S proteasome system. We demonstrate that TEAR1 is colocalized with TIE1 in nuclei and negatively regulates TIE1 protein levels. Overexpression of TEAR1 rescued leaf defects caused by TIE1 overexpression, whereas disruption of TEAR1 resulted in leaf phenotypes resembling those caused by TIE1 overexpression or TCP dysfunction. Deficiency in TEAR partially rescued the leaf defects of TCP4 overexpression line and enhanced the wavy leaf phenotypes of jaw-5D. We propose that TEAR1 positively regulates CIN-like TCP activity to promote leaf development by mediating the degradation of the TCP repressor TIE1. PMID:28100709

Impaired angiopoietin/Tie2 signaling compromises Schlemm’s canal integrity and induces glaucoma

PubMed Central

Kim, Jaeryung; Park, Dae-Young; Park, Do Young; Kim, Dongkyu; Lee, Choong-kun; Song, Sukhyun; Chung, Tae-Young; Lim, Dong Hui; Hong, Young-Kwon; Augustin, Hellmut G.

2017-01-01

Primary open-angle glaucoma (POAG) is often caused by elevated intraocular pressure (IOP), which arises due to increased resistance to aqueous humor outflow (AHO). Aqueous humor flows through Schlemm’s canal (SC), a lymphatic-like vessel encircling the cornea, and via intercellular spaces of ciliary muscle cells. However, the mechanisms underlying increased AHO resistance are poorly understood. Here, we demonstrate that signaling between angiopoietin (Angpt) and the Angpt receptor Tie2, which is critical for SC formation, is also indispensable for maintaining SC integrity during adulthood. Deletion of Angpt1/Angpt2 or Tie2 in adult mice severely impaired SC integrity and transcytosis, leading to elevated IOP, retinal neuron damage, and impairment of retinal ganglion cell function, all hallmarks of POAG in humans. We found that SC integrity is maintained by interconnected and coordinated functions of Angpt-Tie2 signaling, AHO, and Prox1 activity. These functions diminish in the SC during aging, leading to impaired integrity and transcytosis. Intriguingly, Tie2 reactivation using a Tie2 agonistic antibody rescued the POAG phenotype in Angpt1/Angpt2-deficient mice and rejuvenated the SC in aged mice. These results indicate that the Angpt-Tie2 system is essential for SC integrity. The impairment of this system underlies POAG-associated pathogenesis, supporting the possibility that Tie2 agonists could be a therapeutic option for glaucoma. PMID:28920924

Motion of Knots in DNA Stretched by Elongational Fields

NASA Astrophysics Data System (ADS)

Klotz, Alexander R.; Soh, Beatrice W.; Doyle, Patrick S.

2018-05-01

Knots in DNA occur in biological systems, serve as a model system for polymer entanglement, and affect the efficacy of modern genomics technologies. We study the motion of complex knots in DNA by stretching molecules with a divergent electric field that provides an elongational force. We demonstrate that the motion of knots is nonisotropic and driven towards the closest end of the molecule. We show for the first time experimentally that knots can go from a mobile to a jammed state by varying an applied strain rate, and that this jamming is reversible. We measure the mobility of knots as a function of strain rate, demonstrating the conditions under which knots can be driven towards the ends of the molecule and untied.

Escape of a knot from a DNA molecule in flow

NASA Astrophysics Data System (ADS)

Renner, Benjamin; Doyle, Patrick

2014-03-01

Macroscale knots are an everyday occurrence when trying to unravel an unorganized flexible string (e.g. an iPhone cord taken out of your pocket). In nature, knots are found in proteins and viral capsid DNA, and the properties imbued by their topologies are thought to have biological significance. Unlike their macroscale counterparts, thermal fluctuations greatly influence the dynamics of polymer knots. Here, we use Brownian Dynamics simulations to study knot diffusion along a linear polymer chain. The model is parameterized to dsDNA, a model polymer used in previous simulation and experimental studies of knot dynamics. We have used this model to study the process of knot escape and transport along a dsDNA strand extended by an elongational flow. For a range of knot topologies and flow strengths, we show scalings that result in collapse of the data onto a master curve. We show a topologically mediated mode of transport coincides with observed differences in rates of knot transport, and we provide a simple mechanistic explanation for its effect. We anticipate these results will build on the growing body of fundamental studies of knotted polymers and inform future experimental study. This work is supported by the Singapore-MIT Alliance for Research and Technology (SMART) and National Science Foundation (NSF) grant CBET-0852235.

Swedish and South African nursing students' descriptions of family.

PubMed

Erlingsson, Christen; Brysiewicz, Petra

2015-05-01

The purpose of this study was to compare and contrast descriptions of "family" amongst Swedish and South African university nursing students. This qualitative inquiry, using convenience sampling, explored how 232 undergraduate and postgraduate nursing students responded to a two-query, open-response questionnaire designed to elicit a definition of family and a description of who students considered to be members of their own families. Free-text responses were analyzed using manifest and qualitative content analysis. Five categories emerged from the data: Ties of Kinship, Ties of Love, Ties of Influence, Ties of Everyday Life, and Tied by Slipknots. Analysis clarified that students' responses from both countries were addressing the same issues and as such were in general very similar. Contrasting Swedish and South African responses, a noticeable difference in proportions of responses coded into each category was evident. Three conceptualizations of family are offered: for the total sample, Swedish sample, and South African sample. The study provides data on students' conceptualization of family usable in family research, nursing education, and practice as a basis for comparison, and as a starting point for discussions on the nursing of families, not only in South Africa and Sweden, but also in broader international contexts. Because understanding family is important for healthcare providers in their everyday work, awareness about what is meant by family can assist nurses through increasing understanding of the complexities surrounding this issue and encouraging cultural sensitivity and openness to patients' and families' views about who is a family member. © 2015 Sigma Theta Tau International.

22 CFR 64.2 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-04-01

... group of governments and an official agent or representative thereof; an international organization... knowledge or skill, and other influential or distinguished persons.” (d) The “purpose stated in section 101... cultural exchange; to strengthen the ties which unite us with other nations by demonstrating the...

22 CFR 64.2 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-04-01

... group of governments and an official agent or representative thereof; an international organization... knowledge or skill, and other influential or distinguished persons.” (d) The “purpose stated in section 101... cultural exchange; to strengthen the ties which unite us with other nations by demonstrating the...

22 CFR 64.2 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-04-01

... group of governments and an official agent or representative thereof; an international organization... knowledge or skill, and other influential or distinguished persons.” (d) The “purpose stated in section 101... cultural exchange; to strengthen the ties which unite us with other nations by demonstrating the...

22 CFR 64.2 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-04-01

... group of governments and an official agent or representative thereof; an international organization... knowledge or skill, and other influential or distinguished persons.” (d) The “purpose stated in section 101... cultural exchange; to strengthen the ties which unite us with other nations by demonstrating the...

The roles of impact and inertia in the failure of a shoelace knot

NASA Astrophysics Data System (ADS)

Daily-Diamond, Christopher A.; Gregg, Christine E.; O'Reilly, Oliver M.

2017-04-01

The accidental untying of a shoelace while walking often occurs without warning. In this paper, we discuss the series of events that lead to a shoelace knot becoming untied. First, the repeated impact of the shoe on the floor during walking serves to loosen the knot. Then, the whipping motions of the free ends of the laces caused by the leg swing produce slipping of the laces. This leads to eventual runaway untangling of the knot. As demonstrated using slow-motion video footage and a series of experiments, the failure of the knot happens in a matter of seconds, often without warning, and is catastrophic. The controlled experiments showed that increasing inertial effects of the swinging laces leads to increased rate of knot untying, that the directions of the impact and swing influence the rate of failure, and that the knot structure has a profound influence on a knot's tendency to untie under cyclic impact loading.

Asymptotic laws for random knot diagrams

NASA Astrophysics Data System (ADS)

Chapman, Harrison

2017-06-01

We study random knotting by considering knot and link diagrams as decorated, (rooted) topological maps on spheres and pulling them uniformly from among sets of a given number of vertices n, as first established in recent work with Cantarella and Mastin. The knot diagram model is an exciting new model which captures both the random geometry of space curve models of knotting as well as the ease of computing invariants from diagrams. We prove that unknot diagrams are asymptotically exponentially rare, an analogue of Sumners and Whittington’s landmark result for self-avoiding polygons. Our proof uses the same key idea: we first show that knot diagrams obey a pattern theorem, which describes their fractal structure. We examine how quickly this behavior occurs in practice. As a consequence, almost all diagrams are asymmetric, simplifying sampling from this model. We conclude with experimental data on knotting in this model. This model of random knotting is similar to those studied by Diao et al, and Dunfield et al.

3D visualization software to analyze topological outcomes of topoisomerase reactions

PubMed Central

Darcy, I. K.; Scharein, R. G.; Stasiak, A.

2008-01-01

The action of various DNA topoisomerases frequently results in characteristic changes in DNA topology. Important information for understanding mechanistic details of action of these topoisomerases can be provided by investigating the knot types resulting from topoisomerase action on circular DNA forming a particular knot type. Depending on the topological bias of a given topoisomerase reaction, one observes different subsets of knotted products. To establish the character of topological bias, one needs to be aware of all possible topological outcomes of intersegmental passages occurring within a given knot type. However, it is not trivial to systematically enumerate topological outcomes of strand passage from a given knot type. We present here a 3D visualization software (TopoICE-X in KnotPlot) that incorporates topological analysis methods in order to visualize, for example, knots that can be obtained from a given knot by one intersegmental passage. The software has several other options for the topological analysis of mechanisms of action of various topoisomerases. PMID:18440983

Filtration of the classical knot concordance group and Casson-Gordon invariants

NASA Astrophysics Data System (ADS)

Kim, Taehee

2004-09-01

It is known that if every prime power branched cyclic cover of a knot in S(3) is a homology sphere, then the knot has vanishing Casson-Gordon invariants. We construct infinitely many examples of (topologically) non-slice knots in S(3) whose prime power branched cyclic covers are homology spheres. We show that these knots generate an infinite rank subgroup of scrf_{(1.0)}/scrf_{(1.5)} for which Casson-Gordon invariants vanish in Cochran-Orr-Teichner's filtration of the classical knot concordance group. As a corollary, it follows that Casson-Gordon invariants are not a complete set of obstructions to a second layer of Whitney disks.

Knot theory in modern chemistry.

PubMed

Horner, Kate E; Miller, Mark A; Steed, Jonathan W; Sutcliffe, Paul M

2016-11-21

Knot theory is a branch of pure mathematics, but it is increasingly being applied in a variety of sciences. Knots appear in chemistry, not only in synthetic molecular design, but also in an array of materials and media, including some not traditionally associated with knots. Mathematics and chemistry can now be used synergistically to identify, characterise and create knots, as well as to understand and predict their physical properties. This tutorial review provides a brief introduction to the mathematics of knots and related topological concepts in the context of the chemical sciences. We then survey the broad range of applications of the theory to contemporary research in the field.

Sales Training for Army Recruiter Success: Supplementary Information on Modeling the Sales Strategies and Skills of Excellent Recruiters

DTIC Science & Technology

1987-11-01

feel your parachute deploying ... ? The recruiter will want to finish the experience he has created and taken the prospect through in a way that makes... finishing with a pleasant feeling or unspecified experience to relieve the tension: "You’re looking around ... your stomach was tighter than a knot...personal style. Even when the prospect has agreed to join the Army, the recruiter is not finished . He now has to prepare the prospect for processing at the

Knot probabilities in random diagrams

NASA Astrophysics Data System (ADS)

Cantarella, Jason; Chapman, Harrison; Mastin, Matt

2016-10-01

We consider a natural model of random knotting—choose a knot diagram at random from the finite set of diagrams with n crossings. We tabulate diagrams with 10 and fewer crossings and classify the diagrams by knot type, allowing us to compute exact probabilities for knots in this model. As expected, most diagrams with 10 and fewer crossings are unknots (about 78% of the roughly 1.6 billion 10 crossing diagrams). For these crossing numbers, the unknot fraction is mostly explained by the prevalence of ‘tree-like’ diagrams which are unknots for any assignment of over/under information at crossings. The data shows a roughly linear relationship between the log of knot type probability and the log of the frequency rank of the knot type, analogous to Zipf’s law for word frequency. The complete tabulation and all knot frequencies are included as supplementary data.

[Mechanical behaviour of three types of surgical knots using 4/0 monofilament].

PubMed

Gil Santos, Luis; Más-Estellés, Jorge; Salmerón Sánchez, Manuel; Barrios, Carlos

2012-01-01

To experimentally study the behaviour of 4 types of monofilament with 3 knotting techniques, very often used in surgery, employing mechanical tests. Four 4/0 monofilaments were chosen, two of nylon, and the other two of polypropylene. Three types of knot designs were made with each thread. The first design (D-S-S) consisted of a double half-knot (D) followed by one single (S) in the opposite direction, a third S in turn in the opposite direction. The configuration of the second design was D-S-D, and the third, S-S-D. A mechanical fracture test was performed by stretching the thread at a rate of 4N/s, the force and deformation being recorded at intervals of 100 ms. There was a decrease in the force and deformation in the tests on threads with knots compared to threads without knots. In all cases the rupture of the thread occurred in the knot area, presumably due to damage caused to the thread during the knotting process. The D-S-D knot had the greatest resistance with polypropylene threads, and S-S-D provided the greatest resistance with nylon threads Polypropylene threads, with D-S-D knots, should be more indicated to suture tissues that have to support great forces and with little deformation of the suture (e.g., tendons). Nylon threads, with S-S-D knots, would be better indicated for tissues that have to support smaller forces and that require greater elasticity (e.g., skin). Copyright © 2011 AEC. Published by Elsevier Espana. All rights reserved.

Parent-implemented behavioral skills training of social skills.

PubMed

Dogan, Rebecca K; King, Melissa L; Fischetti, Anthony T; Lake, Candice M; Mathews, Therese L; Warzak, William J

2017-10-01

Impairment in social skills is a primary feature of Autism Spectrum Disorders (ASDs). Research indicates that social skills are intimately tied to social development and negative social consequences can persist if specific social behaviors are not acquired. The present study evaluated the effects of behavioral skills training (BST) on teaching four parents of children with ASDs to be social skills trainers. A nonconcurrent multiple baseline design across parent-child dyads was employed and direct observation was used to assess parent and child behaviors Results demonstrated substantial improvement in social skills teaching for all participants for trained and untrained skills. Ancillary measures of child performance indicated improvement in skills as well. High levels of correct teaching responses were maintained at a 1 month follow-up. This study extends current literature on BST while also providing a helpful, low-effort strategy to modify how parents can work with their children to improve their social skills. © 2017 Society for the Experimental Analysis of Behavior.

Boot cAMP: educational outcomes after 4 successive years of preparatory simulation-based training at onset of internship.

PubMed

Fernandez, Gladys L; Page, David W; Coe, Nicholas P; Lee, Patrick C; Patterson, Lisa A; Skylizard, Loki; St Louis, Myron; Amaral, Marisa H; Wait, Richard B; Seymour, Neal E

2012-01-01

Preparatory training for new trainees beginning residency has been used by a variety of programs across the country. To improve the clinical orientation process for our new postgraduate year (PGY)-1 residents, we developed an intensive preparatory training curriculum inclusive of cognitive and procedural skills, training activities considered essential for early PGY-1 clinical management. We define our surgical PGY-1 Boot Camp as preparatory simulation-based training implemented at the onset of internship for introduction of skills necessary for basic surgical patient problem assessment and management. This orientation process includes exposure to simulated patient care encounters and technical skills training essential to new resident education. We report educational results of 4 successive years of Boot Camp training. Results were analyzed to determine if performance evidenced at onset of training was predictive of later educational outcomes. Learners were PGY-1 residents, in both categorical and preliminary positions, at our medium-sized surgical residency program. Over a 4-year period, from July 2007 to July 2010, all 30 PGY-1 residents starting surgical residency at our institution underwent specific preparatory didactic and skills training over a 9-week period. This consisted of mandatory weekly 1-hour and 3-hour sessions in the Simulation Center, representing a 4-fold increase in time in simulation laboratory training compared with the remainder of the year. Training occurred in 8 procedural skills areas (instrument use, knot-tying, suturing, laparoscopic skills, airway management, cardiopulmonary resuscitation, central venous catheter, and chest tube insertion) and in simulated patient care (shock, surgical emergencies, and respiratory, cardiac, and trauma management) using a variety of high- and low-tech simulation platforms. Faculty and senior residents served as instructors. All educational activities were structured to include preparatory materials, pretraining briefing sessions, and immediate in-training or post-training review and debriefing. Baseline cognitive skills were assessed with written tests on basic patient management. Post-Boot Camp tests similarly evaluated cognitive skills. Technical skills were assessed using a variety of task-specific instruments, and expressed as a mean score for all activities for each resident. All measurements were expressed as percent (%) best possible score. Cognitive and technical performance in Boot Camp was compared with subsequent clinical and core curriculum evaluations including weekly quiz scores, annual American Board of Surgery In-Training Examination (ABSITE) scores, program in-training evaluations (New Innovations, Uniontown, Ohio), and operative assessment instrument scores (OP-Rate, Baystate Medical Center, Springfield, Massachusetts) for the remainder of the PGY-1 year. Performance data were available for 30 PGY-1 residents over 4 years. Baseline cognitive skills were lower for the first year of Boot Camp as compared with subsequent years (71 ± 13, 83 ± 9, 84 ± 11, and 86 ± 6, respectively; p = 0.028, analysis of variance; ANOVA). Performance improved between pretests and final testing (81 ± 11 vs 89 ± 7; p < 0.001 paired t test). There was statistically significant correlation between Boot Camp final cognitive test results and American Board of Surgery In-Training Examination scores (p = 0.01; n = 22), but not quite significant for weekly curriculum quiz scores (p = 0.055; n = 22) and New Innovations cognitive assessments (p = 0.09; n = 25). Statistically significant correlation was also noted between Boot Camp mean overall skills and New Innovations technical skills assessments (p = 0.002; n = 25) and OP-Rate assessments (p = 0.01; n = 12). Individual simulation-based Boot Camp performance scores for cognitive and procedural skills assessments in PGY-1 residents correlate with subjective and objective clinical performance evaluations. This concurrent correlation with multiple traditional evaluation methods used to express competency in our residency program supports the use of Boot Camp performance measures as needs assessment tools as well as adjuncts to cumulative resident evaluation data. Copyright © 2012 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

Conflicts of interests in the area of healthcare products and technology. Current state of affairs and recommendations.

PubMed

Demarez, Jean-Paul; Funck-Brentano, Christian; Molimard, Mathieu

2012-01-01

The handling of conflicts of interest in the area of healthcare products and technology has become a major issue for all of those involved in healthcare. Round Table N°4 at the Giens Workshops 2011 has put forward concrete proposals to clarify and optimise the handling of conflicts of interest. Conflicts of interest cannot be defined by the individuals consulted or applying for funds since each institution, whether public or private, that puts out a call for projects or that requests advice, analyses or expert testimony in the healthcare field has different degrees of what it defines as a conflict of interest, depending on the context of the proposal or specific request that it puts out. In contrast, each individual has ties of personal interest that can and must be openly disclosed. The ties are much more diverse than what is commonly found in the conflict of interest statements of large institutions operating in the healthcare field and are not limited to financial and operational ties between companies and individuals. In addition, the statements are difficult to manage because of their sheer number. The Round Table recommends that each individual should openly disclose all of his or her ties of personal interest in a Single Statement of Ties of personal Interest (SSTI). The SSTI would be updated regularly and accessible on line. Each institution could then determine whether or not the reported ties represent a conflict in the context of the mission proposed. Each institution could publish in advance the conditions that would give rise to a conflict and, in this way, an individual could refrain from applying for the mission. Other practical approaches to handling conflicts of interest were put forward. © 2012 Société Française de Pharmacologie et de Thérapeutique.

Characteristic length of the knotting probability revisited

NASA Astrophysics Data System (ADS)

Uehara, Erica; Deguchi, Tetsuo

2015-09-01

We present a self-avoiding polygon (SAP) model for circular DNA in which the radius of impermeable cylindrical segments corresponds to the screening length of double-stranded DNA surrounded by counter ions. For the model we evaluate the probability for a generated SAP with N segments having a given knot K through simulation. We call it the knotting probability of a knot K with N segments for the SAP model. We show that when N is large the most significant factor in the knotting probability is given by the exponentially decaying part exp(-N/NK), where the estimates of parameter NK are consistent with the same value for all the different knots we investigated. We thus call it the characteristic length of the knotting probability. We give formulae expressing the characteristic length as a function of the cylindrical radius rex, i.e. the screening length of double-stranded DNA.

Torus Knots and the Topological Vertex

NASA Astrophysics Data System (ADS)

Jockers, Hans; Klemm, Albrecht; Soroush, Masoud

2014-08-01

We propose a class of toric Lagrangian A-branes on the resolved conifold that is suitable to describe torus knots on S 3. The key role is played by the transformation, which generates a general torus knot from the unknot. Applying the topological vertex to the proposed A-branes, we rederive the colored HOMFLY polynomials for torus knots, in agreement with the Rosso and Jones formula. We show that our A-model construction is mirror symmetric to the B-model analysis of Brini, Eynard and Mariño. Compared to the recent proposal by Aganagic and Vafa for knots on S 3, we demonstrate that the disk amplitude of the A-brane associated with any knot is sufficient to reconstruct the entire B-model spectral curve. Finally, the construction of toric Lagrangian A-branes is generalized to other local toric Calabi-Yau geometries, which paves the road to study knots in other three-manifolds such as lens spaces.

Vortex knots in tangled quantum eigenfunctions

PubMed Central

Taylor, Alexander J.; Dennis, Mark R.

2016-01-01

Tangles of string typically become knotted, from macroscopic twine down to long-chain macromolecules such as DNA. Here, we demonstrate that knotting also occurs in quantum wavefunctions, where the tangled filaments are vortices (nodal lines/phase singularities). The probability that a vortex loop is knotted is found to increase with its length, and a wide gamut of knots from standard tabulations occur. The results follow from computer simulations of random superpositions of degenerate eigenstates of three simple quantum systems: a cube with periodic boundaries, the isotropic three-dimensional harmonic oscillator and the 3-sphere. In the latter two cases, vortex knots occur frequently, even in random eigenfunctions at relatively low energy, and are constrained by the spatial symmetries of the modes. The results suggest that knotted vortex structures are generic in complex three-dimensional wave systems, establishing a topological commonality between wave chaos, polymers and turbulent Bose–Einstein condensates. PMID:27468801

Evolution method and ``differential hierarchy'' of colored knot polynomials

NASA Astrophysics Data System (ADS)

Mironov, A.; Morozov, A.; Morozov, And.

2013-10-01

We consider braids with repeating patterns inside arbitrary knots which provides a multi-parametric family of knots, depending on the "evolution" parameter, which controls the number of repetitions. The dependence of knot (super)polynomials on such evolution parameters is very easy to find. We apply this evolution method to study of the families of knots and links which include the cases with just two parallel and anti-parallel strands in the braid, like the ordinary twist and 2-strand torus knots/links and counter-oriented 2-strand links. When the answers were available before, they are immediately reproduced, and an essentially new example is added of the "double braid", which is a combination of parallel and anti-parallel 2-strand braids. This study helps us to reveal with the full clarity and partly investigate a mysterious hierarchical structure of the colored HOMFLY polynomials, at least, in (anti)symmetric representations, which extends the original observation for the figure-eight knot to many (presumably all) knots. We demonstrate that this structure is typically respected by the t-deformation to the superpolynomials.

Effects of horseshoe crab harvest in delaware bay on red knots: Are harvest restrictions working?

USGS Publications Warehouse

Niles, L.J.; Bart, J.; Sitters, H.P.; Dey, A.D.; Clark, K.E.; Atkinson, P.W.; Baker, Allan J.; Bennett, K.A.; Kalasz, K.S.; Clark, N.A.; Clark, J.; Gillings, S.; Gates, A.S.; Gonzalez, P.M.; Hernandez, D.E.; Minton, C.D.T.; Morrison, R.I.G.; Porter, R.R.; Ross, R.K.; Veitch, C.R.

2009-01-01

Each May, red knots (Calidris canutus rufa) congregate in Delaware Bay during their northward migration to feed on horseshoe crab eggs (Limulus polyphemus) and refuel for breeding in the Arctic. During the 1990s, the Delaware Bay harvest of horseshoe crabs for bait increased 10-fold, leading to a more than 90% decline in the availability of their eggs for knots. The proportion of knots achieving weights of more than 180 grams by 26-28 May, their main departure period, dropped from 0.6-0.8 to 0.14-0.4 over 1997-2007. During the same period, the red knot population stopping in Delaware Bay declined by more than 75%, in part because the annual survival rate of adult knots wintering in Tierra del Fuego declined. Despite restrictions, the 2007 horseshoe crab harvest was still greater than the 1990 harvest, and no recovery of knots was detectable. We propose an adaptive management strategy with recovery goals and annual monitoring that, if adopted, will both allow red knot and horseshoe crab populations to recover and permit a sustainable harvest of horseshoe crabs.

Shadow-driven 4D haptic visualization.

PubMed

Zhang, Hui; Hanson, Andrew

2007-01-01

Just as we can work with two-dimensional floor plans to communicate 3D architectural design, we can exploit reduced-dimension shadows to manipulate the higher-dimensional objects generating the shadows. In particular, by taking advantage of physically reactive 3D shadow-space controllers, we can transform the task of interacting with 4D objects to a new level of physical reality. We begin with a teaching tool that uses 2D knot diagrams to manipulate the geometry of 3D mathematical knots via their projections; our unique 2D haptic interface allows the user to become familiar with sketching, editing, exploration, and manipulation of 3D knots rendered as projected imageson a 2D shadow space. By combining graphics and collision-sensing haptics, we can enhance the 2D shadow-driven editing protocol to successfully leverage 2D pen-and-paper or blackboard skills. Building on the reduced-dimension 2D editing tool for manipulating 3D shapes, we develop the natural analogy to produce a reduced-dimension 3D tool for manipulating 4D shapes. By physically modeling the correct properties of 4D surfaces, their bending forces, and their collisions in the 3D haptic controller interface, we can support full-featured physical exploration of 4D mathematical objects in a manner that is otherwise far beyond the experience accessible to human beings. As far as we are aware, this paper reports the first interactive system with force-feedback that provides "4D haptic visualization" permitting the user to model and interact with 4D cloth-like objects.

Energy landscape of knotted protein folding

PubMed Central

Sułkowska, Joanna I.; Noel, Jeffrey K.; Onuchic, Jose N.

2012-01-01

Recent experiments have conclusively shown that proteins are able to fold from an unknotted, denatured polypeptide to the knotted, native state without the aid of chaperones. These experiments are consistent with a growing body of theoretical work showing that a funneled, minimally frustrated energy landscape is sufficient to fold small proteins with complex topologies. Here, we present a theoretical investigation of the folding of a knotted protein, 2ouf, engineered in the laboratory by a domain fusion that mimics an evolutionary pathway for knotted proteins. Unlike a previously studied knotted protein of similar length, we see reversible folding/knotting and a surprising lack of deep topological traps with a coarse-grained structure-based model. Our main interest is to investigate how evolution might further select the geometry and stiffness of the threading region of the newly fused protein. We compare the folding of the wild-type protein to several mutants. Similarly to the wild-type protein, all mutants show robust and reversible folding, and knotting coincides with the transition state ensemble. As observed experimentally, our simulations show that the knotted protein folds about ten times slower than an unknotted construct with an identical contact map. Simulated folding kinetics reflect the experimentally observed rollover in the folding limbs of chevron plots. Successful folding of the knotted protein is restricted to a narrow range of temperature as compared to the unknotted protein and fits of the kinetic folding data below folding temperature suggest slow, nondiffusive dynamics for the knotted protein. PMID:22891304

Pseudohaptic interaction with knot diagrams

NASA Astrophysics Data System (ADS)

Weng, Jianguang; Zhang, Hui

2012-07-01

To make progress in understanding knot theory, we need to interact with the projected representations of mathematical knots, which are continuous in three dimensions (3-D) but significantly interrupted in the projective images. One way to achieve such a goal is to design an interactive system that allows us to sketch two-dimensional (2-D) knot diagrams by taking advantage of a collision-sensing controller and explore their underlying smooth structures through a continuous motion. Recent advances of interaction techniques have been made that allow progress in this direction. Pseudohaptics that simulate haptic effects using pure visual feedback can be used to develop such an interactive system. We outline one such pseudohaptic knot diagram interface. Our interface derives from the familiar pencil-and-paper process of drawing 2-D knot diagrams and provides haptic-like sensations to facilitate the creation and exploration of knot diagrams. A centerpiece of the interaction model simulates a physically reactive mouse cursor, which is exploited to resolve the apparent conflict between the continuous structure of the actual smooth knot and the visual discontinuities in the knot diagram representation. Another value in exploiting pseudohaptics is that an acceleration (or deceleration) of the mouse cursor (or surface locator) can be used to indicate the slope of the curve (or surface) of which the projective image is being explored. By exploiting these additional visual cues, we proceed to a full-featured extension to a pseudohaptic four-dimensional (4-D) visualization system that simulates the continuous navigation on 4-D objects and allows us to sense the bumps and holes in the fourth dimension. Preliminary tests of the software show that main features of the interface overcome some expected perceptual limitations in our interaction with 2-D knot diagrams of 3-D knots and 3-D projective images of 4-D mathematical objects.

A 'FIREWORK' OF H{sub 2} KNOTS IN THE PLANETARY NEBULA NGC 7293 (THE HELIX NEBULA)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsuura, M.; Speck, A. K.; McHunu, B. M.

2009-08-01

We present a deep and wide field-of-view (4' x 7') image of the planetary nebula (PN) NGC 7293 (the Helix Nebula) in the 2.12 {mu}m H{sub 2} v = 1 {yields} 0 S(1) line. The excellent seeing (0.''4) at the Subaru Telescope, allows the details of cometary knots to be examined. The knots are found at distances of 2.'2-6.'4 from the central star (CS). At the inner edge and in the inner ring (up to 4.'5 from the CS), the knot often show a 'tadpole' shape, an elliptical head with a bright crescent inside and a long tail opposite tomore » the CS. In detail, there are variations in the tadpole shapes, such as narrowing tails, widening tails, meandering tails, or multipeaks within a tail. In the outer ring (4.'5-6.'4 from the CS), the shapes are more fractured, and the tails do not collimate into a single direction. The transition in knot morphology from the inner edge to the outer ring is clearly seen. The number density of knots governs the H{sub 2} surface brightness in the inner ring: H{sub 2} exists only within the knots. Possible mechanisms which contribute to the shaping of the knots are discussed, including photoionization and streaming motions. A plausible interpretation of our images is that inner knots are being overrun by a faster wind, but that this has not (yet) reached the outer knots. Based on H{sub 2} formation and destruction rates, H{sub 2} gas can survive in knots from formation during the late asymptotic giant branch phase throughout the PN phase. These observations provide new constraints on the formation and evolution of knots, and on the physics of molecular gas embedded within ionized gas.« less

A "Firework" of H2 Knots in the Planetary Nebula NGC 7293 (The Helix Nebula)

NASA Astrophysics Data System (ADS)

Matsuura, M.; Speck, A. K.; McHunu, B. M.; Tanaka, I.; Wright, N. J.; Smith, M. D.; Zijlstra, A. A.; Viti, S.; Wesson, R.

2009-08-01

We present a deep and wide field-of-view (4' × 7') image of the planetary nebula (PN) NGC 7293 (the Helix Nebula) in the 2.12 μm H2 v = 1 → 0 S(1) line. The excellent seeing (0farcs4) at the Subaru Telescope, allows the details of cometary knots to be examined. The knots are found at distances of 2farcm2-6farcm4 from the central star (CS). At the inner edge and in the inner ring (up to 4farcm5 from the CS), the knot often show a "tadpole" shape, an elliptical head with a bright crescent inside and a long tail opposite to the CS. In detail, there are variations in the tadpole shapes, such as narrowing tails, widening tails, meandering tails, or multipeaks within a tail. In the outer ring (4farcm5-6farcm4 from the CS), the shapes are more fractured, and the tails do not collimate into a single direction. The transition in knot morphology from the inner edge to the outer ring is clearly seen. The number density of knots governs the H2 surface brightness in the inner ring: H2 exists only within the knots. Possible mechanisms which contribute to the shaping of the knots are discussed, including photoionization and streaming motions. A plausible interpretation of our images is that inner knots are being overrun by a faster wind, but that this has not (yet) reached the outer knots. Based on H2 formation and destruction rates, H2 gas can survive in knots from formation during the late asymptotic giant branch phase throughout the PN phase. These observations provide new constraints on the formation and evolution of knots, and on the physics of molecular gas embedded within ionized gas. Based on data taken with the Subaru Telescope, National Astronomical Observatory of Japan (proposal ID S07B-054).

Habitat use by Red Knots (Calidris canutus rufa): Experiments with oyster racks and reefs on the beach and intertidal of Delaware Bay, New Jersey

NASA Astrophysics Data System (ADS)

Burger, Joanna; Niles, Lawrence J.

2017-07-01

Sea level rise and increasing human activities have decreased intertidal habitat in many places in the world. The expansion of aquaculture in intertidal areas may impact birds and other organisms using these habitats, leading to questions of sustainability of both aquaculture and functioning estuarine ecosystems. Understanding the effect of oyster culture on shorebird activity, particularly on Red Knots (Calidris canutus rufa), a species on the U.S. Threatened List, is important for adaptive management and the expansion of oyster culture. In May 2013 we experimentally compared Red Knot and shorebird use of a beach section with racks and a control, and in 2016 we compared the use of sections with artificial reefs, oyster racks, and control on Delaware Bay, New Jersey (USA). The data included only times when no workers or other people were present. Censuses, conducted every 30 min throughout the day (279 censuses in 2013, 231 censuses in 2016), included the number of Red Knots and other shorebirds in each treatment section. In 2013, the total number of shorebirds was significantly higher in the rack section than in the control section, except for Red Knots and Ruddy Turnstones (Arenaria interpres) that occurred in higher numbers in the control than in the rack section. In 2016 Red Knot numbers were also significantly lower in the rack section. In 2013, the mean number of Red Knots/census was 13 for racks vs 59 for the control (P < 0.0002). In 2016, the mean number of Red Knots/census was 13 for racks and over 68 for other treatments (P < 0.0001). Treatment, date, and number of non-Knot shorebirds explained 60% (2013) and 69% (2016) of the variation in Red Knot numbers. Red Knots avoided the sections with racks while both foraging and roosting, suggesting that caution should be used before placing oyster racks in areas used for foraging by Red Knots.

A New Vision for Professional Development

ERIC Educational Resources Information Center

Eley, Peter M.; Charles, Kelly J.; Leeks, Latonya L.

2013-01-01

High-quality professional development for public school teachers is directly tied to student achievement, teacher quality and retention, and national education priorities (Kroeger et al. 2000). To stay current with the knowledge, skills, and expertise that students need to succeed in the twenty-first century, educators must increasingly retool…

Software Trends and Trendsetters: How They're Shaping an Industry.

ERIC Educational Resources Information Center

McGinty, Tony; And Others

1987-01-01

Discusses trends in educational software and the effects of new developments on publishers and on the computer industry. Marketing prospects for software are examined, and recent advances are highlighted, including integrated learning systems, skill-based software, software tied to textbooks, networking, and freeware. (LRW)

JPRS Report China

DTIC Science & Technology

1990-02-12

military support for the Nicaraguan antigovernment (Contra) forces, generating hope that the " fast knot" in U.S.-Nicaraguan relations can be untied...outpaced the public portion. There is no need to worry no matter how much faster it is growing. What we must be concerned with is not how fast it is...nonferrous metals were smaller. Some that only had a few days of production capacity worked intermittently . Some of the larger, newly opened enterprises

Transumbilical endoscopic surgery for incarcerated inguinal hernias in infants and children.

PubMed

Zhou, Xuewu; Peng, Lei; Sha, Yongliang; Song, Daiqiang

2014-01-01

To describe transumbilical laparoscopic herniorrhaphy after unsuccessful attempted manual reduction of incarcerated inguinal hernias in infants and children. In our two hospitals, two-trocar transumbilical endoscopic surgery (TUES) is the standard technique used to repair incarcerated inguinal hernias in infants and children. Seventeen patients (aged 8months to 2.5years; median, 15months; 15 boys, 2 girls) with incarcerated inguinal hernias underwent urgent laparoscopy after unsuccessful attempted manual reduction. Two 3- or 5-mm trocars were inserted into the abdomen through two intraumbilical incisions, under laparoscopic guidance. The hernia was reduced by combined external manual pressure and internal pulling with bowel forceps. After inspection of the bowel, a round needle with a 2-0 nonabsorbable suture was introduced into the peritoneal cavity through the anterior abdominal wall near the internal inguinal ring. The hernial orifice was closed with an extraperitoneal purse-string suture around the internal inguinal ring, and tied with an intraperitoneal knot. A similar procedure was performed on the contralateral side if the processus vaginalis was patent. The TUES procedure was successful in all patients. No conversions to open surgery were required. The mean operating time was 30min (range, 25-40min). All patients were discharged on the second postoperative day. No complications such as postoperative bleeding, hydrocele, or scrotal edema were observed. The mean follow-up period was 15months. No cases of testicular atrophy, hypotrophy, or hernia recurrence were reported. Our preliminary experience with using TUES for the treatment of incarcerated inguinal hernias in infants and children had satisfactory outcomes. This technique appeared to be safe, effective, and reliable, and had excellent cosmetic results. Published by Elsevier Inc.

Interplay between writhe and knotting for swollen and compact polymers.

PubMed

Baiesi, Marco; Orlandini, Enzo; Whittington, Stuart G

2009-10-21

The role of the topology and its relation with the geometry of biopolymers under different physical conditions is a nontrivial and interesting problem. Aiming at understanding this issue for a related simpler system, we use Monte Carlo methods to investigate the interplay between writhe and knotting of ring polymers in good and poor solvents. The model that we consider is interacting self-avoiding polygons on the simple cubic lattice. For polygons with fixed knot type, we find a writhe distribution whose average depends on the knot type but is insensitive to the length N of the polygon and to solvent conditions. This "topological contribution" to the writhe distribution has a value that is consistent with that of ideal knots. The standard deviation of the writhe increases approximately as square root(N) in both regimes, and this constitutes a geometrical contribution to the writhe. If the sum over all knot types is considered, the scaling of the standard deviation changes, for compact polygons, to approximately N(0.6). We argue that this difference between the two regimes can be ascribed to the topological contribution to the writhe that, for compact chains, overwhelms the geometrical one, thanks to the presence of a large population of complex knots at relatively small values of N. For polygons with fixed writhe, we find that the knot distribution depends on the chosen writhe, with the occurrence of achiral knots being considerably suppressed for large writhe. In general, the occurrence of a given knot thus depends on a nontrivial interplay between writhe, chain length, and solvent conditions.

Maximizing Intellectual Potential in Today's Learner: Can We Really Improve Students' Thinking?

ERIC Educational Resources Information Center

Martin, David S.

1992-01-01

Ties together the educational threads of teaching thinking skills and improving the intellectual performance in deaf learners. Identifies six criteria for curriculum or research decisions related to teaching for higher-level problem solving. Applications of these ideas to mathematics are left to the reader. (MDH)

Inspiration from Nature: Creative Outdoor Writing Activities.

ERIC Educational Resources Information Center

Cardno, Anthony R.

1998-01-01

When campers notice the natural world around them, they can identify with nature and build an emotional connection with the environment. Creative-writing activities tied to nature are presented that can help campers enhance their descriptive and communication skills, and also learn something about themselves in the process. (TD)

A Scholarship Program where Students Give Back

ERIC Educational Resources Information Center

Masterson, Kathryn

2009-01-01

Alumni of the Ron Brown Scholar Program, young adults selected for their intellect, leadership skills, service, and financial need, are finding success in the law, government, science, business, medicine, and the arts. Yet they remain tied to the scholarship program, contributing to its continued success by donating money and volunteer hours to…

Ditties and Dishes: Cooking Connections With Mother Goose.

ERIC Educational Resources Information Center

Norton, Terry L.; Anfin, Carol S.

1997-01-01

Argues involving young children in food preparation activities enhances traditional curriculum areas of language arts, math, science, and social skills. Encourages utilization of children's literature as sources replete with references to food and teaching ideas on food via literary tie-ins. Provides specific recipes which relate to Mother Goose…

Poland's Transition in Business Education

ERIC Educational Resources Information Center

Leven, Bozena

2010-01-01

Prior to Poland's transition from central planning to a market system, which began in 1990, schools of business were non-existent in that country. Instead, university level instruction on economics during the socialist period was closely tied to ideological priorities, and limited to imparting skills suitable for planned economy. All universities…

Electrolyte Racers

ERIC Educational Resources Information Center

Kellie, Shawn; Kellie, Tonya; Corbin-Tipton, Elizabeth

2006-01-01

A fast way to teach investigative skills in science is to tie them to NASCAR using Hot Wheels Formula Fuelers Race Cars. These inexpensive toy cars travel different distances based on the strength of the "electrolyte" (a substance that conducts electricity when dissolved in water) in their "fuel" tanks. Advertisements for these race cars urge kids…

Career Development: A Shared Responsibility. ERIC Digest No. 201.

ERIC Educational Resources Information Center

Brown, Bettina Lankard

The changing workplace has altered workers' roles and forced them to assume primary responsibility for their own career development. Continued employment is increasingly being tied to lifelong learning and ongoing skill development. Just as workers are recognizing the need to ensure their marketability to employers, so too are employers facing…

Combining Education and Work; Experiences in Asia and Oceania: Malaysia.

ERIC Educational Resources Information Center

Murugasu, V.

Work oriented education has been tied to national development in Malaysia since the 1960's. Increasing population, unemployment, and shortages of skilled manpower led the government to relate education more closely to work and develop technical and vocational education. Malaysia extended basic education to lower secondary manpower needs; and…

The Social Imaginary of Study Abroad: Complexities and Contradictions

ERIC Educational Resources Information Center

Kubota, Ryuko

2016-01-01

Many universities around the world today are actively promoting study abroad to raise their international profiles. This trend is tied to the neoliberal social imaginary, which constructs study abroad as a tool for students to develop communication skills, a global mindset, intercultural competence and a competitive edge in global labour…

Making process improvement 'stick'.

PubMed

Studer, Quint

2014-06-01

To sustain gains from a process improvement initiative, healthcare organizations should: Explain to staff why a process improvement initiative is needed. Encourage leaders within the organization to champion the process improvement, and tie their evaluations to its outcomes. Ensure that both leaders and employees have the skills to help sustain the sought-after process improvements.

Thermodynamics of the pseudo-knot in helix 18 of 16S ribosomal RNA.

PubMed

Wojciechowska, Monika; Dudek, Marta; Trylska, Joanna

2018-04-01

A fragment of E. coli 16S rRNA formed by nucleotides 500 to 545 is termed helix 18. Nucleotides 505-507 and 524-526 form a pseudo-knot and its distortion affects ribosome function. Helix 18 isolated from the ribosome context is thus an interesting fragment to investigate the structural properties and folding of RNA with pseudo-knots. With all-atom molecular dynamics simulations, spectroscopic and gel electrophoresis experiments, we investigated thermodynamics of helix 18, with a focus on its pseudo-knot. In solution studies at ambient conditions we observed dimerization of helix 18. We proposed that the loop, containing nucleotides forming the pseudo-knot, interacts with another monomer of helix 18. The native dimer is difficult to break but introducing mutations in the pseudo-knot indeed assured a monomeric form of helix 18. Molecular dynamics simulations at 310 K confirmed the stability of the pseudo-knot but at elevated temperatures this pseudo-knot was the first part of helix 18 to lose the hydrogen bond pattern. To further determine helix 18 stability, we analyzed the interactions of helix 18 with short oligomers complementary to a nucleotide stretch containing the pseudo-knot. The formation of higher-order structures by helix 18 impacts hybridization efficiency of peptide nucleic acid and 2'-O methyl RNA oligomers. © 2018 Wiley Periodicals, Inc.

The Whitefly Bemisia tabaci Knottin-1 Gene Is Implicated in Regulating the Quantity of Tomato Yellow Leaf Curl Virus Ingested and Transmitted by the Insect

PubMed Central

Hariton Shalev, Aliza; Sobol, Iris; Ghanim, Murad; Liu, Shu-Sheng; Czosnek, Henryk

2016-01-01

The whitefly Bemisia tabaci is a major pest to agricultural crops. It transmits begomoviruses, such as Tomato yellow leaf curl virus (TYLCV), in a circular, persistent fashion. Transcriptome analyses revealed that B. tabaci knottin genes were responsive to various stresses. Upon ingestion of tomato begomoviruses, two of the four knottin genes were upregulated, knot-1 (with the highest expression) and knot-3. In this study, we examined the involvement of B. tabaci knottin genes in relation to TYLCV circulative transmission. Knottins were silenced by feeding whiteflies with knottin dsRNA via detached tomato leaves. Large amounts of knot-1 transcripts were present in the abdomen of whiteflies, an obligatory transit site of begomoviruses in their circulative transmission pathway; knot-1 silencing significantly depleted the abdomen from knot-1 transcripts. Knot-1 silencing led to an increase in the amounts of TYLCV ingested by the insects and transmitted to tomato test plants by several orders of magnitude. This effect was not observed following knot-3 silencing. Hence, knot-1 plays a role in restricting the quantity of virions an insect may acquire and transmit. We suggest that knot-1 protects B. tabaci against deleterious effects caused by TYLCV by limiting the amount of virus associated with the whitefly vector. PMID:27455309

46 CFR 174.055 - Calculation of wind heeling moment (Hm).

Code of Federal Regulations, 2010 CFR

2010-10-01

... for an exposed surface on the unit in foot-pounds (kilogram-meters); (2) k=0.00338 lb./(ft.2-knots2) (0.0623 (kg-sec2)/m4); (3) v=wind velocity of— (i) 70 knots (36 meters per second) for normal operating conditions. (ii) 100 knots (51.5 meters per second) for severe storm conditions. (iii) 50 knots...

Prediction during language processing is a piece of cake--but only for skilled producers.

PubMed

Mani, Nivedita; Huettig, Falk

2012-08-01

Are there individual differences in children's prediction of upcoming linguistic input and what do these differences reflect? Using a variant of the preferential looking paradigm (Golinkoff, Hirsh-Pasek, Cauley, & Gordon, 1987), we found that, upon hearing a sentence like, "The boy eats a big cake," 2-year-olds fixate edible objects in a visual scene (a cake) soon after they hear the semantically constraining verb eats and prior to hearing the word cake. Importantly, children's prediction skills were significantly correlated with their productive vocabulary size-skilled producers (i.e., children with large production vocabularies) showed evidence of predicting upcoming linguistic input, while low producers did not. Furthermore, we found that children's prediction ability is tied specifically to their production skills and not to their comprehension skills. Prediction is really a piece of cake, but only for skilled producers.

Total curvature and total torsion of knotted random polygons in confinement

NASA Astrophysics Data System (ADS)

Diao, Yuanan; Ernst, Claus; Rawdon, Eric J.; Ziegler, Uta

2018-04-01

Knots in nature are typically confined spatially. The confinement affects the possible configurations, which in turn affects the spectrum of possible knot types as well as the geometry of the configurations within each knot type. The goal of this paper is to determine how confinement, length, and knotting affect the total curvature and total torsion of random polygons. Previously published papers have investigated these effects in the unconstrained case. In particular, we analyze how the total curvature and total torsion are affected by (1) varying the length of polygons within a fixed confinement radius and (2) varying the confinement radius of polygons with a fixed length. We also compare the total curvature and total torsion of groups of knots with similar complexity (measured as crossing number). While some of our results fall in line with what has been observed in the studies of the unconfined random polygons, a few surprising results emerge from our study, showing some properties that are unique due to the effect of knotting in confinement.

Methyl Transfer by Substrate Signaling from a Knotted Protein Fold

PubMed Central

Christian, Thomas; Sakaguchi, Reiko; Perlinska, Agata P.; Lahoud, Georges; Ito, Takuhiro; Taylor, Erika A.; Yokoyama, Shigeyuki; Sulkowska, Joanna I.; Hou, Ya-Ming

2017-01-01

Proteins with knotted configurations are restricted in conformational space relative to unknotted proteins. Little is known if knotted proteins have sufficient dynamics to communicate between spatially separated substrate-binding sites. In bacteria, TrmD is a methyl transferase that uses a knotted protein fold to catalyze methyl transfer from S-adenosyl methionine (AdoMet) to G37-tRNA. The product m1G37-tRNA is essential for life as a determinant to maintain protein synthesis reading-frame. Using an integrated approach of structure, kinetic, and computational analysis, we show here that the structurally constrained TrmD knot is required for its catalytic activity. Unexpectedly, the TrmD knot has complex internal movements that respond to AdoMet binding and signaling. Most of the signaling propagates the free energy of AdoMet binding to stabilize tRNA binding and to assemble the active site. This work demonstrates new principles of knots as an organized structure that captures the free energies of substrate binding to facilitate catalysis. PMID:27571175

Counterexamples to Moffatt's statements on vortex knots.

PubMed

Bogoyavlenskij, Oleg

2017-04-01

One of the well-known problems of hydrodynamics is studied: the problem of classification of vortex knots for ideal fluid flows. In the literature there are known Moffatt statements that all torus knots K_{m,n} for all rational numbers m/n (0

Ex vivo evaluation of canine lung biopsy techniques.

PubMed

Marvel, Sarah; Monnet, Eric

2013-05-01

An ex vivo comparison of thoracoscopic lung biopsy techniques in dogs. Experimental. Cadaveric canine lung lobes. Lungs were inflated to 10 cmH2 O. After collecting biopsies 3 cm from the edge of lung lobes, leak pressures were recorded as inflation pressure was increased to 40 cmH2 O. Pre-tied loop ligature, square knot (SQ), modified 4S Roeder knot (M4SR) with glycomer 631 and polyglactin 910 size 0 and 2-0 were used in addition to EndoGIA 45-2.5 mm (Covidien, Norwalk, CT) and a vessel sealant device (VSDS single and VSDD double seal). Six biopsies were performed with each of these modalities. Median airway pressure at which leakage occurred was 28 (20-34)cmH2 O for EndoGIA 45; 33 (14-40) for VSDD; and 33 (10-40) for VSDS while other groups reached a median pressure of 40 cmH2 O (P < .0001). Leakage occurred at 20 cmH2 O in 1 sample with the EndoGIA and the VSDS, and in 2 with the VSDD while leakage did not occur in any other group (P = .36). Leakage occurred at 30 cmH2 O in 1 specimen each of the 0-polyglactin SQ, 2-0 glycomer 631 M4SR, 2-0 polyglactin M4SR, and 2-0 Surgitie (Covidien, Norwalk, CT); 2 with the VSDS; and 3 with the EndoGIA and the VSDD while leakage did not occur in any other group (P = .26). All tested techniques seemed safe except the vessel sealant device since it did not consistently seal every biopsy and leaked at pressures <20 cmH2 O. © Copyright 2013 by The American College of Veterinary Surgeons.

NASA's Earth Imagery Service as Open Source Software

NASA Astrophysics Data System (ADS)

De Cesare, C.; Alarcon, C.; Huang, T.; Roberts, J. T.; Rodriguez, J.; Cechini, M. F.; Boller, R. A.; Baynes, K.

2016-12-01

The NASA Global Imagery Browse Service (GIBS) is a software system that provides access to an archive of historical and near-real-time Earth imagery from NASA-supported satellite instruments. The imagery itself is open data, and is accessible via standards such as the Open Geospatial Consortium (OGC)'s Web Map Tile Service (WMTS) protocol. GIBS includes three core software projects: The Imagery Exchange (TIE), OnEarth, and the Meta Raster Format (MRF) project. These projects are developed using a variety of open source software, including: Apache HTTPD, GDAL, Mapserver, Grails, Zookeeper, Eclipse, Maven, git, and Apache Commons. TIE has recently been released for open source, and is now available on GitHub. OnEarth, MRF, and their sub-projects have been on GitHub since 2014, and the MRF project in particular receives many external contributions from the community. Our software has been successful beyond the scope of GIBS: the PO.DAAC State of the Ocean and COVERAGE visualization projects reuse components from OnEarth. The MRF source code has recently been incorporated into GDAL, which is a core library in many widely-used GIS software such as QGIS and GeoServer. This presentation will describe the challenges faced in incorporating open software and open data into GIBS, and also showcase GIBS as a platform on which scientists and the general public can build their own applications.

Knot, heartwood, and sapwood extractives related to VOCs from drying southern pine lumber

Treesearch

Leonard L. Ingram; M. Curry Templeton; G. Wayne McGraw; Richard W. Hemingway

2000-01-01

The presence of knots or heartwood influences the amount and composition of volatile organic compound (VOC) emissions associated with drying of southern pine lumber. Experimental kiln charges of lumber containing 0 to 5% of knot volume gave VOC emissions ranging from 2.86 to 4.25 lb of carbonldry ton of wood. Studies of emissions from sapwood and knots showed that...

Interactive, process-oriented climate modeling with CLIMLAB

NASA Astrophysics Data System (ADS)

Rose, B. E. J.

2016-12-01

Global climate is a complex emergent property of the rich interactions between simpler components of the climate system. We build scientific understanding of this system by breaking it down into component process models (e.g. radiation, large-scale dynamics, boundary layer turbulence), understanding each components, and putting them back together. Hands-on experience and freedom to tinker with climate models (whether simple or complex) is invaluable for building physical understanding. CLIMLAB is an open-ended software engine for interactive, process-oriented climate modeling. With CLIMLAB you can interactively mix and match model components, or combine simpler process models together into a more comprehensive model. It was created primarily to support classroom activities, using hands-on modeling to teach fundamentals of climate science at both undergraduate and graduate levels. CLIMLAB is written in Python and ties in with the rich ecosystem of open-source scientific Python tools for numerics and graphics. The Jupyter Notebook format provides an elegant medium for distributing interactive example code. I will give an overview of the current capabilities of CLIMLAB, the curriculum we have developed thus far, and plans for the future. Using CLIMLAB requires some basic Python coding skills. We consider this an educational asset, as we are targeting upper-level undergraduates and Python is an increasingly important language in STEM fields.

A pseudo-haptic knot diagram interface

NASA Astrophysics Data System (ADS)

Zhang, Hui; Weng, Jianguang; Hanson, Andrew J.

2011-01-01

To make progress in understanding knot theory, we will need to interact with the projected representations of mathematical knots which are of course continuous in 3D but significantly interrupted in the projective images. One way to achieve such a goal would be to design an interactive system that allows us to sketch 2D knot diagrams by taking advantage of a collision-sensing controller and explore their underlying smooth structures through a continuous motion. Recent advances of interaction techniques have been made that allow progress to be made in this direction. Pseudo-haptics that simulates haptic effects using pure visual feedback can be used to develop such an interactive system. This paper outlines one such pseudo-haptic knot diagram interface. Our interface derives from the familiar pencil-and-paper process of drawing 2D knot diagrams and provides haptic-like sensations to facilitate the creation and exploration of knot diagrams. A centerpiece of the interaction model simulates a "physically" reactive mouse cursor, which is exploited to resolve the apparent conflict between the continuous structure of the actual smooth knot and the visual discontinuities in the knot diagram representation. Another value in exploiting pseudo-haptics is that an acceleration (or deceleration) of the mouse cursor (or surface locator) can be used to indicate the slope of the curve (or surface) of whom the projective image is being explored. By exploiting these additional visual cues, we proceed to a full-featured extension to a pseudo-haptic 4D visualization system that simulates the continuous navigation on 4D objects and allows us to sense the bumps and holes in the fourth dimension. Preliminary tests of the software show that main features of the interface overcome some expected perceptual limitations in our interaction with 2D knot diagrams of 3D knots and 3D projective images of 4D mathematical objects.

46 CFR 134.140 - Structural standards.

Code of Federal Regulations, 2010 CFR

2010-10-01

...”, assuming a steady wind speed of 100 knots for liftboats in unrestricted service, and 70 knots for liftboats in restricted service under normal operating conditions and 100 knots under severe storm conditions...

Temporal Stress in the Operating Room: Brain Engagement Promotes "Coping" and Disengagement Prompts "Choking".

PubMed

Modi, Hemel N; Singh, Harsimrat; Orihuela-Espina, Felipe; Athanasiou, Thanos; Fiorentino, Francesca; Yang, Guang-Zhong; Darzi, Ara; Leff, Daniel R

2018-04-01

To investigate the impact of time pressure (TP) on prefrontal activation and technical performance in surgical residents during a laparoscopic suturing task. Neural mechanisms enabling surgeons to maintain performance and cope with operative stressors are unclear. The prefrontal cortex (PFC) is implicated due to its role in attention, concentration, and performance monitoring. A total of 33 residents [Postgraduate Year (PGY)1-2 = 15, PGY3-4 = 8, and PGY5 = 10] performed a laparoscopic suturing task under "self-paced" (SP) and "TP" conditions (TP = maximum 2 minutes per knot). Subjective workload was quantified using the Surgical Task Load Index. PFC activation was inferred using optical neuroimaging. Technical skill was assessed using progression scores (au), error scores (mm), leak volumes (mL), and knot tensile strengths (N). TP led to greater perceived workload amongst all residents (mean Surgical Task Load Index score ± SD: PGY1-2: SP = 160.3 ± 24.8 vs TP = 202.1 ± 45.4, P < 0.001; PGY3-4: SP = 123.0 ± 52.0 vs TP = 172.5 ± 43.1, P < 0.01; PGY5: SP = 105.8 ± 55.3 vs TP = 159.1 ± 63.1, P < 0.05). Amongst PGY1-2 and PGY3-4, deterioration in task progression, error scores and knot tensile strength (P < 0.05), and diminished PFC activation was observed under TP. In PGY5, TP resulted in inferior task progression and error scores (P < 0.05), but preservation of knot tensile strength. Furthermore, PGY5 exhibited less attenuation of PFC activation under TP, and greater activation than either PGY1-2 or PGY3-4 under both experimental conditions (P < 0.05). Senior residents cope better with temporal demands and exhibit greater technical performance stability under pressure, possibly due to sustained PFC activation and greater task engagement. Future work should seek to develop training strategies that recruit prefrontal resources, enhance task engagement, and improve performance under pressure.

Alleviation of whirl-flutter on a joined-wing tilt-rotor aircraft configuration using active controls

NASA Technical Reports Server (NTRS)

Vanaken, Johannes M.

1991-01-01

The feasibility of using active controls to delay the onset of whirl-flutter on a joined-wing tilt rotor aircraft was investigated. The CAMRAD/JA code was used to obtain a set of linear differential equations which describe the motion of the joined-wing tilt-rotor aircraft. The hub motions due to wing/body motion is a standard input to CAMRAD/JA and were obtained from a structural dynamics model of a representative joined-wing tilt-rotor aircraft. The CAMRAD/JA output, consisting of the open-loop system matrices, and the airframe free vibration motion were input to a separate program which performed the closed-loop, active control calculations. An eigenvalue analysis was performed to determine the flutter stability of both open- and closed-loop systems. Sensor models, based upon the feedback of pure state variables and based upon hub-mounted sensors, providing physically measurable accelerations, were evaluated. It was shown that the onset of tilt-rotor whirl-flutter could be delayed from 240 to above 270 knots by feeding back vertical and span-wise accelerations, measured at the rotor hub, to the longitudinal cyclic pitch. Time response calculations at a 270-knot cruise condition showed an active cyclic pitch control level of 0.009 deg, which equates to a very acceptable 9 pound active-control force applied at the rotor hub.

Dynamics of knotted flexible loops settling under a constant force in a viscous fluid

NASA Astrophysics Data System (ADS)

Gruziel, Magdalena; Thyagarajan, Krishnan; Dietler, Giovanni; Szymczak, Piotr; Ekiel-Jezewska, Maria

2017-11-01

Sedimenting chains of metal beads knotted to a topology of a torus knot tend to stabilize in the form of extended, flat, tightly interwound loops. In this configuration they perform an oscillatory motion of the loops swirling periodically around each other. Stokesian dynamics simulations of elastic fibers confirm the long-lasting character of the traveling wave-like swirling motion and show also the accompanying rotation of the system. Moreover, the periodic motion shows striking resemblance to the stable solutions for the evolution of vortices of torus knot topology. Using the results of the simulations we study the dependence of the frequencies and sedimentation velocities on the length of the fiber. We also notice the dependence of the knot dynamics on the bending stiffness of the fiber and the knot rank. NCN-2015/19/D/ST8/03199.

Effect of knots on stress waves in lumber

Treesearch

C.C. Gerhards

1982-01-01

An impact stress wave was induced in the end of 2 by 6 lumber containing knots. Rather than a normal, perpendicular-to-the-axis profile in transiting by a knot, the stress wave tended to Iead in zones of clear wood in the direction of the slope of grain or slope of the annual rings and to lag behind the knot. Of three methods evaluated to time the stress wave, the...

Properties of knotted ring polymers. I. Equilibrium dimensions.

PubMed

Mansfield, Marc L; Douglas, Jack F

2010-07-28

We report calculations on three classes of knotted ring polymers: (1) simple-cubic lattice self-avoiding rings (SARs), (2) "true" theta-state rings, i.e., SARs generated on the simple-cubic lattice with an attractive nearest-neighbor contact potential (theta-SARs), and (3) ideal, Gaussian rings. Extrapolations to large polymerization index N imply knot localization in all three classes of chains. Extrapolations of our data are also consistent with conjectures found in the literature which state that (1) R(g)-->AN(nu) asymptotically for ensembles of random knots restricted to any particular knot state, including the unknot; (2) A is universal across knot types for any given class of flexible chains; and (3) nu is equal to the standard self-avoiding walk (SAW) exponent (congruent with 0.588) for all three classes of chains (SARs, theta-SARs, and ideal rings). However, current computer technology is inadequate to directly sample the asymptotic domain, so that we remain in a crossover scaling regime for all accessible values of N. We also observe that R(g) approximately p(-0.27), where p is the "rope length" of the maximally inflated knot. This scaling relation holds in the crossover regime, but we argue that it is unlikely to extend into the asymptotic scaling regime where knots become localized.

On universal knot polynomials

NASA Astrophysics Data System (ADS)

Mironov, A.; Mkrtchyan, R.; Morozov, A.

2016-02-01

We present a universal knot polynomials for 2- and 3-strand torus knots in adjoint representation, by universalization of appropriate Rosso-Jones formula. According to universality, these polynomials coincide with adjoined colored HOMFLY and Kauffman polynomials at SL and SO/Sp lines on Vogel's plane, respectively and give their exceptional group's counterparts on exceptional line. We demonstrate that [m,n]=[n,m] topological invariance, when applicable, take place on the entire Vogel's plane. We also suggest the universal form of invariant of figure eight knot in adjoint representation, and suggest existence of such universalization for any knot in adjoint and its descendant representations. Properties of universal polynomials and applications of these results are discussed.

Requirements for a Device-Based Training and Testing Program for M1 Gunnery. Volume 1. Rationale and Summary of Results

DTIC Science & Technology

1988-03-01

or cognition skills required, on the difficulty of the motor skills re- quired, and how closely outcomes are tied to behavior. For example, because of...influence whether or not the batter arrives safely on base. Thus, while batting average is an accepted index of hitting proficiency, it ignores potential...instructions be behavioral (let up on the swing) or cognitive (watch for the slow pitch). Third, within limits, there are a variety of ways to hit a baseball

Explicit formulae for Chern-Simons invariants of the twist-knot orbifolds and edge polynomials of twist knots

NASA Astrophysics Data System (ADS)

Ham, J.-Y.; Lee, J.

2016-09-01

We calculate the Chern-Simons invariants of twist-knot orbifolds using the Schläfli formula for the generalized Chern-Simons function on the family of twist knot cone-manifold structures. Following the general instruction of Hilden, Lozano, and Montesinos-Amilibia, we here present concrete formulae and calculations. We use the Pythagorean Theorem, which was used by Ham, Mednykh and Petrov, to relate the complex length of the longitude and the complex distance between the two axes fixed by two generators. As an application, we calculate the Chern-Simons invariants of cyclic coverings of the hyperbolic twist-knot orbifolds. We also derive some interesting results. The explicit formulae of the A-polynomials of twist knots are obtained from the complex distance polynomials. Hence the edge polynomials corresponding to the edges of the Newton polygons of the A-polynomials of twist knots can be obtained. In particular, the number of boundary components of every incompressible surface corresponding to slope -4n+2 turns out to be 2. Bibliography: 39 titles.

Universal Racah matrices and adjoint knot polynomials: Arborescent knots

NASA Astrophysics Data System (ADS)

Mironov, A.; Morozov, A.

2016-04-01

By now it is well established that the quantum dimensions of descendants of the adjoint representation can be described in a universal form, independent of a particular family of simple Lie algebras. The Rosso-Jones formula then implies a universal description of the adjoint knot polynomials for torus knots, which in particular unifies the HOMFLY (SUN) and Kauffman (SON) polynomials. For E8 the adjoint representation is also fundamental. We suggest to extend the universality from the dimensions to the Racah matrices and this immediately produces a unified description of the adjoint knot polynomials for all arborescent (double-fat) knots, including twist, 2-bridge and pretzel. Technically we develop together the universality and the "eigenvalue conjecture", which expresses the Racah and mixing matrices through the eigenvalues of the quantum R-matrix, and for dealing with the adjoint polynomials one has to extend it to the previously unknown 6 × 6 case. The adjoint polynomials do not distinguish between mutants and therefore are not very efficient in knot theory, however, universal polynomials in higher representations can probably be better in this respect.

Color-magnitude Diagrams for the Stellar Open Cluster M 67 in theVilnius Photometric System

NASA Astrophysics Data System (ADS)

Boyle, Richard P.; Janusz, Robert

2015-01-01

Stellar photometry in the Vilnius Photometric System requires one percent quality for deriving luminosity class and spectral type subclass. We use such existing photometry of the open cluster M 67 to calibrate new CCD observations at the Vatican Advanced Technology Telescope (VATT) for correcting the flat-fielding zero-point and deriving the color-transformation in this intermediate-band, seven filter system (Boyle et al., BAAS 37 #4, 2005).Recently we have developed a "tie-in" observational practice to apply the zero-point and color transformation of the M 67 observations to neighboring starfields of interest that have no existing photometry. Sky transparency must remain constant to better than one percent during a round of short exposures in a filter between the field having calibrated photometry and the new field having no photometry as if the new field was exposed simultaneously with the master field.Proof of success for this "tie-in" method is shown with the master field being M 67 and the "tie-in" field being the nearby extended "corona" area. The distinctive color-magnitude diagrams of the old open clusterM 67 reveal the sensitivity to having constant sky transparency during the round of short exposures on M 67 and its extended area. For the extended area has the same form in its color-magnitude diagram as M 67. So variation in sky transparency shows displacement on the color-magnitude diagrams at the one percent quality.We will attempt new analysis concerning evolution of this very old open cluster (2.56 Gyr, WEBDA, http://www.univie.ac.at/webda/) and the surrounding "coronal" extent with reference to previous work by Chupina and Vereshchagin (Astron. Astrophys, 334, 552, 1998).

The Ties That Bind: Linkages among Secondary Schools, Two-Year Colleges and Baccalaureate Institutions.

ERIC Educational Resources Information Center

Lorence, James J.

1995-01-01

Describes a University of Wisconsin program that maintains summer institutes and seminars between university, college, and high school history teachers. Priorities have included upgrading the critical-thinking and research skills of secondary school students. A serendipitous benefit has been an increased mastery of the recent literature by…

Creativity Doesn't Develop in a Vacuum

ERIC Educational Resources Information Center

Barbot, Baptiste; Baer, John

2016-01-01

The skills, knowledge, attitudes, motivations, and personality traits that lead to creative thinking and creative behavior do not exist--and do not develop--in a vacuum. They are inextricably tied to content, to domains, in particular, and they therefore vary by domains. The more we learn about creativity, the more we discover how domain specific…

Two Generations: Partners in Prevention. Youth in Action. Bulletin, Number 5.

ERIC Educational Resources Information Center

Department of Justice, Washington, DC. Office of Juvenile Justice and Delinquency Prevention.

Young and old joining together in intergenerational projects where they share their insights, skills, and experiences can strengthen community ties and improve the well-being of all participants. This bulletin explores ways both younger and older members of a community can work together on a crime prevention initiative. Such a partnership in…

Strategies for Retaining Adult Students: The Educationally Disadvantaged. ERIC Digest No. 76.

ERIC Educational Resources Information Center

Kerka, Sandra

The literature on retention of adult learners strongly suggests that previous educational attainment is closely tied to participation and persistence. Educationally disadvantaged adults are more likely to lack self-confidence and self-esteem, have negative attitudes toward education, and need mastery of basic skills such as literacy before…

Basic Wiring. Third Edition. Teacher Edition [and] Student Edition.

ERIC Educational Resources Information Center

Kaltwasser, Stan; Flowers, Gary; Blasingame, Don; Batson, Larry; Ipock, Dan; Carroll, Charles; Friesen, Wade; Fleming, Glenn

This publication contains both a teacher edition and a student edition of materials for a foundation course in an electrical wiring program. The course introduces basic concepts and skills that are prerequisites to residential wiring and commercial and industrial wiring courses. The contents of the materials are tied to measurable and observable…

Readiness for College: The Role of Noncognitive Factors and Context

ERIC Educational Resources Information Center

Nagaoka, Jenny; Farrington, Camille A.; Roderick, Melissa; Allensworth, Elaine; Keyes, Tasha Seneca; Johnson, David W.; Beechum, Nicole O.

2013-01-01

Research has shown that in addition to academic knowledge, a variety of noncognitive skills are essential to students' post-secondary success. This article summarizes a review by the University of Chicago Consortium on Chicago School Research (CCSR) that brought together hundreds of studies of factors that have been tied to academic success…

An Investigation of Highly Effective Leaders in Outdoor Adventure Programs Using a Multi-Method Approach

ERIC Educational Resources Information Center

Hobbs, William D.

2009-01-01

Research on leadership in outdoor adventure programs has focused primarily on Educational and Outdoor Skills. Anecdotal and practical experience has suggested that the performance of highly effective leaders may depend instead on distinctive qualities and components closely tied to individual character--a perspective of transformational…

Words & Pictures: Literacy, Art and Common Core Together

ERIC Educational Resources Information Center

Chevalier, Juline A.

2015-01-01

In a two-year study, Nasher Museum of Art at Duke University education staff found that students who participated in a museum-school collaboration became more proficient in several Common Core State Standard skills than a control group. The program, Words & Pictures, directly ties to the English Language Arts Common Core State Standards and is…

The Pendulum Weaves All Knots and Links

NASA Astrophysics Data System (ADS)

Starrett, John

2003-08-01

From a topological point of view, periodic orbits of three dimensional dynamical systems are knots, that is, circles (S∧1) embedded in the three sphere (S∧3) or in R∧3. The ensemble of periodic orbits comprising the skeleton of a 3-D strange attractor form a link: a collection of (not necessarily linked) knots. Joan Birman and Robert Williams used a topological device known as the template, a branched two-manifold that results when the stable direction is collapsed out of an attractor, to analyze the knot and link types appearing in the geometric Lorenz attractor. More recently, Robert Ghrist has shown the existence of universal templates: templates that support all knot and link types. I show that the template constructed from the geometric attractor of a forced physical pendulum contains a universal template as a subtemplate, and therefore the orbit set of the pendulum contains every knot and link type.

Malaria in Pregnancy Interacts with and Alters the Angiogenic Profiles of the Placenta

PubMed Central

Ataíde, Ricardo; Murillo, Oscar; Dombrowski, Jamille G.; Souza, Rodrigo M.; Lima, Flávia A.; Lima, Giselle F. M. C.; Hristov, Angélica D.; Valle, Suiane C. N.; Di Santi, Silvia M.; Epiphanio, Sabrina; Marinho, Claudio R. F.

2015-01-01

Malaria in pregnancy remains a substantial public health problem in malaria-endemic areas with detrimental outcomes for both the mother and the foetus. The placental changes that lead to some of these detrimental outcomes have been studied, but the mechanisms that lead to these changes are still not fully elucidated. There is some indication that imbalances in cytokine cascades, complement activation and angiogenic dysregulation might be involved in the placental changes observed. Nevertheless, the majority of studies on malaria in pregnancy (MiP) have come from areas where malaria transmission is high and usually restricted to Plasmodium falciparum, the most pathogenic of the malaria parasite species. We conducted a cross-sectional study in Cruzeiro do Sul, Acre state, Brazil, an area of low transmission and where both P. vivax and P. falciparum circulate. We collected peripheral and placental blood and placental biopsies, at delivery from 137 primigravid women and measured levels of the angiogenic factors angiopoietin (Ang)-1, Ang-2, their receptor Tie-2, and several cytokines and chemokines. We measured 4 placental parameters (placental weight, syncytial knots, placental barrier thickness and mononuclear cells) and associated these with the levels of angiogenic factors and cytokines. In this study, MiP was not associated with severe outcomes. An increased ratio of peripheral Tie-2:Ang-1 was associated with the occurrence of MiP. Both Ang-1 and Ang-2 had similar magnitudes but inverse associations with placental barrier thickness. Malaria in pregnancy is an effect modifier of the association between Ang-1 and placental barrier thickness. PMID:26090803

Malaria in Pregnancy Interacts with and Alters the Angiogenic Profiles of the Placenta.

PubMed

Ataíde, Ricardo; Murillo, Oscar; Dombrowski, Jamille G; Souza, Rodrigo M; Lima, Flávia A; Lima, Giselle F M C; Hristov, Angélica D; Valle, Suiane C N; Di Santi, Silvia M; Epiphanio, Sabrina; Marinho, Claudio R F

2015-01-01

Malaria in pregnancy remains a substantial public health problem in malaria-endemic areas with detrimental outcomes for both the mother and the foetus. The placental changes that lead to some of these detrimental outcomes have been studied, but the mechanisms that lead to these changes are still not fully elucidated. There is some indication that imbalances in cytokine cascades, complement activation and angiogenic dysregulation might be involved in the placental changes observed. Nevertheless, the majority of studies on malaria in pregnancy (MiP) have come from areas where malaria transmission is high and usually restricted to Plasmodium falciparum, the most pathogenic of the malaria parasite species. We conducted a cross-sectional study in Cruzeiro do Sul, Acre state, Brazil, an area of low transmission and where both P. vivax and P. falciparum circulate. We collected peripheral and placental blood and placental biopsies, at delivery from 137 primigravid women and measured levels of the angiogenic factors angiopoietin (Ang)-1, Ang-2, their receptor Tie-2, and several cytokines and chemokines. We measured 4 placental parameters (placental weight, syncytial knots, placental barrier thickness and mononuclear cells) and associated these with the levels of angiogenic factors and cytokines. In this study, MiP was not associated with severe outcomes. An increased ratio of peripheral Tie-2:Ang-1 was associated with the occurrence of MiP. Both Ang-1 and Ang-2 had similar magnitudes but inverse associations with placental barrier thickness. Malaria in pregnancy is an effect modifier of the association between Ang-1 and placental barrier thickness.

Expression of HtKNOT1, a class I KNOX gene, overlaps cell layers and development compartments of differentiating cells in stems and flowers of Helianthus tuberosus.

PubMed

Michelotti, V; Giorgetti, L; Geri, C; Cionini, G; Pugliesi, C; Fambrini, M

2007-10-01

In plant, post-embryonic development relies on the activities of indeterminate cell populations termed meristems, spatially clustered cell lineages, wherein a subset divides indeterminately. For correct growth, the plant must maintain a constant flow of cells through the meristem, where the input of dividing pluripotent cells offsets the output of differentiating cells. KNOTTED1-like homeobox (KNOX) genes are expressed in specific patterns in the plant meristems and play important roles in maintaining meristematic cell identity. We have analyzed the expression pattern of HtKNOT1, a class I KNOX gene of Helianthus tuberosus, in stems, inflorescence meristems, floral meristems and floral organs. HtKNOT1 is expressed in cambial cells, phloem cells and xylematic parenchyma within apical stem internodes, while in basal internodes HtKNOT1 expression was restricted to the presumptive initials and recently derived phloem cells. In the reproductive phase, HtKNOT1 mRNAs were detected in both the inflorescence and floral meristems as well within lateral organ primordia (i.e. floral bracts, petals, stamens and carpels). In more differentiated flowers, the expression of HtKNOT1 was restricted to developing ovules and pollen mother cells. HtKNOT1 may play a dual role being required to maintain the meristem initials as well as initiating differentiation and/or conferring new cell identity. In particular, it is possible that HtKNOT1 cooperates at floral level with additional factors that more specifically control floral organs and pollen development in H. tuberosus.

Untangling the mechanics versus topology of overhand knots

NASA Astrophysics Data System (ADS)

Reis, Pedro; Jawed, Mohammad; Dieleman, Peter; Audoly, Basile

2015-03-01

We study the interplay between mechanics and topology of overhand knots in slender elastic rods. We perform precision desktop experiments of overhand knots with increasing values for the crossing number (our measure of topology) and characterize their mechanical response through tension-displacement tests. The tensile force required to tighten the knot is governed by an intricate balance between topology, bending, friction, and contact forces. Digital imaging is employed to characterize the configuration of the contact braid as a function of crossing number. A robust scaling law is found for the pulling force in terms of the geometric and topological parameters of the knot. A reduced theory is developed, which predictively rationalizes the process.

Training on an inexpensive tablet-based device is equally effective as on a standard laparoscopic box trainer

PubMed Central

Montanari, Eliana; Schwameis, Richard; Louridas, Marisa; Göbl, Christian; Kuessel, Lorenz; Polterauer, Stephan; Husslein, Heinrich

2016-01-01

Abstract Background: The aim of the study was to assess whether an inexpensive tablet-based box trainer (TBT) is at least equally effective compared with a standard box trainer (SBT) to learn basic laparoscopic skills (BLS). BLS training outside the operating room has been shown to be beneficial for surgical residency. However, simulation trainers are expensive and are not consistently available in all training centers. Therefore, TBT and other homemade box trainers were developed. Methods: Medical students were randomized to either a TBT or an SBT and trained 4 fundamentals of laparoscopic surgery (FLS) tasks for 1 hour twice a week for 4 weeks. A baseline test before the training period and a posttraining test were performed. All students then completed a questionnaire to assess their assigned box trainer. The primary outcome measure was the improvement in total test scores. Improvement in the scores for the 4 individual FLS tasks was chosen as a secondary outcome measure. Results: Thirty-two medical students were recruited. Baseline test scores did not differ significantly between the groups. BLS improved significantly in both groups for the total score and for all 4 tasks separately. Participants in the TBT group showed a greater improvement of total scores than those in the SBT group, although this did not reach statistical significance; noninferiority of the TBT compared with the SBT concerning the improvement of total scores could be demonstrated. Regarding the individual FLS tasks, noninferiority of the TBT could be shown for the pattern cutting and the suturing with intracorporeal knot-tying task. The acceptance of the TBT by the trainees was very good. Conclusion: Learning BLS on a homemade TBT is at least equally effective as on an SBT, with the advantage of being very cost saving. Therefore, this readily available box trainer may be used as an effective, flexible training device outside the operating room to improve accessibility to simulation training. PMID:27684813

Climatic Atlas of the Outer Continental Shelf Waters and Coastal Regions of Alaska. Volume 2. Bering Sea. Revision

DTIC Science & Technology

1988-01-01

Joe D. Elms , for their editorial evaluation of the vironmental Assessmant Program. Additional depends to a large extent on weather condi- isopleth...waves, icing rates are open waters and coastal sectionsofAlaska.The temperatures less than 8°C, winds of 25 knots lower. icing causes slippery decks...thereby bias the oceanic climatology towards fair weather. A recent study by Elms (1986), in which he compared the Volunteer Observing Ship (VOS) data

Novel application of an established technique for removing a knotted ureteric stent.

PubMed

Tempest, Heidi; Turney, Ben; Kumar, Sunil

2011-04-13

This report describes a case whereby a ureteric stent became knotted during removal and lodged within the upper ureter. The authors describe a novel minimally invasive technique to remove the knotted ureteric stent using the holmium laser.

Self-assembly of knots and links

NASA Astrophysics Data System (ADS)

Orlandini, Enzo; Polles, Guido; Marenduzzo, Davide; Micheletti, Cristian

2017-03-01

Guiding the self-assembly of identical building blocks towards complex three-dimensional structures with a set of desired properties is a major goal in material science, chemistry and physics. A particularly challenging problem, especially explored in synthetic chemistry, is that of self-assembling closed structures with a target topology starting by simple geometrical templates. Here we overview and revisit recent advancements, based on stochastic simulations, where the geometry of rigid helical templates with functionalised sticky ends has been designed for self-assembling efficiently and reproducibly into a wide range of three-dimensional closed structures. Notably, these include non trivial topologies of links and knots, including the 819 knot that we had predicted to be highly encodable and that has only recently been obtained experimentally. By appropriately tuning the parameters that define the template shape, we show that, for fixed concentration of templates, the assembly process can be directed towards the formation of specific knotted and linked structures such as the trefoils, pentafoil knots, Hopf and Solomon links. More exotic and unexpected knots and links are also found. Our results should be relevant to the design of new protocols that can both increase and broaden the population of synthetise molecular knots and catenanes.

The Energy Landscape, Folding Pathways and the Kinetics of a Knotted Protein

PubMed Central

Prentiss, Michael C.; Wales, David J.; Wolynes, Peter G.

2010-01-01

The folding pathway and rate coefficients of the folding of a knotted protein are calculated for a potential energy function with minimal energetic frustration. A kinetic transition network is constructed using the discrete path sampling approach, and the resulting potential energy surface is visualized by constructing disconnectivity graphs. Owing to topological constraints, the low-lying portion of the landscape consists of three distinct regions, corresponding to the native knotted state and to configurations where either the N or C terminus is not yet folded into the knot. The fastest folding pathways from denatured states exhibit early formation of the N terminus portion of the knot and a rate-determining step where the C terminus is incorporated. The low-lying minima with the N terminus knotted and the C terminus free therefore constitute an off-pathway intermediate for this model. The insertion of both the N and C termini into the knot occurs late in the folding process, creating large energy barriers that are the rate limiting steps in the folding process. When compared to other protein folding proteins of a similar length, this system folds over six orders of magnitude more slowly. PMID:20617197

Novel application of an established technique for removing a knotted ureteric stent

PubMed Central

Tempest, Heidi; Turney, Ben; Kumar, Sunil

2011-01-01

This report describes a case whereby a ureteric stent became knotted during removal and lodged within the upper ureter. The authors describe a novel minimally invasive technique to remove the knotted ureteric stent using the holmium laser. PMID:22701009

Knot invariants from Virasoro related representation and pretzel knots

DOE PAGES

Galakhov, D.; Melnikov, D.; Mironov, A.; ...

2015-08-06

In this study, we remind the method to calculate colored Jones polynomials for the plat representations of knot diagrams from the knowledge of modular transformation (monodromies) of Virasoro conformal blocks with insertions of degenerate fields. As an illustration we use a rich family of pretzel knots, lying on a surface of arbitrary genus g, which was recently analyzed by the evolution method. Further generalizations can be to generic Virasoro modular transformations, provided by integral kernels, which can lead to the Hikami invariants.

Characterization of the inner knot of the crab: The site of the gamma-ray flares?

DOE PAGES

Rudy, Alexander; Horns, Dieter; DeLuca, Andrea; ...

2015-09-16

A particularly intriguing recent result from γ-ray astronomy missions is the detection of powerful flares from the Crab Nebula, which challenges the current understanding of pulsar wind nebulae and acceleration mechanisms. In order to search for the production site(s) of these flares, we conducted a multi-wavelength observing campaign using Keck, the Hubble Space Telescope (HST), and the Chandra X-ray Observatory. As the short timescales of the γ-ray flares (more » $$\\lesssim 1$$ day) suggest a small emitting region, the Crab's inner knot (about 0.6 arcsec from the pulsar) is a candidate site for such flaring. Our paper describes observations of the inner knot, seeking to understand its nature and possible relationship with γ-ray flares. Using singular-value decomposition, analysis of the HST images yielded results consistent with traditional methods while substantially reducing some uncertainties. These analyses show that the knot's intrinsic properties (especially size and brightness) are correlated with its (projected) separation from the pulsar. This characterization of the inner knot helps in constraining standard shock model parameters, under the assumption that the knot lies near the shocked surface. While the standard shock model gives good agreement in several respects, two puzzles persist: (a) the observed angular size of the knot relative to the pulsar–knot separation is much smaller than expected; and (b) the variable high degree of polarization (reported by others) is difficult to reconcile with a highly relativistic downstream flow. But, the IR–optical flux of the inner knot is marginally consistent with the shock accelerating most of the Nebula's optical-emitting particles.« less

Fermi/LAT observations of lobe-dominant radio galaxy 3C 207 and possible radiation region of γ-rays

NASA Astrophysics Data System (ADS)

Guo, Sheng-Chu; Zhang, Hai-Ming; Zhang, Jin; Liang, En-Wei

2018-06-01

3C 207 is a lobe-dominant radio galaxy with a one sided jet and bright knots, spanning a kpc-Mpc scale, which have been resolved in the radio, optical and X-ray bands. This target was confirmed as a γ-ray emitter with Fermi/LAT, but it is uncertain whether the γ-ray emission region is the core or knots due to the low spatial resolution of Fermi/LAT. We present an analysis of its Fermi/LAT data acquired during the past 9 years. Different from the radio and optical emission from the core, it is found that the γ-ray emission is steady without detection of flux variation at over a 2σ confidence level. This likely implies that the γ-ray emission is from its knots. We collect the radio, optical and X-ray data of knot-A, the closest knot from the core at 1.4″, and compile its spectral energy distribution (SED). Although the single-zone synchrotron+SSC+IC/CMB model that assumes knot-A is at rest can reproduce the SED in the radio-optical-X-ray band, the predicted γ-ray flux is lower than the LAT observations and the derived magnetic field strength deviates from the equipartition condition by 3 orders of magnitude. Assuming that knot-A is moving relativistically, its SED from radio to γ-ray bands would be represented well with the single-zone synchrotron+SSC+IC/CMB model under the equipartition condition. These results likely suggest that the γ-ray emission may be from knot-A via the IC/CMB process and the knot should have relativistical motion. The jet power derived from our model parameters is also roughly consistent with the kinetic power estimated with radio data.

Tightening slip knots in raw and degummed silk to increase toughness without losing strength.

PubMed

Pantano, Maria F; Berardo, Alice; Pugno, Nicola M

2016-02-12

Knots are fascinating topological elements, which can be found in both natural and artificial systems. While in most of the cases, knots cannot be loosened without breaking the strand where they are tightened, herein, attention is focused on slip or running knots, which on the contrary can be unfastened without compromising the structural integrity of their hosting material. Two different topologies are considered, involving opposite unfastening mechanisms, and their influence on the mechanical properties of natural fibers, as silkworm silk raw and degummed single fibers, is investigated and quantified. Slip knots with optimized shape and size result in a significant enhancement of fibers energy dissipation capability, up to 300-400%, without affecting their load bearing capacity.

Tightening slip knots in raw and degummed silk to increase toughness without losing strength

PubMed Central

Pantano, Maria F.; Berardo, Alice; Pugno, Nicola M.

2016-01-01

Knots are fascinating topological elements, which can be found in both natural and artificial systems. While in most of the cases, knots cannot be loosened without breaking the strand where they are tightened, herein, attention is focused on slip or running knots, which on the contrary can be unfastened without compromising the structural integrity of their hosting material. Two different topologies are considered, involving opposite unfastening mechanisms, and their influence on the mechanical properties of natural fibers, as silkworm silk raw and degummed single fibers, is investigated and quantified. Slip knots with optimized shape and size result in a significant enhancement of fibers energy dissipation capability, up to 300–400%, without affecting their load bearing capacity. PMID:26868855

TOPICAL REVIEW: Knot theory and a physical state of quantum gravity

NASA Astrophysics Data System (ADS)

Liko, Tomás; Kauffman, Louis H.

2006-02-01

We discuss the theory of knots, and describe how knot invariants arise naturally in gravitational physics. The focus of this review is to delineate the relationship between knot theory and the loop representation of non-perturbative canonical quantum general relativity (loop quantum gravity). This leads naturally to a discussion of the Kodama wavefunction, a state which is conjectured to be the ground state of the gravitational field with positive cosmological constant. This review can serve as a self-contained introduction to loop quantum gravity and related areas. Our intent is to make the paper accessible to a wider audience that may include topologists, knot theorists, and other persons innocent of the physical background to this approach to quantum gravity.

33 CFR 162.205 - Suisun Bay, San Joaquin River, Sacramento River, and connecting waters, CA.

Code of Federal Regulations, 2010 CFR

2010-07-01

.... When going with the current, in slack water, or against a current of two knots or less, the maximum... knots. When going with the current, in slack water, or against a current of two knots or less, the...

Equations on knot polynomials and 3d/5d duality

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mironov, A.; Morozov, A.; ITEP, Moscow

2012-09-24

We briefly review the current situation with various relations between knot/braid polynomials (Chern-Simons correlation functions), ordinary and extended, considered as functions of the representation and of the knot topology. These include linear skein relations, quadratic Plucker relations, as well as 'differential' and (quantum) A-polynomial structures. We pay a special attention to identity between the A-polynomial equations for knots and Baxter equations for quantum relativistic integrable systems, related through Seiberg-Witten theory to 5d super-Yang-Mills models and through the AGT relation to the q-Virasoro algebra. This identity is an important ingredient of emerging a 3d- 5d generalization of the AGT relation. Themore » shape of the Baxter equation (including the values of coefficients) depend on the choice of the knot/braid. Thus, like the case of KP integrability, where (some, so far torus) knots parameterize particular points of the Universal Grassmannian, in this relation they parameterize particular points in the moduli space of many-body integrable systems of relativistic type.« less

Stability of knotted vortices in wave chaos

NASA Astrophysics Data System (ADS)

Taylor, Alexander; Dennis, Mark

Large scale tangles of disordered filaments occur in many diverse physical systems, from turbulent superfluids to optical volume speckle to liquid crystal phases. They can exhibit particular large scale random statistics despite very different local physics. We have previously used the topological statistics of knotting and linking to characterise the large scale tangling, using the vortices of three-dimensional wave chaos as a universal model system whose physical lengthscales are set only by the wavelength. Unlike geometrical quantities, the statistics of knotting depend strongly on the physical system and boundary conditions. Although knotting patterns characterise different systems, the topology of vortices is highly unstable to perturbation, under which they may reconnect with one another. In systems of constructed knots, these reconnections generally rapidly destroy the knot, but for vortex tangles the topological statistics must be stable. Using large scale simulations of chaotic eigenfunctions, we numerically investigate the prevalence and impact of reconnection events, and their effect on the topology of the tangle.

Sedimentation of knotted polymers

NASA Astrophysics Data System (ADS)

Piili, J.; Marenduzzo, D.; Kaski, K.; Linna, R. P.

2013-01-01

We investigate the sedimentation of knotted polymers by means of stochastic rotation dynamics, a molecular dynamics algorithm that takes hydrodynamics fully into account. We show that the sedimentation coefficient s, related to the terminal velocity of the knotted polymers, increases linearly with the average crossing number nc of the corresponding ideal knot. This provides direct computational confirmation of this relation, postulated on the basis of sedimentation experiments by Rybenkov [J. Mol. Biol.10.1006/jmbi.1996.0876 267, 299 (1997)]. Such a relation was previously shown to hold with simulations for knot electrophoresis. We also show that there is an accurate linear dependence of s on the inverse of the radius of gyration Rg-1, more specifically with the inverse of the Rg component that is perpendicular to the direction along which the polymer sediments. When the polymer sediments in a slab, the walls affect the results appreciably. However, Rg-1 remains to a good precision linearly dependent on nc. Therefore, Rg-1 is a good measure of a knot's complexity.

The Ties That Bind: Teacher Relationships, Academic Expectations, and Racial/Ethnic and Generational Inequality

ERIC Educational Resources Information Center

Cherng, Hua-Yu Sebastian

2017-01-01

Teachers not only play a pivotal role in developing students' knowledge and skills but also can serve as role models, which may be particularly beneficial for youth of color and children of immigrants. However, it is unknown whether relationships vary across student racial/ethnic and generational groups. Moreover, the link between teacherstudent…

Graphic Arts: Process Camera, Stripping, and Platemaking. Fourth Edition. Teacher Edition [and] Student Edition.

ERIC Educational Resources Information Center

Multistate Academic and Vocational Curriculum Consortium, Stillwater, OK.

This publication contains both a teacher edition and a student edition of materials for a course in graphic arts that covers the process camera, stripping, and platemaking. The course introduces basic concepts and skills necessary for entry-level employment in a graphic communication occupation. The contents of the materials are tied to measurable…

Software for the Atypical and Severely Handicapped Student.

ERIC Educational Resources Information Center

Levine, Jude Curtis

The Basic Skills Keyboards is a software program that features a variety of game files presented in ways tied to the cognitive deficits associated with autism. The program is based on the hypothesis that such students have problems with cause-effect, means-end, and personal agency, and would develop a working knowledge of these relationships via…

Communicating silviculture: values and benefits for the new millennium

Treesearch

Robert F. Powers; Philip S. Aune

1997-01-01

Forests have been tied to social progress since the dawn of agriculture 10 thousand years ago. Silviculture, groomed the oldest application of ecological principles, contains all the skills needed to produce forests with the myriad conditions valued by modern society. Historically, we have been success-makers. Yet, our profession faces a crisis. Often we are seen as...

Review and Assessment of Personnel Competencies and Job Description Models and Methods

DTIC Science & Technology

2016-04-01

Specifically, the Department of Defense (DoD) defines a competency as “an (observable) measurable pattern of knowledge, abili- ties, skills, and...analyzed how several organizations—selected to represent a breadth of approaches and contexts—use the different forms of competency systems and job...2 B. Employing Competencies....................................................................................3 2. Method and Approach

The strength-of-weak-ties perspective on creativity: a comprehensive examination and extension.

PubMed

Baer, Markus

2010-05-01

Disentangling the effects of weak ties on creativity, the present study separated, both theoretically and empirically, the effects of the size and strength of actors' idea networks and examined their joint impact while simultaneously considering the separate, moderating role of network diversity. I hypothesized that idea networks of optimal size and weak strength were more likely to boost creativity when they afforded actors access to a wide range of different social circles. In addition, I examined whether the joint effects of network size, strength, and diversity on creativity were further qualified by the openness to experience personality dimension. As expected, results indicated that actors were most creative when they maintained idea networks of optimal size, weak strength, and high diversity and when they scored high on the openness dimension. The implications of these results are discussed. PsycINFO Database Record (c) 2010 APA, all rights reserved.

In-law Relationships Before and After Marriage

PubMed Central

Fingerman, Karen L.; Gilligan, Megan; VanderDrift, Laura; Pitzer, Lindsay

2013-01-01

Relationships with in-laws play an important role in individuals’ lives, but we do not know how these ties are formed. We considered two pathways through which early relationships with mothers-in-laws may affect subsequent in-law relationship qualities: a) dimensions of the early relationship and, b) beliefs and expectations of the future relationship. Sixty men and women engaged to be married and their mothers (N = 240) completed interviews prior to, and 6 to 8 months following the wedding. Measures at Time 1 assessed three dimensions of the in-law relationship: a) behavioral (contact by phone, in person), b) emotional (positive and negative relationship qualities), and c) cognitive (knowledge about the other person). Participants also described positive and negative expectations of their future tie. Multilevel models revealed that dimensions of the tie prior to the marriage were associated with post-wedding in-law relationship qualities. When the parties had individual contact with one another and positive feelings before the wedding, ties were stronger following the wedding. Data from open-ended descriptions of negative expectations obtained before the wedding predicted negative relationship qualities after the wedding. Husbands, wives, and mothers-in-law showed similar patterns with regard to relationship qualities. Discussion focuses on the role of early emotional qualities of the in-law tie for subsequent in-law relationships. PMID:23794954

Understanding Solubility through Excel Spreadsheets

NASA Astrophysics Data System (ADS)

Brown, Pamela

2001-02-01

This article describes assignments related to the solubility of inorganic salts that can be given in an introductory general chemistry course. Le Châtelier's principle, solubility, unit conversion, and thermodynamics are tied together to calculate heats of solution by two methods: heats of formation and an application of the van't Hoff equation. These assignments address the need for math, graphing, and computer skills in the chemical technology program by developing skill in the use of Microsoft Excel to prepare spreadsheets and graphs and to perform linear and nonlinear curve-fitting. Background information on the value of understanding and predicting solubility is provided.

Validation of Computer Aided Operations Research Facility (CAORF).

DTIC Science & Technology

1979-01-01

favorable comparison is that of the slow- down effect in performing a turn. From Figure 2.4 it is estimated that ship’s speed was reduced from an...initial speed of 17 knots to 6.6 knots. The data shown in Figure 2.3 for the CAORF ship indicate a reduction from an initial speed of 15 knots to 5.1 knots...follows: The ship is on a steady course at full sea speed . (Exact sea speed is optional.) At time zero, the rudder is put over 20 0 right. This is

Sequence Determines Degree of Knottedness in a Coarse-Grained Protein Model

NASA Astrophysics Data System (ADS)

Wüst, Thomas; Reith, Daniel; Virnau, Peter

2015-01-01

Knots are abundant in globular homopolymers but rare in globular proteins. To shed new light on this long-standing conundrum, we study the influence of sequence on the formation of knots in proteins under native conditions within the framework of the hydrophobic-polar lattice protein model. By employing large-scale Wang-Landau simulations combined with suitable Monte Carlo trial moves we show that even though knots are still abundant on average, sequence introduces large variability in the degree of self-entanglements. Moreover, we are able to design sequences which are either almost always or almost never knotted. Our findings serve as proof of concept that the introduction of just one additional degree of freedom per monomer (in our case sequence) facilitates evolution towards a protein universe in which knots are rare.

Probe Knots and Hopf Insulators with Ultracold Atoms

NASA Astrophysics Data System (ADS)

Deng, Dong-Ling; Wang, Sheng-Tao; Sun, Kai; Duan, L.-M.

2018-01-01

Knots and links are fascinating and intricate topological objects. Their influence spans from DNA and molecular chemistry to vortices in superfluid helium, defects in liquid crystals and cosmic strings in the early universe. Here we find that knotted structures also exist in a peculiar class of three-dimensional topological insulators—the Hopf insulators. In particular, we demonstrate that the momentum-space spin textures of Hopf insulators are twisted in a nontrivial way, which implies the presence of various knot and link structures. We further illustrate that the knots and nontrivial spin textures can be probed via standard time-of-flight images in cold atoms as preimage contours of spin orientations in stereographic coordinates. The extracted Hopf invariants, knots, and links are validated to be robust to typical experimental imperfections. Our work establishes the existence of knotted structures in Hopf insulators, which may have potential applications in spintronics and quantum information processing. D.L.D., S.T.W. and L.M.D. are supported by the ARL, the IARPA LogiQ program, and the AFOSR MURI program, and supported by Tsinghua University for their visits. K.S. acknowledges the support from NSF under Grant No. PHY1402971. D.L.D. is also supported by JQI-NSF-PFC and LPS-MPO-CMTC at the final stage of this paper.

Ohmsett test of NOFI Vee-Sweep and NOFI 600S oilboom. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goodwin, M.J.

1993-10-01

A NOFI Vee-Sweep and a NOFI 600S Oilboom, both manufactured by NOFI TROMSO A/S of Norway, were tested at the Ohmsett test tank in Leonardo, NJ. The V-Shaped Sweep is an oil boom designed for use with a skimmer at the apex of the V-Shaped configuration. Oil is funneled back to the skimmer by the converging sides of the V and concentrated for more efficient skimming. The 60 meter length of the sweep is doubled over to form the V and held in this shape by cross netting at the bottom of the skirt. The bottom netting is claimed tomore » help stabilize the oil in the sweep. The sweep was towed with a 700mm skirt depth and mouth opening of 16 meters. The mouth opening was reduced from the designed 19.8 meters to fit in the tow tank without causing excess blockage. The limiting towing speeds of the sweep were determined with and without oil present, in calm water and in small waves. The sweep's ability to conform to waves was also determined. Towing forces were measured. Limited data on oil loss rates were obtained. Testing confirmed the manufacturer's claim that the sweep can be towed at 1.0 and 1.4 knots with oil in calm water, based on the first loss of oil. The critical tow speed was found to be 3.4 to 3.6 knots in calm water. Oil booms, Tow tank testing.« less

Treatment and retention of relapsed anterior open-bite with low tongue posture and tongue-tie: A 10-year follow-up

PubMed Central

Seo, Yu-Jin; Kim, Su-Jung; Munkhshur, Janchivdorj; Chung, Kyu-Rhim; Ngan, Peter

2014-01-01

The purpose of the current report is to present 6-year long-term stability and 10-year follow-up data for an adult patient who was treated with a tongue elevator for relapsed anterior open-bite. The 19-year-old male patient presented with the chief complaint of difficulty in chewing his food. Collectively, clinical and radiographic examinations revealed an anterior open-bite, low tongue posture, and tongue-tie. The patient opted for orthodontic treatment alone, without any surgical procedure. A lingual frenectomy was recommended to avoid the risk of relapse, but the patient declined because he was not experiencing tongue discomfort. Initial treatment of the anterior open-bite with molar intrusion and tongue exercises was successful, but relapse occurred during the retention period. A tongue elevator was used for retreatment, because the approach was minimally invasive and suited the patient's requirements regarding discomfort, cost, and time. The appliance changed the tongue posture and generated an altered tongue force, which ultimately resulted in intrusive dentoalveolar effects, and a subsequent counterclockwise rotation of the mandible. The results showed long-term stability and were maintained for six years through continual use of the tongue elevator. The results of this case indicated that a tongue elevator could be used not only as an alternative treatment for open-bite, but also as an active retainer. PMID:25133135

Comparative analysis of the folding dynamics and kinetics of an engineered knotted protein and its variants derived from HP0242 of Helicobacter pylori

NASA Astrophysics Data System (ADS)

Wang, Liang-Wei; Liu, Yu-Nan; Lyu, Ping-Chiang; Jackson, Sophie E.; Hsu, Shang-Te Danny

2015-09-01

Understanding the mechanism by which a polypeptide chain thread itself spontaneously to attain a knotted conformation has been a major challenge in the field of protein folding. HP0242 is a homodimeric protein from Helicobacter pylori with intertwined helices to form a unique pseudo-knotted folding topology. A tandem HP0242 repeat has been constructed to become the first engineered trefoil-knotted protein. Its small size renders it a model system for computational analyses to examine its folding and knotting pathways. Here we report a multi-parametric study on the folding stability and kinetics of a library of HP0242 variants, including the trefoil-knotted tandem HP0242 repeat, using far-UV circular dichroism and fluorescence spectroscopy. Equilibrium chemical denaturation of HP0242 variants shows the presence of highly populated dimeric and structurally heterogeneous folding intermediates. Such equilibrium folding intermediates retain significant amount of helical structures except those at the N- and C-terminal regions in the native structure. Stopped-flow fluorescence measurements of HP0242 variants show that spontaneous refolding into knotted structures can be achieved within seconds, which is several orders of magnitude faster than previously observed for other knotted proteins. Nevertheless, the complex chevron plots indicate that HP0242 variants are prone to misfold into kinetic traps, leading to severely rolled-over refolding arms. The experimental observations are in general agreement with the previously reported molecular dynamics simulations. Based on our results, kinetic folding pathways are proposed to qualitatively describe the complex folding processes of HP0242 variants.

Imagery use of athletes in individual and team sports that require open and closed skill.

PubMed

Kizildag, Esen; Tiryaki, M Sefik

2012-06-01

This study compared use of imagery in elite male and female athletes in open and closed and individual or team sports. A total of 151 elite Turkish athletes ages 15 to 29 years old (males' M age=20.7 yr., SD=3.3; females' M age=20.0 yr., SD=3.5) from open-team sports (n=66), open-individual sports (n=26), and closed-individual sports (n=59) completed the sport imagery questionnaire. A significant multivariate effect of sport type was found. Univariate analyses indicated that male and female athletes in team open-skill sports and individual closed-skill sports used more motivational general-mastery imagery than did athletes in individual open-skill sports.

Dental occlusion ties: A rapid, safe, and non‐invasive maxillo‐mandibular fixation technology

PubMed Central

2017-01-01

Objectives For decades, Erich arch bars have been a standard in establishing maxillo‐mandibular fixation (MMF). While reliable, the approach risks sharps injury, consumes operating room time, and inflicts gingival trauma. Newer technologies including screw‐based techniques and “hybrid” techniques have improved MMF by reducing sharps injuries and operating room time, but risk injury to tooth roots, nerves, and gingiva. This study aims to establish the application, strengths, and limitations of dental occlusion ties as a novel alternative in maxillo‐mandibular fixation. Study Design Prospective, non‐blinded, human feasibility clinical trial. Materials and Methods An iterative prototyping process was used to invent dental occlusion ties (brand name: Minne Ties). Development included 3D printing, cadaver prototype testing, human apical embrasure measurement, and ultimately non‐significant risk human clinical trial testing. In the IRB‐approved feasibility clinical trial, the devices were applied to mandible and maxilla fracture candidates with fractures amenable to intra‐operative MMF with open reduction with internal fixation. The ties were removed prior to extubation. Pre‐teens, comminuted fracture patients, and patients requiring post‐operative MMF were excluded. Results Manufactured, sterile prototypes secured MMF successfully in management of unilateral and bilateral mandible and maxilla fractures. All patients reported correction of pre‐operative malocclusion. Application times were typically 12–15 minutes for a single surgeon to achieve MMF. Patients incurred negligible gingival trauma from the technology as the ties require no tissue penetration for application. Conclusions Dental occlusion ties offer a non‐invasive solution featuring operating room efficiency, minimized sharps risk, and less bony and soft tissue trauma than current commercialized solutions. Level of Evidence Therapeutic, IV PMID:28894837

A Thematic Analysis of Mothers' Motivations for Blogging.

PubMed

Pettigrew, Simone; Archer, Catherine; Harrigan, Paul

2016-05-01

Introduction Various forms of social media are used by many mothers to maintain social ties and manage the stress associated with their parenting roles and responsibilities. 'Mommy blogging' as a specific type of social media usage is a common and growing phenomenon, but little is known about mothers' blogging-related experiences and how these may contribute to their wellbeing. This exploratory study investigated the blogging-related motivations and goals of Australian mothers. Methods An online survey was emailed to members of an Australian online parenting community. The survey included open-ended questions that invited respondents to discuss their motivations and goals for blogging. A thematic analysis using a grounded approach was used to analyze the qualitative data obtained from 235 mothers. Results Five primary motivations for blogging were identified: developing connections with others, experiencing heightened levels of mental stimulation, achieving self-validation, contributing to the welfare of others, and extending skills and abilities. Discussion These motivations are discussed in terms of their various properties and dimensions to illustrate how these mothers appear to use blogging to enhance their psychological wellbeing.

Cotton Cultivar Response to Root-Knot Nematodes in Two Tillage Regimes, 2008

USDA-ARS?s Scientific Manuscript database

Six cotton cultivars were evaluated for yield response to the root-knot nematode in a naturally infested field at E. V. Smith Research and Extension Center, near Shorter, Alabama. The field had a long history of root-knot nematode infestation, and the soil type was classified as a sandy loam. Plots ...

Knots in physics

NASA Astrophysics Data System (ADS)

Cho, Y. M.; Oh, Seung Hun; Zhang, Pengming

2018-03-01

After Dirac introduced the monopole, topological objects have played increasingly important roles in physics. In this review we discuss the role of the knot, the most sophisticated topological object in physics, and related topological objects in various areas in physics. In particular, we discuss how the knots appear in Maxwell’s theory, Skyrme theory, and multicomponent condensed matter physics.

14 CFR 25.175 - Demonstration of static longitudinal stability.

Code of Federal Regulations, 2012 CFR

2012-01-01

... resulting free return speed range, or 50 knots plus the resulting free return speed range, above and below... plus the resulting free return speed range, or 50 knots plus the resulting free return speed range... the trim speed plus the resulting free return speed range, or 50 knots plus the resulting free return...

14 CFR 25.175 - Demonstration of static longitudinal stability.

Code of Federal Regulations, 2014 CFR

2014-01-01

... resulting free return speed range, or 50 knots plus the resulting free return speed range, above and below... plus the resulting free return speed range, or 50 knots plus the resulting free return speed range... the trim speed plus the resulting free return speed range, or 50 knots plus the resulting free return...

14 CFR 25.175 - Demonstration of static longitudinal stability.

Code of Federal Regulations, 2013 CFR

2013-01-01

... resulting free return speed range, or 50 knots plus the resulting free return speed range, above and below... plus the resulting free return speed range, or 50 knots plus the resulting free return speed range... the trim speed plus the resulting free return speed range, or 50 knots plus the resulting free return...

Ethnomathematics in Arfak (West Papua-Indonesia): Hidden Mathematics on Knot of Rumah Kaki Seribu

ERIC Educational Resources Information Center

Haryanto; Nusantara, Toto; Subanji; Abadyo

2016-01-01

This ethnomathematics article focused on the models of knot which is used in the frame of "Rumah Kaki Seribu." The knot model itself was studied mathematically. The results of this study revealed the way Arfak tribal communities think mathematically. This article uses exploration, documentation, interview, experiments and literature…

Cost-Benefit and Performance of Handmade Carpets Produced with Wool, Untreated and Chemical Treated Jute Pile Yarns

NASA Astrophysics Data System (ADS)

Gupta, Shravan Kumar; Goswami, Kamal Kanti

2018-03-01

Jute is a natural fibre which is used to make different type of products due to low cost, easy availability and eco-friendliness. However, the stiffness and harshness of jute fibre affect the use of jute in many products like pile yarns in hand knotted carpets. In this research, a study has been done on the application of jute pile yarns in Persian hand knotted carpet. Three types of commercial yarns (wool, untreated jute and woollenized jute) as well as three types of chemical treated jute yarns (hydrogen peroxide bleached, softened bleached and woollenized yarns) have been applied as pile yarns in Persian hand knotted carpets. Cost-benefit analysis of hand knotted carpets shows that manufacturing cost of wool carpet is lower than others. The contribution of manpower charges is higher than material cost during carpet manufacturing. Hand knotted carpet shows the lowest pile abrasion loss and highest compression recovery when wool is used as pile. Wool hand knotted carpet shows higher compression than untreated and treated jute carpets.

Cost-Benefit and Performance of Handmade Carpets Produced with Wool, Untreated and Chemical Treated Jute Pile Yarns

NASA Astrophysics Data System (ADS)

Gupta, Shravan Kumar; Goswami, Kamal Kanti

2018-06-01

Jute is a natural fibre which is used to make different type of products due to low cost, easy availability and eco-friendliness. However, the stiffness and harshness of jute fibre affect the use of jute in many products like pile yarns in hand knotted carpets. In this research, a study has been done on the application of jute pile yarns in Persian hand knotted carpet. Three types of commercial yarns (wool, untreated jute and woollenized jute) as well as three types of chemical treated jute yarns (hydrogen peroxide bleached, softened bleached and woollenized yarns) have been applied as pile yarns in Persian hand knotted carpets. Cost-benefit analysis of hand knotted carpets shows that manufacturing cost of wool carpet is lower than others. The contribution of manpower charges is higher than material cost during carpet manufacturing. Hand knotted carpet shows the lowest pile abrasion loss and highest compression recovery when wool is used as pile. Wool hand knotted carpet shows higher compression than untreated and treated jute carpets.

The Role of Non-Native Interactions in the Folding of Knotted Proteins: Insights from Molecular Dynamics Simulations

PubMed Central

Covino, Roberto; Škrbić, Tatjana; Beccara, Silvio a; Faccioli, Pietro; Micheletti, Cristian

2014-01-01

For several decades, the presence of knots in naturally-occurring proteins was largely ruled out a priori for its supposed incompatibility with the efficiency and robustness of folding processes. For this very same reason, the later discovery of several unrelated families of knotted proteins motivated researchers to look into the physico-chemical mechanisms governing the concerted sequence of folding steps leading to the consistent formation of the same knot type in the same protein location. Besides experiments, computational studies are providing considerable insight into these mechanisms. Here, we revisit a number of such recent investigations within a common conceptual and methodological framework. By considering studies employing protein models with different structural resolution (coarse-grained or atomistic) and various force fields (from pure native-centric to realistic atomistic ones), we focus on the role of native and non-native interactions. For various unrelated instances of knotted proteins, non-native interactions are shown to be very important for favoring the emergence of conformations primed for successful self-knotting events. PMID:24970203

NASA Sees a Wider-Eyed Typhoon Soudelor Near Taiwan

NASA Image and Video Library

2017-12-08

The MODIS instrument aboard NASA's Aqua satellite flew over Typhoon Soudelor on Aug. 7, 2015, at 4:40 UTC (12:40 a.m. EDT) as it was approaching Taiwan. Credits: NASA Goddard's MODIS Rapid Response Team Clouds in Typhoon Soudelor's western quadrant were already spreading over Taiwan early on August 7 when NASA's Aqua satellite passed overhead. Soudelor is expected to make landfall and cross central Taiwan today and make a second landfall in eastern China. NASA satellite imagery revealed that Soudelor's eye "opened" five more miles since August 4. On Aug. 7 at 4:40 UTC (12:40 a.m. EDT) the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA's Aqua satellite captured a visible-light image of Typhoon Soudelor as its western quadrant began brushing eastern Taiwan. The MODIS image showed Soudelor's 17-nautical-mile-wide eye and thick bands of powerful thunderstorms surrounded the storm and spiraled into the center. Just three days before, the eye was 5 nautical miles smaller when the storm was more intense. On Aug. 4 at 4:10 UTC (12:10 a.m. EDT) Aqua's MODIS image showed the eye was 12-nautical-mile-wide eye. At 1500 UTC (11 a.m. EDT) on August 7, 2015, the Joint Typhoon Warning Center (JTWC) noted that Typhoon Soudelor's maximum sustained winds increased from 90 knots (103.6 mph/166.7 kph) to 105 knots (120.8 mph / 194.5 kph). It was centered near 23.1 North latitude and 123.2 East longitude, about 183 nautical miles (210.6 miles/338.9 km) southeast of Taipei, Taiwan. It was moving to the west-northwest at 10 knots (11.5 mph/18.5 kph). For warnings and watches for Taiwan, visit the Central Weather Bureau website: www.cwb.gov.tw/eng/. For warnings in China, visit the China Meteorological Administration website: www.cma.gov.cn/en. Soudelor's final landfall is expected in eastern China on Saturday, August 8. Clouds in Typhoon Soudelor's western quadrant were already spreading over Taiwan early on August 7 when NASA's Aqua satellite passed overhead. Soudelor is expected to make landfall and cross central Taiwan today and make a second landfall in eastern China. NASA satellite imagery revealed that Soudelor's eye "opened" five more miles since August 4. On Aug. 7 at 4:40 UTC (12:40 a.m. EDT) the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA's Aqua satellite captured a visible-light image of Typhoon Soudelor as its western quadrant began brushing eastern Taiwan. The MODIS image showed Soudelor's 17-nautical-mile-wide eye and thick bands of powerful thunderstorms surrounded the storm and spiraled into the center. Just three days before, the eye was 5 nautical miles smaller when the storm was more intense. On Aug. 4 at 4:10 UTC (12:10 a.m. EDT) Aqua's MODIS image showed the eye was 12-nautical-mile-wide eye. At 1500 UTC (11 a.m. EDT) on August 7, 2015, the Joint Typhoon Warning Center (JTWC) noted that Typhoon Soudelor's maximum sustained winds increased from 90 knots (103.6 mph/166.7 kph) to 105 knots (120.8 mph / 194.5 kph). It was centered near 23.1 North latitude and 123.2 East longitude, about 183 nautical miles (210.6 miles/338.9 km) southeast of Taipei, Taiwan. It was moving to the west-northwest at 10 knots (11.5 mph/18.5 kph). For warnings and watches for Taiwan, visit the Central Weather Bureau website: www.cwb.gov.tw/eng/. For warnings in China, visit the China Meteorological Administration website: www.cma.gov.cn/en. Soudelor's final landfall is expected in eastern China on Saturday, August 8.

Effect of Oryzalin and 1,1-Dimethylpiperidinium Chloride on Cotton and Tomato Roots Infected with the Root-knot Nematode, Meloidogyne incognita

PubMed Central

Orum, T. V.; Bartels, P. G.; McClure, M. A.

1979-01-01

Oryzalin (3,5-dinitro-N4,N4-dipropyl-sulfanilamide) and BAS 083 (l,l-dimethylpiperdinium chloride) reduced root-knot infection in tomato roots when respectively applied as a soil drench at 20 ppm and 10,000 ppm. Oryzalin reduced knot counts with various intervals between treatment and inoculation. BAS 083 reduced knot counts only when applied before inoculation. Oryzalin was shown not to be a contact nematicide, and BAS 083 was only a weak one. Neither compound reduced penetration by infective larvae. Postinfection reduction in knot counts by Oryzalin and BAS 083 resulted, in part, from activation of natural defense mechanisms of the host. Giant-cell development in cotton roots inoculated with nematodes was inhibited by Oryzalin. Lateral root development was inhibited by BAS 083. PMID:19305533

Is two-port laparoendoscopic single-site surgery (T-LESS) feasible for pediatric hydroceles? Single-center experience with the initial 59 cases.

PubMed

Wang, Furan; Shou, Tiejun; Zhong, Hongji

2018-02-01

Although T-LESS is increasingly being used to treat pediatric inguinal hernia, there is no study regarding T-LESS for pediatric hydrocele. To further evaluate the feasibility of T-LESS and present our single-center experience for repair of pediatric hydroceles. From January 2016 to July 2016, all boys undergoing T-LESS for hydrocele in our institute were retrospectively reviewed. A laparoscope and a needle-holding forceps were introduced at umbilicus. A round needle with silk suture was stabbed through the abdominal wall. The peritoneum around the internal ring was sutured continuously in a clockwise direction. After a complete purse-string suture, a triple knot was performed by using a single-instrument tie technique. The contralateral patent processus vaginalis (PPV) was repaired simultaneously if present. Overall, 59 boys with hydrocele were included (22 on the left side, 32 on the right side, and 5 bilaterally) (Table). During the procedure, all hydroceles were observed with a PPV but the fluid needed to be aspired in 39 boys. A contralateral PPV was present in 24 boys with unilateral hydrocele, and finally 88 repairs were performed. Mean operative time was 18.3 min for unilateral repair and 27.5 min for bilateral repair, respectively. All procedures were uneventful besides a minor injury to the inferior epigastric vessels. After a mean follow-up of 10.7 months, neither recurrence nor other postoperative complication was observed. There were no visible scars on the abdominal wall. Compared with open repair of pediatric inguinal hernia and hydrocele, laparoscopic surgery had several advantages, such as exploration of contralateral PPV, identification of rare hernias, diminished postoperative pain, improved cosmesis, faster recovery, and fewer complications. Differing from the laparoscopic retroperitoneal approach, T-LESS included no subcutaneous tissue in the ligature, and its knot was completely in the peritoneal cavity which could radically prevent the severe pain and suture granuloma in the ligated region. Furthermore, the skin incisions after T-LESS were hidden in umbilicus, which could achieve an excellent cosmetic result. By performing T-LESS for pediatric hydroceles, the current study showed very satisfactory results, such as high success rate, minor complication, and excellent cosmesis. However, because of the difficult learning curve of T-LESS, some technical details (e.g. avoiding injury to the spermatic cord, completely suturing the peritoneal folds and reducing disturbance between the instruments) still need to be improved in the future. T-LESS appears to be a safe and effective method for repair of pediatric hydroceles. Copyright © 2017 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.

Assessing Fit of Models with Discrete Proficiency Variable in Educational Assessment. Research Report. RR-04-07

ERIC Educational Resources Information Center

Sinharay, Sandip; Almond, Russell; Yan, Duanli

2004-01-01

Model checking is a crucial part of any statistical analysis. As educators tie models for testing to cognitive theory of the domains, there is a natural tendency to represent participant proficiencies with latent variables representing the presence or absence of the knowledge, skills, and proficiencies to be tested (Mislevy, Almond, Yan, &…

Options for Studying Teacher Pay Reform Using Natural Experiments

ERIC Educational Resources Information Center

Glazerman, Steven; Silva, Tom; Addy, Nii; Avellar, Sarah; Max, Jeffrey; McKie, Allison; Natzke, Brenda; Puma, Michael; Wolf, Patrick; Greszler, Rachel Ungerer

2006-01-01

How public school teachers are paid in the U.S. has been a controversial issue for many years. Critics of the traditional system, in which teachers are paid on the basis of years of experience and educational attainment, claim that it does not reward or promote good teaching as fairly as systems that tie pay to performance: having certain skills,…

Improving Parenting Skills of Incarcerated Males in a Community Correctional Center.

ERIC Educational Resources Information Center

Reinhard, Michelle L. Rinehart

A practicum was designed to ease the transition of the male inmate back to his family and his role as father. It was a response to the failure of the corrections system to assist inmates placed in the Community Correctional Center in a county of a southern state in participating in beneficial activities and reestablishing positive ties with family…

Neoliberal Discourses and the Local Policy Implementation of an English Literacy and Civics Education Program

ERIC Educational Resources Information Center

López, Dina

2015-01-01

The issue of language, specifically access to English, has emerged as a key concern for both U.S. policy-makers and immigrant communities alike. Many of these debates are framed by neoliberal and human capital perspectives, which view English as a set of skills and linguistic capital that are inextricably tied to employment opportunities and…

Use the Arts: Add Lustre to the Reading Program.

ERIC Educational Resources Information Center

Anderson, Betty; Midgett, Jeanice

A variety of ways to use television, drama, and music to enhance reading instruction are presented in this paper. The use of television is suggested as a motivator for reading and as a means to teach reading skills, and the use of books with television or movie tie-ins is suggested as a way to motivate readers. Sources for obtaining television…

Topological effects on the mechanical properties of polymer knots

NASA Astrophysics Data System (ADS)

Zhao, Yani; Ferrari, Franco

2017-11-01

The mechanical properties of knotted polymer rings under stretching in a bad or good solvent are investigated by applying a force F to a point of the knot while keeping another point fixed. The Monte Carlo sampling of the polymer conformations is performed on a simple cubic lattice using the Wang-Landau algorithm. The specific energy, specific heat capacity, gyration radius and the force-elongation curves are computed for several knot topologies with lengths up to 120 lattice units. The common features of the mechanical and thermal behavior of stretched short polymer rings forming knots of a given topological type are analyzed as well as the differences arising due to topology and size effects. It is found that these systems admit three different phases depending on the values of the tensile force F and the temperature T. The transitions from one phase to the other are well characterized by the peaks of the specific heat capacity and by the data of the gyration radius and specific energy. At very low temperatures the force-elongation curves show that the stretching of a knot is a stepwise process, which becomes smooth at higher temperatures. Criteria for distinguishing topological and size effects are provided. It turns out from our study that the behavior of short polymer rings is strongly influenced by topological effects. In particular, the swelling and the swelling rate of knots are severely limited by the topological constraints. Several other properties that are affected by topology, like the decay of the specific energy at high tensile forces, are discussed. The fading out of the influences of topological origin with increasing knot lengths has been verified. Some anomalies detected in the plots of the specific heat capacity of very short and complex knots have been explained by the limitations in the number of accessible energy states due to the topological constraints.

Characterization of bacterial knot disease caused by Pseudomonas savastanoi pv. savastanoi on pomegranate (Punica granatum L.) trees: a new host of the pathogen.

PubMed

Bozkurt, I A; Soylu, S; Mirik, M; Ulubas Serce, C; Baysal, Ö

2014-11-01

This study aimed to isolate and identify the causal organism causing hyperplastic outgrowths (knots) on stems and branches of pomegranate trees in the Eastern Mediterranean region of Turkey. Bacterial colonies were isolated from young knots on plates containing selective nutrient media. Biochemical tests, fatty acid analysis and PCR were performed to identify possible causal disease agent. Representative isolates were identified as Pseudomonas.pv.savastanoi (Psv) using biochemical tests, fatty acid profiling and PCR. Following inoculation of pomegranate plants (cv. hicaz) with bacterial suspensions, 25 of 54 bacterial isolates caused typical knots at the site of inoculation. PCR analysis, using specific primer for Psv, generated a single amplicon from all isolates. The similarity of the sequence of Turkish pomegranate isolate was 99% similar to the corresponding gene sequences of Psv in the databases. Based on symptoms, biochemical, molecular, pathogenicity tests and sequence analyses, the disease agent of knots observed on the pomegranate trees is Psv. To the best of our knowledge, this research has revealed pomegranate as a natural host of Psv, which extends the list of host plant species affected by the pathogen in the world and Turkey. Pomegranate trees were affected by the disease with outgrowths (galls or knot) disease. Currently, there is no published study on disease agent(s) causing the galls or knots on pomegranate trees in worldwide. Bacterial colonies were isolated from young knots. The causal agent of the knot Pseudomonas savastanoi pv.savastanoi (Psv) was identified based on symptoms, biochemical, molecular methods, pathogenicity tests and sequence analysis. To the best of our knowledge, this is the first report of Psv on pomegranate as a natural host, which extends the growing list of plant species affected by this bacterium in the world and Turkey. © 2014 The Society for Applied Microbiology.

Colored knot polynomials for arbitrary pretzel knots and links

DOE PAGES

Galakhov, D.; Melnikov, D.; Mironov, A.; ...

2015-04-01

A very simple expression is conjectured for arbitrary colored Jones and HOMFLY polynomials of a rich (g+1)-parametric family of pretzel knots and links. The answer for the Jones and HOMFLY is fully and explicitly expressed through the Racah matrix of Uq(SU N), and looks related to a modular transformation of toric conformal block. Knot polynomials are among the hottest topics in modern theory. They are supposed to summarize nicely representation theory of quantum algebras and modular properties of conformal blocks. The result reported in the present letter, provides a spectacular illustration and support to this general expectation.

Confirming the nature of the knot near the pulsar B1951+32

NASA Astrophysics Data System (ADS)

Zyuzin, D. A.; Shibanov, Yu A.; Pavlov, G. G.; Danilenko, A. A.

2017-12-01

The energetic and fast-moving radio and γ-ray pulsar B1951+32 is associated with the supernova remnant CTB 80. It powers a complex pulsar wind nebula detected in the radio, Hα and X-rays (Moon et al 2004 ApJ 610 L33). A puzzling optical knot was detected about 0″.5 from the pulsar in the optical and near-IR (Moon et al 2004 ApJ 610 L33; Hester 2000 Bulletin of the AAS 32 1542). It is reminiscent of the unique “inner optical knot” located 0″.6 from the Crab pulsar. Until now there has been no evidence that B1951+32 knot is indeed associated with the pulsar. We observed the pulsar field with the Gemini-North telescope in 2016 to check the association. We performed first near-IR high spatial resolution imaging in the K s band using the NIRI+Altair instrument and deep optical imaging in the gr bands using the GMOS instrument. Our observations showed that the current knot position is shifted by ≈ 0″.6 from the position measured with the HST in 1997. This is consistent with the known pulsar proper motion and is direct evidence of the pulsar-knot connection. We compared the spectral energy distribution of the knot emission with that of the Crab knot. Possible implications of the results are discussed.

Knot positioning during McDonald cervical cerclage, does it make a difference? A cohort study.

PubMed

Atia, Hytham; Ellaithy, Mohamed; Altraigey, Ahmed; Ibrahim, Heba

2018-05-15

To study the effect of McDonald cerclage knot position on the different maternal and neonatal outcomes. This historical cohort study included women with singleton pregnancy who had a prophylactic McDonald cervical cerclage between 1 May 2010 and 31 September 2017. Maternal and neonatal outcome parameters were compared between the anterior and posterior knot cerclage procedures. The primary outcome measure was the rate of term birth. 550 Women had a prophylactic McDonald cervical cerclage, 306 with anterior knot (Group A) and 244 with posterior knot (Group B). There were no statistically significant differences regarding gestational age (GA) at delivery (36.3 ± 4.2 versus 35.8 ± 5.3 for groups A and B respectively), term birth rate, post-cerclage cervical length, symptomatic vaginitis, urinary tract infection, difficult cerclage removal and cervical lacerations. Similarly, there were no statistically significant differences as regards the studied neonatal outcomes including take home babies, neonatal intensive care admission, respiratory distress syndrome and neonatal sepsis. Survival analysis on GA at delivery demonstrated no statistically significant difference as regards the proportion of term deliveries in the anterior and posterior knot cerclage groups (log-rank test p-value = .478). Knot positioning during McDonald cervical cerclage, anteriorly or posteriorly, didn't significantly impact the studied maternal and neonatal outcomes.

Predicting internal lumber grade from log surface knots: actual and simulated results.

Treesearch

Christine Todoroki; Robert A. Monserud; Dean L. Parry

2005-01-01

The purpose of this study was threefold: 1) compare actual with simulated lumber yields; 2) examine the effect of measurement errors associated with knot angles and morphology. on lumber grade; and 3) investigate methods for predicting lumber quality within unsawn logs from surface knots. Twenty-eight Douglas-fir (Pseudotsuga menziesii(Mii irb.)...

Use of gadolinium chloride as a contrast agent for imaging spruce knots by magnetic resonance

Treesearch

Thomas L. Eberhardt; Chi-Leung So; Amy H. Herlihy; Po-Wah So

2006-01-01

Treatments of knot-containing spruce wood blocks with a paramagnetic salt, gadolinium (III) chloride, in combination with solvent pretreatments, were evaluated as strategies to enhance the visualization of wood features by magnetic resonance imaging (MRI). Initial experiments with clear wood and excised knot samples showed differences in moisture uptake after...

Expression of almond KNOTTED1 homologue (PdKn1) anticipates adventitious shoot initiation

USDA-ARS?s Scientific Manuscript database

Background and Aims: The transcription factor encoded by the gene Knotted1 is a nuclear homeodomain protein, regulating meristematic cells at the shoot apical meristem. It has been proven that Knotted1 (KN1) has a role in the switch from an indeterminate to determinate cell fate and as such this gen...

Notice of Release of ‘Truhart-NR’, a Root-knot Nematode Resistant, Pimento-type Pepper

USDA-ARS?s Scientific Manuscript database

The USDA has developed a high-yielding, pimento-type pepper (Capsicum annuum L.) cultivar that is highly resistant to root-knot nematodes. The new cultivar, Truhart-NR, is homozygous for the dominant N gene that conditions a high level of resistance to the southern root-knot nematode [Meloidogyne i...

Five Uncommon but Useful Knots.

ERIC Educational Resources Information Center

Chisnall, Rob

1997-01-01

Describes five useful, little-known knots: mooring hitch for securing a line to a stump or post; highwayman's cutaway for securing canoe lines or horses' reins; taut-line hitch or midshipman's hitch for securing tent guys; and Hedden knot and C&F belay hitch, used by rock climbers and mountaineers, which combine in a simple rescue haul system.…

Spline curve matching with sparse knot sets

Treesearch

Sang-Mook Lee; A. Lynn Abbott; Neil A. Clark; Philip A. Araman

2004-01-01

This paper presents a new curve matching method for deformable shapes using two-dimensional splines. In contrast to the residual error criterion, which is based on relative locations of corresponding knot points such that is reliable primarily for dense point sets, we use deformation energy of thin-plate-spline mapping between sparse knot points and normalized local...

High finesse microfiber knot resonators made from double-ended tapered fibers.

PubMed

Xiao, Limin; Birks, T A

2011-04-01

We fabricated optical microfiber knot resonators from thin tapered fibers (diameter down to 1 μm) linked to untapered fiber at both ends. We demonstrated a finesse of about 100, over twice as high as previously reported for microfiber resonators. Low-loss encapsulation of microfiber knot resonators in hydrophobic silica aerogel was also investigated.

Cyborg mini-trainer.

PubMed

Mosso, José L; Nieto, Jesus J; Carbajal, Manuel F; Marmolejo, Jorge; Ochoa, Enrique; De La Fuente, Mireya; Almazan, Andrew; Obrador, Tomas

2009-01-01

We present the smallest surgical trainer with a total weight of 400 gr, built in aluminum of 25 cm large and 24 cm wide, and 23 cm high. It's a system integrated by a small and open module, a lamp and a microcamera connected to a Head Mounted display. It holds two endoscopic instruments, and items to make knots or sutures and enhance visual-motor coordination. The vision we got is by a small microcamera displayed to a Head Mounted Display HMD. This surgical trainer is the smallest in the worldwide, easy to install, and easy to carry.

Knotted versus knotless suture bridge repair of the achilles tendon insertion: a biomechanical study.

PubMed

Cox, Joseph T; Shorten, Peter L; Gould, Gregory C; Markert, Ronald J; Barnett, Michael D; Laughlin, Richard T

2014-11-01

Surgical treatment of insertional Achilles tendinopathy often involves detachment and debridement of the Achilles tendon insertion. A recent study has shown that knotted suture bridge fixation of the Achilles to the calcaneus is biomechanically superior to single-row fixation, but there is an absence of literature on the use of different suture bridge constructs to repair the Achilles tendon. There will be no significant difference in the load to failure, mode of failure, tendon strain, tendon stiffness, repair site gapping, or footprint size when comparing knotted suture bridge repair to knotless suture bridge repair of the Achilles tendon after detachment for insertional Achilles tendinopathy. Controlled laboratory study. A single specimen from each pair of 10 cadaveric Achilles tendons was randomized to 1 of 2 Achilles insertion repair groups: knotted (n = 10) or knotless (n = 10) suture bridge repair. Repaired footprint size was measured, and then cyclic testing from 10 to 100 N for 2000 cycles was performed. This was followed by measurement of tendon strain, repair site displacement, load to failure, and tendon stiffness. The knotted suture bridge repair had a significantly higher load to failure compared with the knotless suture bridge (mean ± SD, 317.8 ± 93.6 N vs 196.1 ± 12.1 N, respectively; P = .001). All constructs failed at the tendon-suture interface. Tendon strain after cyclic testing was significantly greater in the knotless (1.20 ± 1.05) compared with the knotted (0.39 ± 0.4) suture repair groups (P = .011). There was no significant difference in footprint size between the knotted (230.3 ± 63.3 mm(2)) and knotless (248.5 ± 48.8 mm(2)) groups (P = .40). There was also no significant difference in stiffness (knotted = 76.4 ± 8.0 N/mm; knotless = 69.6 ± 10.9 N/mm; P = .17) and repair site displacement after cyclic testing (knotted = 2.8 ± 1.2 mm; knotless = 3.6 ± 1.1 mm; P = .17). During suture bridge repair of the Achilles tendon after detachment, knots at the proximal suture anchors significantly improve the biomechanical strength of the repair. This study demonstrated that the knotless suture bridge repair had a significantly lower load to failure than the knotted suture bridge. Surgeons should be aware of these biomechanical differences, as they influence the postoperative rehabilitation protocol and may lead to higher surgical complication rates. © 2014 The Author(s).

SNP markers tightly linked to root knot nematode resistance in grapevine (Vitis cinerea) identified by a genotyping-by-sequencing approach followed by Sequenom MassARRAY validation

PubMed Central

Morales, Norma B.; Moskwa, Sam; Clingeleffer, Peter R.; Thomas, Mark R.

2018-01-01

Plant parasitic nematodes, including root knot nematode Meloidogyne species, cause extensive damage to agriculture and horticultural crops. As Vitis vinifera cultivars are susceptible to root knot nematode parasitism, rootstocks resistant to these soil pests provide a sustainable approach to maintain grapevine production. Currently, most of the commercially available root knot nematode resistant rootstocks are highly vigorous and take up excess potassium, which reduces wine quality. As a result, there is a pressing need to breed new root knot nematode resistant rootstocks, which have no impact on wine quality. To develop molecular markers that predict root knot nematode resistance for marker assisted breeding, a genetic approach was employed to identify a root knot nematode resistance locus in grapevine. To this end, a Meloidogyne javanica resistant Vitis cinerea accession was crossed to a susceptible Vitis vinifera cultivar Riesling and results from screening the F1 individuals support a model that root knot nematode resistance, is conferred by a single dominant allele, referred as MELOIDOGYNE JAVANICA RESISTANCE1 (MJR1). Further, MJR1 resistance appears to be mediated by a hypersensitive response that occurs in the root apical meristem. Single nucleotide polymorphisms (SNPs) were identified using genotyping-by-sequencing and results from association and genetic mapping identified the MJR1 locus, which is located on chromosome 18 in the Vitis cinerea accession. Validation of the SNPs linked to the MJR1 locus using a Sequenom MassARRAY platform found that only 50% could be validated. The validated SNPs that flank and co-segregate with the MJR1 locus can be used for marker-assisted selection for Meloidogyne javanica resistance in grapevine. PMID:29462210

SNP markers tightly linked to root knot nematode resistance in grapevine (Vitis cinerea) identified by a genotyping-by-sequencing approach followed by Sequenom MassARRAY validation.

PubMed

Smith, Harley M; Smith, Brady P; Morales, Norma B; Moskwa, Sam; Clingeleffer, Peter R; Thomas, Mark R

2018-01-01

Plant parasitic nematodes, including root knot nematode Meloidogyne species, cause extensive damage to agriculture and horticultural crops. As Vitis vinifera cultivars are susceptible to root knot nematode parasitism, rootstocks resistant to these soil pests provide a sustainable approach to maintain grapevine production. Currently, most of the commercially available root knot nematode resistant rootstocks are highly vigorous and take up excess potassium, which reduces wine quality. As a result, there is a pressing need to breed new root knot nematode resistant rootstocks, which have no impact on wine quality. To develop molecular markers that predict root knot nematode resistance for marker assisted breeding, a genetic approach was employed to identify a root knot nematode resistance locus in grapevine. To this end, a Meloidogyne javanica resistant Vitis cinerea accession was crossed to a susceptible Vitis vinifera cultivar Riesling and results from screening the F1 individuals support a model that root knot nematode resistance, is conferred by a single dominant allele, referred as MELOIDOGYNE JAVANICA RESISTANCE1 (MJR1). Further, MJR1 resistance appears to be mediated by a hypersensitive response that occurs in the root apical meristem. Single nucleotide polymorphisms (SNPs) were identified using genotyping-by-sequencing and results from association and genetic mapping identified the MJR1 locus, which is located on chromosome 18 in the Vitis cinerea accession. Validation of the SNPs linked to the MJR1 locus using a Sequenom MassARRAY platform found that only 50% could be validated. The validated SNPs that flank and co-segregate with the MJR1 locus can be used for marker-assisted selection for Meloidogyne javanica resistance in grapevine.

Comparing models of Red Knot population dynamics

USGS Publications Warehouse

McGowan, Conor P.

2015-01-01

Predictive population modeling contributes to our basic scientific understanding of population dynamics, but can also inform management decisions by evaluating alternative actions in virtual environments. Quantitative models mathematically reflect scientific hypotheses about how a system functions. In Delaware Bay, mid-Atlantic Coast, USA, to more effectively manage horseshoe crab (Limulus polyphemus) harvests and protect Red Knot (Calidris canutus rufa) populations, models are used to compare harvest actions and predict the impacts on crab and knot populations. Management has been chiefly driven by the core hypothesis that horseshoe crab egg abundance governs the survival and reproduction of migrating Red Knots that stopover in the Bay during spring migration. However, recently, hypotheses proposing that knot dynamics are governed by cyclical lemming dynamics garnered some support in data analyses. In this paper, I present alternative models of Red Knot population dynamics to reflect alternative hypotheses. Using 2 models with different lemming population cycle lengths and 2 models with different horseshoe crab effects, I project the knot population into the future under environmental stochasticity and parametric uncertainty with each model. I then compare each model's predictions to 10 yr of population monitoring from Delaware Bay. Using Bayes' theorem and model weight updating, models can accrue weight or support for one or another hypothesis of population dynamics. With 4 models of Red Knot population dynamics and only 10 yr of data, no hypothesis clearly predicted population count data better than another. The collapsed lemming cycle model performed best, accruing ~35% of the model weight, followed closely by the horseshoe crab egg abundance model, which accrued ~30% of the weight. The models that predicted no decline or stable populations (i.e. the 4-yr lemming cycle model and the weak horseshoe crab effect model) were the most weakly supported.

Knotted optical vortices in exact solutions to Maxwell's equations

NASA Astrophysics Data System (ADS)

de Klerk, Albertus J. J. M.; van der Veen, Roland I.; Dalhuisen, Jan Willem; Bouwmeester, Dirk

2017-05-01

We construct a family of exact solutions to Maxwell's equations in which the points of zero intensity form knotted lines topologically equivalent to a given but arbitrary algebraic link. These lines of zero intensity, more commonly referred to as optical vortices, and their topology are preserved as time evolves and the fields have finite energy. To derive explicit expressions for these new electromagnetic fields that satisfy the nullness property, we make use of the Bateman variables for the Hopf field as well as complex polynomials in two variables whose zero sets give rise to algebraic links. The class of algebraic links includes not only all torus knots and links thereof, but also more intricate cable knots. While the unknot has been considered before, the solutions presented here show that more general knotted structures can also arise as optical vortices in exact solutions to Maxwell's equations.

B-spline parameterization of the dielectric function and information criteria: the craft of non-overfitting

NASA Astrophysics Data System (ADS)

Likhachev, Dmitriy V.

2017-06-01

Johs and Hale developed the Kramers-Kronig consistent B-spline formulation for the dielectric function modeling in spectroscopic ellipsometry data analysis. In this article we use popular Akaike, corrected Akaike and Bayesian Information Criteria (AIC, AICc and BIC, respectively) to determine an optimal number of knots for B-spline model. These criteria allow finding a compromise between under- and overfitting of experimental data since they penalize for increasing number of knots and select representation which achieves the best fit with minimal number of knots. Proposed approach provides objective and practical guidance, as opposite to empirically driven or "gut feeling" decisions, for selecting the right number of knots for B-spline models in spectroscopic ellipsometry. AIC, AICc and BIC selection criteria work remarkably well as we demonstrated in several real-data applications. This approach formalizes selection of the optimal knot number and may be useful in practical perspective of spectroscopic ellipsometry data analysis.

The Butterfly diagram leopard skin pattern

NASA Astrophysics Data System (ADS)

Ternullo, Maurizio

2011-08-01

A time-latitude diagram where spotgroups are given proportional relevance to their area is presented. The diagram reveals that the spotted area distribution is higly dishomogeneous, most of it being concentrated in few, small portions (``knots'') of the Butterfly Diagram; because of this structure, the BD may be properly described as a cluster of knots. The description, assuming that spots scatter around the ``spot mean latitude'' steadily drifting equatorward, is challenged. Indeed, spots cluster around at as many latitudes as knots; a knot may appear at either lower or higher latitudes than previous ones, in a seemingly random way; accordingly, the spot mean latitude abruptly drifts equatorward or even poleward at any knot activation, in spite of any smoothing procedure. Preliminary analyses suggest that the activity splits, in any hemisphere, into two or more distinct ``activity waves'', drifting equatorward at a rate higher than the spot zone as a whole.

Harmonic field in knotted space

NASA Astrophysics Data System (ADS)

Duan, Xiuqing; Yao, Zhenwei

2018-04-01

Knotted fields enrich a variety of physical phenomena, ranging from fluid flows, electromagnetic fields, to textures of ordered media. Maxwell's electrostatic equations, whose vacuum solution is mathematically known as a harmonic field, provide an ideal setting to explore the role of domain topology in determining physical fields in confined space. In this work, we show the uniqueness of a harmonic field in knotted tubes, and reduce the construction of a harmonic field to a Neumann boundary value problem. By analyzing the harmonic field in typical knotted tubes, we identify the torsion driven transition from bipolar to vortex patterns. We also analogously extend our discussion to the organization of liquid crystal textures in knotted tubes. These results further our understanding about the general role of topology in shaping a physical field in confined space, and may find applications in the control of physical fields by manipulation of surface topology.

State of the evidence on simulation-based training for laparoscopic surgery: a systematic review.

PubMed

Zendejas, Benjamin; Brydges, Ryan; Hamstra, Stanley J; Cook, David A

2013-04-01

Summarize the outcomes and best practices of simulation training for laparoscopic surgery. Simulation-based training for laparoscopic surgery has become a mainstay of surgical training. Much new evidence has accrued since previous reviews were published. We systematically searched the literature through May 2011 for studies evaluating simulation, in comparison with no intervention or an alternate training activity, for training health professionals in laparoscopic surgery. Outcomes were classified as satisfaction, skills (in a test setting) of time (to perform the task), process (eg, performance rating), product (eg, knot strength), and behaviors when caring for patients. We used random effects to pool effect sizes. From 10,903 articles screened, we identified 219 eligible studies enrolling 7138 trainees, including 91 (42%) randomized trials. For comparisons with no intervention (n = 151 studies), pooled effect size (ES) favored simulation for outcomes of knowledge (1.18; N = 9 studies), skills time (1.13; N = 89), skills process (1.23; N = 114), skills product (1.09; N = 7), behavior time (1.15; N = 7), behavior process (1.22; N = 15), and patient effects (1.28; N = 1), all P < 0.05. When compared with nonsimulation instruction (n = 3 studies), results significantly favored simulation for outcomes of skills time (ES, 0.75) and skills process (ES, 0.54). Comparisons between different simulation interventions (n = 79 studies) clarified best practices. For example, in comparison with virtual reality, box trainers have similar effects for process skills outcomes and seem to be superior for outcomes of satisfaction and skills time. Simulation-based laparoscopic surgery training of health professionals has large benefits when compared with no intervention and is moderately more effective than nonsimulation instruction.

Stepfamily Communication Strengths: Understanding the Ties That Bind.

ERIC Educational Resources Information Center

Golish, Tamara D.

2003-01-01

Examines the communication strategies that differentiate "strong" stepfamilies from stepfamilies having more difficulty, inductively deriving a composite of stepfamily "communication strengths." Finds that in general, strong stepfamilies reported using everyday talk, more openness, spending time together as a family, communicating clear rules and…

Key Principles of Open Motor-Skill Training for Peak Performance

ERIC Educational Resources Information Center

Wang, Jin

2016-01-01

Motor-skill training is an imperative element contributing to overall sport performance. In order to help coaches, athletes and practitioners to capture the characteristics of motor skills, sport scientists have divided motor skills into different categories, such as open versus closed, serial or discrete, outcome- or process-oriented, and…

HOMFLYPT polynomial is the best quantifier for topological cascades of vortex knots

NASA Astrophysics Data System (ADS)

Ricca, Renzo L.; Liu, Xin

2018-02-01

In this paper we derive and compare numerical sequences obtained by adapted polynomials such as HOMFLYPT, Jones and Alexander-Conway for the topological cascade of vortex torus knots and links that progressively untie by a single reconnection event at a time. Two cases are considered: the alternate sequence of knots and co-oriented links (with positive crossings) and the sequence of two-component links with oppositely oriented components (negative crossings). New recurrence equations are derived and sequences of numerical values are computed. In all cases the adapted HOMFLYPT polynomial proves to be the best quantifier for the topological cascade of torus knots and links.

Full scale wind tunnel investigation of a bearingless main helicopter rotor. [Ames 40 by 80 foot wind tunnel test using the BO-105 helicopter

NASA Technical Reports Server (NTRS)

1980-01-01

A stability test program was conducted to determine the effects of airspeed, collective pitch, rotor speed and shaft angle on stability and loads at speeds beyond that attained in the BMR/BO-105 flight test program. Loads and performance data were gathered at forward speeds up to 165 knots. The effect of cyclic pitch perturbations on rotor response was investigated at simulated level flight conditions. Two configuration variations were tested for their effect on stability. One variable was the control system stiffness. An axially softer pitch link was installed in place of the standard BO-105 pitch link. The second variation was the addition of elastomeric damper strips to increase the structural damping. The BMR was stable at all conditions tested. At fixed collective pitch, shaft angle and rotor speed, damping generally increased between hover and 60 knots, remained relatively constant from 60 to 90 knots, then decreased above 90 knots. Analytical predictions are in good agreement with test data up to 90 knots, but the trend of decreasing damping above 90 knots is contrary to the theory.

Hurricane Darby off the Pacific Coast of Mexico

NASA Image and Video Library

2004-07-26

Hurricane Darby as observed by the Atmospheric Infrared Sounder AIRS onboard NASA Aqua in July, 2004. This daylight image of Hurricane Darby on July 28 was made with the visible sensor in the AIRS instrument suite. After reaching sustained winds on July 27 of 100 knots (115 mph) with gusts to 120 knots (138 mph), the intensity of the storm is now lowered to 75 knots (86 mph). Located in the eastern north Pacific Ocean located about 1,165 miles west-southwest of the southern tip of Baja California, the storm continues its west/northwest path at 14 knots (16mph). Figure 1 is a daylight snapshot from AIRS visible/near-infrared sensor before Darby became a tropical storm. Darby is in the upper right-hand corner. Circulation is not apparent because the storm was not organized sufficiently to allow the nascent eye to appear. At this time, winds were approximately 35 mph. Figure 2 is an AIRS infrared image. Darby falls on the edge of two AIRS data granules, which have been "stitched" together in this image. Storm intensity is lowered to 75 knots (86 mph), down from 100 knots (115 mph). http://photojournal.jpl.nasa.gov/catalog/PIA00439

Freely Expanding Knots of X-Ray-emitting Ejecta in Kepler’s Supernova Remnant

NASA Astrophysics Data System (ADS)

Sato, Toshiki; Hughes, John P.

2017-08-01

We report measurements of proper motion, radial velocity, and elemental composition for 14 compact X-ray-bright knots in Kepler’s supernova remnant (SNR) using archival Chandra data. The knots with the highest speed show both large proper motions (μ ˜ 0.″11-0.″14 yr-1) and high radial velocities (v ˜ 8700-10,020 km s-1). For these knots the estimated space velocities (9100 km s-1 ≲ v 3D ≲ 10,400 km s-1) are similar to the typical Si velocity seen in supernovae (SNe) Ia near maximum light. High-speed ejecta knots appear only in specific locations and are morphologically and kinematically distinct from the rest of the ejecta. The proper motions of five knots extrapolate back over the age of Kepler’s SNR to a consistent central position. This new kinematic center agrees well with previous determinations, but is less subject to systematic errors and denotes a location about which several prominent structures in the remnant display a high degree of symmetry. These five knots are expanding at close to the free expansion rate (expansion indices of 0.75 ≲ m ≲ 1.0), which we argue indicates either that they were formed in the explosion with a high density contrast (more than 100 times the ambient density) or that they have propagated through regions of relatively low density (n H < 0.1 cm-3) in the ambient medium. X-ray spectral analysis shows that the undecelerated knots have high Si and S abundances, a lower Fe abundance, and very low O abundance, pointing to an origin in the partial Si-burning zone, which occurs in the outer layer of the exploding white dwarf for models of SNe Ia. Other knots show lower speeds and expansion indices consistent with decelerated ejecta knots or features in the ambient medium overrun by the forward shock. Our new accurate location for the explosion site has well-defined positional uncertainties, allowing for a great reduction in the area to be searched for faint surviving donor stars under non-traditional single-degenerate SNe Ia scenarios; because of the lack of bright stars in the search area the traditional scenario remains ruled out.

Freely Expanding Knots of X-Ray-emitting Ejecta in Kepler’s Supernova Remnant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sato, Toshiki; Hughes, John P., E-mail: toshiki@astro.isas.jaxa.jp, E-mail: jph@physics.rutgers.edu

We report measurements of proper motion, radial velocity, and elemental composition for 14 compact X-ray-bright knots in Kepler’s supernova remnant (SNR) using archival Chandra data. The knots with the highest speed show both large proper motions ( μ ∼ 0.″11–0.″14 yr{sup −1}) and high radial velocities ( v ∼ 8700–10,020 km s{sup −1}). For these knots the estimated space velocities (9100 km s{sup −1} ≲ v {sub 3D} ≲ 10,400 km s{sup −1}) are similar to the typical Si velocity seen in supernovae (SNe) Ia near maximum light. High-speed ejecta knots appear only in specific locations and are morphologically andmore » kinematically distinct from the rest of the ejecta. The proper motions of five knots extrapolate back over the age of Kepler’s SNR to a consistent central position. This new kinematic center agrees well with previous determinations, but is less subject to systematic errors and denotes a location about which several prominent structures in the remnant display a high degree of symmetry. These five knots are expanding at close to the free expansion rate (expansion indices of 0.75 ≲ m ≲ 1.0), which we argue indicates either that they were formed in the explosion with a high density contrast (more than 100 times the ambient density) or that they have propagated through regions of relatively low density ( n {sub H} < 0.1 cm{sup −3}) in the ambient medium. X-ray spectral analysis shows that the undecelerated knots have high Si and S abundances, a lower Fe abundance, and very low O abundance, pointing to an origin in the partial Si-burning zone, which occurs in the outer layer of the exploding white dwarf for models of SNe Ia. Other knots show lower speeds and expansion indices consistent with decelerated ejecta knots or features in the ambient medium overrun by the forward shock. Our new accurate location for the explosion site has well-defined positional uncertainties, allowing for a great reduction in the area to be searched for faint surviving donor stars under non-traditional single-degenerate SNe Ia scenarios; because of the lack of bright stars in the search area the traditional scenario remains ruled out.« less

On the universality of knot probability ratios

NASA Astrophysics Data System (ADS)

Janse van Rensburg, E. J.; Rechnitzer, A.

2011-04-01

Let pn denote the number of self-avoiding polygons of length n on a regular three-dimensional lattice, and let pn(K) be the number which have knot type K. The probability that a random polygon of length n has knot type K is pn(K)/pn and is known to decay exponentially with length (Sumners and Whittington 1988 J. Phys. A: Math. Gen. 21 1689-94, Pippenger 1989 Discrete Appl. Math. 25 273-8). Little is known rigorously about the asymptotics of pn(K), but there is substantial numerical evidence (Orlandini et al 1988 J. Phys. A: Math. Gen. 31 5953-67, Marcone et al 2007 Phys. Rev. E 75 41105, Rawdon et al 2008 Macromolecules 41 4444-51, Janse van Rensburg and Rechnitzer 2008 J. Phys. A: Math. Theor. 41 105002) that pn(K) grows as p_n(K) \\simeq C_K \\mu _\\emptyset ^n n^{\\alpha -3+N_K}, \\qquad as\\quad n \\rightarrow \\infty, where NK is the number of prime components of the knot type K. It is believed that the entropic exponent, α, is universal, while the exponential growth rate, μ∅, is independent of the knot type but varies with the lattice. The amplitude, CK, depends on both the lattice and the knot type. The above asymptotic form implies that the relative probability of a random polygon of length n having prime knot type K over prime knot type L is \\frac{p_n(K)/p_n}{p_n(L)/p_n} = \\frac{p_n(K)}{p_n(L)} \\simeq \\left[ \\frac{C_K}{C_L} \\right].\\\\[-8pt] In the thermodynamic limit this probability ratio becomes an amplitude ratio; it should be universal and depend only on the knot types K and L. In this communication we examine the universality of these probability ratios for polygons in the simple cubic, face-centred cubic and body-centred cubic lattices. Our results support the hypothesis that these are universal quantities. For example, we estimate that a long random polygon is approximately 28 times more likely to be a trefoil than be a figure-eight, independent of the underlying lattice, giving an estimate of the intrinsic entropy associated with knot types in closed curves.

Motivational state, reward value, and Pavlovian cues differentially affect skilled forelimb grasping in rats

PubMed Central

de Clauser, Larissa; Kasper, Hansjörg; Schwab, Martin E.

2016-01-01

Motor skills represent high-precision movements performed at optimal speed and accuracy. Such motor skills are learned with practice over time. Besides practice, effects of motivation have also been shown to influence speed and accuracy of movements, suggesting that fast movements are performed to maximize gained reward over time as noted in previous studies. In rodents, skilled motor performance has been successfully modeled with the skilled grasping task, in which animals use their forepaw to grasp for sugar pellet rewards through a narrow window. Using sugar pellets, the skilled grasping task is inherently tied to motivation processes. In the present study, we performed three experiments modulating animals’ motivation during skilled grasping by changing the motivational state, presenting different reward value ratios, and displaying Pavlovian stimuli. We found in all three studies that motivation affected the speed of skilled grasping movements, with the strongest effects seen due to motivational state and reward value. Furthermore, accuracy of the movement, measured in success rate, showed a strong dependence on motivational state as well. Pavlovian cues had only minor effects on skilled grasping, but results indicate an inverse Pavlovian-instrumental transfer effect on movement speed. These findings have broad implications considering the increasing use of skilled grasping in studies of motor system structure, function, and recovery after injuries. PMID:27194796

The influence of ship motion of manual control skills

NASA Technical Reports Server (NTRS)

Mcleod, P.; Poulton, C.; Duross, H.; Lewis, W.

1981-01-01

The effects of ship motion on a range of typical manual control skills were examined on the Warren Spring ship motion simulator driven in heave, pitch, and roll by signals taken from the frigate HMS Avenger at 13 m/s (25 knots) into a force 4 wind. The motion produced a vertical r.m.s. acceleration of 0.024g, mostly between 0.1 and 0.3 Hz, with comparatively little pitch or roll. A task involving unsupported arm movements was seriously affected by the motion; a pursuit tracking task showed a reliable decrement although it was still performed reasonably well (pressure and free moving tracking controls were affected equally by the motion); a digit keying task requiring ballistic hand movements was unaffected. There was no evidence that these effects were caused by sea sickness. The differing response to motion of the different tasks, from virtual destruction to no effect, suggests that a major benefit could come from an attempt to design the man/control interface onboard ship around motion resistant tasks.

A Guide for Industrial Mobilization

DTIC Science & Technology

1989-03-01

packages; and cient, increased production controls may be needed. These actions include: i. Releasing machine tool trigger or- ders and increasing buys...710). the Department of Defense to maintain facili- 4. The National Defense Act authorizes: ties, machine tools , production equipment, and skilled...Defense Industrial Reserve Act pro- Room 3876, U.S. Departm nt of Commerce vides for the reserve of machine tools and other Washington, D.C. 20230 or

The Development of Real-Time Stability Supports Visual Working Memory Performance: Young Children's Feature Binding Can Be Improved through Perceptual Structure

ERIC Educational Resources Information Center

Simmering, Vanessa R.; Wood, Chelsey M.

2017-01-01

Working memory is a basic cognitive process that predicts higher-level skills. A central question in theories of working memory development is the generality of the mechanisms proposed to explain improvements in performance. Prior theories have been closely tied to particular tasks and/or age groups, limiting their generalizability. The cognitive…

Hurricane Odile

NASA Image and Video Library

2017-12-08

At about 10:45 p.m. Mountain Daylight Time (MDT) on September 14, 2014, Hurricane Odile made landfall as a Category 3 storm near Cabo San Lucas, Mexico. According to the U.S. National Hurricane Center, Odile arrived with wind speeds of 110 knots (204 kilometers or 127 miles per hour). The storm tied Olivia (1967) as the strongest hurricane to make landfall in the state of Baja California Sur in the satellite era. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired this natural-color view of the storm at about noon MDT on September 14, when it was still southeast of the Baja California peninsula. Unisys Weather reported that the Category 4 storm had maximum sustained wind speeds of 115 knots (213 kilometers per hour) at the time. Odile had weakened to a Category 2 hurricane by 6 a.m. MDT on September 15. The storm was expected to continue weakening as it moved up the peninsula and over the area’s rough terrain, according to weather blogger Jeff Masters. Meteorologists noted that while damaging winds posed the biggest threat in the short term, inland areas of the U.S. Southwest could face heavy rainfall by September 16. The rain expected from Odile came one week after the U.S. Southwest experienced flash floods from the remnants of Hurricane Norbert. According to weather and climate blogger Eric Holthaus, those floods did little to relieve the area’s ongoing drought. NASA image by Jeff Schmaltz, LANCE/EOSDIS Rapid Response. Caption by Kathryn Hansen. Instrument(s): Terra - MODIS Read more: earthobservatory.nasa.gov/IOTD/view.php?id=84378&eocn... NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

A summary of modulus of elasticity and knot size surveys for laminating grades of lumber

Treesearch

R. W. Wolfe; R. C. Moody

1981-01-01

A summary of modulus of elasticity (MOE) and knot data is presented for grades of lumber commonly used to manufacture glued-laminated (glulam) timber by the laminating Industry. Tabulated values represent 30 different studies covering a time span of over 16 years. Statistical estimates of average and near-maximum knot sizes as well as mean and coefficient of variation...

33 CFR 165.510 - Delaware Bay and River, Salem River, Christina River and Schuylkill River-Regulated Navigation Area.

Code of Federal Regulations, 2010 CFR

2010-07-01

... within the regulated navigation area and: (i) Sustained winds are greater than 25 knots but less than 40 knots, ensure the main engines are ready to provide full power in five minutes or less; and (ii) Sustained winds are 40 knots or over, ensure that the main engines are on line to immediately provide...

Using more of what trees provide - why not knots?

Treesearch

Matthew Bumgardner

2003-01-01

We are all familiar with furniture and paneling made from "knotty" pine. In fact, we expect pine to be knotty and such knots add a certain degree of warmness and authenticity. But have you ever wondered why there isn't more knotty oak furniture! Or knotty cherry cabinets? The fact is that most knot distortions and visual defects such as color streaks and...

Models of knot and stem development in black spruce trees indicate a shift in allocation priority to branches when growth is limited

PubMed Central

Duchateau, Emmanuel; Auty, David; Mothe, Frédéric; Longuetaud, Fleur; Ung, Chhun Huor

2015-01-01

The branch autonomy principle, which states that the growth of individual branches can be predicted from their morphology and position in the forest canopy irrespective of the characteristics of the tree, has been used to simplify models of branch growth in trees. However, observed changes in allocation priority within trees towards branches growing in light-favoured conditions, referred to as ‘Milton’s Law of resource availability and allocation,’ have raised questions about the applicability of the branch autonomy principle. We present models linking knot ontogeny to the secondary growth of the main stem in black spruce (Picea mariana (Mill.) B.S.P.), which were used to assess the patterns of assimilate allocation over time, both within and between trees. Data describing the annual radial growth of 445 stem rings and the three-dimensional shape of 5,377 knots were extracted from optical scans and X-ray computed tomography images taken along the stems of 10 trees. Total knot to stem area increment ratios (KSR) were calculated for each year of growth, and statistical models were developed to describe the annual development of knot diameter and curvature as a function of stem radial increment, total tree height, stem diameter, and the position of knots along an annual growth unit. KSR varied as a function of tree age and of the height to diameter ratio of the stem, a variable indicative of the competitive status of the tree. Simulations of the development of an individual knot showed that an increase in the stem radial growth rate was associated with an increase in the initial growth of the knot, but also with a shorter lifespan. Our results provide support for ‘Milton’s Law,’ since they indicate that allocation priority is given to locations where the potential return is the highest. The developed models provided realistic simulations of knot morphology within trees, which could be integrated into a functional-structural model of tree growth and above-ground resource partitioning. PMID:25870769

Potential of Leguminous Cover Crops in Management of a Mixed Population of Root-knot Nematodes (Meloidogyne spp.)

PubMed Central

Osei, Kingsley; Gowen, Simon R.; Pembroke, Barbara; Brandenburg, Rick L.; Jordan, David L.

2010-01-01

Root-knot nematode is an important pest in agricultural production worldwide. Crop rotation is the only management strategy in some production systems, especially for resource poor farmers in developing countries. A series of experiments was conducted in the laboratory with several leguminous cover crops to investigate their potential for managing a mixture of root-knot nematodes (Meloidogyne arenaria, M. incognita, M. javanica). The root-knot nematode mixture failed to multiply on Mucuna pruriens and Crotalaria spectabilis but on Dolichos lablab the population increased more than 2- fold when inoculated with 500 and 1,000 nematodes per plant. There was no root-galling on M. pruriens and C. spectabilis but the gall rating was noted on D. lablab. Greater mortality of juvenile root-knot nematodes occurred when exposed to eluants of roots and leaves of leguminous crops than those of tomato; 48.7% of juveniles died after 72 h exposure to root eluant of C. spectabilis. The leaf eluant of D. lablab was toxic to nematodes but the root eluant was not. Thus, different parts of a botanical contain different active ingredients or different concentrations of the same active ingredient. The numbers of root-knot nematode eggs that hatched in root exudates of M. pruriens and C. spectabilis were significantly lower (20% and 26%) than in distilled water, tomato and P. vulgaris root exudates (83%, 72% and 89%) respectively. Tomato lacks nematotoxic compounds found in M. pruriens and C. spectabilis. Three months after inoculating plants with 1,000 root-knot nematode juveniles the populations in pots with M. pruriens, C. spectabilis and C. retusa had been reduced by approximately 79%, 85% and 86% respectively; compared with an increase of 262% nematodes in pots with Phaseolus vulgaris. There was significant reduction of 90% nematodes in fallow pots with no growing plant. The results from this study demonstrate that some leguminous species contain compounds that either kill root-knot nematodes or interfere with hatching and affect their capacity to invade and develop within their roots. M. pruriens, C. spectabilis and C. retusa could be used with effect to decrease a mixed field populations of root-knot nematodes. PMID:22736854

Models of knot and stem development in black spruce trees indicate a shift in allocation priority to branches when growth is limited.

PubMed

Duchateau, Emmanuel; Auty, David; Mothe, Frédéric; Longuetaud, Fleur; Ung, Chhun Huor; Achim, Alexis

2015-01-01

The branch autonomy principle, which states that the growth of individual branches can be predicted from their morphology and position in the forest canopy irrespective of the characteristics of the tree, has been used to simplify models of branch growth in trees. However, observed changes in allocation priority within trees towards branches growing in light-favoured conditions, referred to as 'Milton's Law of resource availability and allocation,' have raised questions about the applicability of the branch autonomy principle. We present models linking knot ontogeny to the secondary growth of the main stem in black spruce (Picea mariana (Mill.) B.S.P.), which were used to assess the patterns of assimilate allocation over time, both within and between trees. Data describing the annual radial growth of 445 stem rings and the three-dimensional shape of 5,377 knots were extracted from optical scans and X-ray computed tomography images taken along the stems of 10 trees. Total knot to stem area increment ratios (KSR) were calculated for each year of growth, and statistical models were developed to describe the annual development of knot diameter and curvature as a function of stem radial increment, total tree height, stem diameter, and the position of knots along an annual growth unit. KSR varied as a function of tree age and of the height to diameter ratio of the stem, a variable indicative of the competitive status of the tree. Simulations of the development of an individual knot showed that an increase in the stem radial growth rate was associated with an increase in the initial growth of the knot, but also with a shorter lifespan. Our results provide support for 'Milton's Law,' since they indicate that allocation priority is given to locations where the potential return is the highest. The developed models provided realistic simulations of knot morphology within trees, which could be integrated into a functional-structural model of tree growth and above-ground resource partitioning.

Pinus pinaster Knot: A Source of Polyphenols against Plasmopara viticola.

PubMed

Gabaston, Julien; Richard, Tristan; Cluzet, Stéphanie; Palos Pinto, Antonio; Dufour, Marie-Cécile; Corio-Costet, Marie-France; Mérillon, Jean-Michel

2017-10-11

Pine knot extract from Pinus pinaster byproducts was characterized by UHPLC-DAD-MS and NMR. Fourteen polyphenols divided into four classes were identified as follows: lignans (nortrachelogenin, pinoresinol, matairesinol, isolariciresinol, secoisolariciresinol), flavonoids (pinocembrin, pinobanksin, dihydrokaempferol, taxifolin), stilbenes (pinosylvin, pinosylvin monomethyl ether, pterostilbene), and phenolic acids (caffeic acid, ferulic acid). The antifungal potential of pine knot extract, as well as the main compounds, was tested in vitro against Plasmopara viticola. The ethanolic extract showed a strong antimildew activity. In addition, pinosylvins and pinocembrin demonstrated significant inhibition of zoospore mobility and mildew development. These findings strongly suggest that pine knot is a potential biomass that could be used as a natural antifungal product.

Rare complication of appendix: small bowel gangrene caused by the appendicular knot.

PubMed

Mohana, R T; Zainal, A A

2017-12-01

Intestinal knot formation was first described by Riverius in 16th century and later by Rokitansky in 1836. We report a very rare cause of small bowel gangrene caused by appendiceal knotting on to the ileum in a previously healthy mid aged lady. Patient underwent laparatomy and right hemicolectomy and primary anastomosis. The intra operative findings were the appendix was twisting (knotting) the small bowel about 40cm from the terminal ileum and causing gangrene to the segment of small bowel. Appendicitis is a common condition and management is usually straightforward. However we must be aware of rare complications which may arise that require a change from the standard treatment of acute appendicitis.

The North Texas aerospace manufacturing and aviation industries: An explanatory case study of school-to-work collaborative networks

NASA Astrophysics Data System (ADS)

Miller, Cynthia Ann

The purpose of this study is to explore how educators, business partners and facilitators developed ties or networks to initiate a school-to-work collaboration to prepare students for jobs and careers in the aerospace manufacturing and aviation industries. There is growing concern about preparing a future workforce supply in these industries in North Texas. Workforce projections call for 8000 additional jobs between 2010 and 2020 (North Central Texas Council of Governments, 2013). Collaboration is recognized as a valuable asset to connect disjointed segments within the K-16 trajectory. This study explores the contradiction between the stated need for collaborative strategies and the inability of stakeholders attempting to collaborate across organizational and institutional boundaries to sustain these connections. Through the lens of networking theory, the roles of facilitators and the operation of networks and ties between and among partners are investigated. Ten participants in a high school curriculum development project were interviewed, representing a business, community college, and K-12 education. Data analysis revealed findings associated with three major themes: facilitation, project activity and relationships. Nine individuals were identified as facilitators, and facilitators were perceived as helping the project move forward. Project activity benefited from the structured curriculum development process. Although relationships characterized by strong ties helped start the project, weak ties predominated among project participants. Implications for theory include the need for more knowledge about facilitator roles and group dynamics. Further research about the functioning of weak and strong ties and facilitator skill sets relating to collaborative leadership would be valuable. Implications for practice include capturing lessons learned to apply to other industries, and overtly acknowledging the existence and importance of facilitators.

Systematic review of laparoscopic surgery in low- and middle-income countries: benefits, challenges, and strategies.

PubMed

Chao, Tiffany E; Mandigo, Morgan; Opoku-Anane, Jessica; Maine, Rebecca

2016-01-01

Laparoscopy may prove feasible to address surgical needs in limited-resource settings. However, no aggregate data exist regarding the role of laparoscopy in low- and middle-income countries (LMICs). This study was designed to describe the issues facing laparoscopy in LMICs and to aggregate reported solutions. A search was conducted using Medline, African Index Medicus, the Directory of Open Access Journals, and the LILACS/BIREME/SCIELO database. Included studies were in English, published after 1992, and reported safety, cost, or outcomes of laparoscopy in LMICs. Studies pertaining to arthroscopy, ENT, flexible endoscopy, hysteroscopy, cystoscopy, computer-assisted surgery, pediatrics, transplantation, and bariatrics were excluded. Qualitative synthesis was performed by extracting results that fell into three categories: advantages of, challenges to, and adaptations made to implement laparoscopy in LMICs. PRISMA guidelines for systematic reviews were followed. A total of 1101 abstracts were reviewed, and 58 articles were included describing laparoscopy in 25 LMICs. Laparoscopy is particularly advantageous in LMICs, where there is often poor sanitation, limited diagnostic imaging, fewer hospital beds, higher rates of hemorrhage, rising rates of trauma, and single income households. Lack of trained personnel and equipment were frequently cited challenges. Adaptive strategies included mechanical insufflation with room air, syringe suction, homemade endoloops, hand-assisted techniques, extracorporeal knot tying, innovative use of cheaper instruments, and reuse of disposable instruments. Inexpensive laboratory-based trainers and telemedicine are effective for training. LMICs face many surgical challenges that require innovation. Laparoscopic surgery may be safe, effective, feasible, and cost-effective in LMICs, although it often remains limited in its accessibility, acceptability, and quality. This study may not capture articles written in languages other than English or in journals not indexed by the included databases. Surgeons, policymakers, and manufacturers should focus on plans for sustainability, training and retention of providers, and regulation of efforts to develop laparoscopy in LMICs.

A new suturing instrument that allows the use of microsuture at laparoscopy.

PubMed

McComb, P F

1992-04-01

A surgeon at University Hospital-Shaughnessy Site in Vancouver, British Columbia in Canada has used a new suturing instrument that enters the peritoneal cavity to permit microsutures of size 6-0 or less and 75 cm in length during laparoscopy. Surgeons can use this instrument to perform female sterilizations as well as removal of the gall gladder and appendix and repair of the bowel, bladder, and ureteric injuries. As of April 1992, the suturing instrument was not yet commercially available. It consists of a partial hollow 30 cm x 2 mm (inside diameter) tube with the end that does not enter the peritoneal cavity being occluded. The suturing instrument enters the peritoneal cavity via a standard 5 mm deflection valved trocar sleeve with a 3 mm reduction sleeve or with a 3 mm inside diameter occlusive rubber washer instead of the standard 5 mm washer. The suture must have sufficient tensile strength and have low coefficients for static and for sliding surface frictions. Once the suture and needle are inside the body, forceps which have entered via another cannula detach them from the suturing instrument. A 3 mm laproscopic needle driver replaces the suturing instrument at this point. The surgeon guides the needle through the intended tissues and then withdrawn with the needle driver through the 5 mm sleeve. The surgeon ties the knot outside the body and slides it down the length of the suture to apply it to the tissue. He/she repeats this 1 more time. Scissors inserted through the other opening then cut the suture. Once mastered, this process takes only a few minutes to complete. In all 11 cases or restoration of uterine tube patency done by the surgeon in Vancouver using the new technique, tubal patency has not been hindered. 2 assessed sterilization reversals have been successful.

Universal properties of knotted polymer rings.

PubMed

Baiesi, M; Orlandini, E

2012-09-01

By performing Monte Carlo sampling of N-steps self-avoiding polygons embedded on different Bravais lattices we explore the robustness of universality in the entropic, metric, and geometrical properties of knotted polymer rings. In particular, by simulating polygons with N up to 10(5) we furnish a sharp estimate of the asymptotic values of the knot probability ratios and show their independence on the lattice type. This universal feature was previously suggested, although with different estimates of the asymptotic values. In addition, we show that the scaling behavior of the mean-squared radius of gyration of polygons depends on their knot type only through its correction to scaling. Finally, as a measure of the geometrical self-entanglement of the self-avoiding polygons we consider the standard deviation of the writhe distribution and estimate its power-law behavior in the large N limit. The estimates of the power exponent do depend neither on the lattice nor on the knot type, strongly supporting an extension of the universality property to some features of the geometrical entanglement.

The mutual attraction of magnetic knots. [solar hydromagnetic instability in sunspot regions

NASA Technical Reports Server (NTRS)

Parker, E. N.

1978-01-01

It is observed that the magnetic knots associated with active regions on the sun have an attraction for each other during the formative period of the active regions, when new magnetic flux is coming to the surface. The attraction disappears when new flux ceases to rise through the surface. Then the magnetic spots and knots tend to come apart, leading to disintegration of the sunspots previously formed. The dissolution of the fields is to be expected, as a consequence of the magnetic repulsion of knots of like polarity and as a consequence of the hydromagnetic exchange instability. The purpose of this paper is to show that the mutual attraction of knots during the formative stages of a sunspot region may be understood as the mutual hydrodynamic attraction of the rising flux tubes. Two rising tubes attract each other, as a consequence of the wake of the leading tube when one is moving behind the other, and as a consequence of the Bernoulli effect when rising side by side.

14 CFR Appendix G to Part 36 - Takeoff Noise Requirements for Propeller-Driven Small Airplane and Propeller-Driven, Commuter...

Code of Federal Regulations, 2012 CFR

2012-01-01

... aircraft noise when the wind speed is in excess of 5 knots (9 km/hr). Sec. G36.107Noise Measurement... OF TRANSPORTATION AIRCRAFT NOISE STANDARDS: AIRCRAFT TYPE AND AIRWORTHINESS CERTIFICATION Pt. 36, App..., inclusively; (4) Wind speed may not exceed 10 knots (19 km/h) and cross wind may not exceed 5 knots (9 km/h...

14 CFR Appendix G to Part 36 - Takeoff Noise Requirements for Propeller-Driven Small Airplane and Propeller-Driven, Commuter...

Code of Federal Regulations, 2013 CFR

2013-01-01

... aircraft noise when the wind speed is in excess of 5 knots (9 km/hr). Sec. G36.107Noise Measurement... OF TRANSPORTATION AIRCRAFT NOISE STANDARDS: AIRCRAFT TYPE AND AIRWORTHINESS CERTIFICATION Pt. 36, App..., inclusively; (4) Wind speed may not exceed 10 knots (19 km/h) and cross wind may not exceed 5 knots (9 km/h...

14 CFR 61.327 - How do I obtain privileges to operate a light-sport aircraft that has a VH greater than 87 knots...

Code of Federal Regulations, 2010 CFR

2010-01-01

... light-sport aircraft that has a VH greater than 87 knots CAS? 61.327 Section 61.327 Aeronautics and...: PILOTS, FLIGHT INSTRUCTORS, AND GROUND INSTRUCTORS Sport Pilots § 61.327 How do I obtain privileges to operate a light-sport aircraft that has a VH greater than 87 knots CAS? If you hold a sport pilot...

Multispecies modeling for adaptive management of horseshoe crabs and red knots in the Delaware Bay

USGS Publications Warehouse

McGowan, Conor P.; Smith, David; Sweka, John A.; Martin, Julien; Nichols, James D.; Wong, Richard; Lyons, James E.; Niles, Lawrence J.; Kalasz, Kevin; Brust, Jeffrey; Klopfer, Michelle; Spear, Braddock

2011-01-01

Adaptive management requires that predictive models be explicit and transparent to improve decisions by comparing management actions, directing further research and monitoring, and facilitating learning. The rufa subspecies of red knots (Calidris canutus rufa), which has recently exhibited steep population declines, relies on horseshoe crab (Limulus polyphemus) eggs as their primary food source during stopover in Delaware Bay during spring migration. We present a model with two different parameterizations for use in the adaptive management of horseshoe crab harvests in the Delaware Bay that links red knot mass gain, annual survival, and fecundity to horseshoe crab dynamics. The models reflect prevailing hypotheses regarding ecological links between these two species. When reported crab harvest from 1998 to 2008 was applied, projections corresponded to the observed red knot population abundances depending on strengths of the demographic relationship between these species. We compared different simulated horseshoe crab harvest strategies to evaluate whether, given this model, horseshoe crab harvest management can affect red knot conservation and found that restricting harvest can benefit red knot populations. Our model is the first to explicitly and quantitatively link these two species and will be used within an adaptive management framework to manage the Delaware Bay system and learn more about the specific nature of the linkage between the two species.

Coastal Fishermen as Lifesavers While Sailing at High Speed: A Crossover Study

PubMed Central

Fungueiriño-Suárez, Ramón; Martínez-Isasi, Santiago; Fernández-Méndez, Felipe; González-Salvado, Violeta; Navarro-Patón, Rubén; Rodríguez-Núñez, Antonio

2018-01-01

Purpose Starting basic cardiopulmonary resuscitation (CPR) early improves survival. Fishermen are the first bystanders while at work. Our objective was to test in a simulated scenario the CPR quality performed by fishermen while at port and while navigating at different speeds. Methods Twenty coastal fishermen were asked to perform 2 minutes of CPR (chest compressions and mouth-to-mouth ventilations) on a manikin, in three different scenarios: (A) at port on land, (B) on the boat floor sailing at 10 knots, and (C) sailing at 20 knots. Data was recorded using quality CPR software, adjusted to current CPR international guidelines. Results The quality of CPR (QCPR) was significantly higher at port (43% ± 10) than sailing at 10 knots (30% ± 15; p = 0.01) or at 20 knots (26% ± 12; p = 0.001). The percentage of ventilation that achieved some lung insufflation was also significantly higher when CPR was done at port (77% ± 14) than while sailing at 10 knots (59% ± 18) or 20 knots (57% ± 21) (p = 0.01). Conclusion In the event of drowning or cardiac arrest on a small boat, fishermen should immediately start basic CPR and navigate at a relatively high speed to the nearest port if the sea conditions are safe. PMID:29854735

DYNAMICS OF VERTICAL THREADS AND DESCENDING KNOTS IN A HEDGEROW PROMINENCE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chae, Jongchul

The existence and behavior of vertical fine structures of plasma-threads and knots-are a significant observational clue to understanding the magnetic structure and dynamics of quiescent prominences on the quiet Sun. Based on the equation of motion in ideal MHD, we reason that the non-hydrostatic support of plasma against gravity in general requires either the motion of plasma with a high value of downward acceleration (dynamical support) or the role of horizontal magnetic fields (magnetic support). By carefully tracking the motion of several bright threads seen in a hedgerow prominence observed by the Solar Optical Telescope aboard Hinode, we confirm thatmore » these threads are essentially static and stable, which negates the dynamic support. The application of the Kippenhahn-Schlueter solution suggests that they may be supported by sagged magnetic field lines with a sag angle of about 43{sup 0}. We also track several bright descending knots and find that their descending speeds range from 10 to 30 km s{sup -1}, with a mean value of 16 km s{sup -1}, and their vertical accelerations from -0.10 to 0.10 km s{sup -2}, with a mean of practically zero. This finding suggests that these knots are basically supported by horizontal magnetic fields against gravity even when they descend, and the complex variations of their descending speeds should be attributed to small imbalances between gravity and the force of magnetic tension. Furthermore, some knots are observed to impulsively get accelerated downward from time to time. We conjecture that these impulsive accelerations are a result of magnetic reconnection and the subsequent interchange of magnetic configuration between a knot and its surrounding structure. It is proposed that this process of reconnection and interchange not only initiates the descending motion of the knots, but also allows knots to keep falling long distance through the medium permeated by horizontal magnetic fields.« less

Skill complementarity enhances heterophily in collaboration networks

PubMed Central

Xie, Wen-Jie; Li, Ming-Xia; Jiang, Zhi-Qiang; Tan, Qun-Zhao; Podobnik, Boris; Zhou, Wei-Xing; Stanley, H. Eugene

2016-01-01

Much empirical evidence shows that individuals usually exhibit significant homophily in social networks. We demonstrate, however, skill complementarity enhances heterophily in the formation of collaboration networks, where people prefer to forge social ties with people who have professions different from their own. We construct a model to quantify the heterophily by assuming that individuals choose collaborators to maximize utility. Using a huge database of online societies, we find evidence of heterophily in collaboration networks. The results of model calibration confirm the presence of heterophily. Both empirical analysis and model calibration show that the heterophilous feature is persistent along the evolution of online societies. Furthermore, the degree of skill complementarity is positively correlated with their production output. Our work sheds new light on the scientific research utility of virtual worlds for studying human behaviors in complex socioeconomic systems. PMID:26743687

Development of Open-Ended Problems for Measuring The Higher-Order-Thinking-Skills of High School Students on Global Warming Phenomenon

NASA Astrophysics Data System (ADS)

Fianti; Najwa, F. L.; Linuwih, S.

2017-04-01

Higher-order-thinking-skills can not be developed directly, except by training which is employing open-ended problems for measuring and developing critics, creativeness, and problem-solving thinking-skills of students. This study is a research and development producing open-ended problems. The purpose of this study is to measure the properness and effectiveness of the developed product and to observe the profile of higher-order-thinking-skills of students on global warming phenomenon. The result of properness test of open-ended problems according to the experts is 92,59% on the first stage and 97,53% on the second stage, so we can assume that the product isvery proper. The result of effectiveness test shows the coefficient of correlation between student’s midterm test scores and open-ended questions is 0,634 which is in the category of strong. Higher-order-thinking-skills of SMA Negeri 1 Salatiga students is in the category of good with the average achievement scores 61,28.

Vividness and transformation of mental images in karate and ballet.

PubMed

Di Corrado, Donatella; Guarnera, Maria; Quartiroli, Alessandro

2014-12-01

While imagery research has become popular in recent years, little research has specifically investigated differences in imagery ability between open- and closed-skill sport activities. The purpose of this study was to investigate whether the type of task, open or closed, affects vividness and controllability differently. Thirty female classic dancers (closed skill), 30 female karate athletes (open skill), and 30 female non-athlete students, between 14 and 20 years of age (M = 17.0, SD = 1.6), participated. They completed the Vividness of Visual Imagery Questionnaire, the Vividness of Movement Imagery Questionnaire, and the Subtraction of Parts Task. There was no difference in imagery ability between open- and closed-skill sport groups. Furthermore, dancers and karatekas had higher mean scores on imagery ability than the non-athlete group. A positive correlation was observed between the two questionnaires, supporting findings on the componential basis of imagery. This study contributed to increase the research in the specific area of open- and closed-skill sports and imagery ability.

Extra-team connections for knowledge transfer between staff teams

PubMed Central

Ramanadhan, Shoba; Wiecha, Jean L.; Emmons, Karen M.; Gortmaker, Steven L.; Viswanath, Kasisomayajula

2009-01-01

As organizations implement novel health promotion programs across multiple sites, they face great challenges related to knowledge management. Staff social networks may be a useful medium for transferring program-related knowledge in multi-site implementation efforts. To study this potential, we focused on the role of extra-team connections (ties between staff members based in different site teams) as potential channels for knowledge sharing. Data come from a cross-sectional study of afterschool childcare staff implementing a health promotion program at 20 urban sites of the Young Men's Christian Association of Greater Boston. We conducted a sociometric social network analysis and attempted a census of 91 program staff members. We surveyed 80 individuals, and included 73 coordinators and general staff, who lead and support implementation, respectively, in this study. A multiple linear regression model demonstrated a positive relationship between extra-team connections (β = 3.41, P < 0.0001) and skill receipt, a measure of knowledge transfer. We also found that intra-team connections (within-team ties between staff members) were also positively related to skill receipt. Connections between teams appear to support knowledge transfer in this network, but likely require greater active facilitation, perhaps via organizational changes. Further research on extra-team connections and knowledge transfer in low-resource, high turnover environments is needed. PMID:19528313

Management matters.

PubMed

Gould, Rebecca A; Canter, Deborah

2008-11-01

Fewer than 50% of registered dietitians (RDs) supervise personnel and 76% have no budget authority. Because higher salaries are tied to increasing levels of authority and responsibility, RDs must seek management and leadership roles to enjoy the increased remuneration tied to such positions. Advanced-level practice in any area of dietetics demands powerful communication abilities, proficiency in budgeting and finance, comfort with technology, higher-order decision-making/problem-solving skills, and well-honed human resource management capabilities, all foundational to competent management practice. As RDs envision the future of the dietetics profession, practitioners must evaluate management competence in both hard and soft skills. Just as research is needed to support evidenced-based clinical practice, the same is needed to support management practice across the profession. Dietetics educators and preceptors should be as enthusiastic about management practice as they are clinical practice when educating and mentoring future professionals. Such encouragement and support can mean that new RDs and dietetic technicians, registered, will understand what it takes to advance to higher levels of responsibility, authority, and subsequent enhanced remuneration. In the ever-changing social, legal, ethical, political, economic, technological, and ecological environments of work, food and nutrition professionals who are willing to step forward and assume the risks and responsibilities of management also will share in the rewards, and propel the profession to new heights of recognition and respect.

BRST symmetry for a torus knot

NASA Astrophysics Data System (ADS)

Pandey, Vipul Kumar; Prasad Mandal, Bhabani

2017-08-01

We develop BRST symmetry for the first time for a particle on the surface of a torus knot by analyzing the constraints of the system. The theory contains 2nd-class constraints and has been extended by introducing the Wess-Zumino term to convert it into a theory with first-class constraints. BFV analysis of the extended theory is performed to construct BRST/anti-BRST symmetries for the particle on a torus knot. The nilpotent BRST/anti-BRST charges which generate such symmetries are constructed explicitly. The states annihilated by these nilpotent charges consist of the physical Hilbert space. We indicate how various effective theories on the surface of the torus knot are related through the generalized version of the BRST transformation with finite-field-dependent parameters.

Minimal access surgery of pediatric inguinal hernias: a review.

PubMed

Saranga Bharathi, Ramanathan; Arora, Manu; Baskaran, Vasudevan

2008-08-01

Inguinal hernia is a common problem among children, and herniotomy has been its standard of care. Laparoscopy, which gained a toehold initially in the management of pediatric inguinal hernia (PIH), has managed to steer world opinion against routine contralateral groin exploration by precise detection of contralateral patencies. Besides detection, its ability to repair simultaneously all forms of inguinal hernias (indirect, direct, combined, recurrent, and incarcerated) together with contralateral patencies has cemented its role as a viable alternative to conventional repair. Numerous minimally invasive techniques for addressing PIH have mushroomed in the past two decades. These techniques vary considerably in their approaches to the internal ring (intraperitoneal, extraperitoneal), use of ports (three, two, one), endoscopic instruments (two, one, or none), sutures (absorbable, nonabsorbable), and techniques of knotting (intracorporeal, extracorporeal). In addition to the surgeons' experience and the merits/limitations of individual techniques, it is the nature of the defect that should govern the choice of technique. The emerging techniques show a trend toward increasing use of extracorporeal knotting and diminishing use of working ports and endoscopic instruments. These favor wider adoption of minimal access surgery in addressing PIH by surgeons, irrespective of their laparoscopic skills and experience. Growing experience, wider adoption, decreasing complications, and increasing advantages favor emergence of minimal access surgery as the gold standard for the treatment of PIH in the future. This article comprehensively reviews the laparoscopic techniques of addressing PIH.

Strictly Business

ERIC Educational Resources Information Center

Stuart, Reginald

2011-01-01

When Jackson State University opened for classes this year, it marked its fifth anniversary in the online education business by adding a full four-year, undergraduate degree program in early childhood education to its offerings. Jackson State is among a growing number of historically Black colleges tying part of their future survival and growth…

Cancer Metastasis: Perivascular Macrophages Under Watch.

PubMed

Kadioglu, Ece; De Palma, Michele

2015-09-01

TIE2-expressing macrophages cluster around blood vessels and sustain tumor angiogenesis. Harney and colleagues now use live imaging of mouse mammary tumors to show that these perivascular macrophages also promote the transient opening of tumor blood vessels to facilitate hematogenous cancer cell dissemination and metastasis. ©2015 American Association for Cancer Research.

46 CFR 112.05-3 - Main-emergency bus-tie.

Code of Federal Regulations, 2010 CFR

2010-10-01

... emergency switchboard; (b) Be arranged to prevent parallel operation of an emergency power source with any other source of electric power, except for interlock systems for momentary transfer of loads; and (c) If arranged for feedback operation, open automatically upon overload of the emergency power source before the...

Why Save a Can?

ERIC Educational Resources Information Center

Gutierrez, Melida; Johnson, Cheryl

2009-01-01

This activity ties together the recycling of aluminum and the protection of rain forests. Students use critical thinking to study the effects of open pit mining of bauxite in rain forests and then draw their own conclusions about how to minimize the impact of bauxite mining and boost recycling efforts within their communities. Drawing conclusions…

Analysis of open loop higher harmonic control at high airspeeds on a modern four-bladed articulated rotor

NASA Technical Reports Server (NTRS)

Kottapalli, Sesi; Leyland, Jane

1991-01-01

The effects of open loop higher harmonic control (HHC) on rotor hub loads, performance, and push rod loads of a Sikorsky S-76 helicopter rotor at high airspeeds (up to 200 knots) and moderate lift (10,000 lbs) were studied analytically. The analysis was performed as part of a wind tunnel pre-test prediction and preparation procedure, as well as to provide analytical results for post-test correlation efforts. The test associated with this study is to be concluded in the 40- by 80-Foot Wind Tunnel of the National Full-Scale Aerodynamics Complex (NFAC) at the NASA Ames Research Center. The results from this analytical study show that benefits from HHC can be achieved at high airspeeds. These results clear the way for conducting (with the requirement of safe pushrod loads) an open loop HHC test a high airspeeds in the 40- by 80-Foot Wind Tunnel using an S-76 rotor as the test article.

CLIMLAB: a Python-based software toolkit for interactive, process-oriented climate modeling

NASA Astrophysics Data System (ADS)

Rose, B. E. J.

2015-12-01

Global climate is a complex emergent property of the rich interactions between simpler components of the climate system. We build scientific understanding of this system by breaking it down into component process models (e.g. radiation, large-scale dynamics, boundary layer turbulence), understanding each components, and putting them back together. Hands-on experience and freedom to tinker with climate models (whether simple or complex) is invaluable for building physical understanding. CLIMLAB is an open-ended software engine for interactive, process-oriented climate modeling. With CLIMLAB you can interactively mix and match model components, or combine simpler process models together into a more comprehensive model. It was created primarily to support classroom activities, using hands-on modeling to teach fundamentals of climate science at both undergraduate and graduate levels. CLIMLAB is written in Python and ties in with the rich ecosystem of open-source scientific Python tools for numerics and graphics. The IPython notebook format provides an elegant medium for distributing interactive example code. I will give an overview of the current capabilities of CLIMLAB, the curriculum we have developed thus far, and plans for the future. Using CLIMLAB requires some basic Python coding skills. We consider this an educational asset, as we are targeting upper-level undergraduates and Python is an increasingly important language in STEM fields. However CLIMLAB is well suited to be deployed as a computational back-end for a graphical gaming environment based on earth-system modeling.

Near-Infrared Spectroscopic Study of Supernova Ejecta and Supernova Dust in Cassiopeia A

NASA Astrophysics Data System (ADS)

Lee, Yong-Hyun; Koo, Bon-Chul; Moon, Dae-Sik; Lee, Jae-Joon; Burton, Michael G.

2016-06-01

We have carried out near-infrared (NIR) spectroscopic observations of the Cassiopeia A supernova (SN) remnant. We obtained medium-resolution, JHK (0.95 - 2.46 µm) spectra around the main ejecta shell. Using a clump-finding algorithm, we identified 63 'knots' in the two-dimensional dispersed images, and derived their spectroscopic properties. We first present the result of spectral classification of the knots using Principal Component (PC) Analysis. We found that the NIR spectral characteristics of the knots can be mostly (85%) represented by three PCs composed of different sets of emission lines: (1) recombination lines of H and He together with [N I] lines, (2) forbidden lines of Si, P, and S lines, and (3) forbidden Fe lines. The distribution of the knots in the PC planes matches well with the above spectral groups, and we classified the knots into the three corresponding groups, i.e., He-rich, S-rich, and Fe-rich knots. The kinematic and chemical properties of the former two groups match well with those of Quasi-Stationary Flocculi and Fast-Moving Knots known from optical studies. The Fe-rich knots show intermediate characteristics between the former two groups, and we suggest that they are the SN ejecta material from the innermost layer of the progenitor. We also present the results of extinction measurements using the flux ratios between the two NIR [Fe II] lines at 1.257 and 1.644 µm. We have found a clear correlation between the NIR extinction and the radial velocity of ejecta knots, indicating the presence of a large amount of SN dust inside and around the main ejecta shell. In a southern part of the ejecta shell, by analyzing the NIR extinction together with far-infrared thermal dust emission, we show that there are warm (˜100 K) and cool (˜40 K) SN dust components and that the former needs to be silicate grains while the latter, which is responsible for the observed NIR extinction, could be either small (.0.01 µm) Fe or large (&0.1 µm) Si grains. We suggest that the warm and cool dust components represent grain species produced in diffuse SN ejecta and in dense ejecta clumps, respectively

On the mean and variance of the writhe of random polygons.

PubMed

Portillo, J; Diao, Y; Scharein, R; Arsuaga, J; Vazquez, M

We here address two problems concerning the writhe of random polygons. First, we study the behavior of the mean writhe as a function length. Second, we study the variance of the writhe. Suppose that we are dealing with a set of random polygons with the same length and knot type, which could be the model of some circular DNA with the same topological property. In general, a simple way of detecting chirality of this knot type is to compute the mean writhe of the polygons; if the mean writhe is non-zero then the knot is chiral. How accurate is this method? For example, if for a specific knot type K the mean writhe decreased to zero as the length of the polygons increased, then this method would be limited in the case of long polygons. Furthermore, we conjecture that the sign of the mean writhe is a topological invariant of chiral knots. This sign appears to be the same as that of an "ideal" conformation of the knot. We provide numerical evidence to support these claims, and we propose a new nomenclature of knots based on the sign of their expected writhes. This nomenclature can be of particular interest to applied scientists. The second part of our study focuses on the variance of the writhe, a problem that has not received much attention in the past. In this case, we focused on the equilateral random polygons. We give numerical as well as analytical evidence to show that the variance of the writhe of equilateral random polygons (of length n ) behaves as a linear function of the length of the equilateral random polygon.

On the mean and variance of the writhe of random polygons

PubMed Central

Portillo, J.; Diao, Y.; Scharein, R.; Arsuaga, J.; Vazquez, M.

2013-01-01

We here address two problems concerning the writhe of random polygons. First, we study the behavior of the mean writhe as a function length. Second, we study the variance of the writhe. Suppose that we are dealing with a set of random polygons with the same length and knot type, which could be the model of some circular DNA with the same topological property. In general, a simple way of detecting chirality of this knot type is to compute the mean writhe of the polygons; if the mean writhe is non-zero then the knot is chiral. How accurate is this method? For example, if for a specific knot type K the mean writhe decreased to zero as the length of the polygons increased, then this method would be limited in the case of long polygons. Furthermore, we conjecture that the sign of the mean writhe is a topological invariant of chiral knots. This sign appears to be the same as that of an “ideal” conformation of the knot. We provide numerical evidence to support these claims, and we propose a new nomenclature of knots based on the sign of their expected writhes. This nomenclature can be of particular interest to applied scientists. The second part of our study focuses on the variance of the writhe, a problem that has not received much attention in the past. In this case, we focused on the equilateral random polygons. We give numerical as well as analytical evidence to show that the variance of the writhe of equilateral random polygons (of length n) behaves as a linear function of the length of the equilateral random polygon. PMID:25685182

Characterization of the Inner Knot of the Crab: the Site of the Gamma-ray Flares?

NASA Technical Reports Server (NTRS)

Weisskopf, Martin C.

2015-01-01

One of the most intriguing recent discoveries has been the detection of powerful gamma-ray flares from the Crab Nebula. Such events, with a recurrence time of about once per year, can be so dramatic to make the system the brightest source in the gamma-ray sky as occurred, e.g. in April 2011. These flares challenge our understanding of how pulsar wind nebulae work and defy current astrophysical models for particle acceleration. We present here our study of the inner knot located within a fraction of an arcsecond from the pulsar with the aim of characterizing the feature and asking if this might be the site of the origin of the gamma-ray flares. We took data using Keck, HST, and Chandra obtained as part of our multi-wavelength campaign to identify the source of the enigmatic flares. We set an upper limit as to the gamma-ray flux from the knot. We also find that the dimensions, surface brightness, flux, etc. of the optical and infrared knot are all correlated with distance from the pulsar. This distance, in turn, varies with time. In addition to this most thorough characterization of the inner knot's properties, we examine the hypothesis that the knot may be the site of the flares by examining the knot separation versus the Fermi/LAT gamma-ray flux. Finally, as part of this research, we make use of a new approach employing singular value decomposition (SVD) for analyzing time series of images and compare the approach to more traditional methods. Our conclusions are only refined but not impacted by using the new approach.

Demographic consequences of migratory stopover: linking red knot survival to horseshoe crab spawning abundance

USGS Publications Warehouse

McGowan, Conor P.; Hines, James E.; Nichols, James D.; Lyons, James E.; Smith, David; Kalasz, Kevin S.; Niles, Lawrence J.; Dey, Amanda D.; Clark, Nigel A.; Atkinson, Philip W.; Minton, Clive D.T.; Kendall, William

2011-01-01

Understanding how events during one period of the annual cycle carry over to affect survival and other fitness components in other periods is essential to understanding migratory bird demography and conservation needs. Previous research has suggested that western Atlantic red knot (Calidris canutus rufa) populations are greatly affected by horseshoe crab (Limulus polyphemus) egg availability at Delaware Bay stopover sites during their spring northward migration. We present a mass-based multistate, capturerecapture/resighting model linking (1) red knot stopover mass gain to horseshoe crab spawning abundance and (2) subsequent apparent annual survival to mass state at the time of departure from the Delaware Bay stopover area. The model and analysis use capture-recapture/resighting data with over 16,000 individual captures and 13,000 resightings collected in Delaware Bay over a 12 year period from 1997–2008, and the results are used to evaluate the central management hypothesis that red knot populations can be influenced by horseshoe crab harvest regulations as part of a larger adaptive management effort. Model selection statistics showed support for a positive relationship between horseshoe crab spawning abundance during the stopover and the probability of red knots gaining mass (parameter coefficient from the top model b = 1.71, SE = 0.46). Our analyses also supported the link between red knot mass and apparent annual survival, although average estimates for the two mass classes differed only slightly. The addition of arctic snow depth as a covariate influencing apparent survival improved the fit of the data to the models (parameter coefficient from the top model b = 0.50, SE = 0.08). Our results indicate that managing horseshoe crab resources in the Delaware Bay has the potential to improve red knot population status.

Biochemical and MALDI-TOF Mass Spectrometric Characterization of a Novel Native and Recombinant Cystine Knot Miniprotein from Solanum tuberosum subsp. andigenum cv. Churqueña

PubMed Central

Cotabarren, Juliana; Tellechea, Mariana Edith; Tanco, Sebastián Martín; Garcia-Pardo, Javier; Avilés, Francesc Xavier; Obregón, Walter David

2018-01-01

Cystine-knot miniproteins (CKMPs) are an intriguing group of cysteine-rich molecules that combine the characteristics of proteins and peptides. Typically, CKMPs are fewer than 50 residues in length and share a characteristic knotted scaffold characterized by the presence of three intramolecular disulfide bonds that form the singular knotted structure. The knot scaffold confers on these proteins remarkable chemical, thermal, and proteolytic stability. Recently, CKMPs have emerged as a novel class of natural molecules with interesting pharmacological properties. In the present work, a novel cystine-knot metallocarboxypeptidase inhibitor (chuPCI) was isolated from tubers of Solanum tuberosum, subsp. andigenum cv. Churqueña. Our results demonstrated that chuPCI is a member of the A/B-type family of metallocarboxypeptidases inhibitors. chuPCI was expressed and characterized by a combination of biochemical and mass spectrometric techniques. Direct comparison of the MALDI-TOF mass spectra for the native and recombinant molecules allowed us to confirm the presence of four different forms of chuPCI in the tubers. The majority of such forms have a molecular weight of 4309 Da and contain a cyclized Gln in the N-terminus. The other three forms are derived from N-terminal and/or C-terminal proteolytic cleavages. Taken together, our results contribute to increase the current repertoire of natural CKMPs. PMID:29495576

Knotty structures of the evolving heliospheric magnetic fields.

NASA Astrophysics Data System (ADS)

Roth, Ilan

2013-04-01

The analogy between MHD and knot theory is utilized in an analysis of structure, stability and evolution of complex magnetic heliospheric flux tubes. Planar projection of a three-dimensional magnetic configuration depicts the structure as a two-dimensional diagram with crossings, to which one may assign mathematical operations leading to robust topological invariants. These invariants enrich the topological information of magnetic configurations beyond helicity. It is conjectured that the field which emerges from the solar photosphere is structured as one of simplest knot invariants - unknot or prime knot, and these flux ropes are then stretched while carried by the solar wind into the interplanetary medium. Preservation of invariants for small diffusivity and large cross section of the emerging magnetic flux makes them impervious to large scale reconnection, allowing us to predict the observed structures at 1AU as elongated prime knots. Similar structures may be observed in magnetic clouds which got disconnected from their foot-points and in ion drop-out configurations from a compact flare source in solar impulsive solar events. Observation of small scale magnetic features consistent with prime knot may indicate spatial intermittency and non-Gaussian statistics in the turbulent cascade process. For flux tubes with higher resistivity, magnetic energy decay rate should decrease with increased knot complexity as the invariants are then harder to be violated. Future measurements are suggested for distinctly oriented magnetic fields with directionally varying suprathermal particle fluxes.

RATIONAL SPLINE SUBROUTINES

NASA Technical Reports Server (NTRS)

Schiess, J. R.

1994-01-01

Scientific data often contains random errors that make plotting and curve-fitting difficult. The Rational-Spline Approximation with Automatic Tension Adjustment algorithm lead to a flexible, smooth representation of experimental data. The user sets the conditions for each consecutive pair of knots:(knots are user-defined divisions in the data set) to apply no tension; to apply fixed tension; or to determine tension with a tension adjustment algorithm. The user also selects the number of knots, the knot abscissas, and the allowed maximum deviations from line segments. The selection of these quantities depends on the actual data and on the requirements of a particular application. This program differs from the usual spline under tension in that it allows the user to specify different tension values between each adjacent pair of knots rather than a constant tension over the entire data range. The subroutines use an automatic adjustment scheme that varies the tension parameter for each interval until the maximum deviation of the spline from the line joining the knots is less than or equal to a user-specified amount. This procedure frees the user from the drudgery of adjusting individual tension parameters while still giving control over the local behavior of the spline The Rational Spline program was written completely in FORTRAN for implementation on a CYBER 850 operating under NOS. It has a central memory requirement of approximately 1500 words. The program was released in 1988.

Optical knots and contact geometry II. From Ranada dyons to transverse and cosmetic knots

NASA Astrophysics Data System (ADS)

Kholodenko, Arkady L.

2016-08-01

Some time ago Ranada (1989) obtained new nontrivial solutions of the Maxwellian gauge fields without sources. These were reinterpreted in Kholodenko (2015) [10] (part I) as particle-like (monopoles, dyons, etc.). They were obtained by the method of Abelian reduction of the non-Abelian Yang-Mills functional. The developed method uses instanton-type calculations normally employed for the non-Abelian gauge fields. By invoking the electric-magnetic duality it then becomes possible to replace all known charges/masses by the particle-like solutions of the source-free Abelian gauge fields. To employ these results in high energy physics, it is essential to extend Ranada's results by carefully analyzing and classifying all dynamically generated knotted/linked structures in gauge fields, including those discovered by Ranada. This task is completed in this work. The study is facilitated by the recent progress made in solving the Moffatt conjecture. Its essence is stated as follows: in steady incompressible Euler-type fluids the streamlines could have knots/links of all types. By employing the correspondence between the ideal hydrodynamics and electrodynamics discussed in part I and by superimposing it with the already mentioned method of Abelian reduction, it is demonstrated that in the absence of boundaries only the iterated torus knots and links could be dynamically generated. Obtained results allow to develop further particle-knot/link correspondence studied in Kholodenko (2015) [13].

Race and Gender Differences in Undergraduate Research Mentoring Structures and Research Outcomes

PubMed Central

Aikens, Melissa L.; Robertson, Melissa M.; Sadselia, Sona; Watkins, Keiana; Evans, Mara; Runyon, Christopher R.; Eby, Lillian T.; Dolan, Erin L.

2017-01-01

Participating in undergraduate research with mentorship from faculty may be particularly important for ensuring the persistence of women and minority students in science. Yet many life science undergraduates at research universities are mentored by graduate or postdoctoral researchers (i.e., postgraduates). We surveyed a national sample of undergraduate life science researchers about the mentoring structure of their research experiences and the outcomes they realized from participating in research. We observed two common mentoring structures: an open triad with undergraduate–postgraduate and postgraduate–faculty ties but no undergraduate–faculty tie, and a closed triad with ties among all three members. We found that men and underrepresented minority (URM) students are significantly more likely to report a direct tie to their faculty mentors (closed triad) than women, white, and Asian students. We also determined that mentoring structure was associated with differences in student outcomes. Women’s mentoring structures were associated with their lower scientific identity, lower intentions to pursue a science, technology, engineering, and mathematics (STEM) PhD, and lower scholarly productivity. URM students’ mentoring structures were associated with higher scientific identity, greater intentions to pursue a STEM PhD, and higher scholarly productivity. Asian students reported lower scientific identity and intentions to pursue a STEM PhD, which were unrelated to their mentoring structures. PMID:28550078

Social Features of Online Networks: The Strength of Intermediary Ties in Online Social Media

PubMed Central

Grabowicz, Przemyslaw A.; Ramasco, José J.; Moro, Esteban; Pujol, Josep M.; Eguiluz, Victor M.

2012-01-01

An increasing fraction of today's social interactions occur using online social media as communication channels. Recent worldwide events, such as social movements in Spain or revolts in the Middle East, highlight their capacity to boost people's coordination. Online networks display in general a rich internal structure where users can choose among different types and intensity of interactions. Despite this, there are still open questions regarding the social value of online interactions. For example, the existence of users with millions of online friends sheds doubts on the relevance of these relations. In this work, we focus on Twitter, one of the most popular online social networks, and find that the network formed by the basic type of connections is organized in groups. The activity of the users conforms to the landscape determined by such groups. Furthermore, Twitter's distinction between different types of interactions allows us to establish a parallelism between online and offline social networks: personal interactions are more likely to occur on internal links to the groups (the weakness of strong ties); events transmitting new information go preferentially through links connecting different groups (the strength of weak ties) or even more through links connecting to users belonging to several groups that act as brokers (the strength of intermediary ties). PMID:22247773

Synthesis of Ga 2O 3 chains with closely spaced knots connected by nanowires

NASA Astrophysics Data System (ADS)

Dai, L.; You, L. P.; Duan, X. F.; Lian, W. C.; Qin, G. G.

2004-07-01

Chains of closely spaced metal or semiconductor particles have potential applications in optoelectronics and single electron devices. We report, for the first time, the synthesis of Ga 2O 3 chains with closely spaced knots connected by nanowires using the thermal evaporation method with a specially designed quartz boat. The Ga 2O 3 chains grew only on the Si substrates where Au catalyst or Ga droplets were coated. The average diameter of the knots is about 450 nm and that of the nanowires is about 50 nm. The selected area electron diffraction of either a knot or a connecting nanowire includes two sets of overlapped single crystal electron diffraction patterns which belong to the [1 0 2] and [1 0 1¯] crystal zone axes of the monoclinic β-Ga 2O 3 phase, respectively. The knot and its neighbor nanowire have the common ( 2¯ 0 1) growth planes at their interface. A mechanism model for the Ga 2O 3 chains synthesis based on the vapor-liquid-solid mechanism is discussed.

The FasT-Fix Repair Technique for Ramp Lesion of the Medial Meniscus.

PubMed

Li, Wei-Ping; Chen, Zhong; Song, Bin; Yang, Rui; Tan, Weiquan

2015-03-01

This technical note describes a new arthroscopic technique to repair the peripheral attachment lesion of the posterior horn of the medial meniscus. The operation was performed under arthroscopy using a standard anterior portal. A FasT-Fix needle was inserted obliquely close to the tibial plateau and the first implant was inserted into the joint capsule depending on its bending angle underneath the meniscus. The second implant was inserted through 1/3 periphery of the meniscus into the meniscocapsular area. The pre-tied self-sliding knot was tensioned to achieve secure fixation of the posterior meniscal peripheral attachment at the original attachment point. From August 2011 to February 2014, 23 knees were diagnosed as ramp lesion, underwent meniscal repair using FasT-Fix technique. All patients were followed up for average 14 months. The Lysholm score improved from preoperative 64.4±4.52 to postoperative 91.2±4.60. We believe that the FasT-Fix technique via the standard anterior portal can be a more convenient and less traumatic alternative for repair of the peripheral attachment lesion of the posterior horn of the medial meniscus in the anterior cruciate ligament deficient knee.

Laparoscopy in patients following transverse rectus abdominis myocutaneous flap reconstruction.

PubMed

Muller, C Y; Coleman, R L; Adams, W P

2000-07-01

We report our technique and experience performing laparoscopic pelvic surgery on four women after transverse abdominus rectus myocutaneous flap (TRAM). Examination under anesthesia is performed on all patients in the low lithotomy position parallel with the floor. The abdominal aorta is palpated and outlined. A pneumoperitoneum is created either by umbilical or left upper quadrant Veress placement. Patients with an acceptable umbilical location undergo port placement through the incision of the umbilical relocation. Other options include left upper quadrant or paramedian placement avoiding the ligamentum teres vessels. Lateral operative ports (5 mm) are placed with reference to the transverse incision present, the pelvic pathology, and the location of the umbilicus. Techniques of electrocautery, intra- and extracorporeal suturing and knot tying, and clips are preferred to minimize port size. Following unilateral or bilateral TRAM reconstruction, four consecutive breast cancer survivors underwent successful laparoscopic-assisted vaginal hysterectomy with oophorectomy using the periumbilical incision for trocar placement. The only complication was a superficial skin breakdown from an adhesive allergy that required 6 weeks for complete resolution. Laparoscopic pelvic surgery is feasible in women after TRAM reconstruction. Knowledge of anatomic and physiologic variations related to the TRAM procedure is necessary in planning a safe operation.

The Skillings-Mack test (Friedman test when there are missing data).

PubMed

Chatfield, Mark; Mander, Adrian

2009-04-01

The Skillings-Mack statistic (Skillings and Mack, 1981, Technometrics 23: 171-177) is a general Friedman-type statistic that can be used in almost any block design with an arbitrary missing-data structure. The missing data can be either missing by design, for example, an incomplete block design, or missing completely at random. The Skillings-Mack test is equivalent to the Friedman test when there are no missing data in a balanced complete block design, and the Skillings-Mack test is equivalent to the test suggested in Durbin (1951, British Journal of Psychology, Statistical Section 4: 85-90) for a balanced incomplete block design. The Friedman test was implemented in Stata by Goldstein (1991, Stata Technical Bulletin 3: 26-27) and further developed in Goldstein (2005, Stata Journal 5: 285). This article introduces the skilmack command, which performs the Skillings-Mack test.The skilmack command is also useful when there are many ties or equal ranks (N.B. the Friedman statistic compared with the chi(2) distribution will give a conservative result), as well as for small samples; appropriate results can be obtained by simulating the distribution of the test statistic under the null hypothesis.

Finite-size and asymptotic behaviors of the gyration radius of knotted cylindrical self-avoiding polygons.

PubMed

Shimamura, Miyuki K; Deguchi, Tetsuo

2002-05-01

Several nontrivial properties are shown for the mean-square radius of gyration R2(K) of ring polymers with a fixed knot type K. Through computer simulation, we discuss both finite size and asymptotic behaviors of the gyration radius under the topological constraint for self-avoiding polygons consisting of N cylindrical segments with radius r. We find that the average size of ring polymers with the knot K can be much larger than that of no topological constraint. The effective expansion due to the topological constraint depends strongly on the parameter r that is related to the excluded volume. The topological expansion is particularly significant for the small r case, where the simulation result is associated with that of random polygons with the knot K.

X-Ray Variability in M87

NASA Technical Reports Server (NTRS)

Harris, Daniel E.; Biretta, J. A.; Junor, W.

2000-01-01

We present the evidence for X-ray variability from the core and from knot A in the M87 jet based on data from two observations with the Einstein Observatory High Resolution Imager (HRI) and three observations with the ROSAT HRI. The core intensity showed a 16% increase in 17 months ('79-'80); a 12% increase in the 3 years '92 to '95; and a 17% drop in the last half of 1995. The intensity of knot A appears to have decreased by 16% between 92Jun and 95Dec. Although the core variability is consistent with general expectations for AGB nuclei, the changes in knot A provide constraints on the x-ray emission process and geometry. Thus we predict that the x-ray morphology of knot A will differ significantly from the radio and optical structure.

Anesthesia for awake craniotomy: a how-to guide for the occasional practitioner.

PubMed

Meng, Lingzhong; McDonagh, David L; Berger, Mitchel S; Gelb, Adrian W

2017-05-01

Awake craniotomy (AC), defined as the performance of at least part of an open cranial procedure with the patient awake, has been tied to beneficial outcomes compared with similar surgery under general anesthesia. Improved anesthetic techniques have made a major contribution to the increasing popularity of AC. However, the heterogeneity of practice among institutions doing large numbers of ACs raises questions (often among those who only occasionally perform AC - i.e., practitioners in low-volume AC institutions) as to the ideal anesthetic technique for AC. The procedure presents a variety of decision-making dilemmas, the origins of which are the varying institutional preferences, lack of quality evidence, and several practice controversies. Evidence-based data that support a single anesthetic algorithm for AC are sparse. In this narrative review, the technical nuances of 13 aspects of anesthetic care for AC are discussed based on institutional preferences and available evidence, and the various controversies and research priorities are discussed. The skills, experience, and commitment of both the surgeon and the anesthesiologist are large variables that are likely more important than what the literature suggests about "best" techniques for AC. Optimizing patient outcome is the fundamental goal of the anesthesiologist.

A systematic review comparing open-book and closed-book examinations: Evaluating effects on development of critical thinking skills.

PubMed

Johanns, Beth; Dinkens, Amber; Moore, Jill

2017-11-01

The advantages of using traditional closed-book examinations are closely compared to the advantages of using open-book examinations for the development of critical thinking skills in nursing students. The use of critical thinking skills is vital among nurses to assess patient needs and modify standard approaches to individualize care for better patient outcomes. The following areas are compared and contrasted for both closed-book and open-book examinations: examination preparation, rote memorization versus active learning, intellectual engagement, simulation of working environment, higher order thinking skills, anxiety reduction and student satisfaction. During investigation of closed-book examinations and open-book examinations, the use of collaborative testing was unveiled. Collaborative testing combines areas from both closed-book and open-book examinations. Based on the systematic review of literature, the recommendation is to use a mixed method of examination types throughout the course of the nursing program. Each type of examination helps develop different skill sets in the nursing student. Copyright © 2017 Elsevier Ltd. All rights reserved.

Feasibility of Using Littoral Combat Ships (LCS) for Humanitarian Assistance/Disaster Relief (HA/DR) Operations

DTIC Science & Technology

2012-09-01

when travelling at sprint speed. To help overcome the shortcomings of the LCS in conducting HA/DR operations, the Irregular Warfare (IW) mission...high sprint speed, which allows the LCS to reach the disaster region faster than any other ships, especially if the IW mission package is adopted. The...high sprint speed in excess of 40 knots and a high sustained speed to enable it to run along a 30+ knots CSG or 20+ knots ESG. The high sprint

Open and Distance Education Systems: Do They Enhance Graduates' Soft Skills? The Results from 2009 Universitas Terbuka Tracer Study

ERIC Educational Resources Information Center

Ratnaningsih, Dewi Juliah

2013-01-01

The vision and mission of Universitas Terbuka (UT) is to become a highly qualified open and distance education institution and to provide higher education access to all communities. Graduates of UT are expected to acquire adequate knowledge, hard skills and soft skills. Soft skills play important roles in the world of work. The aim of this article…

Skillful Spring Forecasts of September Arctic Sea Ice Extent Using Passive Microwave Data

NASA Technical Reports Server (NTRS)

Petty, A. A.; Schroder, D.; Stroeve, J. C.; Markus, Thorsten; Miller, Jeffrey A.; Kurtz, Nathan Timothy; Feltham, D. L.; Flocco, D.

2017-01-01

In this study, we demonstrate skillful spring forecasts of detrended September Arctic sea ice extent using passive microwave observations of sea ice concentration (SIC) and melt onset (MO). We compare these to forecasts produced using data from a sophisticated melt pond model, and find similar to higher skill values, where the forecast skill is calculated relative to linear trend persistence. The MO forecasts shows the highest skill in March-May, while the SIC forecasts produce the highest skill in June-August, especially when the forecasts are evaluated over recent years (since 2008). The high MO forecast skill in early spring appears to be driven primarily by the presence and timing of open water anomalies, while the high SIC forecast skill appears to be driven by both open water and surface melt processes. Spatial maps of detrended anomalies highlight the drivers of the different forecasts, and enable us to understand regions of predictive importance. Correctly capturing sea ice state anomalies, along with changes in open water coverage appear to be key processes in skillfully forecasting summer Arctic sea ice.

Tightly-wound miniknot vectors for gene therapy: a potential improvement over supercoiled minicircle DNA.

PubMed

Tolmachov, Oleg E

2010-04-01

Minimized derivatives of bacterial plasmids with removed bacterial backbones are promising vectors for the efficient delivery and for the long-term expression of therapeutic genes. The absence of the bacterial plasmid backbone, a known inducer of innate immune response and a known silencer of transgene expression, provides a partial explanation for the high efficiency of gene transfer using minimized DNA vectors. Supercoiled minicircle DNA is a type of minimized DNA vector obtained via intra-plasmid recombination in bacteria. Minicircle vectors seem to get an additional advantage from their physical compactness, which reduces DNA damage due to the mechanical stress during gene delivery. An independent topological means for DNA compression is knotting, with some knotted DNA isoforms offering superior compactness. I propose that, firstly, knotted DNA can be a suitable compact DNA form for the efficient transfection of a range of human cells with therapeutic genes, and, secondly, that knotted minimized DNA vectors without bacterial backbones ("miniknot" vectors) can surpass supercoiled minicircle DNA vectors in the efficiency of therapeutic gene delivery. Crucially, while the introduction of a single nick to a supercoiled DNA molecule leads to the loss of the compact supercoiled status, the introduction of nicks to knotted DNA does not change knotting. Tight miniknot vectors can be readily produced by the direct action of highly concentrated type II DNA topoisomerase on minicircle DNA or, alternatively, by annealing of the 19-base cohesive ends of the minimized vectors confined within the capsids of Escherichia coli bacteriophage P2 or its satellite bacteriophage P4. After reaching the nucleoplasm of the target cell, the knotted DNA is expected to be unknotted through type II topoisomerase activity and thus to become available for transcription, chromosomal integration or episomal maintenance. The hypothesis can be tested by comparing the gene transfer efficiency achieved with the proposed miniknot vectors, the minicircle vectors described previously, knotted plasmid vectors and standard plasmid vectors. Tightly-wound miniknots can be particularly useful in the gene administration procedures involving considerable forces acting on vector DNA: aerosol inhalation, jet-injection, electroporation, particle bombardment and ultrasound DNA transfer. (c) 2009 Elsevier Ltd. All rights reserved.

A Unifying Curriculum for Museum-Schools

ERIC Educational Resources Information Center

Povis, Kaleen E.

2011-01-01

There are over two dozen schools in the United States with the word "museum" in their names. However, the philosophy and pedagogy that tie these schools together is unclear. A consistent definition, criteria for classification, and a unifying curriculum to guide museum- schools is lacking. Yet, museum-schools continue to open across the country.…

Georgetown's Think Tank on the Potomac

ERIC Educational Resources Information Center

Kondracke, Morton

1978-01-01

The status and activities of the Center for Strategic and International Studies and its ties to Georgetown University are described. CSIS serves as a kind of open university for policy makers, outlining the issues and policy choices that the U.S. will face in the future. It maintains a professional staff of 25, has a politically conservative…

Spinoza's Proposal for a Doctrine of Children's Education

ERIC Educational Resources Information Center

de Rezende, Cristiano Novaes

2018-01-01

The main objective of this article is to analyze the conceptual connection between the Doctrine of Children's Education, briefly mentioned in Spinoza's "Tractatus de Intellectus Emendatione" (TIE), and the concept of emendation present at the very center of this Treatise's title. A close textual exegesis of the opening paragraphs of TIE…

Revisiting Lifelong Learning for the 21st Century.

ERIC Educational Resources Information Center

Medel-Anonuevo, Carolyn; Ohsako, Toshio; Mauch, Werner

Although lifelong learning is being increasingly cited as one of the key principles in the fields of education and development, shared understanding of the term's usage at the global level is lacking. Lifelong learning is closely tied to the challenge of openness and the changes with which modern individuals must cope in their lifetimes. Lifelong…

Axially shaped channel and integral flow trippers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crowther, R.L.; Johansson, E.B.; Matzner, B.

1988-06-07

A fuel assembly is described comprising fuel rods positioned in spaced array by upper and lower tie-plates, an open ended flow channel surrounding the array for conducting coolant upward between a lower support plate having coolant communicated thereto to an upper support grid having a steam/water outlet communicated thereto. The flow channel surrounds the array for conducting coolant about the fuel rods. The open ended channel has a polygon shaped cross section with the channel constituting a closed conduit with flat side sections connected at corners to form the enclosed conduit; means separate from the channel for connecting the uppermore » and lower tie-plates together and maintaining the fuel rods in spaced array independent of the flow channel. The improvement in the flow channel comprises tapered side walls. The tapered side walls extend from an average thick cross section adjacent the lower support plate to an average thin cross section adjacent the upper core grid whereby the channel is reduced in thickness adjacent the upper core grid to correspond with the reduced pressure adjacent the upper core grid.« less

Axially shaped channel and integral flow trippers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crowther, R.L. Jr.; Johansson, E.B.; Matzner, B.

1992-02-11

This patent describes a fuel assembly. It comprises: fuel rods positioned in spaced array by upper and lower tie-plates, and open ended flow channel surrounding the array for conducting coolant upward between a lower support plate having coolant communicated thereto to an upper support grid having a steam/water outlet communicated thereto. The flow channel surrounding the array for conducting coolant about the fuel rods; the open ended channel having a polygon shaped cross section with the channel constituting a closed conduit with flat side sections connected at corners to form the enclosed conduit; means separate from the channel for connectingmore » the upper and lower tie-plates together and maintaining the fuel rods in spaced array independent of the flow channel, the improvement in the flow channel comprising tapered side walls, the tapered side walls extending from an average thick cross section adjacent the lower support plate to an average thin cross section adjacent the upper core grid whereby the channel is reduced in thickness adjacent the upper core grid to correspond with the reduced pressure adjacent the upper core grid.« less

Impact of Magnetic Draping, Convection, and Field Line Tying on Magnetopause Reconnection Under Northward IMF

NASA Technical Reports Server (NTRS)

Wendel, Deirdre E.; Reiff, Patricia H.; Goldstein, Melvyn L.

2010-01-01

We simulate a northward IMF cusp reconnection event at the magnetopause using the OpenGGCM resistive MHD code. The ACE input data, solar wind parameters, and dipole tilt belong to a 2002 reconnection event observed by IMAGE and Cluster. Based on a fully three-dimensional skeleton separators, nulls, and parallel electric fields, we show magnetic draping, convection, ionospheric field line tying play a role in producing a series of locally reconnecting nulls with flux ropes. The flux ropes in the cusp along the global separator line of symmetry. In 2D projection, the flux ropes the appearance of a tearing mode with a series of 'x's' and 'o's' but bearing a kind of 'guide field' that exists only within the magnetopause. The reconnecting field lines in the string of ropes involve IMF and both open and closed Earth magnetic field lines. The observed magnetic geometry reproduces the findings of a superposed epoch impact parameter study derived from the Cluster magnetometer data for the same event. The observed geometry has repercussions for spacecraft observations of cusp reconnection and for the imposed boundary conditions reconnection simulations.

EXPANSION OF HYDROGEN-POOR KNOTS IN THE BORN-AGAIN PLANETARY NEBULAE A30 AND A78

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fang, X.; Guerrero, M. A.; Marquez-Lugo, R. A.

2014-12-20

We analyze the expansion of hydrogen-poor knots and filaments in the born-again planetary nebulae A30 and A78 based on Hubble Space Telescope (HST) images obtained almost 20 yr apart. The proper motion of these features generally increases with distance to the central star, but the fractional expansion decreases, i.e., the expansion is not homologous. As a result, there is not a unique expansion age, which is estimated to be 610-950 yr for A30 and 600-1140 yr for A78. The knots and filaments have experienced complex dynamical processes: the current fast stellar wind is mass loaded by the material ablated from the inner knots;more » the ablated material is then swept up until it shocks the inner edges of the outer, hydrogen-rich nebula. The angular expansion of the outer filaments shows a clear dependence on position angle, indicating that the interaction of the stellar wind with the innermost knots channels the wind along preferred directions. The apparent angular expansion of the innermost knots seems to be dominated by the rocket effect of evaporating gas and by the propagation of the ionization front inside them. Radiation-hydrodynamical simulations show that a single ejection of material followed by a rapid onset of the stellar wind and ionizing flux can reproduce the variety of clumps and filaments at different distances from the central star found in A30 and A78.« less

Determination of the intersegmental plane using the slip-knot method

PubMed Central

Endoh, Makoto; Kato, Hirohisa; Suzuki, Jun; Watarai, Hikaru; Hamada, Akira; Suzuki, Katsuyuki; Nakahashi, Kenta; Sadahiro, Mitsuaki

2018-01-01

Background Visualization of intersegmental planes in the lung is desirable for precise anatomical lung segmentectomy. We developed the slip-knot method for creating inflation-deflation lines. This study aimed to assess relevant data for thoracoscopic segmentectomy performed using this method. Methods In the slip-knot method, the objective segmental bronchus is looped with a monofilament thread. One end of the thread is then pulled during temporary bilateral ventilation, causing the knot to slip toward the bronchus. Thereafter, bronchial ligation is tightened to block the outflow of segmental air, ensuring that the segment remains expanded while the other reserved segments collapse on resumption of unilateral ventilation. Data from 221 patients who underwent thoracoscopic pulmonary segmentectomy between 2010 and 2016 were analyzed. Results A total of 147 patients (67%) were indicated for the slip-knot method, and 74 cases (33%) were non-adaptive cases. Ninety six percent of 147 cases were well adapted to the slip-knot method, which allowed us to obtain good inflation-deflation line images to determine the intersegmental plane. The mean operative time was 171±51 min (range, 71–367 min). The mean duration of chest tube insertion was 1.5±1.2 days (range, 1–7 days). Three cases (2.0%) had prolonged air-leakage and one (0.7%) case had readmission for late air-leakage. Conclusions Our method enables determination of anatomical intersegmental planes using only one monofilament thread, thus facilitating thoracoscopic pulmonary anatomical segmentectomy. PMID:29785297

Particle on a torus knot: Constrained dynamics and semi-classical quantization in a magnetic field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Das, Praloy, E-mail: praloydasdurgapur@gmail.com; Pramanik, Souvik, E-mail: souvick.in@gmail.com; Ghosh, Subir, E-mail: subirghosh20@gmail.com

2016-11-15

Kinematics and dynamics of a particle moving on a torus knot poses an interesting problem as a constrained system. In the first part of the paper we have derived the modified symplectic structure or Dirac brackets of the above model in Dirac’s Hamiltonian framework, both in toroidal and Cartesian coordinate systems. This algebra has been used to study the dynamics, in particular small fluctuations in motion around a specific torus. The spatial symmetries of the system have also been studied. In the second part of the paper we have considered the quantum theory of a charge moving in a torusmore » knot in the presence of a uniform magnetic field along the axis of the torus in a semiclassical quantization framework. We exploit the Einstein–Brillouin–Keller (EBK) scheme of quantization that is appropriate for multidimensional systems. Embedding of the knot on a specific torus is inherently two dimensional that gives rise to two quantization conditions. This shows that although the system, after imposing the knot condition reduces to a one dimensional system, even then it has manifested non-planar features which shows up again in the study of fractional angular momentum. Finally we compare the results obtained from EBK (multi-dimensional) and Bohr–Sommerfeld (single dimensional) schemes. The energy levels and fractional spin depend on the torus knot parameters that specifies its non-planar features. Interestingly, we show that there can be non-planar corrections to the planar anyon-like fractional spin.« less

Optical knots and contact geometry II. From Ranada dyons to transverse and cosmetic knots

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kholodenko, Arkady L., E-mail: string@clemson.edu

2016-08-15

Some time ago Ranada (1989) obtained new nontrivial solutions of the Maxwellian gauge fields without sources. These were reinterpreted in Kholodenko (2015) [10] (part I) as particle-like (monopoles, dyons, etc.). They were obtained by the method of Abelian reduction of the non-Abelian Yang–Mills functional. The developed method uses instanton-type calculations normally employed for the non-Abelian gauge fields. By invoking the electric–magnetic duality it then becomes possible to replace all known charges/masses by the particle-like solutions of the source-free Abelian gauge fields. To employ these results in high energy physics, it is essential to extend Ranada’s results by carefully analyzing and classifying all dynamicallymore » generated knotted/linked structures in gauge fields, including those discovered by Ranada. This task is completed in this work. The study is facilitated by the recent progress made in solving the Moffatt conjecture. Its essence is stated as follows: in steady incompressible Euler-type fluids the streamlines could have knots/links of all types. By employing the correspondence between the ideal hydrodynamics and electrodynamics discussed in part I and by superimposing it with the already mentioned method of Abelian reduction, it is demonstrated that in the absence of boundaries only the iterated torus knots and links could be dynamically generated. Obtained results allow to develop further particle-knot/link correspondence studied in Kholodenko (2015) [13].« less

Evolution of heliospheric magnetized configurations via topological invariants

NASA Astrophysics Data System (ADS)

Roth, Ilan

2013-07-01

The analogy between magnetohydrodynamics (MHD) and knot theory is utilized in presenting a new method for an analysis of stability and evolution of complex magnetic heliospheric flux tubes. Planar projection of a three-dimensional magnetic configuration depicts the structure as a two-dimensional diagram with crossings, to which one may assign mathematical operations leading to robust topological invariants. These invariants enrich the topological information of magnetic configurations beyond helicity. It is conjectured that the field which emerges from the solar photosphere is structured as one of the simplest knots-unknot or prime knot-and these flux ropes are then stretched while carried by the solar wind into the interplanetary medium. Preservation of invariants for small diffusivity and large cross section of the emerging magnetic flux makes them impervious to large scale reconnection, allowing us to predict the observed structures at 1 AU as elongated prime knots. Similar structures may be observed in magnetic clouds which got disconnected from their footpoints and in ion drop-out configurations from a compact flare source in solar impulsive solar events. Observation of small scale magnetic features consistent with prime knots may indicate spatial intermittency and non-Gaussian statistics in the turbulent cascade process. For flux tubes with higher resistivity, magnetic energy decay rate should decrease with increased knot complexity as the invariants are then harder to be violated. These observations could be confirmed if adjacent satellites happen to measure distinctly oriented magnetic fields with directionally varying suprathermal particle fluxes.

Electrician Cluster, STEP Training Plan. Skills Training and Education Program.

ERIC Educational Resources Information Center

Alabama State Dept. of Postsecondary Education, Montgomery.

This guide is a training plan for the electrical skills cluster of the Skills Training and Education Program (STEP), an open-entry, open-exit program funded by the Job Training Partnership Act (JTPA). In the STEP training plan, each task has its own lesson plan guide. This manual contains the following information: definitions, instructions for…

Clerical Cluster, STEP Training Plan. Skills Training and Education Program.

ERIC Educational Resources Information Center

Alabama State Dept. of Postsecondary Education, Montgomery.

This guide is a training plan for the clerical skills cluster of the Skills Training and Education Program (STEP), an open-entry, open-exit program funded by the Job Training Partnership Act (JTPA). In the STEP training plan, each task has its own lesson plan guide. This manual contains the following information: definitions, instructions for…

Mixtures of Olive Pomace with Different Nitrogen Sources for the Control of Meloidogyne spp. on Tomato

PubMed Central

Rodríguez-Kábana, R.; Estaún, V.; Pinochet, J.; Marfá, O.

1995-01-01

The efficacy of mixtures of dry olive (Olea europea) pomace with biuret, guanidine, and melamine for control of root-knot nematodes (Meloidogyne spp.) on tomato (Lycopersicon esculentum) was studied in greenhouse experiments. Olive pomace (OP) applied pre-plant at 10 g/kg soil was phytotoxic. Mixtures of OP (10 g/kg soil) with biuret or guanidine at 200-300 mg/kg soil reduced or eliminated the phytotoxic effect, controlled root-knot nematodes, and increased soil esterase activity indicative of microbial activity. The addition of biuret or guanidine without OP to soil at rates <300 mg/kg soil did not control root-knot nematodes. Melamine applied at 100-400 mg/kg soil was phytotoxic as were mixtures of melamine with OP. Treatment of OP with anhydrous ammonia increased N content of the material. In another greenhouse experiment, NH₃-treated OP added to soil was not phytotoxic to tomato, suppressed root-knot nematodes, and increased soil esterase activity. Greenhouse and microplot experiments with OP plus chicken litter demonstrated the efficacy of these combination amendments to control root-knot nematodes and increase tomato yields in Meloidogyne-infested soil. PMID:19277325

50 CFR 660.702 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... the vessel. (3) Drift gillnet. A panel of netting, 14 inch (35.5 cm) stretched mesh or greater... between the inside of one knot to the inside of the opposing knot when the mesh is stretched, regardless...

50 CFR 660.702 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... the vessel. (3) Drift gillnet. A panel of netting, 14 inch (35.5 cm) stretched mesh or greater... between the inside of one knot to the inside of the opposing knot when the mesh is stretched, regardless...

50 CFR 660.702 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... the vessel. (3) Drift gillnet. A panel of netting, 14 inch (35.5 cm) stretched mesh or greater... between the inside of one knot to the inside of the opposing knot when the mesh is stretched, regardless...

Evaluation of surgical training in the era of simulation

PubMed Central

Shaharan, Shazrinizam; Neary, Paul

2014-01-01

AIM: To assess where we currently stand in relation to simulator-based training within modern surgical training curricula. METHODS: A systematic literature search was performed in PubMed database using keywords “simulation”, “skills assessment” and “surgery”. The studies retrieved were examined according to the inclusion and exclusion criteria. Time period reviewed was 2000 to 2013. The methodology of skills assessment was examined. RESULTS: Five hundred and fifteen articles focussed upon simulator based skills assessment. Fifty-two articles were identified that dealt with technical skills assessment in general surgery. Five articles assessed open skills, 37 assessed laparoscopic skills, 4 articles assessed both open and laparoscopic skills and 6 assessed endoscopic skills. Only 12 articles were found to be integrating simulators in the surgical training curricula. Observational assessment tools, in the form of Objective Structured Assessment of Technical Skills (OSATS) dominated the literature. CONCLUSION: Observational tools such as OSATS remain the top assessment instrument in surgical training especially in open technical skills. Unlike the aviation industry, simulation based assessment has only now begun to cross the threshold of incorporation into mainstream skills training. Over the next decade we expect the promise of simulator-based training to finally take flight and begin an exciting voyage of discovery for surgical trainees. PMID:25228946

Luminous clusters of Wolf-Rayet stars in the SBmIII galaxy NGC 4214

NASA Technical Reports Server (NTRS)

Sargent, Wallace L. W.; Filippenko, Alexei V.

1991-01-01

Observations are reported of strong broad emission lines attributed to WR stars in the spectra of several bright knots in the nearby Magellanic irregular galaxy NGC 4214 (classified as type SBmIII), in addition to the emission produced by the more prevalent WN stars). Data are presented on measurements of the line fluxes, the line equivalent widths, and continuum flux densities in the four observed knots, showing that the strongest WR lines generally appear in knots having the most luminous stellar continuum. The significance of this observation is discussed.

Calibration Tests of a German Log Rodmeter

NASA Technical Reports Server (NTRS)

Mottard, Elmo J.; Stillman, Everette R.

1949-01-01

A German log rodmeter of the pitot static type was calibrated in Langley tank no. 1 at speeds up to 34 knots and angles of yaw from 0 deg to plus or minus 10 3/4 degrees. The dynamic head approximated the theoretical head at 0 degrees yaw but decreased as the yaw was increased. The static head was negative and in general became more negative with increasing speed and yaw. Cavitation occurred at speeds above 31 knots at 0 deg yaw and 21 knots at 10 3/4 deg yaw.

An algorithm for surface smoothing with rational splines

NASA Technical Reports Server (NTRS)

Schiess, James R.

1987-01-01

Discussed is an algorithm for smoothing surfaces with spline functions containing tension parameters. The bivariate spline functions used are tensor products of univariate rational-spline functions. A distinct tension parameter corresponds to each rectangular strip defined by a pair of consecutive spline knots along either axis. Equations are derived for writing the bivariate rational spline in terms of functions and derivatives at the knots. Estimates of these values are obtained via weighted least squares subject to continuity constraints at the knots. The algorithm is illustrated on a set of terrain elevation data.