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Joint Kinetics Of The Ankle And Knee When Running Over Obstacles, Alan Hreljac, Nikolaos Stergiou, Shane D. Scholten

Journal Articles

When running over obstacles of increasing height, heelstrike runners switch to a forefoot landing pattern once a critical obstacle height is reached. The primary purpose of this study was to determine whether ankle or knee joint kinetic variables trigger the gait change from a heelstrike to a forefoot striking pattern as obstacle height increases. Ten subjects were filmed from the sagittal plane as they ran at their preferred running speed over a force platform during six obstacle height conditions ranging from 10% to 22.5% of standing height, as well as an additional baseline condition with no obstacle (0%). An inverse …

A Nonlinear Dynamic Approach For Evaluating Postural Control, James T. Cavanaugh, Kevin M. Guskiewicz, Nikolaos Stergiou

Journal Articles

Recent research suggests that traditional biomechanical models of postural stability do not fully characterise the nonlinear properties of postural control. In sports medicine, this limitation is manifest in the postural steadiness assessment approach, which may not be sufficient for detecting the presence of subtle physiological change after injury. The limitation is especially relevant given that return-to-play decisions are being made based on assessment results. This update first reviews the theoretical foundation and limitations of the traditional postural stability paradigm. It then offers, using the clinical example of athletes recovering from cerebral concussion, an alternative theoretical proposition for measuring changes in …

Excessive Tibial Rotation During High-Demand Activities Is Not Restored By Anterior Cruciate Ligament Reconstruction, Stavros Ristanis, Nikolaos Stergiou, Kostas Patras, Haris S. Vasiliadis, Giannis Giakas, Anastasios D. Georgoulis

Journal Articles

Purpose: Recent in vitro research has suggested that anterior cruciate ligament (ACL) reconstruction does not restore control of tibial rotation. The purpose of this study was to explore these findings in vivo and investigate rotational knee stability during landing and subsequent pivoting. Such an activity places higher demands on the knee, almost similar to those found during high-level sports.

Type of Study: Case control series study.

Methods: We assessed 11 patients who had undergone ACL reconstruction with the same arthroscopic technique using a bone–patellar tendon–bone graft, 11 ACL-deficient subjects who had sustained the injury more than 1 year prior to …

A Method Of Precise Mrna/Dna Homology-Based Gene Structure Prediction, Alexander Churbanov, Mark Pauley, Daniel Quest, Hesham Ali

Information Systems and Quantitative Analysis Faculty Publications

Background: Accurate and automatic gene finding and structural prediction is a common problem in bioinformatics, and applications need to be capable of handling non-canonical splice sites, microexons and partial gene structure predictions that span across several genomic clones.

Results: We present a mRNA/DNA homology based gene structure prediction tool, GIGOgene. We use a new affine gap penalty splice-enhanced global alignment algorithm running in linear memory for a high quality annotation of splice sites. Our tool includes a novel algorithm to assemble partial gene structure predictions using interval graphs. GIGOgene exhibited a sensitivity of 99.08% and a specificity of 99.98% on …

Evolutionary Conservation Suggests A Regulatory Function Of Aug Triplets In 50 -Utrs Of Eukaryotic Genes, Alexander Churbanov, Igor B. Rogozin, Vladimir N. Babenko, Hesham Ali, Eugene V. Koonin

Information Systems and Quantitative Analysis Faculty Publications

By comparing sequences of human, mouse and rat orthologous genes, we show that in 50 -untranslated regions (50 -UTRs) of mammalian cDNAs but not in 30 - UTRs or coding sequences, AUG is conserved to a significantly greater extent than any of the other 63 nt triplets. This effect is likely to reflect, primarily, bona fide evolutionary conservation, rather than cDNA annotation artifacts, because the excess of conserved upstream AUGs (uAUGs) is seen in 50 -UTRs containing stop codons in-frame with the start AUG and many of the conserved AUGs are found in different frames, consistent with the location in …

An Artificial Neural Network That Utilizes Hip Joint Actuations To Control Bifurcations And Chaos In A Passive Dynamic Bipedal Walking Model, Max J. Kurz, Nikolaos Stergiou

Journal Articles

Chaos is a central feature of human locomotion and has been suggested to be a window to the control mechanisms of locomotion. In this investigation, we explored how the principles of chaos can be used to control locomotion with a passive dynamic bipedal walking model that has a chaotic gait pattern. Our control scheme was based on the scientific evidence that slight perturbations to the unstable manifolds of points in a chaotic system will promote the transition to new stable behaviors embedded in the rich chaotic attractor. Here we demonstrate that hip joint actuations during the swing phase can provide …

Electromechanical Delay Of The Knee Extensor Muscles Is Not Altered After Harvesting The Patellar Tendon As A Graft For Acl Reconstruction: Implications For Sports Performance, Anastasios D. Georgoulis, Stavros Ristanis, Anastasios Papadonikolakis, Elias Tsepis, U. Moebius

Journal Articles

Although the scar tissue, which heals the donor site defect, has different elasticity from the neighbouring patellar tissue, it remains unclear if this scar tissue can lead to the changes of the electromechanical delay (EMD) of the knee extensor muscles. If such changes do exist, they can possibly affect both the utilization of the stored energy in the series elastic component, as well as the optimal performance of the knee joint movement. The purpose of this study was to investigate the influence of harvesting the patellar tendon during anterior cruciate ligament (ACL) reconstruction and the associated patellar tendon scar tissue …

Anterior Cruciate Ligament Reconstruction With A Quadrupled Hamstring Autograft Does Not Restore Tibial Rotation, Anastasios D. Georgoulis, Stavros Ristanis, Vasilis Chouliaras, Constantina O. Moraiti, Nikolaos Stergiou

Journal Articles

As a result of the morbidity associated with anterior cruciate ligament (ACL) reconstruction with a bone–patellar–tendon– bone graft, many orthopaedic surgeons prefer hamstrings as the graft for ACL reconstruction. However, this selection is not based on solid scientific evidence. In vitro research shows that this graft cannot restore control of tibial rotation. Our recent in vivo research work has also demonstrated the same result. In particular, patients undergoing ACL repair who were reconstructed with a quadrupled hamstring tendon graft showed excessive tibial rotation during a dynamic activity when compared with healthy control subjects. Although the hamstring tendon graft has a …

Using Three Dimensional Motion Capture Technology To Describe And Assess Piano Technique: A Case Study, Brenda Wristen, Nikolaos Stergiou, Sharon Evans

Health and Kinesiology Faculty Proceedings & Presentations

The purpose of the study was to examine any differences that exist in the quality of motions employed by pianists when they are sight-reading versus performing repertoire. A secondary question of interest was whether or not an improvement in the efficiency of motion could be observed between two sight-reading trials of the same musical excerpt. While data analysis for the full study is ongoing, the following results from a case study are illustrative.

Using Three Dimensional Motion Capture Technology To Describe And Assess Piano Technique: A Case Study, Brenda Wristen, Nikolaos Stergiou, Sharon Evans

Journal Articles

The purpose of the study was to examine any differences that exist in the quality of motions employed by pianists when they are sight-reading versus performing repertoire. A secondary question of interest was whether or not an improvement in the efficiency of motion could be observed between two sight-reading trials of the same musical excerpt. While data analysis for the full study is ongoing, the following results from a case study are illustrative.

Physiological Profile Of Olympic Style Tae Kwon Do Match, Georgios C. Korellis

Student Work

Olympic style Tae Kwon Do training may achieve accepted training intensity threshold for effective aerobic capacity training, energy expenditure thresholds and elevation in excess post-exercise oxygen consumption. Little work regarding the acute metabolic demands during Olympic style Tae Kwon Do competition has been done before. The purpose of this study was to examine the physiological demands of a match in Olympic style Tae Kwon Do. Physiological assessment included measurement of oxygen uptake (V 02), heart rate (HR), blood lactate concentration (BL), rate of perceived exertion (RPE) and body temperature (BT).

A total of 7 subjects between the ages of 19 …

Acute Physiological Responses And Psychological Perceptions Of Various Resistance Training Regimens, William J. Vincent

Student Work

The purpose of the current study was to examine the effects of four different resistance training protocols associated with periodization of resistance training on the biological signals that are associated with exercise regimens to increase muscle hypertrophy. A secondary purpose was to compare the ratings of perceived exertion (RPE) in the four weight training regimens.

A total of eight male resistance trainers within the ages of 23-35 served as subjects for this study. On the first visit all had a baseline blood assay drawn to measure human growth hormone (hGH) and testosterone (T) and their 5 repetition maximum (RM) strength …

The Effect Of Anterior Cruciate Ligament Recontruction On Lower Extremity Relative Phase Dynamics During Walking And Running, Max J. Kurz, Nikolaos Stergiou, Ugo H. Buzzi, Anastasios D. Georgoulis

Journal Articles

The purpose of this investigation was to use relative phase dynamics to evaluate gait in individuals with a reconstructed anterior cruciate ligament (ACL) during walking and running. Relative phase dynamics can describe the coordination strategies between the interacting segments at the lower extremity. Ten subjects who had undergone ACL reconstruction using the central third of their patellar tendon and ten healthy controls walked and ran on a treadmill at a self-selected pace. Relative phase dynamics were calculated for the foot–shank and shank–thigh coordinative relation- ships. Statistical differences between the groups were noted for the foot– shank relationship (p<0.05) during both walking and running and for the shank–thigh relationship (p<0.05) during walking. Our results indicate that current ACL reconstructive techniques may result in altered relative phase dynamics. These changes in relative phase dynamics could be related to a loss of sensory information about joint position and velocity that is typically provided by the intact ACL. Additionally, relative phase adaptations could be a learned response from the early stages of postsurgical rehabilitation. Relative phase dynamics provide quantitative information about the dynamic status of the ACL-reconstructed knee that cannot be gained from the conventional time-series evaluation of gait analysis data. Relative phase dynamics measures should supplement the conventional gait analysis measures that are used today for the clinical evaluation of the functional dynamic stability of the reconstructed knee. The examination of relative phase dynamics could be clinically important for the quantification of new ACL surgical interventions and of patient performance at various stages of rehabilitation. Further research should incorporate relative phase dynamics to understand the influence of ACL reconstruction on coordination and functional patient outcomes.

Hper Biomechanics Laboratory 2004 Annual Report: A Surveillance Of The Neuromuscular System, Issue 3, Nebraska Biomechanics Core Facility

Biomechanics Annual Report

This issue features 2004 - A Great Year for External Funding: Three Grants Awarded to Dr. Stergiou, Robotic Surgery Research is Funded by the Nebraska Research Initiative, Federal Grant is Awarded for the Study of the Development of Posture in Children with Cerebral Palsy, The Nebraska Research Initiative funds our Innovative Research in Gait Analysis, Collaboration with the Department of Surgery of the University of Nebraska Medical Center on the Effects of Peripheral Arterial Disease on Gait, Omaha Media Features Nicholas Stergiou, Dr. Stergiou participates in an NIH Review Panel, Prestigious Teaching Award for Dr. Stergiou, NASA Visits HPER Biomechanics …

Baseline Measures Are Altered In Biomechanical Studies, Nikolaos Stergiou, Melissa Scott

Journal Articles

The purpose of this investigation was to examine if baseline measures are altered between conditions in biomechanical studies and to determine the need for baseline measurements in biomechanics. Ten runners were asked to run at varying speeds and obstacle heights. Baseline measures were acquired between all conditions. Right lower extremity kinematic and kinetic data were collected for all baseline trials and evaluated by both a group and a single subject analysis. The group analysis revealed significant differences between baselines only for the obstacle perturbation. The single subject analysis indicated that baseline measures are altered in a greater degree for kinematics …

Detecting Altered Postural Control After Cerebral Concussion In Athletes With Normal Postural Stability, James T. Cavanaugh, Kevin M. Guskiewicz, Carol Giuliani, Stephen Marshall, Vicki S. Mercer, Nikolaos Stergiou

Journal Articles

Objective: To determine if approximate entropy (ApEn), a regularity statistic from non-linear dynamics, could detect changes in postural control during quiet standing in athletes with normal postural stability after cerebral concussion.

Methods: The study was a retrospective, case series analysis of centre of pressure (COP) data collected during the Sensory Organization Test (SOT) from NCAA Division I (USA) athletes prior to and within 48 h after injury. Subjects were 21 male and six female athletes from a variety of sports who sustained a cerebral concussion between 1997 and 2003. After injury, athletes displayed normal postural stability equivalent to preseason levels. …

Robotic Surgery Training And Performance, Kenji Narazaki, D. Oleynikov, Nikolaos Stergiou

Journal Articles

Background: To understand the process of skill acquisition in robotic surgery and to allow useful real-time feedback to surgeons and trainees in future generations of robotic surgical systems, robotic surgical skills should be determined with objective variables. The aim of this study was to assess skill acquisition through a training protocol, and to identify variables for the quantification of proficiency.

Methods: Seven novice users of the da Vinci Surgical System engaged in 4 weeks of training that involved practicing three bimanual tasks with the system. Seven variables were determined for assessing speed of performance, bimanual coordination, and muscular activation. These …

A Template For The Exploration Of Chaotic Locomotive Patterns, Max J. Kurz, Nikolaos Stergiou, Jack Heidel, E. Terry Foster

Journal Articles

Inverted pendulum and spring-mass models have been successfully used to explore the dynamics of the lower extremity for animal and human locomotion. These models have been classified as templates that describe the biomechanics of locomotion. A template is a simple model with all the joint complexities, muscles and neurons of the locomotor system removed. Such templates relate well to the observed locomotive patterns and provide reference points for the development of more elaborate dynamical systems. In this investigation, we explored if a passive dynamic double pendulum walking model, that walks down a slightly sloped surface (γγ was increased, …

Medicine Meets Virtual Reality 14, James D. Westwood, Timothy N. Judkins, D. Oleynikov, Nikolaos Stergiou

Faculty Books and Monographs

Chapter, Real-Time Augmented Feedback Benefits Robotic Laparoscopic Training, co-authored by Nicholas Steriou, UNO faculty member.

Machine intelligence will eclipse human intelligence within the next few decades - extrapolating from Moore’s Law - and our world will enjoy limitless computational power and ubiquitous data networks. Today’s iPod® devices portend an era when biology and information technology will fuse to create a human experience radically different from our own. Already, our healthcare system now appears on the verge of crisis; accelerating change is part of the problem. Each technological upgrade demands an investment of education and money, and a costly infrastructure more …

Plant Composition Of Mixed-Grass Prairie Of Cedar Point Biological Research Station, Keith County, Nebraska, David A. Mckenzie

Biology Faculty Publications

This study involved a vegetation analysis of 15 permanent plots established on the short-grass and mixed grass prairie slopes at the Cedar Point Biological Station in Keith County, Nebraska. Ninety-nine species were found in the plots, including members of 75 genera and 31 families. Twenty-one were graminoids, 71 were forbs or succulents, 6 were shrubs and one was a tree. Bouteloua gracilis (19 % cover) and Carex filifolia (15 % cover) were the dominant graminoids at the site, while Yucca glauca (1% cover) and Artemisia frigida (1% cover) were the most frequent forbs. Comparisons of species richness by slope categories …

Three-Dimensional Kinematics Of The Tibiofemoral Joint In Acl-Deficient And Reconstructed Patients Shows Increased Tibial Rotation, Anastasios D. Georgoulis, Stavros Ristanis, Constantina O. Moraiti, Argyris Mitsou, Manfred Bernard, Nikolaos Stergiou

Journal Articles

The study of the altered knee joint movement patterns that follow anterior cruciate ligament (ACL) rupture can be very insightful in the development of prevention and therapeutic strategies concerning this injury. This can be achieved through three-dimensional kinematic analysis, because it provides an objective evaluation in vivo of the knee joint function. It has been demonstrated that ACL-deficient patients develop functional adaptations (ie, quadriceps avoidance gait) and walk with the knee in a more extended position to compensate for the ACL loss. Furthermore, it has been shown that ACL rupture results in anterior tibial translation and excessive tibial rotation while …