Introduction
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.
Materials
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.
Results
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.
Conclusion
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.
Background
Force feedback is a critical element for performing and learning surgical suturing skill. Force feedback is impoverished or not present at all in non-open surgery (i.e., in simulation, ...laparoscopic, and robotic-assisted surgery), but it can be augmented using different modalities. This rapid, systematic review examines how the modality of delivering force feedback influences the performance and learning of surgical suturing skills.
Methods
An electronic search was performed on PubMed/MEDLINE, Web of Science, and Embase databases to identify relevant articles. The results were synthesized using vote counting based on direction of effect.
Results
A total of nine studies of medium-to-low quality were included. The synthesis of results suggests that the visual modality could be more beneficial than the tactile and auditory modalities in improving force control and that auditory and tactile modalities could be more beneficial than the visual modality in improving suturing performance. Results are mixed and unclear with regards to how modality affects the reduction of force magnitude and unclear when unimodal was compared to multimodal feedback. The studies have a general low level of evidence.
Conclusion
The low number of studies with low methodological quality and low level of evidence (most were proof of concept) prevents us from drawing any meaningful conclusion and as such it is currently unknown whether and how force feedback modality influences surgical suturing skill. Speculatively, the visual modality may be more beneficial for improving the control of exerted force, while auditory and tactile modalities may be more effective in improving the overall suturing performance. We consider the issue of feedback modality to be highly relevant in this field, and we encourage future research to conduct further investigation integrating principles from learning psychology and neuroscience: identify feedback goal, context, and skill level and then design and compare feedback modalities accordingly.
Recent research presented evidence that producing gestures influences learning and knowledge representations. In this study, we investigated whether this beneficial effect of gesturing is increased ...for procedural learning tasks in that the motor context (i.e. producing gestures) is congruent during the learning and the testing phase. In Experiment 1, participants learned to tie nautical knots with or without producing gestures and were asked to reproduce the knots in the testing phase. Hence, the motor context was congruent for the participants producing gestures in the learning phase and incongruent for the learners that did not produce gestures. Producing gestures during learning improved performance, thus, replicating prior research. In Experiment 2, we manipulated whether participants produced gestures during learning and testing. There were two context-congruent conditions (learning and testing both with producing gestures vs. learning and testing both without producing gestures) and two context-incongruent conditions (producing gestures during learning but not producing gestures during testing vs. not producing gestures during learning but producing gestures during testing). Results showed a context-congruency effect. Performance was higher in the context-congruent than the context-incongruent conditions. We conclude that congruency with regard to the availability of motor information during the learning and the testing phase is an important determinant for successful procedural learning.
•Producing gestures does not foster procedural learning per se.•Producing gestures establishes a motor context.•The motor context has to be congruent across learning and testing.•Gesturing (and non-gesturing) during both learning and testing fosters learning.•In contrast, gesturing only during learning or during testing hampers learning.
Brexit has occasioned a rightward shift in British politics as successive leaders have grappled with the difficulties of negotiating with the European Union and the vicissitudes of politics in the ...governing Conservative party. Explanations for the hardening of Eurosceptic preferences focus on the demands of ‘taking back control’ and the polarisation of post-referendum politics as key drivers. But they have not explored the ways in which negotiation strategies shaped – rather than reflected – domestic political developments. Drawing on two-level games accounts of ‘synergistic’ bargaining, this article argues both David Cameron and Theresa May sought to leverage Eurosceptic sentiment in their respective negotiations to make it more credible the United Kingdom would walk away if its demands were rejected. While both leaders failed to convey their resolve, they inadvertently strengthened Eurosceptic constituencies back home, contributing to the paucity – and the rejection – of their negotiated agreements.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, OILJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We compare monopoly profit, consumer surplus, and total welfare associated with three commonly used tying strategies: no tying, pure tying, and mixed tying. Whereas the previous literature focused ...mainly on profit comparisons, this paper evaluates the relationship between component production costs and total welfare. We identify several market failures where the seller does not adopt the welfare-maximizing tying strategy. Finally, we explore how consumer exclusion rates (uncaptured market) are affected by tying strategy and some implications for unbundling regulation.
Buildings may be subjected during their service life to extreme events which can trigger progressive collapse. On this front, the role played by tying reinforcement in structural members is crucial ...for an adequate load redistribution and the avoidance of disproportionate collapse. This work proposes a robustness-oriented procedure for the design of tying reinforcement placed in the hollow-core units and beams of precast concrete buildings, where limited studies are available in scientific literature. In particular, the aim is to provide a simple yet reliable approach for the design of concentrated and distributed ties in precast floors by adopting fundamental input parameters such as the system’s chord rotation capacity and dynamic amplification factor, which are not considered in current design codes. Firstly, a flow-chart of the design procedure is proposed and discussed. Secondly, the input parameters are calculated based on recent analytical approaches - proposed by some of the authors - to optimize the tying reinforcement design. Finally, the efficiency of the design procedure is demonstrated with an application example, and a novel detailing scheme is proposed which is aimed at a significant enhancement of structural robustness. Due to its simplicity, the proposed design procedure is contended to be applicable in robustness assessment and design of building structures with precast concrete hollow-core floors.
Recent experiments showed that the linear double-stranded DNA in bacteriophage capsids is both highly knotted and neatly structured. What is the physical basis of this organization? Here we show ...evidence from stochastic simulation techniques that suggests that a key element is the tendency of contacting DNA strands to order, as in cholesteric liquid crystals. This interaction favors their preferential juxtaposition at a small twist angle, thus promoting an approximately nematic (and apolar) local order. The ordering effect dramatically impacts the geometry and topology of DNA inside phages. Accounting for this local potential allows us to reproduce the main experimental data on DNA organization in phages, including the cryo-EM observations and detailed features of the spectrum of DNA knots formed inside viral capsids. The DNA knots we observe are strongly delocalized and, intriguingly, this is shown not to interfere with genome ejection out of the phage.
Background:
While most surgeons can tie visually appealing knots under an arthroscope, few surgeons have undergone an objective evaluation of their ability to consistently tie knots with maximum loop ...and knot security.
Purpose/Hypotheses:
The purpose of this study was to evaluate and compare variations in ultimate load to failure, 3-mm displacement (clinical failure), and knot stack height of arthroscopic suture knots tied by 73 independent expert orthopaedic arthroscopists. The hypotheses were (1) that skilled arthroscopic surgeons would be able to routinely tie arthroscopic knots of similar strength, (2) that surgeons with <10 years of clinical practice would tie stronger and more consistent knots, and (3) that surgeons who performed >200 arthroscopic shoulder cases per year would produce stronger and more consistent knots than would surgeons who performed fewer cases.
Study Design:
Controlled laboratory study.
Methods:
Each surgeon tied 5 of the same type of their preferred arthroscopic knot and half-hitch locking mechanism. Each knot was mechanically tested for ultimate load to failure and clinical failure.
Results:
For the 365 individual knots tested, the mean ultimate load across each knot was 231 N (range, 29-360 N). The mean clinical failure load was 139 N (range, 16-328 N). The average knot stack height among the 365 knots was 5.61 mm (range, 2.89-10.32 mm). For an individual surgeon, the standard deviations of the 5 consecutive knots tied ranged from 6 to 133 N. The ultimate load and clinical failure load for surgeons with <10 years of practice (n = 39) were 248 ± 93 N and 142 ± 56 N, respectively. The mean ± SD ultimate and clinical failure loads for surgeons with >10 years of practice (n = 34) were 211 ± 111 N and 136 ± 69 N, respectively. When knot strength was used to measure performance, significant differences existed in ultimate load (P = .001); however, there were no differences in clinical failure load (P = .329). Surgeons with <10 years of practice were able to tie knots more consistently than were surgeons in practice for >10 years, for both ultimate load (P = .018) and clinical failure load (P = .005). There was no significant difference based on number of cases performed with respect to ultimate load or clinical failure load (P = .292 and .479, respectively). There was no difference in consistency, as both groups had similar standard deviations (P = .814 for ultimate load, P = .545 for clinical failure).
Conclusion:
Considerable variations in knot strength exist between arthroscopic knots tied by surgeons. Study findings revealed that surgeons were unable to tie 5 consecutive knots of the same type consistently; that for both ultimate load and clinical failure load, surgeons with <10 years in practice were able to tie knots more consistently than surgeons with >10 years; and that surgeons performing >200 arthroscopic shoulder cases annually failed to tie stronger or more consistent knots than their counterparts performing fewer cases.
Clinical Relevance:
This variation in knot tying has the potential to affect the integrity of arthroscopic repairs. Independent objective testing of the ability to tie secure knots as part of a surgeons’ training may be necessary.
We experimentally study the effects of a uniform electric field on the conformation of single DNA molecules. We demonstrate that a moderate electric field (∼200 V/cm) strongly compresses isolated DNA ...polymer coils into isotropic globules. Insight into the nature of these compressed states is gained by following the expansion of the molecules back to equilibrium after halting the electric field. We observe two distinct types of expansion modes: a continuous molecular expansion analogous to a compressed spring expanding, and a much slower expansion characterized by two long-lived metastable states. Fluorescence microscopy and stretching experiments reveal that the metastable states are the result of intramolecular self-entanglements induced by the electric field. These results have broad importance in DNA separations and single molecule genomics, polymer rheology, and DNA-based nanofabrication.
Is LSD toxic? Nichols, David E.; Grob, Charles S.
Forensic science international,
March 2018, 2018-Mar, 2018-03-00, 20180301, Letnik:
284
Journal Article
Recenzirano
•LSD has rarely been associated with accidental deaths and suicide.•LSD is known to be non-toxic and physiologically safe when used at moderate dosages.•Death attributed to LSD toxicity appear in ...conjunction only with maximal restraint.•Forensic investigators should understand the true causes of LSD-related fatalities.
LSD (lysergic acid diethylamide) was discovered almost 75 years ago, and has been the object of episodic controversy since then. While initially explored as an adjunctive psychiatric treatment, its recreational use by the general public has persisted and on occasion has been associated with adverse outcomes, particularly when the drug is taken under suboptimal conditions. LSD’s potential to cause psychological disturbance (bad trips) has been long understood, and has rarely been associated with accidental deaths and suicide. From a physiological perspective, however, LSD is known to be non-toxic and medically safe when taken at standard dosages (50–200μg). The scientific literature, along with recent media reports, have unfortunately implicated “LSD toxicity” in five cases of sudden death. On close examination, however, two of these fatalities were associated with ingestion of massive overdoses, two were evidently in individuals with psychological agitation after taking standard doses of LSD who were then placed in maximal physical restraint positions (hogtied) by police, following which they suffered fatal cardiovascular collapse, and one case of extreme hyperthermia leading to death that was likely caused by a drug substituted for LSD with strong effects on central nervous system temperature regulation (e.g. 25i-NBOMe). Given the renewed interest in the therapeutic potential of LSD and other psychedelic drugs, it is important that an accurate understanding be established of the true causes of such fatalities that had been erroneously attributed to LSD toxicity, including massive overdoses, excessive physical restraints, and psychoactive drugs other than LSD.
PDF
