Witnessing quantum chaos using observational entropy.

We study observation entropy (OE) for the quantum kicked top model, whose classical counterpart possesses different phases: regular, mixed, or chaotic, depending on the strength of the kicking parameter. We show that OE grows logarithmically with coarse-graining length beyond a critical value in the regular phase, while OE growth is much faster in the chaotic regime. In the dynamics, we demonstrate that the short-time growth rate of OE acts as a measure of the chaoticity in the system, and we compare our results with out-of-time-ordered correlators (OTOC). Moreover, we show that in the deep quantum regime, the results obtained from OE are much more robust compared to OTOC results. Finally, we also investigate the long-time behavior of OE to distinguish between saddle-point scrambling and true chaos, where the former shows large persistent fluctuations compared to the latter.

Measures of Bipedal Toe-Ground Clearance Asymmetry to Characterize Gait in Stroke Survivors.

Post-stroke hemiparesis often impairs gait and increases the risks of falls. Low and variable Minimum Toe Clearance (MTC) from the ground during the swing phase of the gait cycle has been identified as a major cause of such falls. In this paper, we study MTC characteristics in 30 chronic stroke patients, extracted from gait patterns during treadmill walking, using infrared sensors and motion analysis camera units. We propose objective measures to quantify MTC asymmetry between the paretic and non-paretic limbs using Poincaré analysis. We show that these subject independent Gait Asymmetry Indices (GAIs) represent temporal variations of relative MTC differences between the two limbs and can distinguish between healthy and stroke participants. Compared to traditional measures of cross-correlation between the MTC of the two limbs, these measures are better suited to automate gait monitoring during stroke rehabilitation. Further, we explore possible clusters within the stroke data by analysing temporal dispersion of MTC features, which reveals that the proposed GAIs can also be potentially used to quantify the severity of lower limb hemiparesis in chronic stroke.

Upper limb movement profiles during spontaneous motion in acute stroke.

Objective.The clinical assessment of upper limb hemiparesis in acute stroke involves repeated manual examination of hand movements during instructed tasks. This process is labour-intensive and prone to human error as well as being strenuous for the patient. Wearable motion sensors can automate the process by measuring characteristics of hand activity. Existing work in this direction either uses multiple sensors or complex instructed movements, or analyzes only thequantityof upper limb motion. These methods are obtrusive and strenuous for acute stroke patients and are also sensitive to noise. In this work, we propose to use only two wrist-worn accelerometer sensors to study thequalityof completely spontaneous upper limb motion and investigate correlation with clinical scores for acute stroke care.Approach.The velocity time series estimated from acquired acceleration data during spontaneous motion is decomposed into smaller movement elements. Measures of density, duration and smoothness of these component elements are extracted and their disparity is studied across the two hands.Main results.Spontaneous upper limb motion in acute stroke can be decomposed into movement elements that resemble point-to-point reaching tasks. These elements are smoother and sparser in the normal hand than in the hemiparetic hand, and the amount of smoothness correlates with hemiparetic severity. Features characterizing the disparity of these movement elements between the two hands show statistical significance in differentiating mild-to-moderate and severe hemiparesis. Using data from 67 acute stroke patients, the proposed method can classify the two levels of hemiparetic severity with 85% accuracy. Additionally, compared to activity-based features, the proposed method is robust to the presence of noise in acquired data.Significance.This work demonstrates that the quality of upper limb motion can characterize and identify hemiparesis in stroke survivors. This is clinically significant towards the continuous automated assessment of hemiparesis in acute stroke using minimally intrusive wearable sensors.

Creating Ensembles of Dual Unitary and Maximally Entangling Quantum Evolutions.

Maximally entangled bipartite unitary operators or gates find various applications from quantum information to many-body physics wherein they are building blocks of minimal models of quantum chaos. In the latter case, they are referred to as "dual unitaries." Dual unitary operators that can create the maximum average entanglement when acting on product states have to satisfy additional constraints. These have been called "2-unitaries" and are examples of perfect tensors that can be used to construct absolutely maximally entangled states of four parties. Hitherto, no systematic method exists in any local dimension, which results in the formation of such special classes of unitary operators. We outline an iterative protocol, a nonlinear map on the space of unitary operators, that creates ensembles whose members are arbitrarily close to being dual unitaries. For qutrits and ququads we find that a slightly modified protocol yields a plethora of 2-unitaries.

Automated Scoring of Hemiparesis in Acute Stroke From Measures of Upper Limb Co-Ordination Using Wearable Accelerometry.

Stroke survivors usually experience paralysis in one half of the body, i.e., hemiparesis, and the upper limbs are severely affected. Continuous monitoring of hemiparesis progression hours after the stroke attack involves manual observation of upper limb movements by medical experts in the hospital. Hence it is resource and time intensive, in addition to being prone to human errors and inter-rater variability. Wearable devices have found significance in automated continuous monitoring of neurological disorders like stroke. In this paper, we use accelerometer signals acquired using wrist-worn devices to analyze upper limb movements and identify hemiparesis in acute stroke patients, while they perform a set of proposed spontaneous and instructed movements. We propose novel measures of time (and frequency) domain coherence between accelerometer data from two arms at different lags (and frequency bands). These measures correlate well with the clinical gold standard of measurement of hemiparetic severity in stroke, the National Institutes of Health Stroke Scale (NIHSS). The study, undertaken on 32 acute stroke patients with varying levels of hemiparesis and 15 healthy controls, validates the use of short length (< 10 minutes) accelerometry data to identify hemiparesis through leave-one-subject-out cross-validation based hierarchical discriminant analysis. The results indicate that the proposed approach can distinguish between controls, moderate and severe hemiparesis with an average accuracy of 91%.

Arytenoid cartilage feature point detection using laryngeal 3D CT images in Parkinson's disease.

Parkinson's disease is a neurodegenerative disorder that results in progressive degeneration of nerve cells. It is generally associated with the deficiency of dopamine, a neurotransmitter involved in motor control of humans and thus affects the motor system. This results in abnormal vocal fold movements in majority of the Parkinson's patients. Analysis of vocal fold abnormalities may provide useful information to assess the progress of Parkinson's disease. This is accomplished by measuring the distance between the arytenoid cartilages during phonation. In order to automate this process of identifying arytenoid cartilages from CT images, in this work, a rule-based approach is proposed to detect the arytenoid cartilage feature points on either side of the airway. The proposed technique detects feature points by localizing the anterior commissure and analyzing airway boundary pixels to select the optimal feature point based on detected pixels. The proposed approach achieved 83.33% accuracy in estimating clinically-relevant feature points, making the approach suitable for automated feature point detection. To the best of our knowledge, this is the first such approach to detect arytenoid cartilage feature points using laryngeal 3D CT images.

Crowd Event Detection on Optical Flow Manifolds.

Analyzing crowd events in a video is key to understanding the behavioral characteristics of people (humans). Detecting crowd events in videos is challenging because of articulated human movements and occlusions. The aim of this paper is to detect the events in a probabilistic framework for automatically interpreting the visual crowd behavior. In this paper, crowd event detection and classification in optical flow manifolds (OFMs) are addressed. A new algorithm to detect walking and running events has been proposed, which uses optical flow vector lengths in OFMs. Furthermore, a new algorithm to detect merging and splitting events has been proposed, which uses Riemannian connections in the optical flow bundle (OFB). The longest vector from the OFB provides a key feature for distinguishing walking and running events. Using a Riemannian connection, the optical flow vectors are parallel transported to localize the crowd groups. The geodesic lengths among the groups provide a criterion for merging and splitting events. Dispersion and evacuation events are jointly modeled from the walking/running and merging/splitting events. Our results show that the proposed approach delivers a comparable model to detect crowd events. Using the performance evaluation of tracking and surveillance 2009 dataset, the proposed method is shown to produce the best results in merging, splitting, and dispersion events, and comparable results in walking, running, and evacuation events when compared with other methods.

Automatic Detection and Classification of Convulsive Psychogenic Nonepileptic Seizures Using a Wearable Device.

Epilepsy is one of the most common neurological disorders and patients suffer from unprovoked seizures. In contrast, psychogenic nonepileptic seizures (PNES) are another class of seizures that are involuntary events not caused by abnormal electrical discharges but are a manifestation of psychological distress. The similarity of these two types of seizures poses diagnostic challenges that often leads in delayed diagnosis of PNES. Further, the diagnosis of PNES involves high-cost hospital admission and monitoring using video-electroencephalogram machines. A wearable device that can monitor the patient in natural setting is a desired solution for diagnosis of convulsive PNES. A wearable device with an accelerometer sensor is proposed as a new solution in the detection and diagnosis of PNES. The seizure detection algorithm and PNES classification algorithm are developed. The developed algorithms are tested on data collected from convulsive epileptic patients. A very high seizure detection rate is achieved with 100% sensitivity and few false alarms. A leave-one-out error of 6.67% is achieved in PNES classification, demonstrating the usefulness of wearable device in the diagnosis of PNES.

Classification of convulsive psychogenic non-epileptic seizures using histogram of oriented motion of accelerometry signals.

A seizure is caused due to sudden surge of electrical activity within the brain. There is another class of seizures called psychogenic non-epileptic seizure (PNES) that mimics epilepsy, but is caused due to underlying psychology. The diagnosis of PNES is done using video-electroencephalography monitoring (VEM), which is a resource intensive process. Recently, accelerometers have been shown to be effective in classification of epileptic and non-epileptic seizures. In this work, we propose a novel feature called histogram of oriented motion (HOOM) extracted from accelerometer signals for classification of convulsive PNES. An automated algorithm based on HOOM is proposed. The algorithm showed a high sensitivity of (93.33%) and an overall accuracy of (80%) in classifying convulsive PNES.

Direct C-2 arylation of 7-azaindoles: chemoselective access to multiarylated derivatives.

Pd-catalyzed direct C-H arylation of N-methyl-7-azaindole at the C-2 position by diverse arylboronic acids was achieved at room temperature. The method is general and was applied in chemoselective synthesis of multiarylated 7-azaindole derivatives bearing three different aryl groups at the 2, 3, and 5 positions.

A pilot study on the use of accelerometer sensors for monitoring post acute stroke patients.

The high incidence of stroke has raised a major concern among health professionals in recent years. Concerted efforts from medical and engineering communities are being exercised to tackle the problem at its early stage. In this direction, a pilot study to analyze and detect the affected arm of the stroke patient based on hand movements is presented. The premise is that the correlation of magnitude of the activities of the two arms vary significantly for stroke patients from controls. Further, the cross-correlation of right and left arms for three axes are differentiable for patients and controls. A total of 22 subjects (15 patients and 7 controls) were included in this study. An overall accuracy of 95.45% was obtained with sensitivity of 1 and specificity of 0.86 using correlation based method.

Motor recovery monitoring using acceleration measurements in post acute stroke patients.

BACKGROUND: Stroke is one of the major causes of morbidity and mortality. Its recovery and treatment depends on close clinical monitoring by a clinician especially during the first few hours after the onset of stroke. Patients who do not exhibit early motor recovery post thrombolysis may benefit from more aggressive treatment. METHOD: A novel approach for monitoring stroke during the first few hours after the onset of stroke using a wireless accelerometer based motor activity monitoring system is developed. It monitors the motor activity by measuring the acceleration of the arms in three axes. In the presented proof of concept study, the measured acceleration data is transferred wirelessly using iMote2 platform to the base station that is equipped with an online algorithm capable of calculating an index equivalent to the National Institute of Health Stroke Score (NIHSS) motor index. The system is developed by collecting data from 15 patients. RESULTS: We have successfully demonstrated an end-to-end stroke monitoring system reporting an accuracy of calculating stroke index of more than 80%, highest Cohen's overall agreement of 0.91 (with excellent κ coefficient of 0.76). CONCLUSION: A wireless accelerometer based 'hot stroke' monitoring system is developed to monitor the motor recovery in acute-stroke patients. It has been shown to monitor stroke patients continuously, which has not been possible so far with high reliability.

HBMMD: an enhanced database of the microorganisms associated with deeper water marine invertebrates.

The Harbor Branch Marine Microbial Database (HBMMD) provides preliminary taxonomic identifications and features of microorganisms maintained in the Harbor Branch Oceanographic Institution Marine Microbial Culture Collection. The microbes are primarily derived from marine invertebrates such as sponges (phylum Porifera) and soft corals (phylum Cnidaria) found in deep water environments [>120 feet (>35 m) seawater]. The microbes isolated from within marine invertebrates represent some unique taxa and phylogenetic signatures. The database provides a user-friendly method to systemically search or sort a desired input. The site allows a powerful search for multiple parameters of any entry. Images of the microbes are contained within the database and can be accessed from the website. The HBMMD homepage is located at http://www.hboi.edu/dbmr/dbmr_hbmmd.html.

Structural analysis of peptide helices containing centrally positioned lactic acid residues.

The effect of insertion of lactic acid (Lac) residues into peptide helices has been probed using specifically designed sequences. The crystal structures of 11-residue and 14-residue depsipeptides Boc-Val-Val-Ala-Leu-Val-Lac-Leu-Aib-Val-Ala-Leu-OMe (1) and Boc-Val-Ala-Leu-Aib-Val-Ala-Leu-Val-Lac-Leu-Aib-Val-Ala-Leu-OMe (3), containing centrally positioned Lac residues, have been determined. The structure of an 11-residue peptide Boc-Val-Ala-Leu-Aib-Val-Ala-Leu-Aib-Val-Ala-Leu-OMe (2), analog of a which is an amide previously determined Lac-containing depsipeptide, Boc-Val-Ala-Leu-Aib-Val-Lac-Leu-Aib-Val-Ala-Leu-OMe I. L. Karle, C. Das, and P. Balaram, Biopolymers, Vol. 59, (2001) pp. 276-289], is also reported. Peptide 1 adopts a helical fold, which is stabilized by mixture of 4-->1 and 5-->1 hydrogen bonds. Peptide 2 adopts a completely alpha-helical conformation stabilized by eight successive 5-->1 hydrogen bonds. Peptide 3 appears to be predominately alpha-helical, with seven 5-->1 hydrogen bonds and three 4-->1 interaction interspersed in the sequence. In the structure of peptide 3 in addition to water molecules in the head-to-tail region, hydration at an internal segment of the helix is also observed. A comparison of five related peptide helices, containing a single Lac residue, reveals that the hydroxy acid can be comfortably accommodated at interior positions in the helix, with the closest C=O...O distances lying between 2.8 and 3.3 A.

An unusual C-H...O hydrogen bond mediated reversal of polypeptide chain direction in a synthetic peptide helix.

An unusual C-terminal conformation has been detected in a synthetic decapeptide designed to analyze the stereochemistry of helix termination in polypeptides. The crystal structure of the decapeptide Boc-Leu-Aib-Val-Ala-Leu-Aib-Val-(D)Ala-(D)Leu-Aib-OMe reveals a helical segment spanning residues 1-7 and helix termination by formation of a Schellman motif, generated by (D)Ala(8) adopting the left-handed helical (alpha(L)) conformation. The extended conformation at (D)Leu(9) results in a compact folded structure, stabilized by a potentially strong C-H. O hydrogen bond between Ala(4) C(alpha)H and (D)Leu(9) CO. The parameters for C-H. O interaction are Ala(4) C(alpha)H. O=C (D)Leu(9) distance 3.27 A, C(alpha)-H. O angle 176 degrees, and O. H(alpha) distance 2.29 A. This structure suggests that insertion of contiguous D-residues may provide a handle for the generation of designed structures containing more than one helical segment folded in a compact manner.

Secretion of glutathione S-transferase isoforms in the seminiferous tubular fluid, tissue distribution and sex steroid binding by rat GSTM1.

The seminiferous tubular fluid (STF) provides the microenvironment necessary for spermatogenesis in the adluminal compartment of the seminiferous tubule (ST), primarily through secretions of the Sertoli cell. Earlier studies from this laboratory demonstrated the presence of glutathione S-transferase (GST) in STF collected from adult rat testis and in the spent media of ST cultures. This study describes the cellular source, isoform composition and possible function of GSTs in the STF. The major GST isoforms present in STF in vivo share extensive N-terminal similarity with rat GSTM1 (rGSTM1), rGSTM2, rGSTM3 and rGST-Alpha. Molecular masses of rGSTM2, rGSTM3 and rGST-Alpha from liver and testis sources were similar, unlike STF-GSTM1, which was larger by 325 Da than its liver counterpart. Peptide digest analysis profiles on reverse-phase HPLC between liver and STF isoforms were identical, and N-terminal sequences of selected peptides obtained by digestion of the various isoforms were closely similar. The above results confirmed close structural similarity between liver and STF-GST isoforms. Active synthesis and secretion of GSTs by the STs were evident from recovery of radiolabelled GST from the spent media of ST cultures. Analysis of secreted GST isoforms showed that GST-Alpha was not secreted by the STs in vitro, whereas there was an induction of GST-Pi secretion. Detection of immunostainable GST-Mu in Sertoli cells in vitro and during different stages of the seminiferous epithelium in vivo, coupled with the recovery of radiolabelled GST from Sertoli cell-culture media, provided evidence for Sertoli cells as secretors of GST. In addition, STF of 'Sertoli cell only' animals showed no change in the profile of GST isoform secretion, thereby confirming Sertoli cells as prime GST secretors. Non-recovery of [35S]methionine-labelled GSTs from germ cell culture supernatants, but their presence in germ cell lysates, confirm the ability of the germ cells to synthesize, but not to release, GSTs. Functionally, STF-GSTM1 appeared to serve as a steroid-binding protein by its ability to bind to testosterone and oestradiol, two important hormones in the ST that are essential for spermatogenesis, with binding constants of <9.8x10(-7) M for testosterone and 9x10(-6) M for oestradiol respectively.

Studies on glutathione S-transferases important for sperm function: evidence of catalytic activity-independent functions.

Our earlier studies reported the identification of a rat testicular protein of 24 kDa with significant similarity at the N-terminus with Mu class glutathione S-transferases (GSTs). Treatment of goat sperm with antisera against this protein identified immunoreactive sites on the spermatozoa and inhibited in vitro fertilization of goat oocytes by the antibody-treated sperm. The above observations indicated the presence of GST-like molecule(s) important for fertility related events on goat spermatozoa. In this study, we report the purification of goat sperm GSTs (GSP1) which were purified by glutathione affinity chromatography and were enzymically active towards 1-chloro-2,4,-dinitrobenzene, a general GST substrate, and ethacrynic acid, a substrate for Pi class GSTs. GSP1 resolved into three major components on reverse-phase HPLC: peaks 1 and 2 with molecular masses of 26.5 kDa and peak 3 with a molecular mass of 25.5 kDa, as determined by SDS/PAGE. Multiple attempts to obtain N-terminal sequences of the first two peaks failed, indicating N-terminal block; however, they reacted to specific anti-Mu-GST antisera on Western blots and ELISA, and not to anti-Pi-GST antisera, which provides evidence for the presence of Mu-GST-reactive sites on peaks 1 and 2. The third component showed 80% N-terminal similarity with human and rat GSTP1-1 over an overlap of 15 amino acids, and reacted to anti-Pi-specific antisera in ELISA. Sperm labelled with antibodies against a 10-mer and an 11-mer peptide, designed from the N-terminal sequences of Mu and Pi class GSTs respectively, showed the presence of both Mu- and Pi-GST on goat sperm surface at distinct cellular domains. Selective inhibition of Pi class GST by the Pi-specific antisera, either at 0 h or at 3 h after initiation of sperm capacitation, leads to a reduction in fertilization rates. In contrast, the inhibition of Mu class GST by specific antisera at 0 h does not inhibit fertilization, although such treatment at 3 h after the initiation of capacitation reduces fertilization rates. The results indicate that both Pi- and Mu-GSTs are involved in fertilization, but the Mu-GST sites essential for fertilization are exposed only after 3 h of capacitation. The enzymic activity of GSP1 or live spermatozoa is not inhibited by the two antisera. The inability of the antibodies to cause such inhibition indicates that the reduction in fertilization rates and acrosome reaction caused by the antibodies is through a mechanism which does not interfere with the catalytic activity of the molecule. Therefore we established the presence of Pi and Mu class GST on goat sperm, their localization and their possible function in fertility-related events.

A testicular protein important for fertility has glutathione S-transferase activity and is localized extracellularly in the seminiferous tubules.

A 24-kDa protein isolated by preparative gel electrophoresis from rat testes was reported by us as an active immunogen in rats. Anti-24-kDa antibodies inhibited murine sperm-oocyte binding in vitro. Here, we show similarity at the NH2 terminus shared by this protein purified on Sephadex G-75 followed by anion exchange high performance liquid chromatography with glutathione S-transferase (GST)-mu subunits. This protein purified by glutathione affinity chromatography also demonstrated similarity to GST-mu NH2 terminus in a 30-amino-acid overlap. Both proteins showed activity toward the GST substrate 1-chloro-2,4-dinitrobenzene (Km of 33 microM and 50 microM) which was inhibited by 17 beta-estradiol 3-sulfate. Antisera against both proteins recognized liver GST-mu on Western blots and sperm acrosome of multiple species immunocytochemically. Both antisera significantly inhibited in vitro fertilization of goat oocytes by sperm preincubated with them while anti-liver GST sera did not. GST activity was localized on rat sperm, seminiferous tubular fluid, and Sertoli cells. Seminiferous tubular fluid 24-kDa protein shared similarity to the NH2 terminus of GST-mu subunits in a 20-amino-acid overlap. Time-dependent accumulation of GST was detected in the spent culture medium of seminiferous tubules from rats of different ages suggesting secretion.