fixation time
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2022 ◽  
Author(s):  
Mario Santer ◽  
Anne Kupczok ◽  
Tal Dagan ◽  
Hildegard Uecker

Theoretical population genetics has been mostly developed for sexually reproducing diploid and for monoploid (haploid) organisms, focusing on eukaryotes. The evolution of bacteria and archaea is often studied by models for the allele dynamics in monoploid populations. However, many prokaryotic organisms harbor multicopy replicons -- chromosomes and plasmids -- and theory for the allele dynamics in populations of polyploid prokaryotes remains lacking. Here we present a population genetics model for replicons with multiple copies in the cell. Using this model, we characterize the fixation process of a dominant beneficial mutation at two levels: the phenotype and the genotype. Our results show that, depending on the mode of replication and segregation, the fixation time of mutant phenotypes may precede the genotypic fixation time by many generations; we term this time interval the heterozygosity window. We furthermore derive concise analytical expressions for the occurrence and length of the heterozygosity window, showing that it emerges if the copy number is high and selection strong. Replicon ploidy thus allows for the maintenance of genetic variation following phenotypic adaptation and consequently for reversibility in adaptation to fluctuating environmental conditions.


2021 ◽  
Vol 15 (4) ◽  
pp. 35-41
Author(s):  
I. G. Smirnov ◽  
D. O. Khort ◽  
A. I. Kutyrev

The existing models of industrial robots cannot perform technological processes of apple harvesting. It is noted that there is a need for developing special actuators, grippers and new control algorithms for harvesting horticulture products. (Research purpose) The research aimed to develop an intelligent control system for horticulture industrial technologies and robotic techniques for yield monitoring and fruit harvesting. (Materials and methods) The research methodology was based on such modern methods as computer modeling and programming. In particular, the following methods were applied: systems analysis, artificial neural networks theory, pattern recognition, digital signal processing. The development of software, hardware and software was carried out in accordance with the requirements of GOST technical standards. The following programming languages were used: (C / C ++)-based  OpenCV library, Spyder Python Development Environment, PyTorch and Flask frameworks, and JavaScript. Image marking for training neural networks was carried out via VGG ImageAnnotator and in Labelbox. The design process was based on the finite element method, CAD SolidWorks software environment. (Results and discussion) An intelligent management system for horticulture industrial technologies has been created based the on the «Agrointellect VIM» hardware and software complex. The concept of the system is shown to be implemented via computer and communication technology, robotic machines, the software for collecting, organizing, analyzing and storing data. The gripper proves to fix an apple gently and holds it securely. Depending on the size, the fruit fixation time is 1.5-2.0 seconds, the fruit maximum size is 85 per 80 millimeters , and its maximum weight is 500 grams. (Conclusions) The developed intelligent control system for industrial technologies based on «Agrointellect VIM» hardware and software complex ensures the efficient real-time processing of information necessary for the design of intelligent agricultural technologies using robotic machines and artificial intelligence systems.


2021 ◽  
Vol 92 (12) ◽  
pp. 928-936
Author(s):  
Gaurav N. Pradhan ◽  
William Ottestad ◽  
Anders Meland ◽  
Jan Ivar Kåsin ◽  
Lars Øivind Høiseth ◽  
...  

BACKGROUND: Severe acute hypoxia results in a rapid deterioration of cognitive functioning and thus poses a risk for human operations in high altitude environments. This study aimed at investigating the effects of oxygen system failure during a high-altitude high-opening (HAHO) parachute jump scenario from 30,000 ft (9144 m) on human physiology and cognitive performance using a noncontact eye-tracking task.METHODS: Nine healthy male volunteers (ages 27–48) were recruited from the Norwegian Special Operations Commandos. Eye-tracking data were collected to derive information on cognitive performance in the context of rapid dynamic changes in pressure altitude while performing a modified King-Devick test. The baseline data was collected at 8000 ft (2438 m) while breathing 100% oxygen during decompression. For every test, the corresponding arterial blood gas analysis was performed.RESULTS: The study subjects endured severe hypoxia, which resulted in significant prolongations of fixation time (range: 284.1–245.6 ms) until 23,397 ft (131 m) and fixation size (range: 34.6–32.4 mm) until 25,389 ft (7739 m) as compared to the baseline (217.6 ± 17.8 ms and 27.2 ± 4.5 mm, respectively). The increase in the saccadic movement and decrease in the saccadic velocity was observed until 28,998 ft and 27,360 ft (8839 and 8339 m), respectively.DISCUSSION: This is the first study to investigate cognitive performance from measured oculometric variables during severe hypobaric hypoxia in a simulated high-altitude airdrop mission scenario. The measurement of altered oculometric variables under hypoxic conditions represents a potential avenue to study altered cognitive performance using noncontact sensors that can derive information and serve to provide the individual with a warning from impending incapacitation.Pradhan GN, Ottestad W, Meland A, Kåsin JI, Høiseth LØ, Cevette MJ, Stepanek J. Oculometric feature changes during acute hypoxia in a simulated high-altitude airdrop scenario. Aerosp Med Hum Perform. 2021; 92(12):928–936.


2021 ◽  
Vol 42 (6) ◽  
pp. 46-59
Author(s):  
Ya. K. Smirnova ◽  

The article investigates joint attention deficits in various forms of atypical development using eye movement recording. Preschoolers aged 5-7 years from different clinical groups participated in the study: typically developing (n = 20), with mental retardation (ICD-10 class F83) (n = 20), preschoolers with delayed speech development (ICD-10 class R47) (n = 20), with hearing impairment (sensorineural hearing loss, ICD-10 class H90) (n = 10) and with visual impairment (amblyopia and strabismus, IBC-10 class H53) (n = 20). Contrasting group analyses allowed us to identify both specific and universal manifestations of joint attention deficit symptoms in the different forms of atypical development. Gaze tracking was used to analyze fixation duration and frequency, fixation distribution, areas of interest, and to identify markers of joint attention deficits that interfere with the child's productive interaction with an adult. Potential mechanisms of atypical joint attention are described, including atypical direction of gaze, changes in the dynamics of the operative visual field, duration of visual concentration, and accuracy in fixing the object’s elements. It is shown that fixation time in joint attention episodes can be regarded as a prognostic marker of joint attention disorders: joint attention is associated not only with spatial characteristics of areas of interest, but also with fixation duration on the object (decrease/increase in fixation duration).


2021 ◽  
Vol 12 ◽  
Author(s):  
Bastian I. Hougaard ◽  
Hendrik Knoche ◽  
Jim Jensen ◽  
Lars Evald

Purpose: Virtual reality (VR) and eye tracking may provide detailed insights into spatial cognition. We hypothesized that virtual reality and eye tracking may be used to assess sub-types of spatial neglect in stroke patients not readily available from conventional assessments.Method: Eighteen stroke patients with spatial neglect and 16 age and gender matched healthy subjects wearing VR headsets were asked to look around freely in a symmetric 3D museum scene with three pictures. Asymmetry of performance was analyzed to reveal group-level differences and possible neglect sub-types on an individual level.Results: Four out of six VR and eye tracking measures revealed significant differences between patients and controls in this free-viewing task. Gaze-asymmetry between-pictures (including fixation time and count) and head orientation were most sensitive to spatial neglect behavior on a group level analysis. Gaze-asymmetry and head orientation each identified 10 out of 18 (56%), compared to 12 out of 18 (67%) for the best conventional test. Two neglect patients without deviant performance on conventional measures were captured by the VR and eyetracking measures. On the individual level, five stroke patients revealed deviant gaze-asymmetry within-pictures and six patients revealed deviant eye orientation in either direction that were not captured by the group-level analysis.Conclusion: This study is a first step in using VR in combination with eye tracking measures as individual differential neglect subtype diagnostics. This may pave the way for more sensitive and elaborate sub-type diagnostics of spatial neglect that may respond differently to various treatment approaches.


2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Yanshi Liu ◽  
Kai Liu ◽  
Feiyu Cai ◽  
Tao Zhang ◽  
Aihemaitijiang Yusufu

Abstract Background It is challenging to determine the orthogonality of radiographs in daily clinical practice. The purpose of this study was to show the usefulness of an additional foot ring which might determine the orthogonality of postoperative radiographs for the parameter measurement of hexapod external fixator. Methods We retrospectively analyzed 81 consecutive trauma patients with tibial shaft fractures treated by the hexapod external fixator at our institution from September 2014 to July 2019. Starting in March 2016, the postoperative radiographs for parameter measurement were obtained under the control of an additional foot ring. The final data consisted of 47 patients in traditional radiographs (Group I) and 34 patients under the control of foot ring during the radiographic process (Group II). The demographic data, original postoperative deformities, residual deformities after final correction, number of repeated radiographs after the first postoperative radiographs, time to the satisfactory reduction achieved, and external fixation time in all patients were documented and analyzed. The Johner–Wruhs criteria were used for the final clinical outcomes evaluation at the last clinical visit. Results Satisfactory reduction and bone union were achieved in all patients. There were no statistical significances between the two groups in the demographic data, original postoperative deformities, residual deformities after final correction, external fixation time, and the final clinical outcomes (P > 0.05). The mean number of repeated radiographs after the first radiographs (1.4 times) and mean time to the satisfactory reduction achieved (3.3 days) in patients with an additional foot ring used were all less than those without foot ring (2.4 times, 5.3 days) (P < 0.05). Conclusions The additional foot ring is a practical device to ensure the orthogonality of postoperative radiographs for the hexapod external fixator parameter measurement. Radiation exposure, duration of deformity correction, and cost for patients might be reduced due to the less repeated radiographs with the wrong position.


2021 ◽  
Author(s):  
Alimujiang Abulaiti ◽  
Yanshi Liu ◽  
Feiyu Cai ◽  
Kai Liu ◽  
Abulaiti Abula ◽  
...  

Abstract Background: The purpose of this study was to evaluate the clinical effectiveness and determine the differences, if any, between trifocal and bifocal bone transport technique in the reconstruction of long segmental tibial bone defects caused by infection using a monolateral rail external fixator. Methods: A total of 53 consecutive patients with long segmental tibial bone defects caused by infection and treated by monolateral rail external fixator in our department were retrospectively collected and analyzed from January 2013 to April 2019, including 39 males and 14 females with an average age of 38.8±12.4 years (range 19 to 65 years). 32 patients were treated by bifocal bone transport (BFT) technique, and the other 21 patients were managed by trifocal bone transport (TFT) technique. The demographic data, operation duration, docking time, external fixation time, and external fixation index were documented and analyzed. Difficulties that occur during the treatment were classified according to Paley. The clinical outcomes were evaluated by the Association for the Study and Application of the Method of Ilizarov criteria (ASAMI) at the last clinical visit.Results: All patients achieved an infection-free union finally, and there was no significant difference between the two groups in demographic data and both ASAMI bone and functional scores (P>0.05). The mean defect size and operation duration in TFT (9.4±1.5 cm, 161.9±8.9 minutes) were larger than that in BFT (7.8±1.8 cm, 122.5±11.2 minutes) (P<0.05). The mean docking time, external fixation time, and external fixation index in TFT (65.9±10.8 days, 328.0±57.2 days, 34.8±2.1 days/cm) were all less than those in BFT (96.8±22.6 days, 474.5±103.2 days, 60.8±1.9 days/cm) (P<0.05). Difficulties and complications were more prevalent in the BFT group, while less in the TFT group (P<0.05). Conclusions: Both the trifocal and bifocal bone transport technique in the reconstruction of long segmental tibial bone defects caused by infection using a monolateral rail external fixator achieve satisfactory clinical outcomes. The trifocal bone transport technique can significantly decrease the docking time, external fixation time, external fixation index, difficulties, and complications compared with the bifocal bone transport technique.


2021 ◽  
Vol 108 (Supplement_8) ◽  
Author(s):  
James Pilkington ◽  
Catherine Fullwood ◽  
Aali Sheen

Abstract Aim Provide a report on all patients who underwent laparoscopic incisional hernia repair as part of the TACKoMesh RCT prior to unblinding of treatment arms. Material and Methods Trial recruitment was for primary incisional hernia with a defect diameter of 3–10cm. 63 patients (target 74-136) were operated on prior to the outbreak of COVID-19. Post-operative pain is the primary trial outcome. Surgery was performed with either spiral-tack mesh-fixation device (Protack (permanent) or Reliatack (absorbable)), Symbotex IPOM mesh, and fascial closure with no 1 Maxon suture(s) using extracorporeal knot ties – the Manchester Technique. Data was collected on trial forms and lifestyle questionnaires (SF-36 and CCS). All data were explored and described in RStudio v1.4.1106. Results Patients were aged 36-80 and 36(57.1%) patients were male. Mean preoperative BMI was 30.91(sd5.11,range21.15–43.93). Mean operating time was 80.81(37.34,20-240)minutes. In 13(20.6%) patients multiple hernia defects were identified. A good degree of fascial closure was achieved in all patients using a median of 3(IQR 2.0-3.5)knots. Median mesh-fixation time was 286(159.5-428.0)seconds and a mean 25.24(5.49,14-41)tacks/patient were used. Median length of hospital stay was 3.5(2.0–6.0)days. Patients were asked “Please indicate on this scale [VAS 0–10] the pain that you currently experience from your incisional hernia during activity?”. Median responses for Day0/pre-op, Day1, Day6, Day30 and Day365 were 4.5, 8.0, 6.0, 3.0 and 1.5 respectively. At one year, 7(11%) patients had experienced hernia recurrence and 33(52%) post-operative seroma. Conclusions Target recruitment was not possible owing to COVID-19. The Manchester Technique has comparable recurrence rates. Reported pain increases post-operatively but is reduced at post-operative day30 and day365.


2021 ◽  
Author(s):  
Jiajie Zou ◽  
Nai Ding

Abstract Attention is a complex system involving multiple interactive components that jointly regulate information processing in the brain. It has been hypothesized that the computational goal of attention is to optimally integrate information under task demands, and evidence has been provided in relatively simple learning and decision making tasks. It remains unclear, however, whether this hypothesis can explain attention distribution in more complex real-world tasks that engage multiple attention systems. Here, taking advantage of the development of attention mechanisms in deep neural network (DNN) models, we investigate whether human attention during real-world reading comprehension tasks can be explained as a consequence of task optimization. In a goal-directed reading task, participants read a passage to answer a question. Eye tracking results show that the attention on each word, quantified by the fixation time, is modulated by both the top-down reading goal and lower-level visual layout and textual features. When trained to perform the same goal-directed reading task, DNN models yield human-level performance and naturally evolve human-like attention distribution, with deep layers tuned to the reading goal and shallow layers tuned to textual features. Further experiments suggest that different training tasks separately contribute to goal-directed and text-based attention. In summary, the results strongly suggest that human attention can be interpreted as a consequence of task optimization during real-world reading tasks.


Author(s):  
J Chainey ◽  
B Zheng ◽  
M Kim ◽  
A Elomaa ◽  
R Bednarik ◽  
...  

Background: Gaze behavior differences between expert and novice surgeons have been established in previous studies mainly from the general surgery field.Limited information is available about surgeon’s visual attention during microsurgery procedures where surgical microscope is used. Methods: 4 experts and 3 novices performed 37 independent sutures under the surgical microscope.Eye movements of surgeons and scene video of the surgical performance were recorded.Total suturing time and subtask times were compared between level of expertise.We defined three discrete surgical actions and examined eye gaze (fixation) directly related to each of these actions.Fixation duration (measured by total,pre-action,and post-action duration) were compared between expert and novice, over 3 subtasks (piercing, exiting and cutting) and between pre- and post-action phases. Results: Expert surgeons completed the suture with shorter total time than novices.On average,expert displayed longer fixation time than novice.Experts also maintained their visual engagement constantly over the 3 level of subtask in comparison to novices who required a longer fixation time for the challenging subtask (piercing).Experts use longer pre- than post-action fixation, and this pattern is distributed over all three subtasks.This gaze engagement strategy was not shown in novices. Conclusions: The action-related fixation can be used to evaluate microsurgeons’ level of expertise and in surgical education for gaze training.


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