RGB-D Indoor mapping using deep features

RGB-D indoor mapping has been an active research topic in the last decade with the advance of depth sensors. However, despite the great success of deep learning techniques on various problems, similar approaches for SLAM have not been much addressed yet. In this work, an RGB-D SLAM system using a deep learning approach for mapping indoor environments is proposed. A pre-trained CNN model with multiple random recursive structures is utilized to acquire deep features in an efficient way with no need for training. Deep features present strong representations from color frames and enable better data association. To increase computational efficiency, deep feature vectors are considered as points in a high dimensional space and indexed in a priority search k-means tree. The search precision is improved by employing an adaptive mechanism. For motion estimation, a sparse feature based approach is adopted by employing a robust keypoint detector and descriptor combination. The system is assessed on TUM RGB-D benchmark using the sequences recorded in medium and large sized environments. The experimental results demonstrate the accuracy and robustness of the proposed system over the state-of-the-art, especially in large sequences. © 2019 IEEE

Effects of etofenamate and methylprednısolone on spınal cord ınjury

This study evaluates the effects of etofenamate on secondary damage following a spinal cord injury and compares the effects with those of methylprednisolone. A total of 31 male Wistar-Albino rats were used. A weight-drop model was utilized for the experimental spinal cord injury and a 50g-cm impact was applied on the spinal cord. Rats were randomly assigned to one of the three study arms (saline, etofenamate 20 mg/kg, methylprednisolone 30 mg/kg). At the sixth hour of injury electrophysiological evaluations were conducted under anesthesia, and then rats were sacrificed for histopathology. Hematoxylin and eosin staining were applied to the specimens and evaluated under light microscopy. Etofenamate revealed more beneficial results in histopathological evaluations when compared with methylprednisolone, but these favorable results have not been confirmed by electrophysiological measurements. Etofenamate may be a promising agent in the medical treatment of spinal cord injury

Outcomes for revision total knee replacement after unicompartmental knee replacement

Objective: The aim of this retrospective, observational study was to describe the outcomes of total knee replacement (TKR) after failed Oxford phase 3 medial unicompartmental knee replacement (UKR). Methods: The study included 24 revision TKRs (20 females, 4 males; mean age: 61 years) performed following failed aseptic UKR. Outcomes were assessed using the Knee Society Score (KSS). Results: The most common causes for revision were mobile bearing dislocation and unexplained pain. Mean preoperative KSS was 50.3 (range: 37 to 66) and 82.2 (range: 58 to 97) after TKR. There were 17 excellent, 4 good, 2 fair and 1 poor results. Conclusion: The type of UKR performed (cemented versus uncemented) had no effect on TKR success. Revision for failed UKR with TKR appears to be a technically straightforward procedure with satisfactory early clinical results

Non-invasive detection and monitoring of experimental hydrocephalus with distortion product otoacoustic emissions

Objective: We aimed to find out the effects of short term and long term hydrocephalus and intracranial ventricular volume changes on cochlear functions by using distortion product otoacoustic emission (DPOAE) in experimental hydrocephalus rat models for the first time in literature. Methods: This study was performed with 48 healthy, adult (8 weeks old), Sprague–Dawley rats which weighed between 200 and 240 g. Six groups were formed in this study: short term control, short term sham, short term hydrocephalus, long term control, long term sham and long term hydrocephalus groups. Each group contained eight rats. Short term period was 4 weeks and long term period was 8 weeks after the study started. At the end of these periods, DPOAE measurements were performed and then rats were sacrificed to determine ventricular volumes. Results: DPOAE values at all frequencies were significantly decreased in the short term hydrocephalus group when compared to the short term control and short term sham groups. DPOAE values at all frequencies were significantly decreased in the long term hydrocephalus group when compared to the long term control and long term sham groups. Besides, long term sham group which had higher ventricular volumes than long term control group also had lower DPOAE measurements. Significant associations were present between DPOAE measurements and ventricular volumes in hydrocephalus models. Conclusion: The functional disturbances in cochlear functions due to hydrocephalus have been demonstrated with DPOAE measurements in this study. DPOAE measurements may be thought as an easily applicable non-invasive method in detection and follow-up of patients with hydrocephalus. Our findings should be supported with clinical studies in humans

Analysis of Patients Who Present to Emergency Departments During Ramadan

INTRODUCTION: Fasting is one of the five basic obligations of Islam. Muslims fast during the month of Ramadan according to the lunar calendar. Fasting during Ramadan involves abstinence from food and drinks from sunrise to sunset. The present study investigated the effect of fasting during Ramadan in patients who presented to emergency departments. Results of this study may guide healthcare authorities in countries that provide health services to Muslim communities because of increased migration. MATERIAL AND METHODS: This is the first prospective multicentre study to examine emergency department applications for Ramadan. The study was performed between 05.26.2017 and 06.24.2017. Patients were classified according to cardiopulmonary complaints, trauma-associated complaints, neurological complaints, gastrointestinal complaints, headache, renal colic, upper respiratory tract complaints, and malaise. Vital signs, age, gender, presentation type, complaint type, hospital stay duration, requested laboratory examination, radiological examination, treatment outcomes, application time, smoking status, and fasting status of the study patients were recorded by using a questionnaire. RESULTS: Fasting and non-fasting patients showed a significant difference with respect to presentation type, gastrointestinal complaints, upper respiratory tract complaints, hospitalization status, requested radiological and biochemical examinations, hospitalization duration, and application time (p < 0.05). CONCLUSIONS: To the authors’ knowledge, the present study is the first to compare the complaints of fasting and non-fasting patients during Ramadan. The authors feel that this study is superior to several previous studies because it has been performed using a different perspective and provides more accurate and objective data than those reported in previous studies

Measuring tactile sensitivity and mixed-reality-assisted exercise for carpal tunnel syndrome by ultrasound mid-air haptics

IntroductionCarpal tunnel syndrome (CTS) is the most common nerve entrapment neuropathy, which causes numbness and pain in the thumb, the index and middle fingers and the radial side of the ring finger. Regular hand exercises may improve the symptoms and prevent carpal tunnel surgery. This study applied a novel ultrasonic stimulation method to test tactile sensitivity in CTS and also a mixed-reality-assisted (MR-assisted) exercise program which measured hand movements and provided haptic feedback for rehabilitation.MethodsTwenty patients with mild unilateral CTS took part in the experiments. A mid-air haptics device (Ultrahaptics STRATOS Explore) was used to apply amplitude-modulated ultrasound waves (carrier frequency: 40 kHz) onto the skin to create tactile stimulation mechanically. Participants performed a two-alternative forced-choice task for measuring tactile thresholds at 250-Hz modulation frequency. They were tested at the index fingers and the thenar eminences of both hands. Additionally, 15 CTS patients used an MR-assisted program to do hand exercises with haptic feedback. Exercise performance was assessed by calculating errors between target and actual hand configurations. System Usability Scale (SUS) was adopted to verify the practical usability of the program.ResultsThresholds at the thenar eminences of the affected and healthy hands were not significantly different. While the thresholds at the healthy index fingers could be measured, those of the affected fingers were all higher than the stimulation level produced by the maximum output from the ultrasound device. In the exercise program, a significant positive correlation (ρ = 0.89, p < 0.001) was found between the performance scores and the SUS scores, which were above the criterion value established in the literature.DiscussionThe results show that thenar tactile sensitivity is not affected in mild CTS as expected from the palmar cutaneous branch of the median nerve (PCBm), but index finger threshold is likely to be higher. Overall, this study suggests that mid-air haptics, with certain improvements, may be used as a preliminary test in the clinical setting. Moreover, the device is promising to develop gamified rehabilitation programs and for the treatment follow-up of CTS

Maximizing the entropy of

histogram bar heights to explore neural activity: A simulation study on auditory and tactile fiber

Psychophysical detection and learning in freely behaving rats: a probabilistic dynamical model for operant conditioning

We present a stochastic learning model that combines the essential elements of Hebbian and Rescorla-Wagner theories for operant conditioning. The model was used to predict the behavioral data of rats performing a vibrotactile yes/no detection task. Probabilistic nature of learning was implemented by trial-by-trial variability in the random distributions of associative strengths between the sensory and the response representations. By using measures derived from log-likelihoods (corrected Akaike and Bayesian information criteria), the proposed model and its subtypes were compared with each other, and with previous models in the literature, including reinforcement learning model with softmax rule and drift diffusion model. The main difference between these models was the level of stochasticity which was implemented as associative variation or response selection. The proposed model with subject-dependent variance coefficient (SVC) and with trial-dependent variance coefficient (TVC) resulted in better trial-by-trial fits to experimental data than the other tested models based on information criteria. Additionally, surrogate data were simulated with estimated parameters and the performance of the models were compared based on psychophysical measures (A’: non-parametric sensitivity index, hits and false alarms on receiver operating characteristics). Especially the TVC model could produce psychophysical measures closer to those of the experimental data than the alternative models. The presented approach is novel for linking psychophysical response measures with learning in a yes/no detection task, and may be used in neural engineering applications. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.117F481; Boğaziçi Üniversitesi: 17XP2This study was supported by T?B?TAK Grant 117F481 within European Union?s FLAG-ERA JTC 2017 project GRAFIN and Bo?azi?i University BAP no: 17XP2 given to Dr. G??l?. We thank Bige Vardar and Sevgi ?zt?rk for their help in the experiments and comments on the Discussion section.This study was supported by TÜBİTAK Grant 117F481 within European Union’s FLAG-ERA JTC 2017 project GRAFIN and Boğaziçi University BAP no: 17XP2 given to Dr. Güçlü. We thank Bige Vardar and Sevgi Öztürk for their help in the experiments and comments on the Discussion section

Asymmetric response properties of rapidly adapting mechanoreceptive fibers in the rat glabrous skin

Previous histological and neurophysiological studies have shown that the innervation density of rapidly adapting (RA) mechanoreceptive fibers increases towards the fingertip. Since the psychophysical detection threshold depends on the contribution of several RA fibers, a high innervation density would imply lower thresholds. However, our previous human study showed that psychophysical detection thresholds for the Non-Pacinian I channel mediated by RA fibers do not improve towards the fingertip. By recording single-unit spike activity from rat RA fibers, here we tested the hypothesis that the responsiveness of RA fibers is asymmetric in the proximo-distal axis which may counterbalance the effects of innervation density. RA fibers (n = 32) innervating the digital glabrous skin of rat hind paw were stimulated with 40-Hz sinusoidal mechanical bursts at five different stimulus locations relative to the receptive field (RF) center (two distal, one RF center, two proximal). Different contactor sizes (area: 0.39, 1.63, 2.96 mm(2)) were used. Rate-intensity functions were constructed based on average firing rates, and the absolute spike threshold and the entrainment threshold were obtained for each RA fiber. Thresholds for proximal stimulus locations were found to be significantly higher than those for distal stimulus locations, which suggests that the mechanical stimulus is transmitted better towards the proximal direction. The effect of contactor size was not significant. Mechanical impedance of the rat digital glabrous skin was further measured and a lumped-parameter model was proposed to interpret the relationship between the asymmetric response properties of RA fibers and the mechanical properties of the skin.Bogazici University BAPBogazici University [10XP1]; Ministry of Development DPTTurkiye Cumhuriyeti Kalkinma Bakanligi [09K120520]We would like to thank Lorraine Pawson and Adam Pack from Syracuse University for helpful discussions. This study was supported by Bogazici University BAP no. 10XP1 and Ministry of Development DPT project no. 09K120520 to Burak Guclu

Vibrotactile Sensitivity of Freely Behaving Rats and Operant Conditioning by Intracortical Microstimulation

19th National Biomedical Engineering Meeting (BIYOMUT) -- NOV 05-06, 2015 -- Istanbul, TURKEYIn this study, 5 adult Wistar albino rats were trained to detect presence or absence of mechanical vibrations applied on the volar surface of their hindpaws. Vibrotactile sensitivity of glabrous skin of these rats were psychophysically tested at 3 frequencies. 3 out of 5 rats were implanted with microwire arrays in their primary somatosensory cortex hindpaw representation and trained to detect the presence or absence of electrical current pulses injected through these electrodes. Rats were psychophysically tested as in tactile experiments. The results indicate that intracortical microstimulation generates neural activity which results in similar psychophysical performance as in the tactile experiments. We are working to utilize this principle in somatosensory neuroprostheses