551 research outputs found
Investigating the effects of recency and size of training text on author recognition problem
No full text19th International Symposium on Computer and Information Sciences (ISCIS 2004) -- OCT 27-29, 2004 -- Kemer Antalya, TURKEYPrediction by partial match (PPM) is an effective tool to address the author recognition problem. In this study, we have successfully applied the trained PPM technique for author recognition on Turkish texts. Furthermore, we have investigated the effects of recency, as well as size of the training text on the performance of the PPM approach. Results show that, more recent and larger training texts help decrease the compression rate, which, in turn, leads to increased success in author recognition. Comparing the effects of the recency and the size of the training text, we see that the size factor plays a more dominant role on the performance.Bilkent Univ, Dept Comp Engn, Inst Elect & Elect Engineers Turkey Sect, Working Grp, Int Federat Informat Proc, Sci & Tech Res Council Turke
Systematic Design of a Cross-Polarized Dermoscope for Visual Inspection and Digital Imaging
No full textadermoscope is a diagnostic device that can image the skin in situ and is used for early diagnosis of melanoma and pigmented skin lesions. In this paper, we describe the design and construction of a cross-polarized dermoscope including the illumination evaluation, imaging design, and the mechanical setup. By using the cross-polarization dermoscope, specular reflection from the superficial layer of the skin is largely eliminated. Therefore, deeper layers of the skin, such as the inner pigments and the capillary blood vessels, can be visualized.Engineering, Electrical & ElectronicInstruments & InstrumentationSCI(E)0ARTICLE626-311
A new strategy for parameter optimization to improve phase-dependent locomotion mode recognition
No full textPhase-dependent recognition strategy is an effective approach for lower-limb locomotion mode recognition. However, in previous studies, classifiers, feature sets and other parameters for the classification are the same for all the phases. The potential of this method could therefore be limited, as movement characteristics of different phases are not the same. In this paper, we aim to further improve phase-dependent recognition by proposing a new parameter optimization strategy which optimizes classifier, feature set and window size individually for each phase. Seven able-bodied subjects and one transtibial amputee subject are recruited in this research and they are required to perform six kinds of locomotion tasks. Signals recorded from two inertial measurement units and one pressure insole of the measured side are used for feature set calculation. And phase-dependent recognition method with four phases defined is applied for locomotion mode identification. The proposed strategy for parameter optimization is proved to be more efficient than the conventional optimization strategy by providing better overall recognition performance and lower computation burden. (C) 2014 Elsevier B.V. All rights reserved.Computer Science, Artificial IntelligenceSCI(E)[email protected]
Disturbance rejection of Central Pattern Generator based torque-stiffness-controlled dynamic walking
No full textThe concept of torque-stiffness-controlled dynamic walking expands the applicability of passivity-based bipeds while preserving energetic efficiency due to the addition of controllable stiffness. Central Pattern Generator (CPG) based approach introduces limb coordination and simplifies the control structure. In this paper, we study the disturbance rejection of torque-stiffness-controlled bipedal walking with CPGs. To evaluate the performance of rejecting disturbance, we study the locomotion under a perturbation torque and the walking performance on uneven terrains. In simulations, the performance of CPG-controlled walkers is compared with that of walkers without CPG, to study the impacts of CPG-based control. We also analyze the performance under different actuation parameters to clarify the effects of joint torque and joint stiffness on rejecting disturbances. The results may help better understand the flexible human gaits and build stable walking robots adapt to unpredictable environments. (C) 2015 Elsevier B.V. All rights reserved.SCI(E)[email protected]
Combining Vibrotactile Feedback with Volitional Myoelectric Control for Robotic Transtibial Prostheses
No full textIn recent years, the development of myoelectric control for robotic lower-limb prostheses makes it possible for amputee users to volitionally control prosthetic joints. However, the human-centered control loop is not closed due to the lack of sufficient feedback of prosthetic joint movement, and it may result in poor control performance. In this research, we propose a vibrotactile stimulation system to provide the feedback of ankle joint position, and validate the necessity of combining it with volitional myoelectric control to achieve improved control performance. The stimulation system is wearable and consists of six vibrators. Three of the vibrators are placed on the anterior side of the thigh and the other three on the posterior side of the thigh. To explore the potential of applying the proposed vibrotactile feedback system for prosthetic ankle control, eight able-bodied subjects and two transtibial amputee subjects (TT1 and TT2) were recruited in this research, and several experiments were designed to investigate subjects' sensitivities to discrete and continuous vibration stimulations applied on the thigh. Then, we proposed a stimulation controller to produce different stimulation patterns according to current ankle angle. Amputee subjects were asked to control a virtual ankle displayed on the computer screen to reach different target ankle angles with a myoelectric controller, and control performances under different feedback conditions were compared. Experimental results indicated that subjects were more sensitive to stimulation position changes (identification accuracies were 96.39pm0.86%, 91.11% and 93.89% for able-bodied subjects, TT1 and TT2, respectively) than stimulation amplitude changes (identification accuracies were 89.89pm2.40%, 87.04% and 85.19% for able-bodied subjects, TT1 and TT2, respectively). Response times of able-bodied subjects, TT1 and TT2 to stimulation pattern changes were 0.47pm0.02s, 0.53s and 0.48s, respectively. Furthermore, for both TT1 and TT2, the absolute error of virtual ankle control reduced by about 50% with the addition of vibrotactile feedback. These results suggest that it is promising to apply the vibrotactile feedback system for the control of robotic transtibial prostheses
Ischemic tolerance following low dose NMDA involves modulation of cellular stress proteins
No full textMild NMDA receptor activation is correlated with neuroprotection in models of cerebral ischemia. Neuroprotection with NMDA manifests as a form of ischemic tolerance and involves the induction of cellular stress systems sensitive to disturbances in cellular calcium homeostasis. Unilateral micro-injection of 10, 160 and 320 microM NMDA into the prefrontal cortex of a rat 30 min prior to permanent occlusion of the middle cerebral artery (MCAO) significantly reduced the area of infarct observed after 4 h of ischemia. The highest dose of NMDA (320 microM) prevented the propagation of ischemic damage through a direct toxicity on neuronal tissue adjacent to the injection site as demonstrated in thionin-stained sections. As a result, the degree of ischemia-induced damage was similar to that measured in rats pretreated with the low dose of NMDA (10 microM). Expression of heat shock protein (HSP) 70 and glucose-regulated protein (GRP) 94 in cortical samples taken from the region of infarct following MCAO was significantly reduced in rats pretreated with 10 microM NMDA compared to saline-injected control rats and rats pretreated with higher doses of NMDA. Furthermore, 10 microM NMDA did not appear to influence expression of m-calpain or GRP78, however, higher doses of NMDA did significantly induce expression of both proteins as assessed by Western blotting. In summary, our data demonstrate an in vivo rodent model of ischemic tolerance in which 30 min of neuronal preconditioning with 10 microM NMDA confers protection against a 4 h period of MCAO-induced ischemia. This effect may involve modulation of cellular stress signals, in particular HSP70 and GRP94.Accession Number: 18992720 Language: English. Date Created: 20081216. Update Code: 20081218. Publication Type: Journal Article; Research Support, Non-U.S. Gov't. Journal ID: 0045503. Publication Model: Print-Electronic. Cited Medium: Internet. NLM ISO Abbr: Brain Res.Source type: Electronic(1)http://search.ebscohost.com/login.aspx?direct=true&db=cmedm&AN=18992720&loginpage=login.asp&site=ehost-liv
A genetic variation map for chicken with 2.8 million single-nucleotide polymorphisms
No full textWe describe a genetic variation map for the chicken genome containing 2.8 million single-nucleotide polymorphisms (SNPs). This map is based on a comparison of the sequences of three domestic chicken breeds (a broiler, a layer and a Chinese silkie) with that of their wild ancestor, red jungle fowl. Subsequent experiments indicate that at least 90% of the variant sites are true SNPs, and at least 70% are common SNPs that segregate in many domestic breeds. Mean nucleotide diversity is about five SNPs per kilobase for almost every possible comparison between red jungle fowl and domestic lines, between two different domestic lines, and within domestic lines--in contrast to the notion that domestic animals are highly inbred relative to their wild ancestors. In fact, most of the SNPs originated before domestication, and there is little evidence of selective sweeps for adaptive alleles on length scales greater than 100 kilobases
Adaptive Slope Walking With a Robotic Transtibial Prosthesis Based on Volitional EMG Control
No full textAllowing amputees to volitionally control robotic prostheses can improve the adaptability to terrain changes. In this paper, we propose a myoelectric controller for a robotic transtibial prosthesis to realize adaptive slope walking. It works together with the intrinsic controller, enabling amputee users to pay relatively less attention on myoelectric control during walking. Amputee users convey the information of ground slope to prostheses by consciously performing dorsiflexion and plantar flexion of the "phantom ankle" with different intensities at the beginning of the swing phase. Two channels of surface electromyographic signals are measured from the residual shank, and they are mapped to the inclination angle of the slope. Control parameters of the intrinsic controller are then calculated according to the estimated inclination angle. In this preliminary study, two transtibial amputee subjects were recruited. They were asked to convey six targeted inclination angles (+/- 5 degrees, +/- 10 degrees, and +/- 15 degrees) to the prosthesis with the trained myoelectric controller during level-ground walking, and satisfactory control performance was achieved. This experiment was designed to simulate the scenario of transiting from level-ground walking to slope walking. Experimental results of controlling the robotic prosthesis to walk on level ground and slopes further verified that it is promising for amputees to adaptively walk on the ground with varied inclination angles in daily life.R&D Project of the Beijing Disabled Persons' Federation; National Natural Science Foundation of China [61005082, 61020106005]; Beijing Nova Program [Z141101001814001]; PKU-Biomedical Engineering Joint Seed Grant; 985 Project of Peking University [3J0865600]SCI(E)[email protected]; [email protected]; [email protected]
Predict the effects of dolutegravir (DTG) plus lamivudine (3TC) on immunological responses in people living with HIV (PLWHIV)
No full textProducción CientíficaBackground: Immune recovery in people living with HIV (PLWHIV) is a residual aspect of antiretroviral treatment (ART) in most patients, but in a non-negligible proportion of them, the CD4+ lymphocytes count, or CD4/CD8 ratio remains suboptimal. Methods: We performed a model of the immune response after 24 weeks of switching to a 2DR with DTG plus 3TC in a retrospective multicenter cohort of undetectable and experienced patients using significant predictor variables associated with the parameters or situations defined as success and failure. Clinical variables studied were CD4+ and CD8+ lymphocyte count, percentage of CD4, and CD4/CD8 ratio. These parameters were assessed at baseline and 24 weeks after the switch. Based on the evolution of each variable, four categories of immune response and four categories of non-immune response were defined. Immune response was defined as CD4+ count > 500 cells/mm3, %CD4 > 30%, CD8+ count 500 cells/mm3 (p = 0.054); CD4 > 30% (p = 0.054, p = 0.084); CD8 < 1000 cells/mm3 (p = 0.018), and CD4/CD8 ≥ 0.9 (p = 0.013, p = 0.09) are detected as stimulating or conducive to DTG plus 3TC treatment success. Conclusion: These models represent a proof of concept that could become a valuable tool for clinicians to predict the effects of DTG plus 3TC on immunological responses prior to the switch in undetectable pre-treated PLWHIV with immune dysfunction. The main predictors for immunological failure were late HIV diagnosis, stage of AIDS, and current age over 50 years. In contrast, starting with a normalized immune status was detected as stimulating or conducive to DTG plus 3TC treatment success
Combining Human Volitional Control with Intrinsic Controller on Robotic Prosthesis: A Case Study on Adaptive Slope Walking
No full textAffording lower-limb amputees the ability to volitionally control robotic prostheses can improve the adaptability to terrain changes as well as enhancing proprioception. However, it also increases amputees' conscious burdens for prosthesis control. Therefore, in this paper, we aim to propose a hybrid controller which combines human volitional control with the intrinsic controller on the robotic transtibial prosthesis, enabling the amputee actively controlling prosthesis with little conscious attention. In this preliminary study, a hybrid controller for adaptive slope walking was designed. A slope estimator was embedded in the intrinsic controller to estimate the ground slope of the previous step using signals measured by prosthetic sensors. And a myoelectric controller allows the amputee subject to convey slope changes to prosthetic controller by volitionally contract his residual muscles, whose electromyography signals were mapped to the slope increment. The hybrid controller combined these two results to obtain the estimated slope. One male transtibial amputee subject was recruited in this research. Experiment results showed that the intrinsic slope estimator produced satisfactory estimation results with an average absolute error of 0 : 7 0 +/- 0 : 5 4 degrees. By adding amputee's volitional control, the hybrid controller is able to predict the upcoming slope changes.EICPCI-S(ISTP)[email protected]
- …
