Changes In Frequency Distribution Research Articles

Alternate Electrode Placements to Facilitate Frontal Electroencephalography Monitoring in Anesthetized and Critically Ill Patients.

Frontal electroencephalography (EEG) monitoring can be useful in guiding the titration of anesthetics, but it is not always feasible to place electrodes in the standard configuration in some circumstances, including during neurosurgery. This study compares 5 alternate configurations of the Masimo Sedline Sensor. Ten stably sedated patients in the intensive care unit were recruited. Frontal EEG was monitored in the standard configuration (bifrontal upright) and 5 alternate configurations: bifrontal inverse, infraorbital, lateral upright, lateral inverse, and semilateral. Average power spectral densities (PSDs) with 95% CIs in the alternate configurations were compared to PSDs in the standard configuration. Two-one-sided-testing with Wilcoxon signed-rank tests assessed equivalence in the spectral edge frequency (SEF-95), EEG power, and relative delta (0.5 to 3.5Hz), alpha (8 to 12Hz), and beta (20 to 30Hz) power between each alternate and standard configurations. After the removal of unanalyzable tracings, 7 patients were included for analysis in the infraorbital configuration and 9 in all other configurations. In the lateral upright and lateral inverse configurations, PSDs significantly differed from the standard configuration within the 15 to 20Hz band. The greatest decrease in EEG power was in the lateral inverse configuration (median: -97dB; IQR: -130, -62dB). The largest change in frequency distribution of EEG power was in the infraorbital configuration; median SEF-95 change of -1.4Hz (IQR: -2.8, 0.7Hz), median relative delta power change of +7.3% (IQR: 1.4%, 7.9%), and median relative alpha power change of -0.6% (IQR: -5.7%, 0.0%). These 5 alternate Sedline electrode configurations are suitable options for monitoring frontal EEG when the standard configuration is not possible.

Telemetric electroencephalography recording in anesthetized mice—A novel system using minimally-invasive needle electrodes with a wireless OpenBCI™ Cyton Biosensing Board

Telemetric electroencephalography (EEG) recording, using subdermal needle electrodes, is a minimally-invasive method to investigate mammalian neurophysiology during anesthesia. These inexpensive systems may streamline experiments examining global brain phenomena during surgical anesthesia or disease. We utilized the OpenBCI™ Cyton board with subdermal needle electrodes to extract EEG features in six C57BL/6J mice undergoing isoflurane anesthesia. Burst suppression ratio (BSR) and spectral features were compared for a verification of our method. Following an increase from 1.5% to 2.0% isoflurane, the BSR increased (Wilcoxon-signed-rank statistic; p = 0.0313). Furthermore, although the absolute EEG spectral power decreased, the relative spectral power remained comparable (Wilcoxon-Mann-Whitney U-Statistic; 95% CI exclusive AUC=0.5; p < 0.05). Compared to tethered systems, this method confers several improvements for anesthesia specific protocols: 1-Avoiding electrode implant surgical procedures, 2-Anatomical non-specificity for needle electrode placement to monitor global cortical activity representative of anesthetic state, 3-Facility to repeat recordings in the same animal, 4-User-friendly for non-experts, 5-Rapid set-up time, and 6-Lower costs.•Minimally-invasive telemetric EEG recording systems ergonomically improve tethered systems for anesthesia protocols.•Using this method, we verified that higher isoflurane concentrations resulted in an increased EEG burst suppression ratio and decreased EEG absolute spectral power, with no change in frequency distribution.

Changes in Extreme Precipitation across 30 Global River Basins

Extreme precipitation can cause disasters such as floods, landslides and crop destruction. A further study on extreme precipitation is essential for enabling reliable projections of future changes. In this study, the trends and frequency distribution changes in extreme precipitation across different major river basins around the world during 1960–2011 were examined based on two of the latest observational data sets respectively collected from 110,000 and 26,592 global meteorological stations. The results showed that approximately a quarter of basins have experienced statistically significant increase in maximum consecutive one-day, three-day and five-day precipitation (RX1day, RX3day and RX5day, respectively). In particular, dramatic increases were found in the recent decade for the Syr Darya River basin (SDR) and Amu Darya River basin (ADR) in the Middle East, while a decrease in RX3day and RX5day were seen over the Amur River basin in East Asia. One third of basins showed remarkable changes in frequency distributions of the three indices, and in most cases the distributions shifted toward larger amounts of extreme precipitation. Relative to the subperiod of 1960–1984, wider range of the three indices over SDR and ADR were detected for 1985–2011, indicating intensification along with larger fluctuations of extreme precipitation. However, some basins have frequency distributions shifting toward smaller amounts of RX3day and RX5day, such as the Columbia River basin and the Yellow River basin. The study has potential to provide the most up-to-date and comprehensive global picture of extreme precipitation, which help guide wiser public policies in future to mitigate the effects of these changes across global river basins.

Anthropogenic disturbances shift diameter distribution of woody plant species in Shorea robusta Gaertn. (Sal) mixed forests of Nepal

Assessing diameter distribution is an approach of observing regeneration strategies and impacts of anthropogenic disturbances on forest structural attributes. In this study, we evaluated the differences in diameter distributions in highly disturbed, moderately disturbed, and undisturbed forest sites of Buffer Zone Community Forests (BZCFs), viz. Janajagaran BZCF, Musharni Mai BZCF, and Radha Krishna BZCF of Central Terai, Nepal. Weibull and gamma distributions were fitted to explain changes in frequency distribution of diameter data collected. We observed a significant decrease in species richness (overall: p < 0.001) and density of smallest diameter class (0–10 cm diameter at breast height) stems (overall: p < 0.001) with increasing disturbances. Similarly, increase in median diameters (p < 0.01) and parameters of Weibull’s and gamma distributions along gradients from undisturbed to highly disturbed forest sites (except between moderately disturbed and undisturbed sites of Musharni Mai BZCF) were observed. Bowley coefficient of skewness was lower in all highly disturbed sites of BZCFs showing reduction in right skewness of the distribution curves with disturbances. These results indicate anthropogenic disturbances shift diameter structure of forests stands, negatively affecting abundance of small diameter–sized woody species and shifting Shorea robusta mixed forests towards even-aged stands.

Effects of hot compression on distribution of Σ3n boundary and mechanical properties in Cu–Sn alloy

Cu–Sn alloy was put in the high-temperature hot compression test with a strain rate of 0.01 s−1 and distortion temperature of 550–700 °C. Electron backscattered diffraction technology was adopted to analyze the distortion and microstructure features of different parts of the alloy. The results indicate that: As the temperature rises, the distribution frequency of the Σ3n (n = 1, 2, 3) grain boundary increases to 41.9% from 6.8% but drops suddenly at 650 °C, which is similar to the frequency distribution changes in recrystallization and twin crystals. Meanwhile, multiple annealing twin crystals are generated and connected to form grain clusters with Σ3n orientation among each other. In the inverse pole figure, with the recrystallization continuing, the polar densities of the fiber textures of varied orientations in T1, T2, T3, T4 and other areas decreased gradually; in tensile test of Cu–Sn Alloy, yield strength and tensile strength at break decrease slowly.

Quantum statistical vibrational entropy and enthalpy of formation of helium-vacancy complex in BCC W

High-temperature advance-reactor design and operation require knowledge of in-reactor materials properties far from the thermal ground state. Temperature-dependence due to the effects of lattice vibrations is important to the understanding and formulation of atomic processes involved in irradiation-damage accumulation. In this paper, we concentrate on the formation of He-V complex. The free-energy change in this regard is derived via thermodynamic integration from the phase-space trajectories generated from MD simulations based on the quantum fluctuation-dissipation relation. The change of frequency distribution of vibration modes during the complex formation is properly accounted for, and the corresponding entropy change avoids the classical ln(T) divergence that violates the third law. The vibrational enthalpy and entropy of formation calculated this way have significant effects on the He kinetics during irradiation.

How Robust Are Multirater Interrater Reliability Indices to Changes in Frequency Distribution?

ABSTRACTInterrater reliability studies are used in a diverse set of fields. Often, these investigations involve three or more raters, and thus, require the use of indices such as Fleiss’s kappa, Conger’s kappa, or Krippendorff’s alpha. Through two motivating examples—one theoretical and one from practice—this article exposes limitations of these indices when the units to be rated are not well-distributed across the rating categories. Then, using a Monte Carlo simulation and information visualizations, we argue for the use of two alternative indices, the Brennan–Prediger coefficient and Gwet’s AC2, because the agreement levels reported by these indices are more robust to variation in the distribution of units that raters encounter. The article concludes by exploring the complex, interwoven relationship between the number of levels in a rating instrument, the agreement level present among raters, and the distribution of units that are to be scored. Supplementary materials for this article are available online.

Abstract 3648: Resolving copy number variations from existing exome SNP data without the need for sophisticated software

Abstract Several tools exists to evaluate copy-number variation (CNV) from sequencing read data. Here, the aim is to investigate whether larger CNVs in leukemia can be extracted directly from already called variants - without specialized algorithms. Methods: 12 cases of leukemia, with 6 paired and 6 unpaired, were included (Table 1). Following exome sequencing and reference alignment variants were called with GATK to produce recalibrated sets in variant call format (VCF). Passed single nucleotide polymorphisms (SNPs) were limited to depth of coverage &amp;gt; 29x. Each chromosome were visualized as frequency scatter plot and smoothened histograms of frequency distribution in order to inspect frequency bands and number of peaks in histograms. Kolmogorov-Smirnov test was employed to compare distributions between paired samples. Results: None of the AML cases with normal karyotype displayed CNVs and no significant changes in frequency distributions were detected. In the relapse of paired T-ALL a Chr 4 trisomy and a 33×10−6 bp copy-number neutral loss of heterozygosity (CN-LOH) on Chr 9 were detected. Collectively, 7 aberrations confirmed standard cytogenetics, 8 new aberrations were added to the cytogenetical profile and 5 could not be detected as shown in Table 1. The aberrations not detected were, as expected, balanced translocations (3) and microdeletions (2). Discussion: No previously found large aberrations escaped detection, when disregarding translocations. In addition, other CNVs not detected by conventional cytogenetics were found by SNP analysis. Moreover, the added information is in agreement with the literature: 5% of T-ALL patients display del(11)(p12p13) and +12 is one of the most common cytogenetic changes of CLL, e.g. Thus, we suggest that CNV profiling can be initiated by directly evaluating frequencies from existing variant calls. This may ease implementation of “closed toolboxes”, enable analysis of single unpaired samples and function as a direct complement to array-CGH or FISH to detect CN-LOH. Table 1SamplesPairedCytogeneticsCNV detectedNK-AML5YesNormal karyotypeNoneT-ALL relapse1Yes4+, 3p26.2 and Xp22.2 micro-deletions+4, partial del(9p)AML M01YesNormal karyotypePartial del(11p)AML M31Not(15;17)NoneCML1Not(9;22)NoneT-ALLNodel(5) t(7;14)Partial del(5q), +4q, +9p, del(11p), del(12q)CLL1NoNot analyzed+12AML M01NoNormal karyotypePartial +11 Citation Format: Marcus C. Hansen, Laura L. Herborg, Anne S. Roug, Sadudee Chotirat, Chirayu U. Auewarakul, Eigil Kjeldsen, Peter Hokland. Resolving copy number variations from existing exome SNP data without the need for sophisticated software. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3648.

Time series analysis of co-polarization phase difference (PPD) for winter field crops using polarimetric C-band SAR data

ABSTRACTThe utility of time series polarimetric C-band data for vegetation state monitoring was explored to understand the mechanism of growth and phenology for important winter crops in India. Parameters investigated were HH–VV phase difference (co-polarization phase difference, PPD), amplitude ratio, and polarization indices. Data were acquired during the entire growth phase categorized as early, mid/peak vegetative, and post-vegetative /flowering phase. The trend emerging in this study showed a shift in the phase difference distribution for agricultural areas relating to the growth rate for various crops. The time series data set revealed that the PPD is a function of frequency and was directly affected by crop type (planophile or erectophile), vigour, structure, and crop biophysical parameters, particularly biomass. The behaviour of crop biomass with PPD responded differentially across crop architectures and vigour classes. Co-polarization index was found to be a good measure for discrimination in early growth stages while cross-polarization index suited in advanced vegetative stages where geometrical orientation was uniform. The PPD captured the change in frequency distribution resulting in a peaked distribution at sowing changing to smooth, well-spread frequency distribution as the peak vegetation stage approaches. This histogram nature is observed to be gradual for high-biomass crops and peaked in case of the low-biomass crops. It is indicative of the rate of growth; a low peaked normal curve indicates faster growth rate and resulting in high biomass. The amplitude ratio in the later phase of growth as on the third date is similarly altered as in the VV returns from the crop. Intuition of the rate of growth and plant vigour is obtained from the temporal PPD pattern. The current study shows that while phase differences and amplitude ratio carry little information content on a single resolution cell basis, their spatial distribution over a wider time span can be used to derive quantitative relationships between SAR response and crop condition. The synergy of information involving the above parameters were used to derive useful information on the vegetation.

Anomalous Weather Patterns in Relation to Heavy Precipitation Events in Japan during the Baiu Season

Abstract Anomalous weather patterns (WPs) in relation to heavy precipitation events during the baiu season in Japan are investigated using a nonlinear classification technique known as the self-organizing map (SOM). The analysis is performed on daily time scales using the Japanese 55-year Reanalysis Project (JRA-55) to determine the role of circulation and atmospheric moisture on extreme events and to investigate interannual and interdecadal variations for possible linkages with global-scale climate variability. SOM is simultaneously employed on four atmospheric variables over East Asia that are related to baiu front variability, whereby anomalous WPs that dominated during the 1958–2011 period are obtained. Our analysis extracts seven typical WPs, which are linked to frequent occurrences of heavy precipitation events. Each WP is associated with regional variations in the probability of extreme precipitation events. On interannual time scales, El Niño–Southern Oscillation (ENSO) affects the frequency of the WPs in relation to the heavy rainfall events. The warm phase of ENSO results in an increased frequency of a WP that provides a southwesterly intrusion of high equivalent potential temperature at low levels, while the cold phase provides southeastern intrusion. In addition, the results of this analysis suggest that interdecadal variability of frequency for heavy rainfall events corresponds to changes in frequency distributions of WPs and are not due to one particular WP.

J0530301 ビル風利用風力発電モデルの発電特性と実装可能性評価

The aim of this study is to design and propose the size and layout of buildings which provide the better wind speed distribution for the higher power generation of wind turbine. A building model whose layout is like nozzle is proposed to obtain the acceleration of wind blowing through buildings due to contracted flow between buildings. In addition, the effect of the angle between two buildings on the power generation performance of the proposed building model is also investigated. For the feasibility check of installing the building model in some cities actually, the power energy output of wind turbine is investigated by considering the meteorological data such as wind speed and direction distribution for Fukushima city and Tsu city as an example. As a result, the proposed building models which have the angle between two buildings like nozzle of 90, 135 and 180 degree can provide the wind acceleration at the back of buildings for the wind blowing from the main wind direction and the angle of 135 degree is found to be the optimum building layout. In the case of installing the proposed building model in Fukushima city and Tsu city, the wind power energy output in winter is higher while that in summer is lower irrespective of the buildings angle. The interaction between the change in frequency distribution of wind speed direction through the year and the location of open tip of building model decides the power generation characteristics of the proposed building model.

99 EFFECT OF SEASON AND WEIGHT GAIN ON PREGNANCY RATES OF EMBRYO RECIPIENTS RAISED UNDER PASTURE CONDITIONS

In most Brazilian farms, the management of embryo recipients is done exclusively under grazing systems. Thus, the seasonal variation of grass availability can affect the energy balance and reduce weight gain, and consequently affects the rate of pregnancy. The aim of the present study was to evaluate the effect of the seasonal variation of daily weight gain (DWG) on the pregnancy rate of crossbred heifers (Bos taurus × Bos indicus). The study was performed in the southwest region of Minas Gerais State, Brazil, during one year. Two periods were evaluated: dry (April to September, average precipitation of 470 mm and low grass availability) and rainy (October to March, average precipitation of 1930 mm and high grass availability) seasons. The recipients were kept in a grazing system (Brachiaria brizantha) with water and minerals available ad libitum. Embryos were produced in vitro by the same laboratory, using oocytes and sex-sorted semen from the Gir breed (Bos indicus). A total of 404 fresh embryos (N = 484, 45.4% during dry and 54.5% during rainy season) were transferred by the same technician on Day 7 days of the oestrous cycle – synchronized with prostaglandin – of the recipients, which were weighted at the day of embryo transfer and 23 to 25 days later, at the diagnostic of pregnancy. Animals were retrospectively allocated into 4 groups according to the DWG observed between embryo transfer and pregnancy diagnosis: G1 (N = 132) up to 150 g; G2 (N = 132) between 151 and 250 g; G3 (N = 119) between 251 and 350 g; and G4 (N = 99) greater than 350 g of DWG. The pregnancy rates were compared among DWG groups and between seasons by chi-squared. The logistic regression model was performed using the PROC GENMOD to test the model, including the effects of DWG, season, and the interaction (DWG × season). During the dry season, there was change in frequency distribution of the heifers among DWG groups, with lower frequency (P &lt; 0.05) of heifers in high (G3 and G4) when compared with low (G1 and G2) DWG groups (33.2, 31.4, 21.8, and 13.6% for G1, G2, G3, and G4, respectively). Altogether, pregnancy rate was not different between dry and rainy seasons (42.3 v. 45.8%, respectively; P &gt; 0.05). When compared to G1, pregnancy rate was higher (P &lt; 0.05) for recipients with daily weight gain greater than 250 g day–1 (G3 and G4) (35.6, 40.6, 52.1, and 51.0% for G1, G2, G3, and G4, respectively). Only the effect of the DWG was significant in logistic regression, and the odds rate for each gram of DWG was 0.0039, which means that pregnancy rate improved 1.17 times for recipients with 300 g of DWG. In conclusion, the DWG after embryo transfer, but not the season itself, affect pregnancy rate of in vitro-produced embryo recipients. Biotran, FAPEMIG, and CnPQ are acknowledged.

Preliminary study of laser doppler perfusion signal by wavelet transform in patients with critical limb ischemia before and after revascularization

The haemodynamics of skin microcirculation can be quantitatively evaluated by Laser Doppler Fluxmetry (LDF). LDF signal in human skin shows periodic oscillations. Spectral analysis by wavelet transform displays six characteristic frequency intervals (FI) from 0.005 to 2 Hz, related to distinct vascular structures activities: heart (0.6-2 Hz), sympathetic respiratory (0.145-0.6 Hz), myogenic (0.052-0.145 Hz), local sympathetic nerve (0.021-0.052 Hz) and endothelial cells NO dependent (0.0095-0.021 Hz) and NO independent (0.005-0.0095 Hz). The most advanced stage of peripheral arterial obstructive disease is the critical limb ischemia (CLI), which causes the reduction of blood perfusion threatening limb viability. Besides macrocirculatory alterations, many studies have shown microvascular misdistribution of skin blood flow as the main factor that leads patients to CLI. Revascularization can save limb and patient's life, too. In the present study, LDF signals have been recorded on the skin of the foot dorsum in 15 patients suffering from CLI. LDF signals have been analyzed before and after limb revascularization by means of the wavelet analysis. Significant changes in frequency distribution before and after limb revascularization have been detected: the median normalized values of spectral power increases for 49.8% (p = 0.0341) in the frequency range 0.050328-0.053707 Hz, whereas spectral power decreases for 77.1% (p = 0.0179) in the frequency range 0.018988-0.029284 Hz. We can conclude that changes in the frequency intervals occur after revascularization, shifting from a prevailing endothelial activity toward a prevailing sympathetic activity.

Hydrologic characterization of 56 geographically isolated wetlands in west-central Florida using a probabilistic method

Wetlands are important hydrological elements of watersheds that influence water storage, surface water runoff, groundwater recharge/discharge processes, and evapotranspiration. Understanding the cumulative effect wetlands have on a watershed requires a good understanding of representative water-level fluctuations and storage characteristics associated with multiple wetlands across a region. We introduce a probabilistic approach based on frequency analysis of water levels in numerous geographically isolated wetlands across the mantled karst terrain of west-central Florida, in the Tampa Bay region. This approach estimates the probabilities, or percentage of time, that water levels in a wetland or upland groundwater wells are at or below a specific elevation. We applied this hydrologic characterization to 56 wetlands in west-central Florida, and documented that standing water was present in the wetlands 61 % of the time and that these wetlands were groundwater recharge zones at least 50 % of the time over the 7 year study. Additionally, we demonstrated that various wetland types, classified according to vegetation community composition and structure, exhibit similar means, extremes and ranges in water-level behavior. We believe that this is the first paper to robustly quantify inundation frequency and recharge status in seasonally flooded wetlands at a regional scale. The analytical tool introduced in this manuscript could be used to detect, through changes in water-level frequency distribution, wetland hydrological response to different climatological or anthropogenic stressors. This tool is timely as changes in frequency distribution shape may provide early warnings of ecosystem regime change.

Changes in peak flow with decreased forestry practices: Analysis using watershed runoff data

The prevalence of forestry practices such as thinning and pruning have gradually decreased since the 1980s. Researchers have noted an increased flood risk with decreased forestry practices for coniferous plantations in Japan on the basis of infiltration and overland flow measurements at a plot scale (typically several square meters). However, no studies have examined changes in peak flow with decreased forestry practices at a watershed scale (typically several tens or hundreds of square kilometers) even though flood disasters generally occur at this scale in Japan. We examined changes in frequency distributions of daily precipitation (P) and runoff (Q) during the period 1979–2007 at the Terauchi watershed, where forestry practices are known to have decreased. For this purpose, we divided P and Q data into 14 and 15 classes according to the magnitude, respectively, and examined changes in the frequency for each class during the period. We observed no significant increasing trend for any P or Q class. Even when taking into account the effect of interannual variations in precipitation on the frequency for each Q class, there was no significant increasing trend in the frequencies except for two Q classes with moderate Q values. These results suggest that the increase in flood risk due to decreased forestry practices might be less than expected.

Changes with altitude of the stand structure of temperate forests on Mount Norikura, central Japan

Changes in stand structure with altitude have been studied at ten sites between 800 and 2,500 m above sea level (a.s.l.) in temperate forests on Mount Norikura (36°06′N, 137°33′E, 3,026 m a.s.l.) in central Japan. Vegetation in this range of altitudes was roughly classified as a montane deciduous broad-leaved forest zone between 800 and 1,600 m a.s.l. and a subalpine coniferous forest zone between 1,600 and 2,500 m a.s.l. at the timberline. The frequency distribution of trunk height was an L-shaped pattern at 800 m a.s.l., changed to a flat pattern with increasing altitude up to 2,000 m a.s.l., but changed to an L-shaped pattern again from 2,000 to 2,500 m a.s.l. This change in frequency distribution of trunk height with altitude was related to the change in maximum trunk height with altitude. The maximum trunk height did not change with altitude between 800 and 2,000 m a.s.l. but it decreased markedly from 2,000 to 2,500 m a.s.l. Although mechanical damage to conifer trunks and branches was not observed between 800 and 2,000 m a.s.l., the proportion of damaged trees increased from 2,000 to 2,500 m a.s.l., suggesting that subalpine conifers cannot grow in height near the timberline because of mechanical damage. The increase in the number of small trees from 2,000 m a.s.l. to the timberline was therefore because of a less developed canopy structure, i.e. small trees can grow without shading by canopy trees. This study suggests that mechanical damage, probably because of strong winds in the winter, affects changes with altitude in regeneration and formation of the timberline.

Parties, Institutional Control, and Trust in Government*

Objectives. Partisanship should affect evaluations of Congress just as it affects evaluations of the president, and these institutional evaluations should affect political trust. We argue that the relationship between partisanship and trust is dependent on partisan control of Congress and that much of party identification's influence on trust occurs indirectly through approval of governmental institutions.Methods. Using data collected before and after the 2002 congressional elections by the Center for Survey Research and Analysis at the University of Connecticut, we examine changes in frequency distributions and mean values for trust and institutional approval. We use multivariate regression models and a path model to estimate the causes of political trust and self‐perceived change in trust.Results. We find evidence that party control of government and party identification are important in explaining trust and institutional approval. The Republican takeover of the Senate led Republicans to evaluate the Senate more favorably and to become more trusting of the government, while having the opposite effect on Democrats.Conclusions. The changes in approval and trust resulting from the 2002 elections suggest that at least some segment of the population is cognizant of changes in the political environment and updates its views of government when the political environment changes.

Modulation effects of epidural spinal cord stimulation on muscle activities during walking

Epidural spinal cord stimulation (ESCS) combined with partial weight bearing therapy (PWBT) has been reported to facilitate recovery of functional walking for individuals after chronic incomplete spinal cord injury (ISCI). Muscle activities were analyzed in this report to examine the modulation effect of ESCS on muscle recruitment during gait training. Two ISCI individuals participated in the study and both are classified as ASIA C with low motor scores in the lower limbs. Stimulating electrodes were placed at the epidural space over T10-L2 spinal segments, along the midline in participant 1 (S1), and off-midline in participant 2 (S2). Surface electromyograms (EMGs) from leg muscles under both ESCS ON and OFF conditions recorded during treadmill gait were analyzed in time-frequency domains. ESCS application produced acute modulations in muscle activities in both participants, but the observed pattern, magnitude, and spectral content of the EMGs differed. In S1, ESCS induced a significant shift in the temporal pattern of muscle activity toward normal comparing with that when ESCS was OFF, though without eliciting noticeable change in frequency distribution between ESCS ON and OFF conditions. When ESCS was applied in S2, a modulation of EMG magnitude was observed and, consequently, improved joint kinematics during walking. In this case, a stimulation entrainment appeared in time-frequency analysis. The results suggest that ESCS activates neural structures in the dorsal aspect of the spinal cord and facilitates gait-related muscle recruitment. The exact effects of ESCS depend on the electrode placement and possibly injury history and residual functions, but in general ESCS produces a positive effect on improved walking speed, endurance, and reduced sense of effort in both ISCI subjects.

Quantitative results assessing design issues of selection-supportive menus

As a list of menu items becomes longer, users have increasing difficulty finding the desired item. Researchers have noticed that some menu items are selected more frequently than others, and have suggested various kinds of adaptive menus that support the selection of these high-frequency items. In this paper, we investigate existing selection-supportive menus and find that they support the selection of high-frequency items by providing them with either spatial or spatio–temporal priority. For example, split menus (ACM Trans. Comput. Human Interaction 1 (1994) 27–51) offer spatial priority and the menus of Microsoft Office 2000 provides both spatial and temporal priority. This finding leads us to define a new type of adaptive menu that provides only temporal priority, where only high-frequency items are displayed at first. A controlled experiment was performed to assess the issues involved in the design of adaptive menus. The results revealed that each type of adaptive menu has both strengths and weaknesses. Spatial prioritization significantly decreases the selection time of high-frequency items if the variations in selection frequency are small; however, if the selection frequency distribution changes greatly, then the mean selection time rapidly deteriorates. In comparison, temporal selection-support is less effective at reducing selection time for high-frequency items, but is more robust due to its insensitivity to variations in selection frequency. Based on experimental data, quantitative criteria are provided to assist designers when deciding which type of menu to use. Relevance to industryThere exist several types of adaptive menus that support menu selection tasks. Designers of commercial applications must decide whether to adopt adaptive menus, and, if so, which of the menu styles to implement. Although there have been discussions of the advantages and disadvantages of the various types of adaptive menus, designers have not been provided with quantitative data to assist in making these decisions. This paper provides a quantitative assessment of the design tradeoffs involved in using adaptive menus.

Markov zero-inflated Poisson regression models for a time series of counts with excess zeros

This paper discusses a class of Markov zero-inflated Poisson regression models for a time series of counts with the presence of excess zero relative to a Poisson distribution, in which the frequency distribution changes according to an underlying two-state Markov chain. Features of the proposed model, estimation method based on the EM and quasi-Newton algorithms, and other implementation issues are discussed. A Monte Carlo study shows that the estimation method is accurate and reliable as long as the sample size is reasonably large, and the choice of starting probabilities for the Markov process has little impact on the parameter estimates. The methodology is illustrated using daily numbers of phone calls reporting faults for a mainframe computer system.