Vibration isolation and damping in high precision equipment

NASA Astrophysics Data System (ADS)

Bukkems, B.; Ruijl, T.; Simons, J.

2017-06-01

All systems located in a laboratory environment or factory are subject to disturbances. These disturbances can either come from the surroundings, e.g. floor-induced vibrations, or from the system itself, e.g. stage-induced vibrations. In many cases it is needed to minimize the effect of these disturbances. This can either be done by isolating the system from its disturbance source or by applying damping to the system. In this paper we present various cases in which we have effectively reduced the impact of disturbances on the system's performance, either by improving its isolation system, by minimizing the impact of stage reaction forces, or by designing polymer damping into the system.

Rovers minimize human disturbance in research on wild animals.

PubMed

Le Maho, Yvon; Whittington, Jason D; Hanuise, Nicolas; Pereira, Louise; Boureau, Matthieu; Brucker, Mathieu; Chatelain, Nicolas; Courtecuisse, Julien; Crenner, Francis; Friess, Benjamin; Grosbellet, Edith; Kernaléguen, Laëtitia; Olivier, Frédérique; Saraux, Claire; Vetter, Nathanaël; Viblanc, Vincent A; Thierry, Bernard; Tremblay, Pascale; Groscolas, René; Le Bohec, Céline

2014-12-01

Investigating wild animals while minimizing human disturbance remains an important methodological challenge. When approached by a remote-operated vehicle (rover) which can be equipped to make radio-frequency identifications, wild penguins had significantly lower and shorter stress responses (determined by heart rate and behavior) than when approached by humans. Upon immobilization, the rover-unlike humans-did not disorganize colony structure, and stress rapidly ceased. Thus, rovers can reduce human disturbance of wild animals and the resulting scientific bias.

Multi-Objective Online Initialization of Spacecraft Formations

NASA Technical Reports Server (NTRS)

Jeffrey, Matthew; Breger, Louis; How, Jonathan P.

2007-01-01

This paper extends a previously developed method for finding spacecraft initial conditions (ICs) that minimize the drift resulting from J2 disturbances while also minimizing the fuel required to attain those ICs. It generalizes the single spacecraft optimization to a formation-wide optimization valid for an arbitrary number of vehicles. Additionally, the desired locations of the spacecraft, separate from the starting location, can be specified, either with respect to a reference orbit, or relative to the other spacecraft in the formation. The three objectives (minimize drift, minimize fuel, and maintain a geometric template) are expressed as competing costs in a linear optimization, and are traded against one another through the use of scalar weights. By carefully selecting these weights and re-initializing the formation at regular intervals, a closed-loop, formation-wide control system is created. This control system can be used to reconfigure the formations on the fly, and creates fuel-efficient plans by placing the spacecraft in semi-invariant orbits. The overall approach is demonstrated through nonlinear simulations for two formations a GEO orbit, and an elliptical orbit.

SPS pilot signal design and power transponder analysis, volume 2, phase 3

NASA Technical Reports Server (NTRS)

Lindsey, W. C.; Scholtz, R. A.; Chie, C. M.

1980-01-01

The problem of pilot signal parameter optimization and the related problem of power transponder performance analysis for the Solar Power Satellite reference phase control system are addressed. Signal and interference models were established to enable specifications of the front end filters including both the notch filter and the antenna frequency response. A simulation program package was developed to be included in SOLARSIM to perform tradeoffs of system parameters based on minimizing the phase error for the pilot phase extraction. An analytical model that characterizes the overall power transponder operation was developed. From this model, the effects of different phase noise disturbance sources that contribute to phase variations at the output of the power transponders were studied and quantified. Results indicate that it is feasible to hold the antenna array phase error to less than one degree per power module for the type of disturbances modeled.

Space Technology 7 Disturbance Reduction System - precision control flight Validation

NASA Technical Reports Server (NTRS)

Carmain, Andrew J.; Dunn, Charles; Folkner, William; Hruby, Vlad; Spence, Doug; O'Donnell, James; Markley, Landis; Maghami, Peiman; Hsu, Oscar; Demmons, N.;

A clinical analysis of 32 brainstem haemorrhages; with special reference to surviving but severely disabled cases.

PubMed

Komiyama, M; Boo, Y E; Yagura, H; Yasui, T; Baba, M; Hakuba, A; Nishimura, S

1989-01-01

Thirty-two patients with CT-documented primary brainstem haemorrhage were reviewed retrospectively to obtain a clearer overall clinical picture, especially of the severely disabled survivors. They were divided into 3 groups according to outcome: eleven cases (Group 1) died within 1 month following haemorrhage, 11 cases (Group 2) survived but became bedridden, necessitating full living support, and 10 cases (Group 3) showed minimal neurological deficits and resumed normal activities. Owing to CT and improved critical care, the survival rate was 66% for the whole series. Group 2 comprised 34% of all cases. These patients were mostly alert, quadruplegic, and communicated only with great difficulty. The most common initial symptoms and CT finding in each group were as follows; Group 1: unconsciousness, respiratory disturbance, negative light reflex, tachycardia, and haematoma greater than 3.0 cm; Group 2: disturbance of consciousness, respiratory disturbance, positive light reflex, normal heart rate, and 2.0 greater than haematoma less than 3.5 cm; and Group 3: alertness or only slight disturbance of consciousness, normal respiration, positive light reflex, normal heart rate, haematoma less than 2.5 cm. Although there is an overlap among them, these findings will be useful to distinguish the three groups from each other. Patients with disturbance of consciousness, respiratory disturbance, positive light reflex, normal heart rate, and 2.0 greater than haematoma less than 3.5 cm, have a chance to survive, but in severely disabled condition, if they were treated with vigorous intensive care in the acute stage.

Visually Determined Soil Disturbance Classes Used as Indices of Forest Harvesting Disturbance

Treesearch

W. Michael Aust; James A. Burger; Emily A. Carter; David P. Preston; Steven C. Patterson

1998-01-01

Visual estimates of soil and site disturbances are used by foresters, soil scientists, logging supervisors. and machinery operators to minimize harvest disturbances to forest sites, to evaluate compliance with forestry Best Management Practices (BMPs), and to determine the need for ameliorative practices such as tnechanical site preparation. Although estimates are...

The Then and Now of Reference Conditions in Streams of the Central Plains

NASA Astrophysics Data System (ADS)

Huggins, D.; Angelo, R.; Baker, D. S.; Welker, G.

2005-05-01

Models of contemporary and pre-settlement reference conditions were constructed for streams that once drained the tallgrass prairies of Iowa, Nebraska, Kansas and Missouri (e.g. Western Corn Belt Plains ecoregion), and for streams within the heart of the mixed grass prairie (e.g. Southwestern Tablelands ecoregion). Data on watershed, habitat, chemistry and biology compiled for existing reference streams (least or minimally impacted systems) were used to characterize contemporary reference conditions. Contemporary reference conditions within these two prairie regions are contrasted against hypothetical pre-settlement conditions using information from the best streams (upper 25%) of the current reference population, historical accounts, museum records, natural heritage programs, Public Land Survey and current remote sensing data. Similar comparisons were made between historical and current reference conditions for the Southwestern Tablelands located in central Kansas and Oklahoma. Much of this region remains in mixed grass prairie; has limited hydrological alterations (e.g. impoundments, dewatering) and low human and livestock densities. Within the tablelands these factors have preserved reference conditions that resemble historic conditions. Qualitative and quantitative comparisons indicate that many regions within the Central Plains require caution when using "least disturbed" reference streams and conditions to identify regional biological integrity goals relative to the Clean Water Act.

Disturbance rejection performance analyses of closed loop control systems by reference to disturbance ratio.

PubMed

Alagoz, Baris Baykant; Deniz, Furkan Nur; Keles, Cemal; Tan, Nusret

2015-03-01

This study investigates disturbance rejection capacity of closed loop control systems by means of reference to disturbance ratio (RDR). The RDR analysis calculates the ratio of reference signal energy to disturbance signal energy at the system output and provides a quantitative evaluation of disturbance rejection performance of control systems on the bases of communication channel limitations. Essentially, RDR provides a straightforward analytical method for the comparison and improvement of implicit disturbance rejection capacity of closed loop control systems. Theoretical analyses demonstrate us that RDR of the negative feedback closed loop control systems are determined by energy spectral density of controller transfer function. In this manner, authors derived design criteria for specifications of disturbance rejection performances of PID and fractional order PID (FOPID) controller structures. RDR spectra are calculated for investigation of frequency dependence of disturbance rejection capacity and spectral RDR analyses are carried out for PID and FOPID controllers. For the validation of theoretical results, simulation examples are presented. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

A novel bench-scale column assay to investigate site-specific nitrification biokinetics in biological rapid sand filters.

PubMed

Tatari, K; Smets, B F; Albrechtsen, H-J

2013-10-15

A bench-scale assay was developed to obtain site-specific nitrification biokinetic information from biological rapid sand filters employed in groundwater treatment. The experimental set-up uses granular material subsampled from a full-scale filter, packed in a column, and operated with controlled and continuous hydraulic and ammonium loading. Flowrates and flow recirculation around the column are chosen to mimic full-scale hydrodynamic conditions, and minimize axial gradients. A reference ammonium loading rate is calculated based on the average loading experienced in the active zone of the full-scale filter. Effluent concentrations of ammonium are analyzed when the bench-scale column is subject to reference loading, from which removal rates are calculated. Subsequently, removal rates above the reference loading are measured by imposing short-term loading variations. A critical loading rate corresponding to the maximum removal rate can be inferred. The assay was successfully applied to characterize biokinetic behavior from a test rapid sand filter; removal rates at reference loading matched those observed from full-scale observations, while a maximum removal capacity of 6.9 g NH4(+)-N/m(3) packed sand/h could easily be determined at 7.5 g NH4(+)-N/m(3) packed sand/h. This assay, with conditions reflecting full-scale observations, and where the biological activity is subject to minimal physical disturbance, provides a simple and fast, yet powerful tool to gain insight in nitrification kinetics in rapid sand filters. Copyright © 2013 Elsevier Ltd. All rights reserved.

Space Technology 7 : Micropropulsion and Mass Distribution

NASA Technical Reports Server (NTRS)

Carnaub, A.; Dunn, C.; Ziemer, J,; Hruby, V.; Spence, D.; Demmons, N.; Roy, T.; McCormick, R.; Gasaska, C.; Young, J.;

Production of minimally disturbed synchronous cultures of hematopoietic cells

NASA Technical Reports Server (NTRS)

Thornton, Maureen; Eward, Kathryn Leigh; Helmstetter, Charles E.; Edward, K. L. (Principal Investigator)

2002-01-01

A method is describedforproducing sizable quantities of synchronously dividing, minimally disturbed mammalian cells. Cultures were grown immobilized on surfaces such that cell division within the population resulted in the continuous release of synchronous newborn cells. As judged by the quality and duration of synchronous growth, cell size distributions, and DNA compositions, newborn mouse L1210 cells grew with a very high level of synchrony without overt evidence of growth disturbances. The technology should be applicable to a variety of hematopoietic cells, as evidenced by similar results with human MOLT-4 and U937 cell lines.

Natural disturbance production functions

Treesearch

Jeffrey P. Prestemon; D. Evan Mercer; John M. Pye

2008-01-01

Natural disturbances in forests are driven by physical and biological processes. Large, landscape scale disturbances derive primarily from weather (droughts, winds, ice storms, and floods), geophysical activities (earthquakes, volcanic eruptions), fires, insects, and diseases. Humans have invented ways to minimize their negative impacts and reduce their rates of...

Control of integrated micro-resonator wavelength via balanced homodyne locking.

PubMed

Cox, Jonathan A; Lentine, Anthony L; Trotter, Douglas C; Starbuck, Andrew L

2014-05-05

We describe and experimentally demonstrate a method for active control of resonant modulators and filters in an integrated photonics platform. Variations in resonance frequency due to manufacturing processes and thermal fluctuations are corrected by way of balanced homodyne locking. The method is compact, insensitive to intensity fluctuations, minimally disturbs the micro-resonator, and does not require an arbitrary reference to lock. We demonstrate long-term stable locking of an integrated filter to a laser swept over 1.25 THz. In addition, we show locking of a modulator with low bit error rate while the chip temperature is varied from 5 to 60° C.

GOES-16 On-Orbit Dual Isolation Performance Characterization Results

NASA Technical Reports Server (NTRS)

Carter, Delano; Clapp, Brian; Early, Derrick; Freesland, Douglas; Chapel, Jim; Bailey, Robert; Krimchansky, Alexander

2016-01-01

The Geostationary Operational Environmental Satellite-R Series (GOES-R) is the first of the next generation geostationary weather satellites. GOES-R successfully launched on November19, 2016 and renamed GOES-16 upon entering geostationary orbit. Subsequently, GOES-16post-launch testing began. This paper presents the GOES-16 Satellite Dynamic Interaction Characterization results for the Earth Pointed Platform (EPP) stowed, referred to as the Reaction Wheel Assembly (RWA) Isolation Only configuration, and deployed, referred to as the Dual Isolation configuration. GOES-R represents a quantum increase in Earth and solar weather observation capabilities, with 4 times the resolution, 5 times the observation rate, and 3 times the number of spectral bands for Earth observations. With the improved resolution, comes the instrument suites increased sensitivity to disturbances over a broad spectrum 0-512Hz. Sources of disturbance include reaction wheels, thruster firings for station keeping and momentum management, gimbal motion, and internal instrument disturbances. To minimize the impact of these disturbances, the baseline design included an EPP, a stiff optical bench to which the two nadir pointed instruments are collocated together with the Guidance Navigation Control (GNC) star trackers and Inertial Measurement Units (IMUs). The EPP is passively isolated from the spacecraft bus with Honeywell D-Strut isolators providing attenuation for frequencies above 5 Hz in all six degrees-of-freedom. To reduce the risk of wheel disturbances impacting performance, a secondary passive isolation system manufactured by Moog CSA Engineering was incorporated under each of the six 160 Nms reaction wheels, tuned to provide attenuation at frequencies above 50 Hz. Integrated wheel and isolator testing was performed on a Kistler table at NASA Goddard Space Flight Center. Pre-launch Satellite Dynamic Interaction Characterization high-fidelity simulations and ground testing were conducted to evaluate jitter performance for two cases: 1) deployed EPP and reaction wheel (Dual Isolation) and 2) EPP hard mounted (RWA Isolation Only) to the spacecraft. A comparison of pre-launch to post-launch Satellite Dynamic Interaction Characterization results are also presented in this paper.

A Pathogen-Selective Antibiotic Minimizes Disturbance to the Microbiome

PubMed Central

Yao, Jiangwei; Carter, Robert A.; Vuagniaux, Grégoire; Barbier, Maryse; Rosch, Jason W.

2016-01-01

Broad-spectrum antibiotic therapy decimates the gut microbiome, resulting in a variety of negative health consequences. Debio 1452 is a staphylococcus-selective enoyl-acyl carrier protein reductase (FabI) inhibitor under clinical development and was used to determine whether treatment with pathogen-selective antibiotics would minimize disturbance to the microbiome. The effect of oral Debio 1452 on the microbiota of mice was compared to the effects of four commonly used broad-spectrum oral antibiotics. During the 10 days of oral Debio 1452 treatment, there was minimal disturbance to the gut bacterial abundance and composition, with only the unclassified S24-7 taxon reduced at days 6 and 10. In comparison, broad-spectrum oral antibiotics caused ∼100- to 4,000-fold decreases in gut bacterial abundance and severely altered the microbial composition. The gut bacterial abundance and composition of Debio 1452-treated mice were indistinguishable from those of untreated mice 2 days after the antibiotic treatment was stopped. In contrast, the bacterial abundance in broad-spectrum-antibiotic-treated mice took up to 7 days to recover, and the gut composition of the broad-spectrum-antibiotic-treated mice remained different from that of the control group 20 days after the cessation of antibiotic treatment. These results illustrate that a pathogen-selective approach to antibiotic development will minimize disturbance to the gut microbiome. PMID:27161626

Scheduling policies of intelligent sensors and sensor/actuators in flexible structures

NASA Astrophysics Data System (ADS)

Demetriou, Michael A.; Potami, Raffaele

2006-03-01

In this note, we revisit the problem of actuator/sensor placement in large civil infrastructures and flexible space structures within the context of spatial robustness. The positioning of these devices becomes more important in systems employing wireless sensor and actuator networks (WSAN) for improved control performance and for rapid failure detection. The ability of the sensing and actuating devices to possess the property of spatial robustness results in reduced control energy and therefore the spatial distribution of disturbances is integrated into the location optimization measures. In our studies, the structure under consideration is a flexible plate clamped at all sides. First, we consider the case of sensor placement and the optimization scheme attempts to produce those locations that minimize the effects of the spatial distribution of disturbances on the state estimation error; thus the sensor locations produce state estimators with minimized disturbance-to-error transfer function norms. A two-stage optimization procedure is employed whereby one first considers the open loop system and the spatial distribution of disturbances is found that produces the maximal effects on the entire open loop state. Once this "worst" spatial distribution of disturbances is found, the optimization scheme subsequently finds the locations that produce state estimators with minimum transfer function norms. In the second part, we consider the collocated actuator/sensor pairs and the optimization scheme produces those locations that result in compensators with the smallest norms of the disturbance-to-state transfer functions. Going a step further, an intelligent control scheme is presented which, at each time interval, activates a subset of the actuator/sensor pairs in order provide robustness against spatiotemporally moving disturbances and minimize power consumption by keeping some sensor/actuators in sleep mode.

Cogging effect minimization in PMSM position servo system using dual high-order periodic adaptive learning compensation.

PubMed

Luo, Ying; Chen, Yangquan; Pi, Youguo

2010-10-01

Cogging effect which can be treated as a type of position-dependent periodic disturbance, is a serious disadvantage of the permanent magnetic synchronous motor (PMSM). In this paper, based on a simulation system model of PMSM position servo control, the cogging force, viscous friction, and applied load in the real PMSM control system are considered and presented. A dual high-order periodic adaptive learning compensation (DHO-PALC) method is proposed to minimize the cogging effect on the PMSM position and velocity servo system. In this DHO-PALC scheme, more than one previous periods stored information of both the composite tracking error and the estimate of the cogging force is used for the control law updating. Asymptotical stability proof with the proposed DHO-PALC scheme is presented. Simulation is implemented on the PMSM servo system model to illustrate the proposed method. When the constant speed reference is applied, the DHO-PALC can achieve a faster learning convergence speed than the first-order periodic adaptive learning compensation (FO-PALC). Moreover, when the designed reference signal changes periodically, the proposed DHO-PALC can obtain not only faster convergence speed, but also much smaller final error bound than the FO-PALC. Copyright © 2010 ISA. Published by Elsevier Ltd. All rights reserved.

Determining the size of a complete disturbance landscape: multi-scale, continental analysis of forest change.

PubMed

Buma, Brian; Costanza, Jennifer K; Riitters, Kurt

2017-11-21

The scale of investigation for disturbance-influenced processes plays a critical role in theoretical assumptions about stability, variance, and equilibrium, as well as conservation reserve and long-term monitoring program design. Critical consideration of scale is required for robust planning designs, especially when anticipating future disturbances whose exact locations are unknown. This research quantified disturbance proportion and pattern (as contagion) at multiple scales across North America. This pattern of scale-associated variability can guide selection of study and management extents, for example, to minimize variance (measured as standard deviation) between any landscapes within an ecoregion. We identified the proportion and pattern of forest disturbance (30 m grain size) across multiple landscape extents up to 180 km 2 . We explored the variance in proportion of disturbed area and the pattern of that disturbance between landscapes (within an ecoregion) as a function of the landscape extent. In many ecoregions, variance between landscapes within an ecoregion was minimal at broad landscape extents (low standard deviation). Gap-dominated regions showed the least variance, while fire-dominated showed the largest. Intensively managed ecoregions displayed unique patterns. A majority of the ecoregions showed low variance between landscapes at some scale, indicating an appropriate extent for incorporating natural regimes and unknown future disturbances was identified. The quantification of the scales of disturbance at the ecoregion level provides guidance for individuals interested in anticipating future disturbances which will occur in unknown spatial locations. Information on the extents required to incorporate disturbance patterns into planning is crucial for that process.

Adaptive fuzzy logic controller with direct action type structures for InnoSAT attitude control system

NASA Astrophysics Data System (ADS)

Bakri, F. A.; Mashor, M. Y.; Sharun, S. M.; Bibi Sarpinah, S. N.; Abu Bakar, Z.

2016-10-01

This study proposes an adaptive fuzzy controller for attitude control system (ACS) of Innovative Satellite (InnoSAT) based on direct action type structure. In order to study new methods used in satellite attitude control, this paper presents three structures of controllers: Fuzzy PI, Fuzzy PD and conventional Fuzzy PID. The objective of this work is to compare the time response and tracking performance among the three different structures of controllers. The parameters of controller were tuned on-line by adjustment mechanism, which was an approach similar to a PID error that could minimize errors between actual and model reference output. This paper also presents a Model References Adaptive Control (MRAC) as a control scheme to control time varying systems where the performance specifications were given in terms of the reference model. All the controllers were tested using InnoSAT system under some operating conditions such as disturbance, varying gain, measurement noise and time delay. In conclusion, among all considered DA-type structures, AFPID controller was observed as the best structure since it outperformed other controllers in most conditions.

Second-order sliding mode controller with model reference adaptation for automatic train operation

NASA Astrophysics Data System (ADS)

Ganesan, M.; Ezhilarasi, D.; Benni, Jijo

2017-11-01

In this paper, a new approach to model reference based adaptive second-order sliding mode control together with adaptive state feedback is presented to control the longitudinal dynamic motion of a high speed train for automatic train operation with the objective of minimal jerk travel by the passengers. The nonlinear dynamic model for the longitudinal motion of the train comprises of a locomotive and coach subsystems is constructed using multiple point-mass model by considering the forces acting on the vehicle. An adaptation scheme using Lyapunov criterion is derived to tune the controller gains by considering a linear, stable reference model that ensures the stability of the system in closed loop. The effectiveness of the controller tracking performance is tested under uncertain passenger load, coupler-draft gear parameters, propulsion resistance coefficients variations and environmental disturbances due to side wind and wet rail conditions. The results demonstrate improved tracking performance of the proposed control scheme with a least jerk under maximum parameter uncertainties when compared to constant gain second-order sliding mode control.

Ionospheric Peak Electron Density and Performance Evaluation of IRI-CCIR Near Magnetic Equator in Africa During Two Extreme Solar Activities

NASA Astrophysics Data System (ADS)

Adebesin, B. O.; Rabiu, A. B.; Obrou, O. K.; Adeniyi, J. O.

2018-03-01

The F2 layer peak electron density (NmF2) was investigated over Korhogo (Geomagnetic: 1.26°S, 67.38°E), a station near the magnetic equator in the African sector. Data for 1996 and 2000 were, respectively, categorized into low solar quiet and disturbed and high solar quiet and disturbed. NmF2 prenoon peak was higher than the postnoon peak during high solar activity irrespective of magnetic activity condition, while the postnoon peak was higher for low solar activity. Higher NmF2 peak amplitude characterizes disturbed magnetic activity than quiet magnetic condition for any solar activity. The maximum peaks appeared in equinox. June solstice noontime bite out lagged other seasons by 1-2 h. For any condition of solar and magnetic activities, the daytime NmF2 percentage variability (%VR) measured by the relative standard deviation maximizes/minimizes in June solstice/equinox. Daytime variability increases with increasing magnetic activity. The highest peak in the morning time NmF2 variability occurs in equinox, while the highest evening/nighttime variability appeared in June solstice for all solar/magnetic conditions. The nighttime annual variability amplitude is higher during disturbed than quiet condition regardless of solar activity period. At daytime, variability is similar for all conditions of solar activities. NmF2 at Korhogo is well represented on the International Reference Ionosphere-International Radio Consultative Committee (IRI-CCIR) option. The model/observation relationship performed best between local midnight and postmidnight period (00-08 LT). The noontime trough characteristics is not prominent in the IRI pattern during high solar activity but evident during low solar conditions when compared with Korhogo observations. The Nash-Sutcliffe coefficients revealed better model performance during disturbed activities.

Real time PI-backstepping induction machine drive with efficiency optimization.

PubMed

Farhani, Fethi; Ben Regaya, Chiheb; Zaafouri, Abderrahmen; Chaari, Abdelkader

2017-09-01

This paper describes a robust and efficient speed control of a three phase induction machine (IM) subjected to load disturbances. First, a Multiple-Input Multiple-Output (MIMO) PI-Backstepping controller is proposed for a robust and highly accurate tracking of the mechanical speed and rotor flux. Asymptotic stability of the control scheme is proven by Lyapunov Stability Theory. Second, an active online optimization algorithm is used to optimize the efficiency of the drive system. The efficiency improvement approach consists of adjusting the rotor flux with respect to the load torque in order to minimize total losses in the IM. A dSPACE DS1104 R&D board is used to implement the proposed solution. The experimental results released on 3kW squirrel cage IM, show that the reference speed as well as the rotor flux are rapidly achieved with a fast transient response and without overshoot. A good load disturbances rejection response and IM parameters variation are fairly handled. The improvement of drive system efficiency reaches up to 180% at light load. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Towards a remote sensing based indicator of rangeland ecosystem resistance and resilience

USDA-ARS?s Scientific Manuscript database

Understanding ecosystem resistance and resilience to disturbance and invasive species is critical to the sustainable management of rangeland systems. In this context, resistance refers to the inherent ability of an ecosystem to resist disturbance, while resilience refers to the capacity of an ecosys...

Interaction of historical and nonhistorical disturbances maintains native plant communities.

PubMed

Davies, K W; Svejcar, T J; Bates, J D

2009-09-01

Historical disturbance regimes are often considered a critical element in maintaining native plant communities. However, the response of plant communities to disturbance may be fundamentally altered as a consequence of invasive plants, climate change, or prior disturbances. The appropriateness of historical disturbance patterns under modern conditions and the interactions among disturbances are issues that ecologists must address to protect and restore native plant communities. We evaluated the response of Artemisia tridentata ssp. wyomingensis (Beetle & A. Young) S.L. Welsh plant communities to their historical disturbance regime compared to other disturbance regimes. The historical disturbance regime of these plant communities was periodic fires with minimal grazing by large herbivores. We also investigated the influence of prior disturbance (grazing) on the response of these communities to subsequent disturbance (burning). Treatments were: (1) ungrazed (livestock grazing excluded since 1936) and unburned, (2) grazed and unburned, (3) ungrazed and burned (burned in 1993), and (4) grazed and burned. The ungrazed-burned treatment emulated the historical disturbance regime. Vegetation cover, density, and biomass production were measured the 12th, 13th, and 14th year post-burning. Prior to burning the presence of Bromus tectorum L., an exotic annual grass, was minimal (<0.5% cover), and vegetation characteristics were similar between grazed and ungrazed treatments. However, litter accumulation was almost twofold greater in ungrazed than in grazed treatments. Long-term grazing exclusion followed by burning resulted in a substantial B. tectorum invasion, but burning the grazed areas did not produce an invasion. The ungrazed-burned treatment also had less perennial vegetation than other treatments. The accumulation of litter (fuel) in ungrazed treatments may have resulted in greater fire-induced mortality of perennial vegetation in ungrazed compared to grazed treatments. Our results demonstrate that prior disturbances exert a strong influence on the response of plant communities to subsequent disturbances and suggest that low-severity disturbances may be needed in some plant communities to increase their resilience to more severe disturbances. Modern deviations from historical conditions can alter ecosystem response to disturbances, thus restoring the historical disturbance regime may not be an appropriate strategy for all ecosystems.

Conservation of disturbance-dependent birds in eastern North America

Treesearch

William C. Hunter; David A. Buehler; Ronald A. Canterbury; John L. Confer; Paul B. Hamel

2001-01-01

Populations of most bird species associated with grassland, shrub-scrub habitats, and disturbed areas in forested habitats (hereafter all referred to as disturbance-dependent species) have declined steeply. However, a widespread perception exists that disturbance-dependent species are merely returning to population levels likely found by the first European explorers...

32 CFR 643.114 - Civil disturbances.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 32 National Defense 4 2010-07-01 2010-07-01 true Civil disturbances. 643.114 Section 643.114... ESTATE Additional Authority of Commanders § 643.114 Civil disturbances. Without reference to higher... facilities during civil disturbance for not more than 30 days to the National Guard and to municipal, county...

32 CFR 643.114 - Civil disturbances.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 32 National Defense 4 2011-07-01 2011-07-01 false Civil disturbances. 643.114 Section 643.114... ESTATE Additional Authority of Commanders § 643.114 Civil disturbances. Without reference to higher... facilities during civil disturbance for not more than 30 days to the National Guard and to municipal, county...

32 CFR 643.114 - Civil disturbances.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 32 National Defense 4 2014-07-01 2013-07-01 true Civil disturbances. 643.114 Section 643.114... ESTATE Additional Authority of Commanders § 643.114 Civil disturbances. Without reference to higher... facilities during civil disturbance for not more than 30 days to the National Guard and to municipal, county...

32 CFR 643.114 - Civil disturbances.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 32 National Defense 4 2012-07-01 2011-07-01 true Civil disturbances. 643.114 Section 643.114... ESTATE Additional Authority of Commanders § 643.114 Civil disturbances. Without reference to higher... facilities during civil disturbance for not more than 30 days to the National Guard and to municipal, county...

32 CFR 643.114 - Civil disturbances.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 32 National Defense 4 2013-07-01 2013-07-01 false Civil disturbances. 643.114 Section 643.114... ESTATE Additional Authority of Commanders § 643.114 Civil disturbances. Without reference to higher... facilities during civil disturbance for not more than 30 days to the National Guard and to municipal, county...

Periodic-disturbance accommodating control of the space station for asymptotic momentum management

NASA Technical Reports Server (NTRS)

Warren, Wayne; Wie, Bong; Geller, David

1989-01-01

Periodic-disturbance accommodating control is investigated for asymptotic momentum management of control moment gyros used as primary actuating devices for the Space Station. The proposed controller utilizes the concepts of quaternion feedback control and periodic-disturbance accommodation to achieve oscillations about the constant torque equilibrium attitude, while minimizing the control effort required. Three-axis coupled equations of motion, written in terms of quaternions, are derived for roll/yaw controller design and stability analysis. The quaternion feedback controller designed using the linear-quadratic regulator synthesis technique is shown to be robust for a wide range of pitch angles. It is also shown that the proposed controller tunes the open-loop unstable vehicle to a stable oscillatory motion which minimizes the control effort needed for steady-state operations.

18-Degree-of-Freedom Controller Design for the ST7 Disturbance Reduction System

NASA Technical Reports Server (NTRS)

Markley, F. L.; Maghami, P. G.; Houghton, M. B.; Hsu, O. C.

2003-01-01

The Space Technology 7 experiment will perform an on-orbit system-level validation of a Disturbance Reduction System employing gravitational reference sensors and micronewton colloidal thrusters to maintain a spacecraft s position with respect to free-floating test masses in the gravitational reference sensors to less than 10 nm/dHz over the frequency range 1 to 30 mHz. This paper presents the design and analysis of the control system that closes the loop between the gravitational reference sensors and the micronewton thrusters while incorporating star tracker data at low frequencies. The effects of disturbances and actuation and measurement noise are evaluated in a eighteen-degree-of-freedom model.

Economics of Soil Disturbance

Treesearch

Han-Sup Han

2007-01-01

Economic implications of soil disturbance are discussed in four categories: planning and layout, selection of harvesting systems and equipment, long-term site productivity loss, and rehabilitation treatments. Preventive measures are more effective in minimizing impacts on soils than rehabilitation treatments because of the remedial expenses, loss of productivity until...

Appilications of National Wetland Condition Assessment Data ...

EPA Pesticide Factsheets

The first National Wetland Condition Assessment (NWCA) was conducted in 2011 by the US Environmental Protection Agency (USEPA) and its federal and state partners, using a survey design allowing extrapolation of results to national and regional scales. Vegetation, algae, soil, water chemistry, and hydrologic data were collected at each of 1138 locations across the contiguous US. Ecological condition was assessed in relation to a disturbance gradient anchored by least (reference) and most disturbed sites and identified using chemical, physical, and biological disturbance indices based on site-level data. A vegetation multimetric index (VMMI) was used as the indicator of condition. Potential stressors to condition were incorporated into indices of hydrologic alteration, physical alteration and a soil heavy metals, and a nonnative plant indicator. The indices were used to quantify national and regional stressor extent, and their associated relative and attributable risk. All 1138 sites sampled were placed along a quantitatively defined disturbance gradient customized by the ecoregions used in NWCA reporting. The characteristics of the 277 sites at the end of the gradient identified as least disturbed were considered reference condition. The pool of reference sites will be increased with future assessments using the definition of reference set in 2011 and can serve as a benchmark for management decisions and restoration. Approximately 48±6% of the national wetland

Minimal gain marching schemes: searching for unstable steady-states with unsteady solvers

NASA Astrophysics Data System (ADS)

de S. Teixeira, Renan; S. de B. Alves, Leonardo

2017-12-01

Reference solutions are important in several applications. They are used as base states in linear stability analyses as well as initial conditions and reference states for sponge zones in numerical simulations, just to name a few examples. Their accuracy is also paramount in both fields, leading to more reliable analyses and efficient simulations, respectively. Hence, steady-states usually make the best reference solutions. Unfortunately, standard marching schemes utilized for accurate unsteady simulations almost never reach steady-states of unstable flows. Steady governing equations could be solved instead, by employing Newton-type methods often coupled with continuation techniques. However, such iterative approaches do require large computational resources and very good initial guesses to converge. These difficulties motivated the development of a technique known as selective frequency damping (SFD) (Åkervik et al. in Phys Fluids 18(6):068102, 2006). It adds a source term to the unsteady governing equations that filters out the unstable frequencies, allowing a steady-state to be reached. This approach does not require a good initial condition and works well for self-excited flows, where a single nonzero excitation frequency is selected by either absolute or global instability mechanisms. On the other hand, it seems unable to damp stationary disturbances. Furthermore, flows with a broad unstable frequency spectrum might require the use of multiple filters, which delays convergence significantly. Both scenarios appear in convectively, absolutely or globally unstable flows. An alternative approach is proposed in the present paper. It modifies the coefficients of a marching scheme in such a way that makes the absolute value of its linear gain smaller than one within the required unstable frequency spectra, allowing the respective disturbance amplitudes to decay given enough time. These ideas are applied here to implicit multi-step schemes. A few chosen test cases shows that they enable convergence toward solutions that are unstable to stationary and oscillatory disturbances, with either a single or multiple frequency content. Finally, comparisons with SFD are also performed, showing significant reduction in computer cost for complex flows by using the implicit multi-step MGM schemes.

Accessible Information Without Disturbing Partially Known Quantum States on a von Neumann Algebra

NASA Astrophysics Data System (ADS)

Kuramochi, Yui

2018-04-01

This paper addresses the problem of how much information we can extract without disturbing a statistical experiment, which is a family of partially known normal states on a von Neumann algebra. We define the classical part of a statistical experiment as the restriction of the equivalent minimal sufficient statistical experiment to the center of the outcome space, which, in the case of density operators on a Hilbert space, corresponds to the classical probability distributions appearing in the maximal decomposition by Koashi and Imoto (Phys. Rev. A 66, 022,318 2002). We show that we can access by a Schwarz or completely positive channel at most the classical part of a statistical experiment if we do not disturb the states. We apply this result to the broadcasting problem of a statistical experiment. We also show that the classical part of the direct product of statistical experiments is the direct product of the classical parts of the statistical experiments. The proof of the latter result is based on the theorem that the direct product of minimal sufficient statistical experiments is also minimal sufficient.

Sediment and discharge yields within a minimally disturbed, headwater watershed in North Central Pennsylvania, USA, with an emphasis on Superstorm Sandy

USGS Publications Warehouse

Maloney, Kelly O.; Shull, Dustin R.

2015-01-01

We estimated discharge and suspended sediment (SS) yield in a minimally disturbed watershed in North Central Pennsylvania, USA, and compared a typical storm (September storm, 4.80 cm) to a large storm (Superstorm Sandy, 7.47 cm rainfall). Depending on branch, Sandy contributed 9.7–19.9 times more discharge and 11.5–37.4 times more SS than the September storm. During the September storm, the upper two branches accounted for 60.6% of discharge and 88.8% of SS at Lower Branch; during Sandy these percentages dropped to 36.1% for discharge and 30.1% for SS. The branch with close proximity roads had over two-three times per area SS yield than the branch without such roads. Hysteresis loops showed typical clockwise patterns for the September storm and more complicated patterns for Sandy, reflecting the multipeak event. Estimates of SS and hysteresis in minimally disturbed watersheds provide useful information that can be compared spatially and temporally to facilitate management.

Risk determinants of small and medium-sized manufacturing enterprises (SMEs) - an exploratory study in New Zealand

NASA Astrophysics Data System (ADS)

Islam, Ariful; Tedford, Des

2012-08-01

The smooth running of small and medium-sized manufacturing enterprises (SMEs) presents a significant challenge irrespective of the technological and human resources they may have at their disposal. SMEs continuously encounter daily internal and external undesirable events and unwanted setbacks to their operations that detract from their business performance. These are referred to as `disturbances' in our research study. Among the disturbances, some are likely to create risks to the enterprises in terms of loss of production, manufacturing capability, human resource, market share, and, of course, economic losses. These are finally referred to as `risk determinant' on the basis of their correlation with some risk indicators, which are linked to operational, occupational, and economic risks. To deal with these risk determinants effectively, SMEs need a systematic method of approach to identify and treat their potential effects along with an appropriate set of tools. However, initially, a strategic approach is required to identify typical risk determinants and their linkage with potential business risks. In this connection, we conducted this study to explore the answer to the research question: what are the typical risk determinants encountered by SMEs? We carried out an empirical investigation with a multi-method research approach (a combination of a questionnaire-based mail survey involving 212 SMEs and five in-depth case studies) in New Zealand. This paper presents a set of typical internal and external risk determinants, which need special attention to be dealt with to minimize operational risks of an SME.

Soils

Treesearch

Emily Moghaddas; Ken Hubbert

2014-01-01

When managing for resilient forests, each soil’s inherent capacity to resist and recover from changes in soil function should be evaluated relative to the anticipated extent and duration of soil disturbance. Application of several key principles will help ensure healthy, resilient soils: (1) minimize physical disturbance using guidelines tailored to specific soil types...

Trip-specific training enhances recovery after large postural disturbances for which there is NO expectation.

PubMed

Oludare, Simisola O; Pater, Mackenzie L; Rosenblatt, Noah J; Grabiner, Mark D

2018-03-01

Informed consent usually provides foreknowledge of experimental methods that can potentially increase expectation of stimuli and, therefore, influence the response. We determined the effects of increased expectation and trip-specific training on the recovery response following a treadmill-delivered, trip-specific disturbance. To deliver unexpected disturbances, subjects were deceived during the informed consent process. The primary hypothesis was that the recovery response following an expected postural disturbance would be characterized by trunk kinematics that have been shown to decrease the likelihood of a fall, compared to following an unexpected postural disturbance. We further hypothesized that following an unexpected postural disturbance, the recovery response of the subjects who had completed a trip-specific training protocol would be more biomechanically favorable to recovery compared to those of subjects who had not received the training. Young adults were randomized into Untrained or Trained groups. During the informed consent process, the purpose of the study was explained to subjects in both groups as being to determine the effect of trip-specific training on postural sway while performing an attention-demanding task. Untrained subjects completed two trials during which they minimized their postural sway. During the second trial, an unexpected disturbance was delivered while they performed the attention-demanding task. Trained subjects performed a pre-training postural sway trial, followed by the delivery of a series of expected, training disturbances. Finally, an unexpected disturbance was delivered while they minimized postural sway and performed the attention-demanding task. Expectation significantly improved trunk kinematics (p < .05). In addition, participation in the trip-specific training protocol following the unexpected disturbance the trunk kinematics of the Trained subjects were more biomechanically favorable to recovery than those of the Untrained subjects (p < .01). Improved trunk kinematics following trip-specific training may be independent of the extent to which the disturbance is expected. Copyright © 2018 Elsevier B.V. All rights reserved.

SELECTING LEAST-DISTURBED SURVEY SITES FOR GREAT PLAINS STREAMS AND RIVERS

EPA Science Inventory

True reference condition probably does not exist for streams in highly utilized regions such as the Great Plains. Selecting least-disturbed sites for large regions is confounded by the association between human uses and natural gradients, and by multiple kinds of disturbance. U...

Do Doppler color flow algorithms for mapping disturbed flow make sense?

PubMed

Gardin, J M; Lobodzinski, S M

1990-01-01

It has been suggested that a major advantage of Doppler color flow mapping is its ability to visualize areas of disturbed ("turbulent") flow, for example, in valvular stenosis or regurgitation and in shunts. To investigate how various color flow mapping instruments display disturbed flow information, color image processing was used to evaluate the most common velocity-variance color encoding algorithms of seven commercially available ultrasound machines. In six of seven machines, green was reportedly added by the variance display algorithms to map areas of disturbed flow. The amount of green intensity added to each pixel along the red and blue portions of the velocity reference color bar was calculated for each machine. In this study, velocities displayed on the reference color bar ranged from +/- 46 to +/- 64 cm/sec, depending on the Nyquist limit. Of note, changing the Nyquist limits depicted on the color reference bars did not change the distribution of the intensities of red, blue, or green within the contour of the reference map, but merely assigned different velocities to the pixels. Most color flow mapping algorithms in our study added increasing intensities of green to increasing positive (red) or negative (blue) velocities along their color reference bars. Most of these machines also added increasing green to red and blue color intensities horizontally across their reference bars as a marker of increased variance (spectral broadening). However, at any given velocity, marked variations were noted between different color flow mapping instruments in the amount of green added to their color velocity reference bars.(ABSTRACT TRUNCATED AT 250 WORDS)

Disturbance automated reference toolset (DART): Assessing patterns in ecological recovery from energy development on the Colorado Plateau

USGS Publications Warehouse

Nauman, Travis; Duniway, Michael C.; Villarreal, Miguel; Poitras, Travis

2017-01-01

A new disturbance automated reference toolset (DART) was developed to monitor human land surface impacts using soil-type and ecological context. DART identifies reference areas with similar soils, topography, and geology; and compares the disturbance condition to the reference area condition using a quantile-based approach based on a satellite vegetation index. DART was able to represent 26–55% of variation of relative differences in bare ground and 26–41% of variation in total foliar cover when comparing sites with nearby ecological reference areas using the Soil Adjusted Total Vegetation Index (SATVI). Assessment of ecological recovery at oil and gas pads on the Colorado Plateau with DART revealed that more than half of well-pads were below the 25th percentile of reference areas. Machine learning trend analysis of poorly recovering well-pads (quantile < 0.23) had out-of-bag error rates between 37 and 40% indicating moderate association with environmental and management variables hypothesized to influence recovery. Well-pads in grasslands (median quantile [MQ] = 13%), blackbrush (Coleogyne ramosissima) shrublands (MQ = 18%), arid canyon complexes (MQ = 18%), warmer areas with more summer-dominated precipitation, and state administered areas (MQ = 12%) had low recovery rates. Results showcase the usefulness of DART for assessing discrete surface land disturbances, and highlight the need for more targeted rehabilitation efforts at oil and gas well-pads in the arid southwest US.

Disturbance automated reference toolset (DART): Assessing patterns in ecological recovery from energy development on the Colorado Plateau.

PubMed

Nauman, Travis W; Duniway, Michael C; Villarreal, Miguel L; Poitras, Travis B

2017-04-15

A new disturbance automated reference toolset (DART) was developed to monitor human land surface impacts using soil-type and ecological context. DART identifies reference areas with similar soils, topography, and geology; and compares the disturbance condition to the reference area condition using a quantile-based approach based on a satellite vegetation index. DART was able to represent 26-55% of variation of relative differences in bare ground and 26-41% of variation in total foliar cover when comparing sites with nearby ecological reference areas using the Soil Adjusted Total Vegetation Index (SATVI). Assessment of ecological recovery at oil and gas pads on the Colorado Plateau with DART revealed that more than half of well-pads were below the 25th percentile of reference areas. Machine learning trend analysis of poorly recovering well-pads (quantile<0.23) had out-of-bag error rates between 37 and 40% indicating moderate association with environmental and management variables hypothesized to influence recovery. Well-pads in grasslands (median quantile [MQ]=13%), blackbrush (Coleogyne ramosissima) shrublands (MQ=18%), arid canyon complexes (MQ=18%), warmer areas with more summer-dominated precipitation, and state administered areas (MQ=12%) had low recovery rates. Results showcase the usefulness of DART for assessing discrete surface land disturbances, and highlight the need for more targeted rehabilitation efforts at oil and gas well-pads in the arid southwest US. Published by Elsevier B.V.

Repeated disturbances affect functional but not compositional resistance and resilience in an aquatic bacterioplankton community.

PubMed

Sjöstedt, Johanna; Langenheder, Silke; Kritzberg, Emma; Karlsson, Christofer M G; Lindström, Eva S

2018-05-07

Disturbances are believed to be one of the main factors influencing variations in community diversity and functioning. Here we investigated if exposure to a pH press disturbance affected the composition and functional performance of a bacterial community and its resistance, recovery and resilience to a second press disturbance (salt addition). Lake bacterial assemblages were initially exposed to reduced pH in six mesocosms whereas another six mesocosms were kept as reference. Seven days after the pH disturbance, three tanks from each treatment were exposed to a salt disturbance. Both bacterial production and enzyme activity were negatively affected by the salt treatment, regardless if the communities had been subject to a previous disturbance or not. However, cell-specific enzyme activity had a higher resistance in communities pre-exposed to the pH disturbance compared to the reference treatment. In contrast, for cell-specific bacterial production resistance was not affected, but recovery was faster in the communities that had previously been exposed to the pH disturbance. Over time, bacterial community composition diverged among treatments, in response to both pH and salinity. The difference in functional recovery, resilience and resistance may depend on differences in community composition caused by the pH disturbance, niche breadth or acquired stress resistance. This article is protected by copyright. All rights reserved. © 2018 Society for Applied Microbiology and John Wiley & Sons Ltd.

An Online Observer for Minimization of Pulsating Torque in SMPM Motors

PubMed Central

Roșca, Lucian

2016-01-01

A persistent problem of surface mounted permanent magnet (SMPM) motors is the non-uniformity of the developed torque. Either the motor design or the motor control needs to be improved in order to minimize the periodic disturbances. This paper proposes a new control technique for reducing periodic disturbances in permanent magnet (PM) electro-mechanical actuators, by advancing a new observer/estimator paradigm. A recursive estimation algorithm is implemented for online control. The compensating signal is identified and added as feedback to the control signal of the servo motor. Compensation is evaluated for different values of the input signal, to show robustness of the proposed method. PMID:27089182

THE CONCEPT OF REFERENCE CONDITION, REVISITED ...

EPA Pesticide Factsheets

Ecological assessments of aquatic ecosystems depend on the ability to compare current conditions against some expectation of how they could be in the absence of significant human disturbance. The concept of a ‘‘reference condition’’ is often used to describe the standard or benchmark against which current condition is compared. If assessments are to be conducted consistently, then a common understanding of the definitions and complications of reference condition is necessary. A 2006 paper (Stoddard et al., 2006, Ecological Applications 16:1267-1276) made an early attempt at codifying the reference condition concept; in this presentation we will revisit the points raised in that paper (and others) and examine how our thinking has changed in a little over 10 years.Among the issues to be discussed: (1) the “moving target” created when reference site data are used to set thresholds in large scale assessments; (2) natural vs. human disturbance and their effects on reference site distributions; (3) circularity and the use of biological data to assist in reference site identification; (4) using site-scale (in-stream or in-lake) measurements vs. landscape-level human activity to identify reference conditions. Ecological assessments of aquatic ecosystems depend on the ability to compare current conditions against some expectation of how they could be in the absence of significant human disturbance. The concept of a ‘‘reference condition’’ is often use

The effects of drought and disturbance on the growth and developmental instability of loblolly pine (Pinus taeda L.)

Treesearch

John H. Graham; Jeffrey J. Duda; Michelle L. Brown; Stanley Kitchen; John M. Emlen; Jagadish Malol; Elizabeth Bankstahl; Anthony J. Krzysik; Harold Balbach; D. Carl Freeman

2012-01-01

Ecological indicators provide early warning of adverse environmental change, helping land managers adaptively manage their resources while minimizing costly remediation. In 1999 and 2000, we studied two such indicators, growth and developmental instability, of loblolly pine (Pinus taeda L.) influenced by mechanized infantry training at Fort Benning, Georgia. Disturbed...

Using a detailed uncertainty analysis to adjust mapped rates of forest disturbance derived from Landsat time series data (Invited)

NASA Astrophysics Data System (ADS)

Cohen, W. B.; Yang, Z.; Stehman, S.; Huang, C.; Healey, S. P.

2013-12-01

Forest ecosystem process models require spatially and temporally detailed disturbance data to accurately predict fluxes of carbon or changes in biodiversity over time. A variety of new mapping algorithms using dense Landsat time series show great promise for providing disturbance characterizations at an annual time step. These algorithms provide unprecedented detail with respect to timing, magnitude, and duration of individual disturbance events, and causal agent. But all maps have error and disturbance maps in particular can have significant omission error because many disturbances are relatively subtle. Because disturbance, although ubiquitous, can be a relatively rare event spatially in any given year, omission errors can have a great impact on mapped rates. Using a high quality reference disturbance dataset, it is possible to not only characterize map errors but also to adjust mapped disturbance rates to provide unbiased rate estimates with confidence intervals. We present results from a national-level disturbance mapping project (the North American Forest Dynamics project) based on the Vegetation Change Tracker (VCT) with annual Landsat time series and uncertainty analyses that consist of three basic components: response design, statistical design, and analyses. The response design describes the reference data collection, in terms of the tool used (TimeSync), a formal description of interpretations, and the approach for data collection. The statistical design defines the selection of plot samples to be interpreted, whether stratification is used, and the sample size. Analyses involve derivation of standard agreement matrices between the map and the reference data, and use of inclusion probabilities and post-stratification to adjust mapped disturbance rates. Because for NAFD we use annual time series, both mapped and adjusted rates are provided at an annual time step from ~1985-present. Preliminary evaluations indicate that VCT captures most of the higher intensity disturbances, but that many of the lower intensity disturbances (thinnings, stress related to insects and disease, etc.) are missed. Because lower intensity disturbances are a large proportion of the total set of disturbances, adjusting mapped disturbance rates to include these can be important for inclusion in ecosystem process models. The described statistical disturbance rate adjustments are aspatial in nature, such that the basic underlying map is unchanged. For spatially explicit ecosystem modeling, such adjustments, although important, can be difficult to directly incorporate. One approach for improving the basic underlying map is an ensemble modeling approach that uses several different complementary maps, each derived from a different algorithm and having their own strengths and weaknesses relative to disturbance magnitude and causal agent of disturbance. We will present results from a pilot study associated with the Landscape Change Monitoring System (LCMS), an emerging national-level program that builds upon NAFD and the well-established Monitoring Trends in Burn Severity (MTBS) program.

Importance of riparian forests in urban catchments contingent on sediment and hydrologic regimes

USGS Publications Warehouse

Roy, A.H.; Freeman, Mary C.; Freeman, B.J.; Wenger, S.J.; Meyer, J.L.; Ensign, W.E.

2006-01-01

Forested riparian corridors are thought to minimize impacts of landscape disturbance on stream ecosystems; yet, the effectiveness of streamside forests in mitigating disturbance in urbanizing catchments is unknown. We expected that riparian forests would provide minimal benefits for fish assemblages in streams that are highly impaired by sediment or hydrologic alteration. We tested this hypothesis in 30 small streams along a gradient of urban disturbance (1–65% urban land cover). Species expected to be sensitive to disturbance (i.e., fluvial specialists and “sensitive” species that respond negatively to urbanization) were best predicted by models including percent forest cover in the riparian corridor and a principal components axis describing sediment disturbance. Only sites with coarse bed sediment and low bed mobility (vs. sites with high amounts of fine sediment) had increased richness and abundances of sensitive species with higher percent riparian forests, supporting our hypothesis that response to riparian forests is contingent on the sediment regime. Abundances of Etheostoma scotti, the federally threatened Cherokee darter, were best predicted by models with single variables representing stormflow (r2 = 0.34) and sediment (r2 = 0.23) conditions. Lentic-tolerant species richness and abundance responded only to a variable representing prolonged duration of low-flow conditions. For these species, hydrologic alteration overwhelmed any influence of riparian forests on stream biota. These results suggest that, at a minimum, catchment management strategies must simultaneously address hydrologic, sediment, and riparian disturbance in order to protect all aspects of fish assemblage integrity.

Importance of riparian forests in urban catchments contingent on sediment and hydrologic regimes.

PubMed

Roy, Allison H; Freeman, Mary C; Freeman, Byron J; Wenger, Seth J; Ensign, William E; Meyer, Judith L

2006-04-01

Forested riparian corridors are thought to minimize impacts of landscape disturbance on stream ecosystems; yet, the effectiveness of streamside forests in mitigating disturbance in urbanizing catchments is unknown. We expected that riparian forests would provide minimal benefits for fish assemblages in streams that are highly impaired by sediment or hydrologic alteration. We tested this hypothesis in 30 small streams along a gradient of urban disturbance (1-65% urban land cover). Species expected to be sensitive to disturbance (i.e., fluvial specialists and "sensitive" species that respond negatively to urbanization) were best predicted by models including percent forest cover in the riparian corridor and a principal components axis describing sediment disturbance. Only sites with coarse bed sediment and low bed mobility (vs. sites with high amounts of fine sediment) had increased richness and abundances of sensitive species with higher percent riparian forests, supporting our hypothesis that response to riparian forests is contingent on the sediment regime. Abundances of Etheostoma scotti, the federally threatened Cherokee darter, were best predicted by models with single variables representing stormflow (r(2) = 0.34) and sediment (r(2) = 0.23) conditions. Lentic-tolerant species richness and abundance responded only to a variable representing prolonged duration of low-flow conditions. For these species, hydrologic alteration overwhelmed any influence of riparian forests on stream biota. These results suggest that, at a minimum, catchment management strategies must simultaneously address hydrologic, sediment, and riparian disturbance in order to protect all aspects of fish assemblage integrity.

Multivariate and geo-spatial approach for seawater quality of Chidiyatappu Bay, south Andaman Islands, India.

PubMed

Jha, Dilip Kumar; Vinithkumar, Nambali Valsalan; Sahu, Biraja Kumar; Dheenan, Palaiya Sukumaran; Das, Apurba Kumar; Begum, Mehmuna; Devi, Marimuthu Prashanthi; Kirubagaran, Ramalingam

2015-07-15

Chidiyatappu Bay is one of the least disturbed marine environments of Andaman & Nicobar Islands, the union territory of India. Oceanic flushing from southeast and northwest direction is prevalent in this bay. Further, anthropogenic activity is minimal in the adjoining environment. Considering the pristine nature of this bay, seawater samples collected from 12 sampling stations covering three seasons were analyzed. Principal Component Analysis (PCA) revealed 69.9% of total variance and exhibited strong factor loading for nitrite, chlorophyll a and phaeophytin. In addition, analysis of variance (ANOVA-one way), regression analysis, box-whisker plots and Geographical Information System based hot spot analysis further simplified and supported multivariate results. The results obtained are important to establish reference conditions for comparative study with other similar ecosystems in the region. Copyright © 2015 Elsevier Ltd. All rights reserved.

Students' Attitudes toward Campus Environment: A Comparative Study of Public and Private Universities in Kenya

ERIC Educational Resources Information Center

Chepchieng, Micah C.; Kiboss, Joel K.; Sindabi, Aggrey; Kariuki, Mary W.; Mbugua, Stephen N.

2006-01-01

One of the serious problems facing education in Kenya's public universities has been a persistent student disturbance. Private universities on the other hand, seem to have established a reputation of having minimal incidence of student disturbances. As such private universities are known to have had a good record of student conduct. This may be…

Logging Options to Minimize Soil Disturbance in the Northern Lake States

Treesearch

Douglas M. Stone

2002-01-01

Forest harvesting is likely to have greater impacts on site productivity than any other activity during the rotation. We determined effects of commercial, winter-logging of four aspen-dominated stands on site disturbance and development of regeneration on clay soils in western Upper Michigan. A large skidder caused deep rutting on 20% of a site in a thinning that...

Comparison of silvicultural and natural disturbance effects on terrestrial salamanders in northern hardwood forests

Treesearch

Daniel J. Hocking; Kimberly J. Babbitt; Mariko Yamasaki

2013-01-01

In forested ecosystems timber harvesting has the potential to emulate natural disturbances, thereby maintaining the natural communities adapted to particular disturbances. We compared the effects of even-aged (clearcut and patch cut) and uneven-aged (group cut, single-tree selection) timber management techniques with natural ice-storm damage and unmanipulated reference...

Discrete-time nonlinear damping backstepping control with observers for rejection of low and high frequency disturbances

NASA Astrophysics Data System (ADS)

Kim, Wonhee; Chen, Xu; Lee, Youngwoo; Chung, Chung Choo; Tomizuka, Masayoshi

2018-05-01

A discrete-time backstepping control algorithm is proposed for reference tracking of systems affected by both broadband disturbances at low frequencies and narrow band disturbances at high frequencies. A discrete time DOB, which is constructed based on infinite impulse response filters is applied to compensate for narrow band disturbances at high frequencies. A discrete-time nonlinear damping backstepping controller with an augmented observer is proposed to track the desired output and to compensate for low frequency broadband disturbances along with a disturbance observer, for rejecting narrow band high frequency disturbances. This combination has the merit of simultaneously compensating both broadband disturbances at low frequencies and narrow band disturbances at high frequencies. The performance of the proposed method is validated via experiments.

Disturbance Reduction Control Design for the ST7 Flight Validation Experiment

NASA Technical Reports Server (NTRS)

Maghami, P. G.; Hsu, O. C.; Markley, F. L.; Houghton, M. B.

2003-01-01

The Space Technology 7 experiment will perform an on-orbit system-level validation of two specific Disturbance Reduction System technologies: a gravitational reference sensor employing a free-floating test mass, and a set of micro-Newton colloidal thrusters. The ST7 Disturbance Reduction System is designed to maintain the spacecraft's position with respect to a free-floating test mass to less than 10 nm/Hz, over the frequency range of 1 to 30 mHz. This paper presents the design and analysis of the coupled, drag-free and attitude control systems that close the loop between the gravitational reference sensor and the micro-Newton thrusters, while incorporating star tracker data at low frequencies. A full 18 degree-of-freedom model, which incorporates rigid-body models of the spacecraft and two test masses, is used to evaluate the effects of actuation and measurement noise and disturbances on the performance of the drag-free system.

Predictive Feedback and Feedforward Control for Systems with Unknown Disturbances

NASA Technical Reports Server (NTRS)

Juang, Jer-Nan; Eure, Kenneth W.

1998-01-01

Predictive feedback control has been successfully used in the regulation of plate vibrations when no reference signal is available for feedforward control. However, if a reference signal is available it may be used to enhance regulation by incorporating a feedforward path in the feedback controller. Such a controller is known as a hybrid controller. This paper presents the theory and implementation of the hybrid controller for general linear systems, in particular for structural vibration induced by acoustic noise. The generalized predictive control is extended to include a feedforward path in the multi-input multi-output case and implemented on a single-input single-output test plant to achieve plate vibration regulation. There are cases in acoustic-induce vibration where the disturbance signal is not available to be used by the hybrid controller, but a disturbance model is available. In this case the disturbance model may be used in the feedback controller to enhance performance. In practice, however, neither the disturbance signal nor the disturbance model is available. This paper presents the theory of identifying and incorporating the noise model into the feedback controller. Implementations are performed on a test plant and regulation improvements over the case where no noise model is used are demonstrated.

Legacy effects of no-analogue disturbances alter plant community diversity and composition in semi-arid sagebrush steppe

USGS Publications Warehouse

Ripplinger, Julie; Franklin, Janet; Edwards, Thomas C.

2015-01-01

Questions(i) What role does the type of managed disturbance play in structuring sagebrush steppe plant communities? (ii) How does the composition of post-disturbance plant communities change with time since disturbance? (iii) Does plant community diversity change over time following managed disturbance?LocationField study within the sagebrush steppe ecosystem. Rich County, Utah, USA.MethodsWe developed a chronosequence spanning up to 50 yrs post-treatment to study sagebrush steppe vegetation dynamics. Direct ordination was used to examine plant community composition by managed disturbance type and time since disturbance, and factorial analysis of covariance was used to examine diversity dynamics following disturbance. Indicator species values were calculated in order to identify characteristic species for each disturbance type.ResultsPlant communities experienced a shift toward distinct community composition for each of the three managed disturbance types, and gave no indication of returning to untreated community composition or diversity. Small post-disturbance increases in the number of non-native grass species were observed in the treatments relative to reference, with native forb species making the largest contribution to altered composition. On fire- and chemically-treated sites the proportional native forb species richness increased over time since disturbance, while the proportional contribution of non-native forbs to total species richness decreased. For all three treatment types, native grasses contributed less on average to total richness than on reference sites, while non-native grasses made up a higher proportion of total richness.ConclusionsCommon shrubland management techniques have legacy effects on the composition and diversity of sagebrush steppe plant communities, and no-analogue disturbances, such as chemical or mechanical treatments, have more pronounced legacy effects than treatments similar to natural disturbance regimes (fire). This study informs a broader understanding of how management actions affect natural systems by highlighting the importance of long-term management legacies as drivers of plant community structure and function.

Emotional Disturbance

MedlinePlus

... body of research exists regarding methods of providing students with positive behavioral support (PBS) in the school environment, so that problem behaviors are minimized and positive, appropriate behaviors are ...

An analytic-numerical method for the construction of the reference law of operation for a class of mechanical controlled systems

NASA Astrophysics Data System (ADS)

Mizhidon, A. D.; Mizhidon, K. A.

2017-04-01

An analytic-numerical method for the construction of a reference law of operation for a class of dynamic systems describing vibrations in controlled mechanical systems is proposed. By the reference law of operation of a system, we mean a law of the system motion that satisfies all the requirements for the quality and design features of the system under permanent external disturbances. As disturbances, we consider polyharmonic functions with known amplitudes and frequencies of the harmonics but unknown initial phases. For constructing the reference law of motion, an auxiliary optimal control problem is solved in which the cost function depends on a weighting coefficient. The choice of the weighting coefficient ensures the design of the reference law. Theoretical foundations of the proposed method are given.

Periodic-disturbance accommodating control of the space station for asymptotic momentum management

NASA Technical Reports Server (NTRS)

Warren, Wayne; Wie, Bong

1989-01-01

Periodic maneuvering control is developed for asymptotic momentum management of control gyros used as primary actuating devices for the Space Station. The proposed controller utilizes the concepts of quaternion feedback control and periodic-disturbance accommodation to achieve oscillations about the constant torque equilibrium attitude, while minimizing the control effort required. Three-axis coupled equations of motion, written in terms of quaternions, are derived for roll/yaw controller design and stability analysis. It is shown that the quaternion feedback controller is very robust for a wide range of pitch angles. It is also shown that the proposed controller tunes the open-loop unstable vehicle to a stable oscillatory motion which minimizes the control effort needed for steady-state operations.

Psychopathology of the bodily self and the brain: the case of schizophrenia.

PubMed

Gallese, Vittorio; Ferri, Francesca

2014-01-01

In the present paper, we review the recent empirical evidence on the neurobiological basis of a minimal notion of the self, the bodily self. We show the relationship between the body, its motor potentialities and the notion of minimal self. We argue that this approach can shed new light onto self-disturbances and social deficits characterizing schizophrenia. We discuss our approach with other views on the neural correlates of self-disturbances in schizophrenia and propose that cognitive neuroscience can today address the classical topics of psychopathology by adding a new level of description, finally enabling the correlation between the first-person experiential aspects of psychiatric diseases and their neurobiological roots. © 2014 S. Karger AG, Basel.

Noise-Driven Manifestation of Learning in Mature Neural Networks

NASA Astrophysics Data System (ADS)

Monterola, Christopher; Saloma, Caesar

2002-10-01

We show that the generalization capability of a mature thresholding neural network to process above-threshold disturbances in a noise-free environment is extended to subthreshold disturbances by ambient noise without retraining. The ability to benefit from noise is intrinsic and does not have to be learned separately. Nonlinear dependence of sensitivity with noise strength is significantly narrower than in individual threshold systems. Noise has a minimal effect on network performance for above-threshold signals. We resolve two seemingly contradictory responses of trained networks to noise-their ability to benefit from its presence and their robustness against noisy strong disturbances.

Thermal elastic shock and its effect on TOPEX spacecraft attitude control

NASA Technical Reports Server (NTRS)

Zimbelman, Darrell F.

1991-01-01

Thermal elastic shock (TES) is a twice per orbit impulsive disturbance torque experienced by low-Earth orbiting spacecraft. The fundamental equations used to model the TES disturbance torque for typical spacecraft appendages (e.g., solar arrays and antenna booms) are derived in detail. In particular, the attitude-pointing performance of the TOPEX spacecraft, when subjected to the TES disturbance, is analyzed using a three-axis nonlinear time-domain simulation. Results indicate that the TOPEX spacecraft could exceed its roll-axis attitude-control requirement during penumbral transitions, and remain in violation for approximately 150 sec each orbit until the umbra collapses. A localized active-control system is proposed as a solution to minimize and/or eliminate the degrading effects of the TES disturbance.

Hypersonic Boundary Layer Instability Over a Corner

NASA Technical Reports Server (NTRS)

Balakumar, Ponnampalam; Zhao, Hong-Wu; McClinton, Charles (Technical Monitor)

2001-01-01

A boundary-layer transition study over a compression corner was conducted under a hypersonic flow condition. Due to the discontinuities in boundary layer flow, the full Navier-Stokes equations were solved to simulate the development of disturbance in the boundary layer. A linear stability analysis and PSE method were used to get the initial disturbance for parallel and non-parallel flow respectively. A 2-D code was developed to solve the full Navier-stokes by using WENO(weighted essentially non-oscillating) scheme. The given numerical results show the evolution of the linear disturbance for the most amplified disturbance in supersonic and hypersonic flow over a compression ramp. The nonlinear computations also determined the minimal amplitudes necessary to cause transition at a designed location.

Tire Force Estimation using a Proportional Integral Observer

NASA Astrophysics Data System (ADS)

Farhat, Ahmad; Koenig, Damien; Hernandez-Alcantara, Diana; Morales-Menendez, Ruben

2017-01-01

This paper addresses a method for detecting critical stability situations in the lateral vehicle dynamics by estimating the non-linear part of the tire forces. These forces indicate the road holding performance of the vehicle. The estimation method is based on a robust fault detection and estimation approach which minimize the disturbance and uncertainties to residual sensitivity. It consists in the design of a Proportional Integral Observer (PIO), while minimizing the well known H ∞ norm for the worst case uncertainties and disturbance attenuation, and combining a transient response specification. This multi-objective problem is formulated as a Linear Matrix Inequalities (LMI) feasibility problem where a cost function subject to LMI constraints is minimized. This approach is employed to generate a set of switched robust observers for uncertain switched systems, where the convergence of the observer is ensured using a Multiple Lyapunov Function (MLF). Whilst the forces to be estimated can not be physically measured, a simulation scenario with CarSimTM is presented to illustrate the developed method.

Final Environmental Assessment for a Solar Power System at Davis-Monthan Air Force Tucson, Arizona

DTIC Science & Technology

2009-09-01

construction would occur in previously disturbed area, soil condition would not be substantially altered. Best Management Practices (BMP), to include...installation of silt fencing and sediment traps, water spray application, disturbed area revegatation, would be used to limit soil movement, stabilize...implementation of BMPs and adherence to the Arizona Pollutant Discharge Elimination System Permit would minimize the potential for exposed soils or other

Terrain, weather pose challenges in Minnesota project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trojack, L.

1994-12-01

This paper briefly reviews an innovative method used in installing a natural gas pipeline in Minnesota which traversed a marsh area. Because of the special problems associated with this wetland area, special equipment and techniques had to be used to minimize disturbance associated with the construction. It describes the equipment and the resulting performance the equipment had. It proved to significantly reduce disturbance and result in minimum site restoration work.

Concepts of Resilience for Coastal Systems

DTIC Science & Technology

2015-11-06

respond to, and adapt to changing conditions and to withstand and recover rapidly from disruptions with minimal damage.” Urban Land Institute, “After...AR5/images/uploads/WGIIAR5-Glossary_FGD.pdf “The capacity of a social- ecological system to cope with a hazardous event or disturbance, responding or...dunes, wetlands Ecological Resilience The capacity of a system to absorb disturbance and reorganize while undergoing change Ecological Resilience

Quasi-minimal active disturbance rejection control of MIMO perturbed linear systems based on differential neural networks and the attractive ellipsoid method.

PubMed

Salgado, Iván; Mera-Hernández, Manuel; Chairez, Isaac

2017-11-01

This study addresses the problem of designing an output-based controller to stabilize multi-input multi-output (MIMO) systems in the presence of parametric disturbances as well as uncertainties in the state model and output noise measurements. The controller design includes a linear state transformation which separates uncertainties matched to the control input and the unmatched ones. A differential neural network (DNN) observer produces a nonlinear approximation of the matched perturbation and the unknown states simultaneously in the transformed coordinates. This study proposes the use of the Attractive Ellipsoid Method (AEM) to optimize the gains of the controller and the gain observer in the DNN structure. As a consequence, the obtained control input minimizes the convergence zone for the estimation error. Moreover, the control design uses the estimated disturbance provided by the DNN to obtain a better performance in the stabilization task in comparison with a quasi-minimal output feedback controller based on a Luenberger observer and a sliding mode controller. Numerical results pointed out the advantages obtained by the nonlinear control based on the DNN observer. The first example deals with the stabilization of an academic linear MIMO perturbed system and the second example stabilizes the trajectories of a DC-motor into a predefined operation point. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Effect of Ecological Restoration on Body Condition of a Predator

PubMed Central

González-Tokman, Daniel; Martínez-Garza, Cristina

2015-01-01

Ecological restoration attempts to recover the structure and function of ecosystems that have been degraded by human activities. A crucial test of ecosystem recovery would be to determine whether individuals in restored environments are as healthy as those in conserved environments. However, the impact of restoration on physiology of terrestrial animals has never been tested. Here, we evaluated the effect of two restoration methods on body condition measured as body size, body mass, lipid and muscle content of the spider Nephila clavipes in a tropical dry forest that has suffered chronic disturbance due to cattle grazing. We used experimental plots that had been excluded from disturbance by cattle grazing during eight years. Plots were either planted with native trees (i. e. maximal intervention), or only excluded from disturbance (i. e. minimal intervention), and were compared with control conserved (remnants of original forest) and disturbed plots (where cattle is allowed to graze). We predicted (1) better body condition in spiders of conserved and restored sites, compared to disturbed sites, and (2) better body condition in plots with maximal intervention than in plots with minimal intervention. The first prediction was not supported in males or females, and the second prediction was only supported in females: body dry mass was higher in planted than in conserved plots for spiders of both sexes and also higher that in disturbed plots for males, suggesting that plantings are providing more resources. We discuss how different life histories and environmental pressures, such as food availability, parasitism, and competition for resources can explain our contrasting findings in male and female spiders. By studying animal physiology in restoration experiments it is possible to understand the mechanistic basis of ecological and evolutionary processes that determine success of ecological restoration. PMID:26226363

Effect of Ecological Restoration on Body Condition of a Predator.

PubMed

González-Tokman, Daniel; Martínez-Garza, Cristina

2015-01-01

Ecological restoration attempts to recover the structure and function of ecosystems that have been degraded by human activities. A crucial test of ecosystem recovery would be to determine whether individuals in restored environments are as healthy as those in conserved environments. However, the impact of restoration on physiology of terrestrial animals has never been tested. Here, we evaluated the effect of two restoration methods on body condition measured as body size, body mass, lipid and muscle content of the spider Nephila clavipes in a tropical dry forest that has suffered chronic disturbance due to cattle grazing. We used experimental plots that had been excluded from disturbance by cattle grazing during eight years. Plots were either planted with native trees (i. e. maximal intervention), or only excluded from disturbance (i. e. minimal intervention), and were compared with control conserved (remnants of original forest) and disturbed plots (where cattle is allowed to graze). We predicted (1) better body condition in spiders of conserved and restored sites, compared to disturbed sites, and (2) better body condition in plots with maximal intervention than in plots with minimal intervention. The first prediction was not supported in males or females, and the second prediction was only supported in females: body dry mass was higher in planted than in conserved plots for spiders of both sexes and also higher that in disturbed plots for males, suggesting that plantings are providing more resources. We discuss how different life histories and environmental pressures, such as food availability, parasitism, and competition for resources can explain our contrasting findings in male and female spiders. By studying animal physiology in restoration experiments it is possible to understand the mechanistic basis of ecological and evolutionary processes that determine success of ecological restoration.

Experimental investigation of measurement-induced disturbance and time symmetry in quantum physics

NASA Astrophysics Data System (ADS)

Curic, D.; Richardson, M. C.; Thekkadath, G. S.; Flórez, J.; Giner, L.; Lundeen, J. S.

2018-04-01

Unlike regular time evolution governed by the Schrödinger equation, standard quantum measurement appears to violate time-reversal symmetry. Measurement creates random disturbances (e.g., collapse) that prevent back-tracing the quantum state of the system. The effect of these disturbances is explicit in the results of subsequent measurements. In this way, the joint result of sequences of measurements depends on the order in time in which those measurements are performed. One might expect that if the disturbance could be eliminated this time-ordering dependence would vanish. Following a recent theoretical proposal [Bednorz, Franke, and Belzig, New J. Phys. 15, 023043 (2013), 10.1088/1367-2630/15/2/023043], we experimentally investigate this dependence for a kind of measurement that creates an arbitrarily small disturbance: weak measurement. We perform various sequences of a set of polarization weak measurements on photons. We experimentally demonstrate that, although the weak measurements are minimally disturbing, their time ordering affects the outcome of the measurement sequence for quantum systems.

Tolerance to disturbance regulated by attractiveness of resources: A case study of desert bighorn sheep within the River Mountains, Nevada

USGS Publications Warehouse

Lowrey, Chris E.; Longshore, Kathleen M.

2017-01-01

Human activity may mimic predation risks for wildlife by causing abandonment of foraging sites and increasing expenditure of energy. Animals that can tolerate nonlethal disturbance may minimize these fitness costs. We examine this aspect of the risk—disturbance hypothesis by first analyzing recent habitat use of desert bighorn sheep relative to areas of attraction and disturbance. We then compare and contrast sheep responses to differing levels of anthropogenic disturbance between 2 time periods, 30 years apart. Desert bighorn sheep were tolerant of suburban activity when a consistent forage resource (municipal grass) was provided. Males were more tolerant than females, and females returned to natural, steep areas during the birthing season. Increased recreation activity, specifically mountain bike use, may have resulted in avoidance by sheep of otherwise suitable habitat that had been occupied decades earlier, thereby reducing availability of limited habitat. Tolerance increased only when attractiveness was relatively high and decreased as perceived fitness decreased, supporting risk—disturbance theory.

A set-theoretic model reference adaptive control architecture for disturbance rejection and uncertainty suppression with strict performance guarantees

NASA Astrophysics Data System (ADS)

Arabi, Ehsan; Gruenwald, Benjamin C.; Yucelen, Tansel; Nguyen, Nhan T.

2018-05-01

Research in adaptive control algorithms for safety-critical applications is primarily motivated by the fact that these algorithms have the capability to suppress the effects of adverse conditions resulting from exogenous disturbances, imperfect dynamical system modelling, degraded modes of operation, and changes in system dynamics. Although government and industry agree on the potential of these algorithms in providing safety and reducing vehicle development costs, a major issue is the inability to achieve a-priori, user-defined performance guarantees with adaptive control algorithms. In this paper, a new model reference adaptive control architecture for uncertain dynamical systems is presented to address disturbance rejection and uncertainty suppression. The proposed framework is predicated on a set-theoretic adaptive controller construction using generalised restricted potential functions.The key feature of this framework allows the system error bound between the state of an uncertain dynamical system and the state of a reference model, which captures a desired closed-loop system performance, to be less than a-priori, user-defined worst-case performance bound, and hence, it has the capability to enforce strict performance guarantees. Examples are provided to demonstrate the efficacy of the proposed set-theoretic model reference adaptive control architecture.

Sleep and sleepiness in environmental intolerances: a population-based study.

PubMed

Nordin, Maria; Nordin, Steven

2016-08-01

About one fourth of the general population report environmental intolerance (EI) to odorous/pungent chemicals, certain buildings, electromagnetic fields (EMFs), and/or sounds. EI sufferers show various clinical features, of which sleep disturbance is one. Sleep disturbance is common also in the general population, but it is not known whether the disturbance is more prominent in EI sufferers than in individuals who do not experience EI. Therefore, EI was compared on various sleep aspects with referents without EI. A population-based sample of 3406 individuals, aged 18-79 years, was recruited from Northern Sweden. Sleep quality, non-restorative sleep, daytime sleepiness, obstructive breathing, and nocturnal insomnia were assessed with the Karolinska Sleep Questionnaire. Single questions assessed time slept, amount of hours of needed sleep, and extent of enough time slept. All four EI groups, compared to the referents, reported significantly poorer sleep quality, more non-restorative sleep, more daytime sleepiness, more obstructive breathing and higher prevalence of nocturnal insomnia than the referents. Nocturnal insomnia was an important factor for EI groups attributing their most prevalent symptoms to chemicals and sounds, irrespective of distress and certain syndromes. None of the EI groups differed significantly from the referents on time slept, but reported needing more sleep time (the EMF-intolerance group showing only a tendency), and all four groups reported to perceive enough sleep to a significantly lesser extent. Sleep disturbance and daytime sleepiness are more common in individuals reporting EI compared to normal referents. Moreover, nocturnal insomnia is an important symptom in its own right in various types of EI. This evokes the question of whether or not sleep therapy may attenuate the severity of the EI. Copyright © 2016. Published by Elsevier B.V.

Prevalence and predictors of headache in patients referred to polysomnography.

PubMed

Beiske, Kornelia Katalin; Russell, Michael Bjørn; Stavem, Knut

2013-11-18

The objectives of this study were; (1) to assess the prevalence and frequency of headache in patients referred to polysomnography (PSG) due to a clinical suspicion of obstructive sleep apnea (OSA) or another sleep disturbance and compare with a reference population, and (2) to assess the association of OSA severity with headache and headache frequency. A total of 784 participants filled in a headache questionnaire between 2003 and 2009 at the Department of Clinical Neurophysiology, Akershus University Hospital. Of these patients 477 were suspected to have OSA, and 307 had other sleep complaints. We assessed the prevalence of headache and monthly headache frequencies, as well as sleep apnea severity using an apnea-hypopnea index (AHI). The association of headache and monthly headache frequencies with PSG subgroups was assessed using multivariate logistic and ordered logistic regression analysis. The frequency of headache was not associated with the severity of OSA. Patients referred to a sleep study for any reason had higher odds ratio (OR) for having experienced headache during the past year than population controls after adjustment for age, gender and education, i.e. patients with normal AHI had OR of 3.56, patients with OSA had OR of 3.51, and patients with other sleep disturbances had OR of 3.33. Similarly, the adjusted OR of being in a higher category of monthly headache frequency compared to controls was higher in those with normal AHI (OR 3.42), OSA (OR 3.29), and other sleep disturbances (OR 3.00). The odds of headache and headache frequency were higher in subjects referred to a PSG for any sleep disturbance independently of OSA, compared to general population controls. However, there was no association between experiencing headache during the past year or headache frequency with OSA severity.

Difficulties Associated with the Diagnosis of Emotional Disturbance.

ERIC Educational Resources Information Center

Welch, Frances C.

School psychologists have traditionally experienced difficulty in assessing children referred for special services. In order to determine if the diagnosis of emotional disturbance in South Carolina schools follows the guidelines provided by the South Carolina Department of Education publication "Procedures for the Survey, Screening,…

High temperature thermocouple and heat flux gauge using a unique thin film-hardware hot juncture

NASA Technical Reports Server (NTRS)

Liebert, C. H.; Holanda, R.; Hippensteele, S. A.; Andracchio, C. A.

1984-01-01

A special thin film-hardware material thermocouple (TC) and heat flux gauge concept for a reasonably high temperature and high flux flat plate heat transfer experiment was fabricated and tested to gauge temperatures of 911 K. This concept was developed for minimal disturbance of boundary layer temperature and flow over the plates and minimal disturbance of heat flux through the plates. Comparison of special heat flux gauge Stanton number output at steady-state conditions with benchmark literature data was good and agreement was within a calculated uncertainty of the measurement system. Also, good agreement of special TC and standard TC outputs was obtained and the results are encouraging. Oxidation of thin film thermoelements was a primary failure mode after about 5 of operation.

High-temperature thermocouple and heat flux gauge using a unique thin film-hardware hot junction

NASA Technical Reports Server (NTRS)

Liebert, C. H.; Holanda, R.; Hippensteele, S. A.; Andracchio, C. A.

1985-01-01

A special thin film-hardware material thermocouple (TC) and heat flux gauge concept for a reasonably high temperature and high flux flat plate heat transfer experiment was fabricated and tested to gauge temperatures of 911 K. This concept was developed for minimal disturbance of boundary layer temperature and flow over the plates and minimal disturbance of heat flux through the plates. Comparison of special heat flux gauge Stanton number output at steady-state conditions with benchmark literature data was good and agreement was within a calculated uncertainty of the measurement system. Also, good agreement of special TC and standard TC outputs was obtained and the results are encouraging. Oxidation of thin film thermoelements was a primary failure mode after about 5 of operation.

Controller Design for the ST7 Disturbance Reduction System

NASA Technical Reports Server (NTRS)

Maghami, Peiman; Markley, F. Landis; Dennehey, Neil; Houghton, Martin B.; Folkner, William M.; Bauer, Frank (Technical Monitor)

2002-01-01

The Space Technology 7 experiment will perform an on-orbit system-level validation of two specific Disturbance Reduction System technologies: a gravitational reference sensor employing a free-floating test mass and a set of micro-Newton colloidal thrusters. The Disturbance Reduction System is designed to maintain a spacecraft's position with respect to the free-floating test mass to less than 10 nm/ square root of Hz, over the frequency range 10(exp -3) Hz to 10(exp -2) Hz. This paper presents the design and analysis of the coupled drag-free and attitude control system that closes the loop between the gravitational reference sensor and the micro-Newton thrusters while incorporating star tracker data at low frequencies. The effects of actuation and measurement noise and disturbances on the spacecraft and test masses are evaluated in a seven-degree-of-freedom planar model incorporating two translational and one rotational degrees of freedom for the spacecraft and two translational degrees of freedom for each test mass.

Design and Analysis of the ST7 Disturbance Reduction System (DRS) Spacecraft Controller

NASA Technical Reports Server (NTRS)

Maghami, P. G.; Markley, F. L.; Houghton, M. B.; Dennehy, C. J.

2003-01-01

The Space Technology 7 experiment will perform an on-orbit system-level validation of two specific Disturbance Reduction System technologies: a gravitational reference sensor employing a free-floating test mass and a set of micronewton colloidal thrusters. The Disturbance Reduction System is designed to maintain a spacecraft's position with respect to the free-floating test mass to less than 10 nm/square root of Hz, over the frequency range 10(exp -3) Hz to 10(exp -2) Hz. This paper presents the design and analysis of the coupled drag-free and attitude control system that closes the loop between the gravitational reference sensor and the micronewton thrusters while incorporating star tracker data at low frequencies. The effects of actuation and measurement noise and disturbances on the spacecraft and test masses are evaluated in a seven-degree-of-freedom planar model incorporating two translational and one rotational degrees of freedom for the spacecraft and two translational degrees of freedom for each test mass.

Finding of No Significant Impact & Tiered Environmental Assessment: Public Law 84-99 Rehabilitation Program Dry Creek Flood Risk Reduction Project Hawarden, Sioux County, Iowa

DTIC Science & Technology

2014-11-01

by the National Pollutant Discharge Elimination System (NPDES) permit (i.e., silt trapping devices) would be implemented as required to minimize...Natural Resources MBTA Migratory Bird Treaty Act NEPA National Environmental Policy Act NPDES National Pollutant Discharge Elimination System NWI...disturbance, bank disturbance, and riparian vegetation. This condition does not further restrict otherwise authorized drainage ditch maintenance activities

Establishment of reference scores and interquartile ranges for the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) in patients with low back pain.

PubMed

Tominaga, Ryoji; Sekiguchi, Miho; Yonemoto, Koji; Kakuma, Tatsuyuki; Konno, Shin-Ichi

2018-05-01

The Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) was developed in 2007, including the five domains of Pain-related disorder, Lumbar spine dysfunction, Gait disturbance, Social life disturbance, and Psychological disorder. It is used by physicians to evaluate treatment efficacy by comparing scores before and after treatment. However, the JOABPEQ does not allow evaluation of the severity of a patient's condition compared to the general population at a single time point. Given the unavailability of a standard measurement of back pain, we sought to establish reference scores and interquartile ranges using data obtained from a multicenter, cross-sectional survey taken in Japanese primary care settings. The Lumbar Spinal Stenosis Diagnosis Support Tool project was conducted from 2011 to 2012 in 1657 hospitals in Japan to investigate the establishment of reference scores using JOABPEQ. Patients aged ≥ 20 years undergoing medical examinations by either non-orthopaedic primary care physicians or general orthopedists were considered for enrollment. A total of 10,651 consecutive low back pain patients (5331 men, 5320 women, 18 subjects with missing sex data) who had undergone a medical examination were included. Reference scores and interquartile ranges for each of the five domains of the JOABPEQ according to age and sex were recorded. The median score and interquartile range are the same in the domain of Pain-related disorder in all ages and sexes. The reference scores for Gait disturbance, Social life disturbance and Psychological disorder declined with increasing age in both age- and sex-stratified groups, while there was some different trend in Lumbar spine dysfunction between men and women. Reference scores and interquartile ranges for JOABPEQ were generated based on the data from the examination data. These provide a measurement standard to assess patient perceptions of low back pain at any time point during evaluation or therapy. Copyright © 2018 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.

Binge drinking disturbs hepatic microcirculation after transplantation: prevention with free radical scavengers.

PubMed

Zhong, Z; Arteel, G E; Connor, H D; Schemmer, P; Chou, S C; Raleigh, J A; Mason, R P; Lemasters, J J; Thurman, R G

1999-08-01

Disturbances in hepatic microcirculation increase graft injury and failure; therefore, this study evaluates the effects of ethanol on microcirculation after liver transplantation. Donor rats were given one dose of ethanol (5 g/kg) by gavage 20 h before explantation, and grafts were stored in University of Wisconsin solution for 24 h before implantation. Acute ethanol treatment decreased 7-day survival of grafts from about 90 to 30%, increased transaminase release nearly 4-fold, and decreased bile production by 60%. Moreover, portal pressure increased significantly and liver surface oxygen tension decreased about 50%, indicating that ethanol disturbs hepatic microcirculation. Pimonidazole, a 2-nitroimidazole hypoxia marker, was given i.v. to recipients 30 min after implantation, and grafts were harvested 1 h later. Ethanol increased hepatic pimonidazole binding about 3-fold, indicating that ethanol led to hypoxia in fatty grafts. Ethanol also significantly increased free radicals in bile. Catechin (30 mg/kg i.v. upon reperfusion), a free radical scavenger, and Carolina Rinse solution, which contains several agents that inhibit free radical formation, minimized disturbances in microcirculation and prevented pimonidazole adduct formation significantly. These treatments also blunted increases in transaminase release and improved survival of fatty grafts. Destruction of Kupffer cells with GdCl(3) (20 mg/kg i.v. 24 h before explantation) or inhibition of formation of leukotrienes with MK-886 (50 microM in University of Wisconsin or rinse solution) also minimized hypoxia and improved survival after transplantation. Taken together, these results demonstrate that ethanol disturbs hepatic microcirculation, leading to graft hypoxia after transplantation, most likely by activating Kupffer cells and increasing free radical production.

Confrontation and Support in Group Therapy in the Residential Treatment of Severely Disturbed Adolescents.

ERIC Educational Resources Information Center

Siegel, Leonard Israel

1987-01-01

Focuses on various forms of group therapy for severely emotionally and behaviorally disturbed adolescents. Discusses eclectic theoretical frame of reference including elements of psychodynamic, object relations, and structural and strategic family therapy theory. Identifies precedents for confrontational-supportive approach to be encounter group…

DETECTABILITY AND UNCERTAINTIES IN THE ESTIMATION OF THE IMPACTS OF LAND DISTURBANCES ON CATCHMENT RUNOFF

EPA Science Inventory

Interpretation of the impacts of land disturbances on hydrology is confounded by climate variations. Clear definition of the anthropogenic impacts has been difficult, especially in cases where a clearly defined base line or reference point is absent. This study investigates the d...

Forests planted for ecosystem restoration or conservation.

Treesearch

Constance A. Harrington

1999-01-01

Although the phrase, "planting for ecosystem restoration," is of recent origin, many of the earliest large-scale tree plantings were made for what we now refer to as "'restoration" or "conservation" goals. Forest restoration activities may be needed when ecosystems are disturbed by either natural or anthropogenic forces. Disturbances...

Novel probabilistic and distributed algorithms for guidance, control, and nonlinear estimation of large-scale multi-agent systems

NASA Astrophysics Data System (ADS)

Bandyopadhyay, Saptarshi

Multi-agent systems are widely used for constructing a desired formation shape, exploring an area, surveillance, coverage, and other cooperative tasks. This dissertation introduces novel algorithms in the three main areas of shape formation, distributed estimation, and attitude control of large-scale multi-agent systems. In the first part of this dissertation, we address the problem of shape formation for thousands to millions of agents. Here, we present two novel algorithms for guiding a large-scale swarm of robotic systems into a desired formation shape in a distributed and scalable manner. These probabilistic swarm guidance algorithms adopt an Eulerian framework, where the physical space is partitioned into bins and the swarm's density distribution over each bin is controlled using tunable Markov chains. In the first algorithm - Probabilistic Swarm Guidance using Inhomogeneous Markov Chains (PSG-IMC) - each agent determines its bin transition probabilities using a time-inhomogeneous Markov chain that is constructed in real-time using feedback from the current swarm distribution. This PSG-IMC algorithm minimizes the expected cost of the transitions required to achieve and maintain the desired formation shape, even when agents are added to or removed from the swarm. The algorithm scales well with a large number of agents and complex formation shapes, and can also be adapted for area exploration applications. In the second algorithm - Probabilistic Swarm Guidance using Optimal Transport (PSG-OT) - each agent determines its bin transition probabilities by solving an optimal transport problem, which is recast as a linear program. In the presence of perfect feedback of the current swarm distribution, this algorithm minimizes the given cost function, guarantees faster convergence, reduces the number of transitions for achieving the desired formation, and is robust to disturbances or damages to the formation. We demonstrate the effectiveness of these two proposed swarm guidance algorithms using results from numerical simulations and closed-loop hardware experiments on multiple quadrotors. In the second part of this dissertation, we present two novel discrete-time algorithms for distributed estimation, which track a single target using a network of heterogeneous sensing agents. The Distributed Bayesian Filtering (DBF) algorithm, the sensing agents combine their normalized likelihood functions using the logarithmic opinion pool and the discrete-time dynamic average consensus algorithm. Each agent's estimated likelihood function converges to an error ball centered on the joint likelihood function of the centralized multi-sensor Bayesian filtering algorithm. Using a new proof technique, the convergence, stability, and robustness properties of the DBF algorithm are rigorously characterized. The explicit bounds on the time step of the robust DBF algorithm are shown to depend on the time-scale of the target dynamics. Furthermore, the DBF algorithm for linear-Gaussian models can be cast into a modified form of the Kalman information filter. In the Bayesian Consensus Filtering (BCF) algorithm, the agents combine their estimated posterior pdfs multiple times within each time step using the logarithmic opinion pool scheme. Thus, each agent's consensual pdf minimizes the sum of Kullback-Leibler divergences with the local posterior pdfs. The performance and robust properties of these algorithms are validated using numerical simulations. In the third part of this dissertation, we present an attitude control strategy and a new nonlinear tracking controller for a spacecraft carrying a large object, such as an asteroid or a boulder. If the captured object is larger or comparable in size to the spacecraft and has significant modeling uncertainties, conventional nonlinear control laws that use exact feed-forward cancellation are not suitable because they exhibit a large resultant disturbance torque. The proposed nonlinear tracking control law guarantees global exponential convergence of tracking errors with finite-gain Lp stability in the presence of modeling uncertainties and disturbances, and reduces the resultant disturbance torque. Further, this control law permits the use of any attitude representation and its integral control formulation eliminates any constant disturbance. Under small uncertainties, the best strategy for stabilizing the combined system is to track a fuel-optimal reference trajectory using this nonlinear control law, because it consumes the least amount of fuel. In the presence of large uncertainties, the most effective strategy is to track the derivative plus proportional-derivative based reference trajectory, because it reduces the resultant disturbance torque. The effectiveness of the proposed attitude control law is demonstrated by using results of numerical simulation based on an Asteroid Redirect Mission concept. The new algorithms proposed in this dissertation will facilitate the development of versatile autonomous multi-agent systems that are capable of performing a variety of complex tasks in a robust and scalable manner.

Demographics of an ornate box turtle population experiencing minimal human-induced disturbances

USGS Publications Warehouse

Converse, S.J.; Iverson, J.B.; Savidge, J.A.

2005-01-01

Human-induced disturbances may threaten the viability of many turtle populations, including populations of North American box turtles. Evaluation of the potential impacts of these disturbances can be aided by long-term studies of populations subject to minimal human activity. In such a population of ornate box turtles (Terrapene ornata ornata) in western Nebraska, we examined survival rates and population growth rates from 1981-2000 based on mark-recapture data. The average annual apparent survival rate of adult males was 0.883 (SE = 0.021) and of adult females was 0.932 (SE = 0.014). Minimum winter temperature was the best of five climate variables as a predictor of adult survival. Survival rates were highest in years with low minimum winter temperatures, suggesting that global warming may result in declining survival. We estimated an average adult population growth rate (????) of 1.006 (SE = 0.065), with an estimated temporal process variance (????2) of 0.029 (95% CI = 0.005-0.176). Stochastic simulations suggest that this mean and temporal process variance would result in a 58% probability of a population decrease over a 20-year period. This research provides evidence that, unless unknown density-dependent mechanisms are operating in the adult age class, significant human disturbances, such as commercial harvest or turtle mortality on roads, represent a potential risk to box turtle populations. ?? 2005 by the Ecological Society of America.

Children with developmental dyslexia showed greater sleep disturbances than controls, including problems initiating and maintaining sleep.

PubMed

Carotenuto, M; Esposito, M; Cortese, S; Laino, D; Verrotti, A

2016-09-01

Although there have been frequent clinical reports about sleep disturbances in children with learning disabilities, no data are available about the prevalence of sleep disturbances in children with developmental dyslexia (DD). This study evaluated sleep disturbances in children with DD referred to a hospital clinic and compared their scores with healthy controls. We consecutively enrolled 147 children (66% male) aged 10.26 ± 2.63 years who were referred by clinical paediatricians to the Clinic for Child and Adolescent Neuropsychiatry at the Second University of Naples with DD and 766 children without DD (60% male) aged 10.49 ± 2.39 years recruited from schools in the same urban area. Sleep disturbances were assessed with the Sleep Disturbances Scale for Children (SDSC), which was filled out by the children's main carers. Compared with the controls, the children with DD showed significantly higher rates of above threshold scores on the total SDSC score (p < 0.001) and on the subscales for disorders in initiating and maintaining sleep (p < 0.001), sleep breathing disorders (p < 0.001) and disorders of arousal (p < 0.001). Sleep disorders were significantly more frequent in children with DD than in healthy controls. A possible relationship between dyslexia and sleep disorders may have relevant clinical implications. ©2016 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

Influence of disturbance on temperate forest productivity

USGS Publications Warehouse

Peters, Emily B.; Wythers, Kirk R.; Bradford, John B.; Reich, Peter B.

2013-01-01

Climate, tree species traits, and soil fertility are key controls on forest productivity. However, in most forest ecosystems, natural and human disturbances, such as wind throw, fire, and harvest, can also exert important and lasting direct and indirect influence over productivity. We used an ecosystem model, PnET-CN, to examine how disturbance type, intensity, and frequency influence net primary production (NPP) across a range of forest types from Minnesota and Wisconsin, USA. We assessed the importance of past disturbances on NPP, net N mineralization, foliar N, and leaf area index at 107 forest stands of differing types (aspen, jack pine, northern hardwood, black spruce) and disturbance history (fire, harvest) by comparing model simulations with observations. The model reasonably predicted differences among forest types in productivity, foliar N, leaf area index, and net N mineralization. Model simulations that included past disturbances minimally improved predictions compared to simulations without disturbance, suggesting the legacy of past disturbances played a minor role in influencing current forest productivity rates. Modeled NPP was more sensitive to the intensity of soil removal during a disturbance than the fraction of stand mortality or wood removal. Increasing crown fire frequency resulted in lower NPP, particularly for conifer forest types with longer leaf life spans and longer recovery times. These findings suggest that, over long time periods, moderate frequency disturbances are a relatively less important control on productivity than climate, soil, and species traits.

Gimbal Control Algorithms for the Global Precipitation Measurement Core Observatory

NASA Technical Reports Server (NTRS)

Welter, Gary L.; Liu, Kuo Chia; Blaurock, Carl

2012-01-01

There are two gimbaled systems on the Global Precipitation Measurement Core Observatory: two single-degree-of-freedom solar arrays (SAs) and one two-degree-of-freedom high gain antenna (HGA). The guidance, navigation, and control analysis team was presented with the following challenges regarding SA orientation control during periods of normal mission science: (1) maximize solar flux on the SAs during orbit day, subject to battery charging limits, (2) minimize atmospheric drag during orbit night to reduce frequency of orbit maintenance thruster usage, (3) minimize atmospheric drag during orbits for which solar flux is nearly independent of SA orientation, and (4) keep array-induced spacecraft attitude disturbances within allocated tolerances. The team was presented with the following challenges regarding HGA control during mission science periods: (1) while tracking a ground-selected Tracking Data and Relay Satellite (TDRS), keep HGA control error below about 4', (2) keep array-induced spacecraft attitude disturbances small, and (3) minimize transition time between TDRSs subject to constraints imposed by item 2. This paper describes the control algorithms developed to achieve these goals and certain analysis done as part of that work.

Progress towards a Drag-free SmallSat

NASA Astrophysics Data System (ADS)

Saraf, Shailendhar

The net force acting on a drag-free satellite is purely gravitational as all other forces, mainly atmospheric drag and solar radiation pressure, are canceled out. In order to achieve this, a free floating reference (test mass) inside the satellite is shielded against all forces but gravity and a system of thrusters is commanded by a control algorithm such that the relative displacement between the reference and the satellite stays constant. The main input to that control algorithm is the output of a sensor which measures the relative displacement between the satellite and the test mass. Internal disturbance forces such as electrostatic or magnetic forces cannot be canceled out his way and have to be minimized by a careful design of the satellite. A drag-free technology package is under development at Stanford since 2004. It includes an optical displacement sensor to measure the relative position of the test mass inside the satellite, a caging mechanism to lock the test mass during launch, a UV LED based charge management system to minimize the effect of electrostatic forces, a thermal enclosure, and the drag-free control algorithms. Possible applications of drag-free satellites in fundamental physics (Gravity Probe B, LISA), geodesy (GOCE), and navigation (TRIAD I). In this presentation we will highlight the progress of the technology development towards a drag-free mission. The planned mission on a SaudiSat bus will demonstrate drag-free technology on a small spacecraft at a fraction of the cost of previous drag-free missions. The target acceleration noise is 10-12 m/sec2. With multiple such satellites a GRACE-like mission with improved sensitivity and potentially improved spatial and temporal resolution can be achieved.

A low-disturbance capture technique for ground-nesting Double-crested Cormorants (Phalacrocorax auritus)

USGS Publications Warehouse

Courtot, Karen; Roby, Daniel D.; Kerr, Lauren H.; Lyons, Donald E.; Adkins, Jessica Y.

2016-01-01

Capturing breeding adults of colonially nesting species can entail risks of nest failure and even colony abandonment, especially in species that react strongly to human disturbance. A low-disturbance technique for capturing specific adult Double-crested Cormorants (Phalacrocorax auritus) at a ground-nesting colony was developed to reduce these risks and is described here. Nesting habitat enhancement was used to attract Doublecrested Cormorants to nest adjacent to above-ground tunnels constructed so that researchers could capture birds by hand. Using this technique, Double-crested Cormorants (n = 87) were captured during the incubation and chick-rearing stages of the nesting cycle. Unlike alternative capture techniques, this approach allowed targeting of specific individuals for capture and recapture, minimized local disturbance, and eliminated colony-wide disturbances. The tunnel-based system presented here could be adapted to capture adults or to access the nest contents of other ground-nesting colonial species that are inclined to nest in areas of enhanced nesting habitat and adapt to anthropogenic structures in their nesting area. This system would be particularly beneficial for other wary and easily disturbed species.

Combined input shaping and feedback control for double-pendulum systems

NASA Astrophysics Data System (ADS)

Mar, Robert; Goyal, Anurag; Nguyen, Vinh; Yang, Tianle; Singhose, William

2017-02-01

A control system combining input shaping and feedback is developed for double-pendulum systems subjected to external disturbances. The proposed control method achieves fast point-to-point response similar to open-loop input-shaping control. It also minimizes transient deflections during the motion of the system, and disturbance-induced residual swing using the feedback control. Effects of parameter variations such as the mass ratio of the double pendulum, the suspension length ratio, and the move distance were studied via numerical simulation. The most important results were also verified with experiments on a small-scale crane. The controller effectively suppresses the disturbances and is robust to modelling uncertainties and task variations.

Permafrost thaw and intense thermokarst activity decreases abundance of stream benthic macroinvertebrates.

PubMed

Chin, Krista S; Lento, Jennifer; Culp, Joseph M; Lacelle, Denis; Kokelj, Steven V

2016-08-01

Intensification of permafrost thaw has increased the frequency and magnitude of large permafrost slope disturbances (mega slumps) in glaciated terrain of northwestern Canada. Individual thermokarst disturbances up to 40 ha in area have made large volumes of previously frozen sediments available for leaching and transport to adjacent streams, significantly increasing sediment and solute loads in these systems. To test the effects of this climate-sensitive disturbance regime on the ecology of Arctic streams, we explored the relationship between physical and chemical variables and benthic macroinvertebrate communities in disturbed and undisturbed stream reaches in the Peel Plateau, Northwest Territories, Canada. Highly disturbed and undisturbed stream reaches differed with respect to taxonomic composition and invertebrate abundance. Minimally disturbed reaches were not differentiated by these variables but rather were distributed along a disturbance gradient between highly disturbed and undisturbed sites. In particular, there was evidence of a strong negative relationship between macroinvertebrate abundance and total suspended solids, and a positive relationship between abundance and the distance from the disturbance. Increases in both sediments and nutrients appear to be the proximate cause of community differences in highly disturbed streams. Declines in macroinvertebrate abundance in response to slump activity have implications for the food webs of these systems, potentially leading to negative impacts on higher trophic levels, such as fish. Furthermore, the disturbance impacts on stream health can be expected to intensify as climate change increases the frequency and magnitude of thermokarst. © 2016 John Wiley & Sons Ltd.

Emotional Disturbance. NICHCY Disability Fact Sheet #5

ERIC Educational Resources Information Center

National Dissemination Center for Children with Disabilities, 2010

2010-01-01

The mental health of our children is a natural and important concern for us all. The fact is, many mental disorders have their beginnings in childhood or adolescence, yet may go undiagnosed and untreated for years. "Umbrella" terms such as emotional disturbance, behavioral disorders, or mental illness are used to refer to mental…

Conservation importance of early post-disturbance temperate forests

Treesearch

Charles Kwit; David I. King; Beverly Collins; Mark E. Swanson

2014-01-01

The early post-disturbance stage of temperate forest succession (also referred to as 'early-seral' or 'early-successional' forest) has been the subject of interest and debate. Often thought of as an ephemeral (and often disorganized) state of eventual closed-canopy systems, its direct and immediate role in conservation traditionally has been ignored...

Influence of restoration and succession on bottomland hardwood hydrology

Treesearch

Randy K. Kolka; J. H. Singer; C. R. Coppock; W. P. Casey; C. C. Trettin

2000-01-01

The hydrologic pathways of four bottomland hardwood wetland sites were investigated with transects consisting of nests of shallow wells and piezometers. Sites included a disturbed but recently restored system, two disturbed systems that are recovering naturally and a relatively undisturbed reference site. Water table elevations in both uplands and bottomlands were...

Long-term trends from ecosystem research at the Hubbard Brook Experimental Forest

Treesearch

John L. Campbell; Charles T. Driscoll; Christopher Eagar; Gene E. Likens; Thomas G. Siccama; Chris E. Johnson; Timothy J. Fahey; Steven P. Hamburg; Richard T. Holmes; Amey S. Bailey; Donald C. Buso

2007-01-01

Summarizes 52 years of collaborative, long-term research conducted at the Hubbard Brook (NH) Experimental Forest on ecosystem response to disturbances such as air pollution, climate change, forest disturbance, and forest management practices. Also provides explanations of some of the trends and lists references from scientific literature for further reading.

Foreign bodies in the aerodigestive tract.

PubMed

Lawson, V G; Middleton, W G

1986-04-01

Foreign bodies in the aerodigestive tract are common. They may cause minimal disturbance of function, severe morbidity or even sudden death. They enter the aerodigestive tract because of haste during eating, disturbances in physical function, impairments due to extreme youth or age, or contamination of food with foreign bodies. Common symptoms are pain, dysphagia, odynophagia, cough, airway distress, hemoptysis and hematemesis. Signs include point tenderness, respiratory distress and surgical emphysema. Clinical, radiological and endoscopic investigations are described, as are principles of crisis and elective management.

Logging affects fledgling sex ratios and baseline corticosterone in a forest songbird.

PubMed

Leshyk, Rhiannon; Nol, Erica; Burke, Dawn M; Burness, Gary

2012-01-01

Silviculture (logging) creates a disturbance to forested environments. The degree to which forests are modified depends on the logging prescription and forest stand characteristics. In this study we compared the effects of two methods of group-selection ("moderate" and "heavy") silviculture (GSS) and undisturbed reference stands on stress and offspring sex ratios of a forest interior species, the Ovenbird (Seiurus aurocapilla), in Algonquin Provincial Park, Canada. Blood samples were taken from nestlings for corticosterone and molecular sexing. We found that logging creates a disturbance that is stressful for nestling Ovenbirds, as illustrated by elevated baseline corticosterone in cut sites. Ovenbirds nesting in undisturbed reference forest produce fewer male offspring per brood (proportion male = 30%) while logging with progressively greater forest disturbance, shifted the offspring sex ratio towards males (proportion male: moderate = 50%, heavy = 70%). If Ovenbirds in undisturbed forests usually produce female-biased broods, then the production of males as a result of logging may disrupt population viability. We recommend a broad examination of nestling sex ratios in response to anthropogenic disturbance to determine the generality of our findings.

Tracking and disturbance rejection of MIMO nonlinear systems with PI controller

NASA Technical Reports Server (NTRS)

Desoer, C. A.; Lin, C. A.

1985-01-01

The tracking and disturbance rejection of a class of MIMO nonlinear systems with a linear proportional plus integral (PI) compensator is studied. Roughly speaking, it is shown that if the given nonlinear plant is exponentially stable and has a strictly increasing dc steady-state I/O map, then a simple PI compensator can be used to yield a stable unity-feedback closed-loop system which asymptotically tracks reference inputs that tend to constant vectors and asymptotically rejects disturbances that tend to constant vectors.

Tracking and disturbance rejection of MIMO nonlinear systems with PI controller

NASA Technical Reports Server (NTRS)

Desoer, C. A.; Lin, C.-A.

1985-01-01

The tracking and disturbance rejection of a class of MIMO nonlinear systems with linear proportional plus integral (PI) compensator is studied. Roughly speaking, it is shown that if the given nonlinear plant is exponentially stable and has a strictly increasing dc steady-state I/O map, then a simple PI compensator can be used to yield a stable unity-feedback closed-loop system which asymptotically tracks reference inputs that tend to constant vectors and asymptotically rejects disturbances that tend to constant vectors.

On the minimal risk threshold in research with children.

PubMed

Binik, Ariella

2014-01-01

To protect children in research, procedures that are not administered in the medical interests of a child must be restricted. The risk threshold for these procedures is generally measured according to the concept of minimal risk. Minimal risk is often defined according to the risks of "daily life." But it is not clear whose daily life should serve as the baseline; that is, it is not clear to whom minimal risk should refer. Commentators in research ethics often argue that "minimal risk" should refer to healthy children or the subjects of the research. I argue that neither of these interpretations is successful. I propose a new interpretation in which minimal risk refers to children who are not unduly burdened by their daily lives. I argue that children are not unduly burdened when they fare well, and I defend a substantive goods account of children's welfare.

The effects of drought and disturbance on the growth and developmental instability of loblolly pine (Pinus taeda L.)

USGS Publications Warehouse

Graham, John H.; Duda, Jeffrey J.; Brown, Michelle L.; Kitchen, Stanley G.; Emlen, John M.; Malol, Jagadish; Bankstahl, Elizabeth; Krzysik, Anthony J.; Balbach, Harold E.; Freeman, D. Carl

2012-01-01

Ecological indicators provide early warning of adverse environmental change, helping land managers adaptively manage their resources while minimizing costly remediation. In 1999 and 2000, we studied two such indicators, growth and developmental instability, of loblolly pine (Pinus taeda L.) influenced by mechanized infantry training at Fort Benning, Georgia. Disturbed areas were used for military training; tracked and wheeled vehicles damaged vegetation and soils. Highly disturbed sites had fewer trees, diminished ground cover, warmer soils in the summer, and more compacted soils with a shallower A-horizon. We hypothesized that disturbance would decrease the growth of needles, branches, and tree rings, increase the complexity of tree rings, and increase the developmental instability of needles. Contrary to our expectations, however, disturbance enhanced growth in the first year of the study, possibly by reducing competition. In the second year, a drought reduced growth of branches and needles, eliminating the stimulatory effect of disturbance. Growth-ring widths increased with growing-season precipitation, and decreased with growing-season temperature over the last 40 years. Disturbance had no effect on tree-ring complexity, as measured by the Hurst exponent. Within-fascicle variation of current-year needle length, a measure of developmental instability, differed among the study populations, but appeared unrelated to mechanical disturbance or drought.

Cumulative Industrial Activity Alters Lotic Fish Assemblages in Two Boreal Forest Watersheds of Alberta, Canada

NASA Astrophysics Data System (ADS)

Scrimgeour, Garry J.; Hvenegaard, Paul J.; Tchir, John

2008-12-01

We evaluated the cumulative effects of land use disturbance resulting from forest harvesting, and exploration and extraction of oil and gas resources on the occurrence and structure of stream fish assemblages in the Kakwa and Simonette watersheds in Alberta, Canada. Logistic regression models showed that the occurrence of numerically dominant species in both watersheds was related to two metrics defining industrial activity (i.e., percent disturbance and road density), in addition to stream wetted width, elevation, reach slope, and percent fines. Occurrences of bull trout, slimy sculpin, and white sucker were negatively related to percent disturbance and that of Arctic grayling, and mountain whitefish were positively related to percent disturbance and road density. Assessments of individual sites showed that 76% of the 74 and 46 test sites in the Kakwa and Simonette watersheds were possibly impaired or impaired. Impaired sites in the Kakwa Watershed supported lower densities of bull trout, mountain whitefish, and rainbow trout, but higher densities of Arctic grayling compared to appropriate reference sites. Impaired sites in the Simonette Watershed supported lower densities of bull trout, but higher densities of lake chub compared to reference sites. Our data suggest that current levels of land use disturbance alters the occurrence and structure of stream fish assemblages.

Lichen Persistence and Recovery in Response to Varied Volcanic Disturbances

NASA Astrophysics Data System (ADS)

Nelson, P.; Wheeler, T. B.

2015-12-01

Volcanic eruptions produce many ecological disturbances that structure vegetation. While lichens are sensitive to disturbances, little is known about their responses to volcanic disturbances, except for colonization of lava. We examined lichen community responses through time to different disturbances produced by the May 1, 2008 eruption of Volcan Chaiten in south-central Chile. Pre-eruption vegetation near the volcano was old-growth Valdivian temperate rainforest dominated by closed-canopy Nothofagus sp... In 2012, we installed thirteen 1-acre plots across volcanic disturbance zones on which a time-constrained search was done for all macrolichen species, each of which was assigned an approximate log10 categorical abundance. We also installed a 0.2 m2 quadrat on two representative trees per plot for repeat photography of lichen cover. We remeasured at least one plot per disturbance zone in 2014 and re-photographed tree quadrats in 2013 and 2014. We then analyzed species composition and abundance differences among disturbance zones. In 2012, the blast (pyroclastic density flow), scorch (standing scorched forest at the edge of the blast) and deep tephra (>10 cm) zones had the lowest lichen species richness (5-13 species), followed by reference (unimpacted) and shallow (<10 cm) tephra (17-20 species). Gravel rain (preexisting rock ejected by eruption initiation), gravel rain + pumice and flooded forests (fluvially reworked volcanic material entrained by heavy rains) were species-rich (25-42 species). In 2014, the blast and deep tephra had regained 2-3 times the number of lichen species since 2012 while the light tephra and reference were essentially unchanged. Gravel rain, gravel rain + pumice and flooded forest plots all had about the same number of species in 2014 as 2012. Lichen colonization and growth in tree quadrats varied widely, from very little colonization in the blast to prolific colonization in the gravel rain + pumice zone. Lichen's varied responses to different volcanic disturbances were attributable to varying degrees of mortality and subsequent availability of substrate, quantity of light and removal of competitors. While sensitive to disturbance, lichens are apparently resilient to and can quickly recolonize after a variety of large, violent volcanic disturbances.

Controlling erosion along highways with vegetation or other protective cover.

DOT National Transportation Integrated Search

1976-01-01

Construction operations in highway corridors disturb the natural vegetation and land contours causing potential erosion sites if left denuded. Minimizing erosion on these areas is based on the principles of maximizing water infiltration and reducing ...

A new momentum management controller for the space station

NASA Technical Reports Server (NTRS)

Wie, B.; Byun, K. W.; Warren, V. W.

1988-01-01

A new approach to CMG (control moment gyro) momentum management and attitude control of the Space Station is developed. The control algorithm utilizes both the gravity-gradient and gyroscopic torques to seek torque equilibrium attitude in the presence of secular and cyclic disturbances. Depending upon mission requirements, either pitch attitude or pitch-axis CMG momentum can be held constant: yaw attitude and roll-axis CMG momentum can be held constant, while roll attitude and yaw-axis CMG momentum cannot be held constant. As a result, the overall attitude and CMG momentum oscillations caused by cyclic aero-dynamic disturbances are minimized. A state feedback controller with minimal computer storage requirement for gain scheduling is also developed. The overall closed-loop system is stable for + or - 30 percent inertia matrix variations and has more than + or - 10 dB and 45 deg stability margins in each loop.

Cooperative solution in the synthesis of multidegree-of-freedom shock isolation systems

NASA Astrophysics Data System (ADS)

Hati, S. K.; Rao, S. S.

1983-01-01

It is noted that there are essentially two major criteria in the synthesis of shock isolation stems. One is related to the minimization of the relative displacement between the main mass (which is to be isolated from vibration) and the base (where disturbance is given); the other concerns the minimization of force transmitted to the main mass. From the available literature, it is observed that nearly all the investigators have considered the design problem by treating one of these factors as the objective and the other as a constraint. This problem is treated here as a multicriteria optimization problem, and the trade-off between the two objectives is determined by using a game theory approach. The synthesis of a multidegree-of-freedom shock isolation system under a sinusoidal base disturbance is given as an example problem to illustrate the theory.

THE CONCEPT OF REFERENCE CONDITION, REVISITED

EPA Science Inventory

Ecological assessments of aquatic ecosystems depend on the ability to compare current conditions against some expectation of how they could be in the absence of significant human disturbance. The concept of a ‘‘reference condition’’ is often used to descri...

A Concept for Power Cycling the Electronics of CALICE-AHCAL with the Train Structure of ILC

NASA Astrophysics Data System (ADS)

Göottlicher, Peter; The Calice-Collaboration

Particle flow algorithm calorimetry requires high granularity three-dimensional readout. The tight power requirement of 40 μW/channel is reached by enabling readout ASIC currents only during beam delivery, corresponding to a 1% duty cycle. EMI noise caused by current switching needs to be minimized by the power system and this paper presents ideas, simulations and first measurements for minimizing disturbances. A carefully design of circuits, printed circuit boards, grounding scheme and use of floating supplies allows current loops to be closed locally, stabilized voltages and minimal currents in the metal structures.

Referent control and motor equivalence of reaching from standing

PubMed Central

Tomita, Yosuke; Feldman, Anatol G.

2016-01-01

Motor actions may result from central changes in the referent body configuration, defined as the body posture at which muscles begin to be activated or deactivated. The actual body configuration deviates from the referent configuration, particularly because of body inertia and environmental forces. Within these constraints, the system tends to minimize the difference between these configurations. For pointing movement, this strategy can be expressed as the tendency to minimize the difference between the referent trajectory (RT) and actual trajectory (QT) of the effector (hand). This process may underlie motor equivalent behavior that maintains the pointing trajectory regardless of the number of body segments involved. We tested the hypothesis that the minimization process is used to produce pointing in standing subjects. With eyes closed, 10 subjects reached from a standing position to a remembered target located beyond arm length. In randomly chosen trials, hip flexion was unexpectedly prevented, forcing subjects to take a step during pointing to prevent falling. The task was repeated when subjects were instructed to intentionally take a step during pointing. In most cases, reaching accuracy and trajectory curvature were preserved due to adaptive condition-specific changes in interjoint coordination. Results suggest that referent control and the minimization process associated with it may underlie motor equivalence in pointing. NEW & NOTEWORTHY Motor actions may result from minimization of the deflection of the actual body configuration from the centrally specified referent body configuration, in the limits of neuromuscular and environmental constraints. The minimization process may maintain reaching trajectory and accuracy regardless of the number of body segments involved (motor equivalence), as confirmed in this study of reaching from standing in young healthy individuals. Results suggest that the referent control process may underlie motor equivalence in reaching. PMID:27784802

Population biology of sugar pine (Pinus lambertiana Dougl.) with reference to historical disturbances in the Lake Tahoe Basin: implications for restoration

Treesearch

Patricia E. Maloney; Detlev R. Vogler; Andrew J. Eckert; Camille E. Jensen; David B. Neale

2011-01-01

Historical logging, fire suppression, and an invasive pathogen, Cronartium ribicola, the cause of white pine blister rust (WPBR), are assumed to have dramatically affected sugar pine (Pinus lambertiana) populations in the Lake Tahoe Basin. We examined population- and genetic-level consequences of these disturbances within 10...

The human and fire connection

Treesearch

Theresa B. Jain

2014-01-01

We refer to fire as a natural disturbance, but unlike other disturbances such as forest insects and diseases, fire has had an intimate relationship with humans. Fire facilitated human evolution over two million years ago when our ancestors began to use fire to cook. Fire empowered our furbearers to adapt to cold climates, allowing humans to disperse and settle into...

Disturbance departure and fragmentation of natural systems in the interior Columbia basin.

Treesearch

Wendel J. Hann; Michael J. Wisdom; Mary M. Rowland

2003-01-01

We integrated landscape data from science assessments of the interior Columbia basin (basin) into one variable that functions as a robust index of departure from native conditions. This variable, referred to as the disturbance departure and fragmentation index, is a spatially explicit measure of landscape quality and resiliency. Primary causes of departure and...

Sleep disturbances in patients of liver cirrhosis with minimal hepatic encephalopathy before and after lactulose therapy.

PubMed

Singh, Jatinderpal; Sharma, Barjesh Chander; Puri, Vinod; Sachdeva, Sanjeev; Srivastava, Siddharth

2017-04-01

Sleep disturbances are common in patients of cirrhosis with minimal hepatic encephalopathy (MHE) and affect health related quality of life (HRQOL). No study has evaluated effect of lactulose on sleep disturbances and correlation with HRQOL in patients with MHE. We assessed sleep disturbances in cirrhosis with MHE and effect of lactulose on sleep disturbances and HRQOL. One hundred patients of cirrhosis [MHE; (n = 50, age 45.3 ± 11.2 years, 45 males) no-MHE (n = 50, age 46.3 ± 10.4 years, 44 males)] were included. MHE was diagnosed with psychometric hepatic encephalopathy score (PHES) ≤ -5. All patients underwent laboratory parameters including arterial ammonia and critical flicker frequency (CFF) Sleep disturbances were measured with Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS) and polysomnography. HRQOL was measured with SF-36(v2) questionnaire. Patients with MHE were given lactulose therapy for 3 months and all the parameters were repeated. Poor quality of sleep and excessive day time sleepiness were more common in patients with MHE, compared to without MHE. With lactulose therapy there was improvement in MHE in 21 patients and arterial ammonia levels (93.74 ± 14.8 vs. 71.44 ± 18.8 μmol/L: p < 0.001), CFF (34.83 ± 3.54 vs. 39.44 ± 4.95 Hz: p < 0.001), PHES (-7.64 ± 2.1 vs. -5.58 ± 2.09: p < 0.001), PSQI (8.6 ± 3.3 vs. 5.2 ± 1.5: p < 0.001), ESS (12.52 ± 3.01 vs. 9.24 ± 2.27: p < 0.001) and HRQOL (p = 0.01). Excessive day time sleepiness and impaired sleep quality are common in patients with MHE and correlate with neuropsychiatric impairment. Improvement in MHE with lactulose also leads to improvement in sleep disturbances and HRQOL.

Modeling and control for closed environment plant production systems

NASA Technical Reports Server (NTRS)

Fleisher, David H.; Ting, K. C.; Janes, H. W. (Principal Investigator)

2002-01-01

A computer program was developed to study multiple crop production and control in controlled environment plant production systems. The program simulates crop growth and development under nominal and off-nominal environments. Time-series crop models for wheat (Triticum aestivum), soybean (Glycine max), and white potato (Solanum tuberosum) are integrated with a model-based predictive controller. The controller evaluates and compensates for effects of environmental disturbances on crop production scheduling. The crop models consist of a set of nonlinear polynomial equations, six for each crop, developed using multivariate polynomial regression (MPR). Simulated data from DSSAT crop models, previously modified for crop production in controlled environments with hydroponics under elevated atmospheric carbon dioxide concentration, were used for the MPR fitting. The model-based predictive controller adjusts light intensity, air temperature, and carbon dioxide concentration set points in response to environmental perturbations. Control signals are determined from minimization of a cost function, which is based on the weighted control effort and squared-error between the system response and desired reference signal.

75 FR 33593 - Office of Special Education and Rehabilitative Services; Overview Information; Personnel...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-14

... ``high-incidence disabilities'' refers to learning disabilities, emotional disturbance, or mental... purposes of this priority, the term high-incidence disabilities refers to learning disabilities, emotional... Information; Personnel Development To Improve Services and Results for Children With Disabilities; Notice...

Music the Healer: A Bibliography.

ERIC Educational Resources Information Center

Washington State Library, Olympia.

The bibliography contains references to primarily journal literature dealing with music as a therapeutic tool. References to articles concerned with music as a healer are listed under one of the following categories: activities, audioanalgesia, education, effects, emotionally disturbed children, geriatrics, handicapped; medicine, mentally ill,…

Rapid assessment of urban wetlands: Do hydrogeomorpic classification and reference criteria work?

EPA Science Inventory

The Hydrogeomorphic (HGM) functional assessment method is predicated on the ability of a wetland classification method based on hydrology (HGM classification) and a visual assessment of disturbance and alteration to provide reference standards against which functions in individua...

Physical modeling of stepped spillways

USDA-ARS?s Scientific Manuscript database

Stepped spillways applied to embankment dams are becoming popular for addressing the rehabilitation of aging watershed dams, especially those situated in the urban landscape. Stepped spillways are typically placed over the existing embankment, which provides for minimal disturbance to the original ...

Reduction of adverse aerodynamic effects of large trucks, Volume I. Technical report

DOT National Transportation Integrated Search

1978-09-01

The overall objective of this study has been to develop methods of minimizing three aerodynamic-related phenomena: truck-induced aerodynamic disturbances, splash, and spray. An analytical methodology has been developed and used to characterize aerody...

Propagation of Disturbances in Traffic Flow

DOT National Transportation Integrated Search

1977-09-01

The system-optimized static traffic-assignment problem in a freeway corridor network is the problem of choosing a distribution of vehicles in the network to minimize average travel time. It is of interest to know how sensitive the optimal steady-stat...

Architectural Considerations for Classrooms for Exceptional Children.

ERIC Educational Resources Information Center

Texas Education Agency, Austin.

Definitions are provided of the following exceptionalities: blind, partially sighted, physically handicapped, minimally brain injured, deaf, educable mentally retarded (primary, junior, and senior high levels), trainable mentally retarded, speech handicapped, and emotionally disturbed. Architectural guidelines specify classroom location, size,…

Disturbing effects of attitude control maneuvers on the orbital motion of the Helios spacecraft

NASA Technical Reports Server (NTRS)

Georgevic, R. M.

1976-01-01

The position of the spin axis of the Helios A spacecraft has been maintained and updated by a series of attitude control maneuvers, by means of a sequence of unbalanced jet forces which produce an additional disturbed motion of the spacecraft's center of mass. The character of this motion, its magnitude and direction was studied. For practical purposes of the orbit determination of the spacecraft, a computer program is given which shows how the components of the disturbing acceleration in the spacecraft-fixed reference frame can be easily computed.

Intensive MHD-structures penetration in the middle atmosphere initiated in the ionospheric cusp under quiet geomagnetic conditions

NASA Technical Reports Server (NTRS)

Mateev, L. N.; Nenovski, P. I.; Vellinov, P. I.

1989-01-01

In connection with the recently detected quasiperiodical magnetic disturbances in the ionospheric cusp, the penetration of compressional surface magnetohydrodynamic (MHD) waves through the middle atmosphere is modelled numerically. For the COSPAR International Reference Atmosphere (CIRA) 72 model the respective energy density flux of the disturbances in the middle atmosphere is determined. On the basis of the developed model certain conclusions are reached about the height distribution of the structures (energy losses, currents, etc.) initiated by intensive magnetic cusp disturbances.

Defining And Employing Reference Conditions For Ecological Restoration Of The Lower Missouri River, USA

NASA Astrophysics Data System (ADS)

Jacobson, R. B.; Elliott, C. M.; Reuter, J. M.

2008-12-01

Ecological reference conditions are especially challenging for large, intensively managed rivers like the Lower Missouri. Historical information provides broad understanding of how the river has changed, but translating historical information into quantitative reference conditions remains a challenge. Historical information is less available for biological and chemical conditions than for physical conditions. For physical conditions, much of the early historical condition is documented in date-specific measurements or maps, and it is difficult to determine how representative these conditions are for a river system that was characterized historically by large floods and high channel migration rates. As an alternative to a historically defined least- disturbed condition, spatial variation within the Missouri River basin provides potential for defining a best- attainable reference condition. A possibility for the best-attainable condition for channel morphology is an unchannelized segment downstream of the lowermost dam (rkm 1298 - 1203). This segment retains multiple channels and abundant sandbars although it has a highly altered flow regime and a greatly diminished sediment supply. Conversely, downstream river segments have more natural flow regimes, but have been narrowed and simplified for navigation and bank stability. We use two computational tools to compensate for the lack of ideal reference conditions. The first is a hydrologic model that synthesizes natural and altered flow regimes based on 100 years of daily inputs to the river (daily routing model, DRM, US Army Corps of Engineers, 1998); the second tool is hydrodynamic modeling of habitat availability. The flow-regime and hydrodynamic outputs are integrated to define habitat-duration curves as the basis for reference conditions (least-disturbed flow regime and least-disturbed channel morphology). Lacking robust biological response models, we use mean residence time of water and a habitat diversity index as generic ecosystem indicators.

The 3.5-meter telescope enclosure

NASA Astrophysics Data System (ADS)

Brady, Michael H.

1994-04-01

The 3.5-m telescope enclosure is designed to perform two functions as part of the U.S. Air Force's 3.5-m telescope system: (1) to provide weather and temperature protection when the telescope is not in use and (2) to permit open-air operation of the telescope while minimizing atmospheric disturbances in the field of view (FOV). The use of a standard rotating dome is impractical because of the large telescope and its high rotational rate and acceleration. The enclosure is a 40-ft tall cylinder with a diameter of 72 ft. This steel and aluminum structure does not rotate but collapses vertically to fully expose the telescope to the open air and to provide it with an unobscured view of the horizon at all azimuthal angles. To lessen wind disturbances in the FOV, the enclosure has a moderately sloped roof and smooth, vertical walls. To minimize thermal flow, the outer surface has a high-reflectivity, low-emissivity coating and ambient air is forced through the double-skinned walls and roof. These measures make it possible to keep the enclosure surface temperature near that of the ambient air during viewing. With these features, the enclosure adds minimal degradation to the seeing.

Posteruption arthropod succession on the Mount St. Helens volcano: the ground-dwelling beetle fauna (Coleoptera).

Treesearch

R.R. Parmenter; C.M. Crisafulli; N. Korbe; G. Parsons; M. Edgar; J.A. MacMahon

2005-01-01

The 1980 eruptions of Mount St. Helens created a complex mosaic of disturbance types over a 600 km2 area. From 1980 through 2000 we monitored beetle species relative abundance and faunal composition of assemblages at undisturbed reference sites and in areas subjected to tephra-fall, blowdown, and pyroclastic flow volcanic disturbance. We...

Effects of land use intensification on fish assemblages in Mediterranean climate streams.

PubMed

Matono, P; Sousa, D; Ilhéu, M

2013-11-01

Southern Portugal is experiencing a rapid change in land use due to the spread of intensive farming systems, namely olive production systems, which can cause strong negative environmental impacts and affect the ecological integrity of aquatic ecosystems. This study aimed to identify the main environmental disturbances related with olive grove intensification on Mediterranean-climate streams in southern Portugal, and to evaluate their effects on fish assemblage structure and integrity. Twenty-six stream sites within the direct influence of traditional, intensive, and hyper-intensive olive groves were sampled. Human-induced disturbances were analyzed along the olive grove intensity gradient. The integrity of fish assemblages was evaluated by comparison with an independent set of least disturbed reference sites, considering metrics and guilds, based on multivariate analyses. Along the gradient of olive grove intensification, the study observed overall increases in human disturbance variables and physicochemical parameters, especially organic/nutrient enrichment, sediment load, and riparian degradation. Animal load measured the impact of livestock production. This variable showed an opposite pattern, since traditional olive groves are often combined with high livestock production and are used as grazing pasture by the cattle, unlike more intensive olive groves. Stream sites influenced by olive groves were dominated by non-native and tolerant fish species, while reference sites presented higher fish richness, density and were mainly occupied by native and intolerant species. Fish assemblage structure in olive grove sites was significantly different from the reference set, although significant differences between olive grove types were not observed. Bray-Curtis similarities between olive grove sites and references showed a decreasing trend in fish assemblage integrity along the olive grove intensification gradient. Olive production, even in traditional groves, led to multiple in-stream disturbances, whose cumulative effects promoted the loss of biota integrity. The impacts of low intensity traditional olive groves on aquatic ecosystems can be much greater when they are coupled with livestock production. This paper recommends best practices to reduce negative impacts of olive production on streams, contributing to guide policy decision-makers in agricultural and water management.

Drifts and Environmental Disturbances in Atomic Clock Subsystems: Quantifying Local Oscillator, Control Loop, and Ion Resonance Interactions.

PubMed

Enzer, Daphna G; Diener, William A; Murphy, David W; Rao, Shanti R; Tjoelker, Robert L

2017-03-01

Linear ion trap frequency standards are among the most stable continuously operating frequency references and clocks. Depending on the application, they have been operated with a variety of local oscillators (LOs), including quartz ultrastable oscillators, hydrogen-masers, and cryogenic sapphire oscillators. The short-, intermediate-, and long-term stability of the frequency output is a complicated function of the fundamental performances, the time dependence of environmental disturbances, the atomic interrogation algorithm, the implemented control loop, and the environmental sensitivity of the LO and the atomic system components. For applications that require moving these references out of controlled lab spaces and into less stable environments, such as fieldwork or spaceflight, a deeper understanding is needed of how disturbances at different timescales impact the various subsystems of the clock and ultimately the output stability. In this paper, we analyze which perturbations have an impact and to what degree. We also report on a computational model of a control loop, which keeps the microwave source locked to the ion resonance. This model is shown to agree with laboratory measurements of how well the feedback removes various disturbances and also with a useful analytic approach we developed for predicting these impacts.

Understanding the Spatio-Temporal Pattern of Fire Disturbance in the Eastern Mongolia Using Modis Product

NASA Astrophysics Data System (ADS)

Wurihan; Zhang, H.; Zhang, Z.; Guo, X.; Zhao, J.; Duwala; Shan, Y.; Hongying

2018-04-01

Fire disturbance plays an important role in maintaining ecological balance, biodiversity and self-renewal. In this paper, the spatio-temporal pattern of fire disturbances in eastern Mongolia are studied by using the ArcGIS spatial analysis method, using the MCD45A1 data of MODIS fire products with long time series. It provides scientific basis and reference for the regional ecological environment security construction and international ecological security. Research indicates: (1) The fire disturbance in eastern Mongolia has obvious high and low peak interleaving phenomenon in the year, and the seasonal change is obvious. (2) The distribution pattern of fire disturbance in eastern Mongolia is aggregated, which indicates that the fire disturbance is not random and it is caused by certain influence. (3) Fire disturbance is mainly distributed in the eastern province of Mongolia, the border between China and Mongolia and the northern forest area of Sukhbaatar province. (4) The fire disturbance in the eastern part of the study area is strong and the southwest is weaker. The spreading regularity of fire disturbances in eastern Mongolia is closer to the natural level of ecosystem.

The magnitude of lost ecosystem structure and function in urban streams and the effectiveness of watershed-based management (Invited)

NASA Astrophysics Data System (ADS)

Smucker, N. J.; Detenbeck, N. E.; Kuhn, A.

2013-12-01

Watershed development is a leading cause of stream impairment and increasingly threatens the availability, quality, and sustainability of freshwater resources. In a recent global meta-analysis, we found that measures of desirable ecological structure (e.g., algal, macroinvertebrate, and fish communities) and functions (e.g., metabolism, nutrient uptake, and denitrification) in streams with developed watersheds were only 23% and 34%, respectively, of those in minimally disturbed reference streams. As humans continue to alter watersheds in response to growing and migrating populations, characterizing ecological responses to watershed development and management practices is urgently needed to inform future development practices, decisions, and policy. In a study of streams in New England, we found that measures of macroinvertebrate and algal communities had threshold responses between 1-10% and 1-5% impervious cover, respectively. Macroinvertebrate communities had decreases in sensitive taxa and predators occurring from 1-3.5% and transitions in trophic and habitat guilds from 4-9% impervious cover. Sensitive algal taxa declined at 1%, followed by increases in tolerant taxa at 3%. Substantially altered algal communities persisted above 5% impervious cover and were dominated by motile taxa (sediment resistant) and those with high nutrient demands. Boosted regression tree analysis showed that sites with >65% and ideally >80% forest and wetland cover in near-stream buffers were associated with a 13-34% decrease in the effects of watershed impervious cover on algal communities. While this reduction is substantial, additional out-of-stream management efforts are needed to protect and restore stream ecosystems (e.g., created wetlands and stormwater ponds), but understanding their effectiveness is greatly limited by sparse ecological monitoring. Our meta-analysis found that restoration improved ecological structure and functions in streams by 48% and 14%, respectively, when compared to streams with developed watersheds and no management practices in place. However, ecosystem measures at restored sites were still only 53% of those in minimally disturbed reference streams. Some of our ongoing work further examines how watershed development and riparian condition affect stream ecosystem functions by altering the sources and delivery of nutrients and carbon. Our results can help inform management priorities and expectations, and they emphasize the importance of implementing mindful development and protective actions in a watershed context, especially in watersheds near impervious cover thresholds. Continued research on linked terrestrial-aquatic systems, improved BMP tracking, and ongoing monitoring will be essential to conserving and restoring the mechanisms that sustain valued ecological attributes and ecosystem services of streams.

Body Doping Profile of Select Device to Minimize Program Disturbance in Three-Dimensional Stack NAND Flash Memory

NASA Astrophysics Data System (ADS)

Choe, Byeong-In; Park, Byung-Gook; Lee, Jong-Ho

2013-06-01

The program disturbance characteristic in the three-dimensional (3D) stack NAND flash was analyzed for the first time in terms of string select line (SSL) threshold voltage (Vth) and p-type body doping profile. From the edge word line (W/L) program disturbance, we can observe the boosted channel potential loss as a function of SSL Vth and body doping profile for SSL device. According to simulation work, a high Vth of the SSL device is required to suppress channel leakage during programming. When the body doping of the SSL device is high in the channel, there is a large band bending near the gate edge of the SSL adjacent to the edge W/L cell of boosted cell strings, which generates significantly electron-hole pairs. The generated electrons decreases the boosted channel potential, resulting in increase of program disturbance of the inhibit strings. Through optimization of the body doping profile of the SSL device, both channel leakage and the program disturbance are successfully suppressed for a highly reliable 3D stack NAND flash memory cell operation.

Megabenthic Community Structure Within and Surrounding the DISCOL Experimental Area 26 Years After Simulated Manganese Nodule Mining Disturbance.

NASA Astrophysics Data System (ADS)

Purser, A.; Marcon, Y.; Boetius, A.

2016-02-01

The current supplies of many high technology elements from land-based sources are at capacity, such as copper, nickel and yttrium. Potential future sources of some of these elements include the deep sea manganese nodule fields of the Atlantic, Indian and Pacific oceans. Large swathes of deep-sea seafloor are covered with high densities of 5 - 25 cm diameter nodules - agglomerations of manganese, iron and trace metals. In the 1980's these manganese fields were first seriously considered as mining targets, and the ''DISturbance and reCOLonization (DISCOL) experiment was started in the South Pacific, to simulate the likely environmental impacts of mining. In September 1989, 'RV Sonne', deploying a custom-built plough device, removed manganese nodules from the seafloor surface by ploughing them down into the sediment. This removal of nodules (and therefore hard substrate) was considered to likely be the most significant environmental impact of any future mining efforts. 78 plough tracks of 8 - 16m width were made across a 10.8 km diameter circular area centered on 7°04.4´S 88°27.6´W. Megafauna abundances were assessed prior and post ploughing, both within the disturbed area and at reference stations 6 km from the disturbed area. Research cruises in the 1990s investigated the short-term temporal impact ploughing had on the faunal community in the DISCOL area. Cruises conducted 3 and 7 years after disturbance showed that megafaunal communities within ploughed areas remained quite distinct from those observed pre-disturbance or in the reference areas. In 2016 the 'RV Sonne' revisited the DISCOL site with two research cruises, as part of the 'JPI-Oceans' programme. Here we report the current megafaunal community structures observed by SO242-2 within the DISCOL area, and the slow recovery rates of many taxa 26 years after the initial experimental disturbance, and provide images of the long term impact of experimental disturbances at the seafloor.

SETTING EXPECTATIONS FOR THE ECOLOGICAL CONDITION OF STREAMS: THE CONCEPT OF REFERENCE CONDITION

EPA Science Inventory

An important component of the biological assessment of stream condition is an evaluation of the direct or indirect effects of human activities or disturbances. The concept of a "reference condition" is increasingly used to describe the standard or benchmark against which current ...

The influence of disturbance events on survival and dispersal rates of Florida box turtles

USGS Publications Warehouse

Dodd, C.K.; Ozgul, A.; Oli, M.K.

2006-01-01

Disturbances have the potential to cause long-term effects to ecosystem structure and function, and they may affect individual species in different ways. Long-lived vertebrates such as turtles may be at risk from such events, inasmuch as their life histories preclude rapid recovery should extensive mortality occur. We applied capture–mark–recapture models to assess disturbance effects on a population of Florida box turtles (Terrapene carolina bauri) on Egmont Key, Florida, USA. Near the midpoint of the study, a series of physical disturbances affected the island, from salt water overwash associated with several tropical storms to extensive removal of nonindigenous vegetation. These disturbances allowed us to examine demographic responses of the turtle population and to determine if they affected dispersal throughout the island. Adult survival rates did not vary significantly either between sexes or among years of the study. Survival rates did not vary significantly between juvenile and adult turtles, or among years of the study. Furthermore, neither adult nor juvenile survival rates differed significantly between pre- and post-disturbance. However, dispersal rates varied significantly among the four major study sites, and dispersal rates were higher during the pre-disturbance sampling periods compared to post-disturbance. Our results suggest few long-term effects on the demography of the turtle population. Florida box turtles responded to tropical storms and vegetation control by moving to favorable habitats minimally affected by the disturbances and remaining there. As long as turtles and perhaps other long-lived vertebrates can disperse to non-disturbed habitat, and high levels of mortality do not occur in a population, a long life span may allow them to wait out the impact of disturbance with potentially little effect on long-term population processes.

The role of natural vegetative disturbance in determining stream reach characteristics in central Idaho and western Montana

USGS Publications Warehouse

Roper, B.B.; Jarvis, B.; Kershner, J.L.

2007-01-01

We evaluated the relationship between natural vegetative disturbance and changes in stream habitat and macroinvertebrate metrics within 33 randomly selected minimally managed watersheds in central Idaho and western Montana. Changes in stream reach conditions were related to vegetative disturbance for the time periods from 1985 to 1993 and 1993 to 2000, respectively, at the following three spatial scales; within the stream buffer and less than 1 km from the evaluated reach, within the watershed and within 1 km of the stream reach, and within the watershed. Data for stream reaches were based on field surveys and vegetative disturbance was generated for the watershed above the sampled reach using remotely sensed data and geographical information systems. Large scale (>100 ha) vegetative disturbance was common within the study area. Even though natural vegetative disturbance rates were high, we found that few of the measured attributes were related to the magnitude of vegetative disturbance. The three physical habitat attributes that changed significantly were sinuosity, median particle size, and percentage of undercut bank; each was related to the disturbance in the earlier (1985-1993) time frame. There was a significant relationship between changes in two macroinvertebrate metrics, abundance and percent collectors/filterers, and the magnitude of disturbance during the more recent time period (1993-2000). We did not find a consistent relationship between the location of the disturbance within the watershed and changes in stream conditions. Our findings suggest that natural vegetative disturbance within the northern Rocky Mountains is complex but likely does not result in substantial short-term changes in the characteristics of most stream reaches. ?? 2007 by the Northwest Scientific Association. All rights reserved.

Just-in-time adaptive disturbance estimation for run-to-run control of photolithography overlay

NASA Astrophysics Data System (ADS)

Firth, Stacy K.; Campbell, W. J.; Edgar, Thomas F.

2002-07-01

One of the main challenges to implementations of traditional run-to-run control in the semiconductor industry is a high mix of products in a single factory. To address this challenge, Just-in-time Adaptive Disturbance Estimation (JADE) has been developed. JADE uses a recursive weighted least-squares parameters estimation technique to identify the contributions to variation that are dependent on product, as well as the tools on which the lot was processed. As applied to photolithography overlay, JADE assigns these sources of variation to contributions from the context items: tool, product, reference tool, and reference reticle. Simulations demonstrate that JADE effectively identifies disturbances in contributing context items when the variations are known to be additive. The superior performance of JADE over traditional EWMA is also shown in these simulations. The results of application of JADE to data from a high mix production facility show that JADE still performs better than EWMA, even with the challenges of a real manufacturing environment.

Immune response of greenback flounder Rhombosolea tapirina after exposure to contaminated marine sediment and diet.

PubMed

Mondon, J A; Duda, S; Nowak, B F

2000-01-01

Non-specific immune response of greenback flounder, Rhombosolea tapirina, exposed to contaminated marine sediments was examined. Reference sediments from Port Sorell and contaminated sediments from Deceitful Cove, Tasmania, Australia were investigated. Hatchery-reared flounder were exposed to reference sediment, contaminated sediment or contaminated sediment and diet for 6 weeks. Phagocytic capacity and lysozyme response in flounder were examined on cessation of exposure trial. Significant differences were found in phagocytic capacity and lysozyme response between treatments. Exposure to contaminated sediment, irrespective of diet or benthic disturbance elicited inhibition of phagocytic efficiency in flounder. Disturbance of contaminated sediment stimulated lysozyme activity. The immune response in flounder indicates potential immunotoxicity of sediment from Deceitful Cove.

Fiscal Year 2016 Revegetation Assessment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nordstrom, Jenifer B.

This report summarizes the Fiscal Year (FY) 2016 Revegetation Assessment by Battelle Energy Alliance, LLC. This assessment was conducted to document revegetation efforts at Idaho National Laboratory to verify restoration of disturbed vegetation and soil at various locations occurs as required. This report provides the following information for projects at Idaho National Laboratory completed during FY 2016 that were identified during the National Environmental Policy Act review process as having the potential to disturb soils or vegetation: 1) A summary of all projects identified as having the potential to require revegetation efforts 2) A summary of site disturbance and restorationmore » efforts of each project. For FY 2016, one project required revegetation and sagebrush restoration. For other projects, implementation of best management practices minimized impacts to vegetation and revegetation efforts were not required.« less

A Study to Assess the Achievement Motivation of Higher Secondary Students in Relation to Their Noise Sensitivity

ERIC Educational Resources Information Center

Latha, Prema

2014-01-01

Disturbing sounds are often referred to as noise, and if extreme enough in degree, intensity or frequency, it is referred to as noise pollution. Achievement refers to a change in study behavior in relation to their noise sensitivity and learning in the educational sense by achieving results in changed responses to certain types of stimuli like…

MPLP and the Catalog Record as a Finding Aid

ERIC Educational Resources Information Center

Bowen Maier, Shannon

2011-01-01

The cataloging of otherwise unprocessed collections is an innovative minimal processing technique with important implications for reference service. This article mines the existing literature for how institutions engaged in minimal processing view reference, the strengths and weaknesses of catalog records as finding aids, and information about…

Accurate Attitude Estimation Using ARS under Conditions of Vehicle Movement Based on Disturbance Acceleration Adaptive Estimation and Correction

PubMed Central

Xing, Li; Hang, Yijun; Xiong, Zhi; Liu, Jianye; Wan, Zhong

2016-01-01

This paper describes a disturbance acceleration adaptive estimate and correction approach for an attitude reference system (ARS) so as to improve the attitude estimate precision under vehicle movement conditions. The proposed approach depends on a Kalman filter, where the attitude error, the gyroscope zero offset error and the disturbance acceleration error are estimated. By switching the filter decay coefficient of the disturbance acceleration model in different acceleration modes, the disturbance acceleration is adaptively estimated and corrected, and then the attitude estimate precision is improved. The filter was tested in three different disturbance acceleration modes (non-acceleration, vibration-acceleration and sustained-acceleration mode, respectively) by digital simulation. Moreover, the proposed approach was tested in a kinematic vehicle experiment as well. Using the designed simulations and kinematic vehicle experiments, it has been shown that the disturbance acceleration of each mode can be accurately estimated and corrected. Moreover, compared with the complementary filter, the experimental results have explicitly demonstrated the proposed approach further improves the attitude estimate precision under vehicle movement conditions. PMID:27754469

Radio-scintillation observations of interplanetary disturbances

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watanabe, T.; Kakinuma, T.

1984-01-01

Recent developments in the studies of interplanetary disturbances by scintillation techniques are briefly reviewed. The turbulent postshock region of an interplanetary disturbance produces transient enhancements in the scintillation level and the flow speed in many cases. An empirical method to determine three-dimensional angular distribution of the propagation speed of the disturbance on the basis of interplanetary scintillation measurements of postshock flow speeds is applied to 17 events which took place in 1978-1981. Among them, four representative examples, including two events which were associated with disappearing solar filaments, are described in detail. Several disturbances had oblate configurations the latitudinal extent ismore » smaller than the longitudinal extent. On the average, the angular distribution of the propagation speed at 1-AU heliocentric distance is quasi-isotropic over a longitudinal range of 100 deg centered at the normal of relevant solar phenomenon. The net excess mass and energy in an interplanetary disturbance associated with a disappearing solar filament can be comparable to those of an interplanetary disturbance associated with a large solar flare. 57 references.« less

Accurate Attitude Estimation Using ARS under Conditions of Vehicle Movement Based on Disturbance Acceleration Adaptive Estimation and Correction.

PubMed

Xing, Li; Hang, Yijun; Xiong, Zhi; Liu, Jianye; Wan, Zhong

2016-10-16

This paper describes a disturbance acceleration adaptive estimate and correction approach for an attitude reference system (ARS) so as to improve the attitude estimate precision under vehicle movement conditions. The proposed approach depends on a Kalman filter, where the attitude error, the gyroscope zero offset error and the disturbance acceleration error are estimated. By switching the filter decay coefficient of the disturbance acceleration model in different acceleration modes, the disturbance acceleration is adaptively estimated and corrected, and then the attitude estimate precision is improved. The filter was tested in three different disturbance acceleration modes (non-acceleration, vibration-acceleration and sustained-acceleration mode, respectively) by digital simulation. Moreover, the proposed approach was tested in a kinematic vehicle experiment as well. Using the designed simulations and kinematic vehicle experiments, it has been shown that the disturbance acceleration of each mode can be accurately estimated and corrected. Moreover, compared with the complementary filter, the experimental results have explicitly demonstrated the proposed approach further improves the attitude estimate precision under vehicle movement conditions.

Investigation and process optimization of SONOS cell's drain disturb in 2-transistor structure flash arrays

NASA Astrophysics Data System (ADS)

Xu, Zhaozhao; Qian, Wensheng; Chen, Hualun; Xiong, Wei; Hu, Jun; Liu, Donghua; Duan, Wenting; Kong, Weiran; Na, Wei; Zou, Shichang

2017-03-01

The mechanism and distribution of drain disturb (DD) are investigated in silicon-oxide-nitride-oxide-silicon (SONOS) flash cells. It is shown that DD is the only concern in this paper. First, the distribution of trapped charge in nitride layer is found to be non-localized (trapped in entire nitride layer along the channel) after programming. Likewise, the erase is also non-localized. Then, the main disturb mechanism: Fowler Nordheim tunneling (FNT) has been confirmed in this paper with negligible disturb effect from hot-hole injection (HHI). And then, distribution of DD is confirmed to be non-localized similarly, which denotes that DD exists in entire tunneling oxide (Oxide for short). Next, four process optimization ways are proposed for minimization of DD, and VTH shift is measured. It reveals that optimized lightly doped drain (LDD), halo, and channel implant are required for the fabrication of a robust SONOS cell. Finally, data retention and endurance of the optimized SONOS are demonstrated.

A Non-Intrusive GMA Welding Process Quality Monitoring System Using Acoustic Sensing.

PubMed

Cayo, Eber Huanca; Alfaro, Sadek Crisostomo Absi

2009-01-01

Most of the inspection methods used for detection and localization of welding disturbances are based on the evaluation of some direct measurements of welding parameters. This direct measurement requires an insertion of sensors during the welding process which could somehow alter the behavior of the metallic transference. An inspection method that evaluates the GMA welding process evolution using a non-intrusive process sensing would allow not only the identification of disturbances during welding runs and thus reduce inspection time, but would also reduce the interference on the process caused by the direct sensing. In this paper a nonintrusive method for weld disturbance detection and localization for weld quality evaluation is demonstrated. The system is based on the acoustic sensing of the welding electrical arc. During repetitive tests in welds without disturbances, the stability acoustic parameters were calculated and used as comparison references for the detection and location of disturbances during the weld runs.

A Non-Intrusive GMA Welding Process Quality Monitoring System Using Acoustic Sensing

PubMed Central

Cayo, Eber Huanca; Alfaro, Sadek Crisostomo Absi

2009-01-01

Most of the inspection methods used for detection and localization of welding disturbances are based on the evaluation of some direct measurements of welding parameters. This direct measurement requires an insertion of sensors during the welding process which could somehow alter the behavior of the metallic transference. An inspection method that evaluates the GMA welding process evolution using a non-intrusive process sensing would allow not only the identification of disturbances during welding runs and thus reduce inspection time, but would also reduce the interference on the process caused by the direct sensing. In this paper a nonintrusive method for weld disturbance detection and localization for weld quality evaluation is demonstrated. The system is based on the acoustic sensing of the welding electrical arc. During repetitive tests in welds without disturbances, the stability acoustic parameters were calculated and used as comparison references for the detection and location of disturbances during the weld runs. PMID:22399990

Accounting for regional variation in both natural environment and human disturbance to improve performance of multimetric indices of lotic benthic diatoms.

PubMed

Tang, Tao; Stevenson, R Jan; Infante, Dana M

2016-10-15

Regional variation in both natural environment and human disturbance can influence performance of ecological assessments. In this study we calculated 5 types of benthic diatom multimetric indices (MMIs) with 3 different approaches to account for variation in ecological assessments. We used: site groups defined by ecoregions or diatom typologies; the same or different sets of metrics among site groups; and unmodeled or modeled MMIs, where models accounted for natural variation in metrics within site groups by calculating an expected reference condition for each metric and each site. We used data from the USEPA's National Rivers and Streams Assessment to calculate the MMIs and evaluate changes in MMI performance. MMI performance was evaluated with indices of precision, bias, responsiveness, sensitivity and relevancy which were respectively measured as MMI variation among reference sites, effects of natural variables on MMIs, difference between MMIs at reference and highly disturbed sites, percent of highly disturbed sites properly classified, and relation of MMIs to human disturbance and stressors. All 5 types of MMIs showed considerable discrimination ability. Using different metrics among ecoregions sometimes reduced precision, but it consistently increased responsiveness, sensitivity, and relevancy. Site specific metric modeling reduced bias and increased responsiveness. Combined use of different metrics among site groups and site specific modeling significantly improved MMI performance irrespective of site grouping approach. Compared to ecoregion site classification, grouping sites based on diatom typologies improved precision, but did not improve overall performance of MMIs if we accounted for natural variation in metrics with site specific models. We conclude that using different metrics among ecoregions and site specific metric modeling improve MMI performance, particularly when used together. Applications of these MMI approaches in ecological assessments introduced a tradeoff with assessment consistency when metrics differed across site groups, but they justified the convenient and consistent use of ecoregions. Copyright © 2016 Elsevier B.V. All rights reserved.

Unconventional gas development and its effect on forested ecosystems in the Northern Appalachians, USA

NASA Astrophysics Data System (ADS)

Drohan, Patrick; Brittingham, Margaret; Mortensen, David; Barlow, Kathryn; Langlois, Lillie

2017-04-01

Worldwide unconventional shale-gas development has the potential to cause substantial landscape disturbance. The northeastern U.S.A. Appalachian Mountains across the states of Pennsylvania, West Virginia, Ohio, and Kentucky, are experiencing rapid landscape change as unconventional gas development occurs. We highlight several years of our research from this region in order to demonstrate the unique effect unconventional development has had on forested ecosystems. Infrastructure development has had a wide-reaching and varied effect on forested ecosystems and their services, which has resulted in temporary disturbances and long-lasting ones altering habitats and their viability. Corridor disturbances, such as pipelines, are the most spatially extensive disturbance and have substantially fragmented forest cover. Core forest disturbance, especially, in upper watershed positions, has resulted in disproportionate disturbances to forested ecosystems and their wildlife, and suggests a need for adaptive land management strategies to minimize and mitigate the effects of gas development. Soil and water resources are most affected by surface disturbances; however, soil protection and restoration strategies are evolving as the gas play changes economically. Dynamic soil properties related to soil organic matter and water availability respond uniquely to unconventional gas development and new, flexible restoration strategies are required to support long-term ecosystem stability. While the focus of management and research to date has been on acute disturbances to forested ecosystems, unconventional gas development is clearly a greater chronic, long-term disturbance factor in the Appalachian Mountains. Effectively managing ecosystems where unconventional gas development is occurring is a complicated interplay between public, private and corporate interests.

30 CFR 817.41 - Hydrologic-balance protection.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Hydrologic-balance protection. 817.41 Section... ACTIVITIES § 817.41 Hydrologic-balance protection. (a) General. All underground mining and reclamation activities shall be conducted to minimize disturbance of the hydrologic balance within the permit and...

30 CFR 817.41 - Hydrologic-balance protection.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Hydrologic-balance protection. 817.41 Section... ACTIVITIES § 817.41 Hydrologic-balance protection. (a) General. All underground mining and reclamation activities shall be conducted to minimize disturbance of the hydrologic balance within the permit and...

Mapping forest height, foliage height profiles and disturbance characteristics with time series of gap-filled Landsat and ALI imagery

NASA Astrophysics Data System (ADS)

Helmer, E.; Ruzycki, T. S.; Wunderle, J. M.; Kwit, C.; Ewert, D. N.; Voggesser, S. M.; Brandeis, T. J.

2011-12-01

We mapped tropical dry forest height (RMSE = 0.9 m, R2 = 0.84, range 0.6-7 m) and foliage height profiles with a time series of gap-filled Landsat and Advanced Land Imager (ALI) imagery for the island of Eleuthera, The Bahamas. We also mapped disturbance type and age with decision tree classification of the image time series. Having mapped these variables in the context of studies of wintering habitat of an endangered Nearctic-Neotropical migrant bird, the Kirtland's Warbler (Dendroica kirtlandii), we then illustrated relationships between forest vertical structure, disturbance type and counts of forage species important to the Kirtland's Warbler. The ALI imagery and the Landsat time series were both critical to the result for forest height, which the strong relationship of forest height with disturbance type and age facilitated. Also unique to this study was that seven of the eight image time steps were cloud-gap-filled images: mosaics of the clear parts of several cloudy scenes, in which cloud gaps in a reference scene for each time step are filled with image data from alternate scenes. We created each cloud-cleared image, including a virtually seamless ALI image mosaic, with regression tree normalization of the image data that filled cloud gaps. We also illustrated how viewing time series imagery as red-green-blue composites of tasseled cap wetness (RGB wetness composites) aids reference data collection for classifying tropical forest disturbance type and age.

A causal examination of the effects of confounding factors on multimetric indices

USGS Publications Warehouse

Schoolmaster, Donald R.; Grace, James B.; Schweiger, E. William; Mitchell, Brian R.; Guntenspergen, Glenn R.

2013-01-01

The development of multimetric indices (MMIs) as a means of providing integrative measures of ecosystem condition is becoming widespread. An increasingly recognized problem for the interpretability of MMIs is controlling for the potentially confounding influences of environmental covariates. Most common approaches to handling covariates are based on simple notions of statistical control, leaving the causal implications of covariates and their adjustment unstated. In this paper, we use graphical models to examine some of the potential impacts of environmental covariates on the observed signals between human disturbance and potential response metrics. Using simulations based on various causal networks, we show how environmental covariates can both obscure and exaggerate the effects of human disturbance on individual metrics. We then examine from a causal interpretation standpoint the common practice of adjusting ecological metrics for environmental influences using only the set of sites deemed to be in reference condition. We present and examine the performance of an alternative approach to metric adjustment that uses the whole set of sites and models both environmental and human disturbance effects simultaneously. The findings from our analyses indicate that failing to model and adjust metrics can result in a systematic bias towards those metrics in which environmental covariates function to artificially strengthen the metric–disturbance relationship resulting in MMIs that do not accurately measure impacts of human disturbance. We also find that a “whole-set modeling approach” requires fewer assumptions and is more efficient with the given information than the more commonly applied “reference-set” approach.

Pathogenesis of Hepatic Encephalopathy

PubMed Central

Ciećko-Michalska, Irena; Szczepanek, Małgorzata; Słowik, Agnieszka; Mach, Tomasz

2012-01-01

Hepatic encephalopathy can be a serious complication of acute liver failure and chronic liver diseases, predominantly liver cirrhosis. Hyperammonemia plays the most important role in the pathogenesis of hepatic encephalopathy. The brain-blood barrier disturbances, changes in neurotransmission, neuroinflammation, oxidative stress, GABA-ergic or benzodiazepine pathway abnormalities, manganese neurotoxicity, brain energetic disturbances, and brain blood flow abnormalities are considered to be involved in the development of hepatic encephalopathy. The influence of small intestine bacterial overgrowth (SIBO) on the induction of minimal hepatic encephalopathy is recently emphasized. The aim of this paper is to present the current views on the pathogenesis of hepatic encephalopathy. PMID:23316223

Quickly Removable Valve

NASA Technical Reports Server (NTRS)

Robbins, John S.

1988-01-01

Unit removed with minimal disturbance. Valve inlet and outlet ports adjacent to each other on same side of valve body. Ports inserted into special manifold on fluid line. Valve body attached to manifold by four bolts or, alternatively, by toggle clamps. Electromechanical actuator moves in direction parallel to fluid line to open and close valve. When necessary to clean valve, removed simply by opening bolts or toggle clamps. No need to move or separate ports of fluid line. Valve useful where disturbance of fluid line detrimental or where fast maintenance essential - in oil and chemical industries, automotive vehicles, aircraft, and powerplants.

Ecological Catastrophes and Disturbance Relicts: A Case Study from Easter Island

NASA Astrophysics Data System (ADS)

Wynne, J.

2014-12-01

Caves are often considered buffered environments in terms of their ability to sustain near constant microclimatic conditions. However, environments within cave entrances are expected to respond most quickly to changing surface conditions. We cataloged a relict assemblage of at least 10 endemic arthropods likely restricted to caves and occurring primarily within cave entranceways. Of these animals, eight were considered new undescribed species. These endemic arthropods have persisted in Rapa Nui (Easter Island) caves despite a catastrophic ecological shift induced by island-wide deforestation, fire intolerance, and drought, as well as intensive livestock grazing and surface ecosystems dominated by invasive species. We consider these animals to be "disturbance relicts" - species whose distributions are now limited to areas that experienced minimal human disturbance historically. Today, these species represent one-third of the Rapa Nui's known endemic arthropods. Given the island's severely depauperate native fauna, these arthropods should be considered among the highest priority targets for biological conservation. In other regions globally, epigean examples of imperiled disturbance relicts persisting within narrow distributional ranges have been documented. As human activity intensifies, and habitat loss and fragmentation continues worldwide, additional disturbance relicts will be identified. We expect extinction debts, global climate change and interactions with invasive species will challenge the persistence of both hypogean and epigean disturbance relict species.

Physically disturbed deep-sea macrofauna in the Peru Basin, southeast Pacific, revisited 7 years after the experimental impact

NASA Astrophysics Data System (ADS)

Borowski, Christian

Long-term disturbance effects of a physical disturbance experiment on the benthic macrofauna (>500 μm), with particular emphasis on the dominant Polychaeta, were investigated in connection with the German ATESEPP joint programme in 4150 m depth in the Peru Basin of the tropical southeast (SE) Pacific. The study site was the 10.8 km 2 experimental field of the disturbance and re colonization experiment (DISCOL) conducted in early 1989. This programme had the objective to simulate some of the potential disturbance effects of manganese nodule mining on the bottom-dwelling biota with a towed "plough-harrow" disturber, and subsequently to investigate the resultant community responses with three post-impact samplings during a period of 3 years. Seven years after disturbance, in early 1996, the DISCOL site was revisited, and this study focuses on temporal development of the macrofauna over that extended period. Box core samples obtained during all post-impact expeditions from the disturber tracks ( disturbed treatment) were compared with unploughed sediments from the experimental field ( undisturbed treatment) and with samples from unimpacted sites of the surrounding ( reference treatment). The experiment did not cause the disastrous long-term community changes in the sediment dwelling macrofauna that previously were predicted to follow large-scale disturbances. Abundance recoveries of the macrofaunal taxa were largely terminated after 7 years. Major differences in the faunal compositions at the selected taxonomic levels of higher macrofauna taxa, polychaete families and polychaete species between disturbed and control sites were not observed, but certain disturbance effects remained present over the entire 7-year period: Within-treatment data heterogeneity for the higher macrofauna taxa and the polychaete families was greater in the disturber track samples than in undisturbed and reference treatments. Enhanced heterogeneity was expressed by significantly steeper regression slopes of variance-to-mean ratios of faunal abundances ( p<0.05) and enhanced spatial aggregation at the levels of higher macrofauna taxa and polychaete families. Hurlbert rarefaction E( Sn) and Shannon's diversity index H' calculated in non-standard ways for polychaete species revealed that patterns of diminished "diversity" in the disturbed treatments, which were observed during the later DISCOL period, were still present after 7 years, although the intensity of this signal became weaker. Recent abundance differences between treatments for the Bivalvia, Cumacea and the sigalionid polychaete species Leanira sp. A suggested that unploughed areas from the experimental field possibly were also affected by subtle long-term influences of particle plume settlement caused by the disturber action. A brief comparison with macrofauna abundance data from other ATESEPP sample locations in the Peru Basin revealed highest similarity between the sites located in the manganese nodule province, suggesting that similar disturbance effects can be expected for these areas. Nevertheless, the experimental impact by far did not reach industrial mining impact dimensions and interpretation of the results with regard to commercial mining requires caution.

Cadence Tracking and Disturbance Rejection in Functional Electrical Stimulation Cycling for Paraplegic Subjects: A Case Study.

PubMed

Fonseca, Lucas O da; Bó, Antônio P L; Guimarães, Juliana A; Gutierrez, Miguel E; Fachin-Martins, Emerson

2017-11-01

Functional electrical stimulation cycling has been proposed as an assistive technology with numerous health and fitness benefits for people with spinal cord injury, such as improvement in cardiovascular function, increase in muscular mass, and reduction of bone mass loss. However, some limitations, for example, lack of optimal control strategies that would delay fatigue, may still prevent this technology from achieving its full potential. In this work, we performed experiments on a person with complete spinal cord injury using a stationary tadpole trike when both cadence tracking and disturbance rejection were evaluated. In addition, two sets of experiments were conducted 6 months apart and considering activation of different muscles. The results showed that reference tracking is achieved above the cadence of 25 rpm with mean absolute errors between 1.9 and 10% when only quadriceps are activated. The disturbance test revealed that interferences may drop the cadence but do not interrupt a continuous movement if the cadence does not drop below 25 rpm, again when only quadriceps are activated. When other muscle groups were added, strong spasticity caused larger errors on reference tracking, but not when a disturbance was applied. In addition, spasticity caused the last experiments to result in less smooth cycling. © 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Assessment and mitigation of power quality problems for PUSPATI TRIGA Reactor (RTP)

NASA Astrophysics Data System (ADS)

Zakaria, Mohd Fazli; Ramachandaramurthy, Vigna K.

2017-01-01

An electrical power systems are exposed to different types of power quality disturbances. Investigation and monitoring of power quality are necessary to maintain accurate operation of sensitive equipment especially for nuclear installations. This paper will discuss the power quality problems observed at the electrical sources of PUSPATI TRIGA Reactor (RTP). Assessment of power quality requires the identification of any anomalous behavior on a power system, which adversely affects the normal operation of electrical or electronic equipment. A power quality assessment involves gathering data resources; analyzing the data (with reference to power quality standards) then, if problems exist, recommendation of mitigation techniques must be considered. Field power quality data is collected by power quality recorder and analyzed with reference to power quality standards. Normally the electrical power is supplied to the RTP via two sources in order to keep a good reliability where each of them is designed to carry the full load. The assessment of power quality during reactor operation was performed for both electrical sources. There were several disturbances such as voltage harmonics and flicker that exceeded the thresholds. To reduce these disturbances, mitigation techniques have been proposed, such as to install passive harmonic filters to reduce harmonic distortion, dynamic voltage restorer (DVR) to reduce voltage disturbances and isolate all sensitive and critical loads.

Secondary School Education in Assam (India) with Special Reference to Mathematics

ERIC Educational Resources Information Center

Das, N. R.; Baruah, Karuna

2010-01-01

This paper describes the prevailing academic scenarios of a representative group of secondary schools in Assam (India) with special references to students performance in general and mathematics performance in particular. The state of Assam is one of the economically backward regions of India and is witnessing socio-political disturbances mainly…

Reference conditions for silvicultural field studies in Maine: limitations and opportunities

Treesearch

Laura S. Kenefic; Alan S. White; Shawn Fraver

2004-01-01

There are many types of controls or reference conditions for silvicultural experiments. The most basic are pretreatment records of composition and structure, but such data provide little information about response to treatment compared to natural developmental and disturbance patterns. Ideally, experiments should have untreated stand replicates in which development can...

32 CFR Appendix H to Part 623 - References

Code of Federal Regulations, 2011 CFR

2011-07-01

...-50Civil Disturbances. AR 500-60Disaster Relief. AR 500-70Military Support of Civil Defense. AR 525... 32 National Defense 3 2011-07-01 2009-07-01 true References H Appendix H to Part 623 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY SUPPLIES AND EQUIPMENT LOAN OF ARMY...

Inflatable bladder provides accurate calibration of pressure switch

NASA Technical Reports Server (NTRS)

Smith, N. J.

1965-01-01

Calibration of a pressure switch is accurately checked by a thin-walled circular bladder. It is placed in the pressure switch and applies force to the switch diaphragm when expanded by an external pressure source. The disturbance to the normal operation of the switch is minimal.

Minimizing soil impacts from forest operations

Treesearch

Emily A. Carter

2011-01-01

Several studies were conducted by Forest Service researchers and University and Industrial collaborators that investigated the potential for lessening soil surface disturbances and compaction in forest operations through modifications of machine components or harvest systems. Specific machine modifications included change in tire size, use of dual tire systems,...

Synchronicity of long-term nitrate patterns in forested catchments across the northeastern U.S.

EPA Science Inventory

Nitrogen movement through minimally-disturbed catchments can be affected by a variety of biogeochemical processes, climatic effects, hydrology and in-stream or in-lake processes. These combine to create dizzying complexity in long-term and seasonal nitrate patterns, with adjacen...

30 CFR 816.41 - Hydrologic-balance protection.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Hydrologic-balance protection. 816.41 Section... ACTIVITIES § 816.41 Hydrologic-balance protection. (a) General. All surface mining and reclamation activities shall be conducted to minimize disturbance of the hydrologic balance within the permit and adjacent...

30 CFR 816.41 - Hydrologic-balance protection.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Hydrologic-balance protection. 816.41 Section... ACTIVITIES § 816.41 Hydrologic-balance protection. (a) General. All surface mining and reclamation activities shall be conducted to minimize disturbance of the hydrologic balance within the permit and adjacent...

Environmental Assessment for Clean and Stabilize Ditches at the Golf Course and C Street

DTIC Science & Technology

2003-08-01

proposed action would require the disturbance of installation property, minimal decrease in storm water quality during the cleaning and a temporary...increase in noise levels during construction. Storm water quality would improve following the cleaning and stabilization. Erosion and sediment controls

Some anomalies between wind tunnel and flight transition results

NASA Technical Reports Server (NTRS)

Harvey, W. D.; Bobbitt, P. J.

1981-01-01

A review of environmental disturbance influence and boundary layer transition measurements on a large collection of reference sharp cone tests in wind tunnels and of recent transonic-supersonic cone flight results have previously demonstrated the dominance of free-stream disturbance level on the transition process from the beginning to end. Variation of the ratio of transition Reynolds number at onset-to-end with Mach number has been shown to be consistently different between flight and wind tunnels. Previous correlations of the end of transition with disturbance level give good results for flight and large number of tunnels, however, anomalies occur for similar correlation based on transition onset. Present cone results with a tunnel sonic throat reduced the disturbance level by an order of magnitude with transition values comparable to flight.

Ellipsoidal Harmonic Vertical Deflections. Global and Regional Modeling of The Horizontal Derivative of The Terrestrial Garvity Field

NASA Astrophysics Data System (ADS)

Grafarend, E. W.; Ardalan, A.; Finn, G.

In terms of elliptic coordinates of Jacobi type (longitude, latitude, semi-minor axis) the horizontal derivative is computed as a linear operator acting on an ellipsoidal har- monic disturbing/incremental gravitational potential. Such disturbing potential is de- fined with respect to the Somigliana-Pizzetti Reference Potential, the potential field of a level ellipsoid, and the International Reference Ellipsoid/WGS84 or World Geode- tic Datum 2000/WGD2000. Case studies of those vertical deflections on a global as well as regional scale are presented which take advantage of SEGEN (Special Ellipsoidal Gravity Earth Normal: ellipsoidal harmonics expansion 130321 coeffi- cients: http://www.uni-stuttgart.de/gi/research/paper/coefficients/coefficients.zip) and of CENT (precise centrifugal potential)

Detecting significant change in stream benthic macroinvertebrate communities in wilderness areas

USGS Publications Warehouse

Milner, Alexander M.; Woodward, Andrea; Freilich, Jerome E.; Black, Robert W.; Resh, Vincent H.

2016-01-01

Within a region, both MDS analyses typically identified similar years as exceeding reference condition variation, illustrating the utility of the approach for identifying wider spatial scale effects that influence more than one stream. MDS responded to both simulated water temperature stress and a pollutant event, and generally outlying years on MDS plots could be explained by environmental variables, particularly higher precipitation. Multivariate control charts successfully identified whether shifts in community structure identified by MDS were significant and whether the shift represented a press disturbance (long-term change) or a pulse disturbance. We consider a combination of TD and MDS with control charts to be a potentially powerful tool for determining years significantly outside of a reference condition variation.

Adaptive nonlinear control for autonomous ground vehicles

NASA Astrophysics Data System (ADS)

Black, William S.

We present the background and motivation for ground vehicle autonomy, and focus on uses for space-exploration. Using a simple design example of an autonomous ground vehicle we derive the equations of motion. After providing the mathematical background for nonlinear systems and control we present two common methods for exactly linearizing nonlinear systems, feedback linearization and backstepping. We use these in combination with three adaptive control methods: model reference adaptive control, adaptive sliding mode control, and extremum-seeking model reference adaptive control. We show the performances of each combination through several simulation results. We then consider disturbances in the system, and design nonlinear disturbance observers for both single-input-single-output and multi-input-multi-output systems. Finally, we show the performance of these observers with simulation results.

Designing a Hybrid Laminar-Flow Control Experiment: The CFD-Experiment Connection

NASA Technical Reports Server (NTRS)

Streett, C. L.

2003-01-01

The NASA/Boeing hybrid laminar flow control (HLFC) experiment, designed during 1993-1994 and conducted in the NASA LaRC 8-foot Transonic Pressure Tunnel in 1995, utilized computational fluid dynamics and numerical simulation of complex fluid mechanics to an unprecedented extent for the design of the test article and measurement equipment. CFD was used in: the design of the test wing, which was carried from definition of desired disturbance growth characteristics, through to the final airfoil shape that would produce those growth characteristics; the design of the suction-surface perforation pattern that produced enhanced crossflow-disturbance growth: and in the design of the hot-wire traverse system that produced minimal influence on measured disturbance growth. These and other aspects of the design of the test are discussed, after the historical and technical context of the experiment is described.

Intermittent fasting is neuroprotective in focal cerebral ischemia by minimizing autophagic flux disturbance and inhibiting apoptosis.

PubMed

Jeong, Ji Heun; Yu, Kwang Sik; Bak, Dong Ho; Lee, Je Hun; Lee, Nam Seob; Jeong, Young Gil; Kim, Dong Kwan; Kim, Jwa-Jin; Han, Seung-Yun

2016-11-01

Previous studies have demonstrated that autophagy induced by caloric restriction (CR) is neuroprotective against cerebral ischemia. However, it has not been determined whether intermittent fasting (IF), a variation of CR, can exert autophagy-related neuroprotection against cerebral ischemia. Therefore, the neuroprotective effect of IF was evaluated over the course of two weeks in a rat model of focal cerebral ischemia, which was induced by middle cerebral artery occlusion and reperfusion (MCAO/R). Specifically, the role of autophagy modulation as a potential underlying mechanism for this phenomenon was investigated. It was demonstrated that IF reduced infarct volume and brain edema, improved neurobehavioral deficits, and rescued neuronal loss after MCAO/R. Furthermore, neuronal apoptosis was decreased by IF in the rat cortex. An increase in the number of autophagosomes (APs) was demonstrated in the cortices of IF-treated rats, using immunofluorescence staining and transmission electron microscopy. Using immunoblots, an IF-induced increase was detected in microtubule-associated protein 1 light chain 3 (LC3)-II, Rab7, and cathepsin D protein levels, which corroborated previous morphological studies. Notably, IF reduced the accumulation of APs and p62, demonstrating that IF attenuated the MCAO/R-induced disturbance of autophagic flux in neurons. The findings of the present study suggest that IF-induced neuroprotection in focal cerebral ischemia is due, at least in part, to the minimization of autophagic flux disturbance and inhibition of apoptosis.

Attractive Flicker--Guiding Attention in Dynamic Narrative Visualizations.

PubMed

Waldner, Manuela; Le Muzic, Mathieu; Bernhard, Matthias; Purgathofer, Werner; Viola, Ivan

2014-12-01

Focus+context techniques provide visual guidance in visualizations by giving strong visual prominence to elements of interest while the context is suppressed. However, finding a visual feature to enhance for the focus to pop out from its context in a large dynamic scene, while leading to minimal visual deformation and subjective disturbance, is challenging. This paper proposes Attractive Flicker, a novel technique for visual guidance in dynamic narrative visualizations. We first show that flicker is a strong visual attractor in the entire visual field, without distorting, suppressing, or adding any scene elements. The novel aspect of our Attractive Flicker technique is that it consists of two signal stages: The first "orientation stage" is a short but intensive flicker stimulus to attract the attention to elements of interest. Subsequently, the intensive flicker is reduced to a minimally disturbing luminance oscillation ("engagement stage") as visual support to keep track of the focus elements. To find a good trade-off between attraction effectiveness and subjective annoyance caused by flicker, we conducted two perceptual studies to find suitable signal parameters. We showcase Attractive Flicker with the parameters obtained from the perceptual statistics in a study of molecular interactions. With Attractive Flicker, users were able to easily follow the narrative of the visualization on a large display, while the flickering of focus elements was not disturbing when observing the context.

Influence of free-stream disturbances on boundary-layer transition

NASA Technical Reports Server (NTRS)

Harvey, W. D.

1978-01-01

Considerable experimental evidence exists which shows that free stream disturbances (the ratio of root-mean-square pressure fluctuations to mean values) in conventional wind tunnels increase with increasing Mach number at low supersonic to moderate hypersonic speeds. In addition to local conditions, the free stream disturbance level influences transition behavior on simple test models. Based on this observation, existing noise transition data obtained in the same test facility were correlated for a large number of reference sharp cones and flat plates and are shown to collapse along a single curve. This result is a significant improvement over previous attempts to correlate noise transition data.

Self-disturbance and schizophrenia: structure, specificity, pathogenesis (Current issues, New directions).

PubMed

Sass, Louis A

2014-01-01

This paper offers an overview and clarification of the ipseity-disturbance or self-disorder hypothesis regarding schizophrenia, with focus on some recent and recommended research and theoretical refinements. There is need to expand research and theorizing in several directions-in order to: 1, specify more precisely what is truly distinctive in the schizophrenia spectrum, 2, explore internal structure and explanatory potential of this purported disturbance of minimal- or core-self experience, 3, generate testable hypotheses concerning pathogenetic pathways and psychotherapeutic interventions. Comparative studies can make a crucial scientific contribution. Some recent, exploratory studies are described: published reports were examined for alterations of self-experience in conditions outside the schizophrenia spectrum-mania, psychotic depression, and depersonalization disorder-and in one unusual attitudinal stance: intense introspection (as refined in early 20th century psychological research). Remarkable similarities (e.g., alienation/reification of thoughts and bodily experiences, fading of self and world) as well as some important differences (e.g., absence, outside schizophrenia, of severe erosion of minimal self-experience or real confusion of self and other) in types of self-anomalies were found. These support but also refine the ipseity-disturbance model. Future research should treat self-experience as an independent variable, manipulating and measuring this dimension (in both schizophrenic and non-schizophrenic populations) to study its associations with anomalies of cognition, affect, expression, and neural functioning already identified in schizophrenia. The self-disorder model offers an integrative and dynamic view of schizophrenia congruent with recent trends in cognitive neuroscience and consistent with the heterogeneous, varying, and holistic nature of this enigmatic illness. Copyright © 2013. Published by Elsevier B.V.

Evaluation of Utah trefoil collections for rangeland restoration in the southern Great Basin

USDA-ARS?s Scientific Manuscript database

Wildfires, weed invasion, and various other land disturbances are common in rangeland ecosystems of the Intermountain Region in the western U.S. Revegetation/restoration may be required on many of these rangelands to improve degraded conditions, speed recovery, and minimize soil erosion. Legumes n...

30 CFR 717.17 - Protection of the hydrologic system.

Code of Federal Regulations, 2011 CFR

2011-07-01

... the location of surface water drainage channels shall be minimized and applicable Federal and State... quick growing stands of temporary vegetation, and lining drainage channels. If treatment is required to... disturbed areas that have met the requirements of § 717.20 shall be passed through a sedimentation pond or a...

30 CFR 817.97 - Protection of fish, wildlife, and related environmental values.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 3 2012-07-01 2012-07-01 false Protection of fish, wildlife, and related... STANDARDS-UNDERGROUND MINING ACTIVITIES § 817.97 Protection of fish, wildlife, and related environmental..., minimize disturbances and adverse impacts on fish, wildlife, and related environmental values and shall...

30 CFR 816.97 - Protection of fish, wildlife, and related environmental values.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Protection of fish, wildlife, and related... STANDARDS-SURFACE MINING ACTIVITIES § 816.97 Protection of fish, wildlife, and related environmental values..., minimize disturbances and adverse impacts on fish, wildlife, and related environmental values and shall...

30 CFR 816.97 - Protection of fish, wildlife, and related environmental values.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 3 2014-07-01 2014-07-01 false Protection of fish, wildlife, and related... STANDARDS-SURFACE MINING ACTIVITIES § 816.97 Protection of fish, wildlife, and related environmental values..., minimize disturbances and adverse impacts on fish, wildlife, and related environmental values and shall...

30 CFR 817.97 - Protection of fish, wildlife, and related environmental values.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 3 2014-07-01 2014-07-01 false Protection of fish, wildlife, and related... STANDARDS-UNDERGROUND MINING ACTIVITIES § 817.97 Protection of fish, wildlife, and related environmental..., minimize disturbances and adverse impacts on fish, wildlife, and related environmental values and shall...

30 CFR 816.97 - Protection of fish, wildlife, and related environmental values.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 3 2012-07-01 2012-07-01 false Protection of fish, wildlife, and related... STANDARDS-SURFACE MINING ACTIVITIES § 816.97 Protection of fish, wildlife, and related environmental values..., minimize disturbances and adverse impacts on fish, wildlife, and related environmental values and shall...

30 CFR 817.97 - Protection of fish, wildlife, and related environmental values.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Protection of fish, wildlife, and related... STANDARDS-UNDERGROUND MINING ACTIVITIES § 817.97 Protection of fish, wildlife, and related environmental..., minimize disturbances and adverse impacts on fish, wildlife, and related environmental values and shall...

30 CFR 819.15 - Auger mining: Hydrologic balance.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Auger mining: Hydrologic balance. 819.15... MINING § 819.15 Auger mining: Hydrologic balance. (a) Auger mining shall be planned and conducted to minimize disturbances of the prevailing hydrologic balance in accordance with the requirements of §§ 816.41...

30 CFR 819.15 - Auger mining: Hydrologic balance.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Auger mining: Hydrologic balance. 819.15... MINING § 819.15 Auger mining: Hydrologic balance. (a) Auger mining shall be planned and conducted to minimize disturbances of the prevailing hydrologic balance in accordance with the requirements of §§ 816.41...

Modeling Geomagnetically Induced Currents From Magnetometer Measurements: Spatial Scale Assessed With Reference Measurements

NASA Astrophysics Data System (ADS)

Butala, Mark D.; Kazerooni, Maryam; Makela, Jonathan J.; Kamalabadi, Farzad; Gannon, Jennifer L.; Zhu, Hao; Overbye, Thomas J.

2017-10-01

Solar-driven disturbances generate geomagnetically induced currents (GICs) that can result in power grid instability and, in the most extreme cases, even failure. Magnetometers provide direct measurements of the geomagnetic disturbance (GMD) effect on the surface magnetic field and GIC response can be determined from the power grid topology and engineering parameters. This paper considers this chain of models: transforming surface magnetic field disturbance to induced surface electric field through an electromagnetic transfer function and, then, induced surface electric field to GIC using the PowerWorld simulator to model a realistic power grid topology. Comparisons are made to transformer neutral current reference measurements provided by the American Transmission Company. Three GMD intervals are studied, with the Kp index reaching 8- on 2 October 2013, 7 on 1 June 2013, and 6- on 9 October 2013. Ultimately, modeled to measured GIC correlations are analyzed as a function of magnetometer to GIC sensor distance. Results indicate that modeling fidelity during the three studied GMD intervals is strongly dependent on both magnetometer to substation transformer baseline distance and GMD intensity.

Ranitidine-Associated Sleep Disturbance: Case Report and Review of H2 Antihistamine-Related Central Nervous System Adverse Effects.

PubMed

Werbel, Tyler; Cohen, Philip R

2018-04-03

Ranitidine is an H2 antihistamine used as an off-label therapy for recalcitrant verruca vulgaris. We describe a man who developed a sleep disturbance after initiating therapy with ranitidine and review similar adverse effects associated with other drugs in this class. The patient was a 40-year-old man with an eight-year history of a wart on his right plantar foot that was recalcitrant to several topical therapies. Adjunctive treatment with ranitidine 150 mg twice daily was initiated. He developed sleep disturbance with bizarre dreams and gastrointestinal symptoms. All symptoms resolved after discontinuation of the medication and recurred when he restarted the drug. PubMed was searched for the following terms: disturbance, dream, ranitidine, verruca, wart, and Zantac. The papers containing these terms and their references were reviewed. Sleep disturbance caused by ranitidine is an uncommon adverse event in patients receiving the drug. However, similar reactions have been observed with other H2 antihistamines such as cimetidine and famotidine. Clinicians should be aware that sleep disturbance secondary to ranitidine is a potential side effect of this medication.

Feral swine disturbance at important archaeological sites.

PubMed

Engeman, Richard M; Couturier, Kathy J; Felix, Rodney K; Avery, Michael L

2013-06-01

Feral swine are well known as environmentally destructive invasive animals in many areas around the world, where they degrade native habitats, harm rare plant and animal species, damage agricultural interests, and spread disease. We provide the first quantification of their potential as agents of disturbance at archaeological sites. Our study was conducted in south-central Florida at Avon Park Air Force Range, a base comprising over 40,000 ha and containing many archaeological sites. To determine the identifiable prevalence of feral swine disturbance, we examined 36 sites registered with the Florida State Historic Preservation Office and also eligible for inclusion in the National Register of Historic Places (NRHP). Moreover, we evaluated the extent of swine disturbance at a prehistoric site of extraordinary significance to Florida's prehistory, "Dead Cow." Fifteen of the 36 NRHP-eligible sites (42 %) had some level of swine disturbance, including 14 of 30 (47 %) sites known to have artifacts within 20 cm of the surface (well within swine rooting depths). At the Dead Cow site, we documented disturbance at 74 % of shovel test points. Sites with shallow artifact depositions appeared highly vulnerable to disturbance by feral swine, threatening destruction of artifact stratigraphy and provenience. Our observations likely are a minimal representation of accumulated damage. These irreplaceable sites tell the area's land use story across the millennia. That they are under threat from feral swine should serve broad notice of potential threats that feral swine may pose to archaeological sites globally, making effective swine management imperative for site protection.

Singular and interactive effects of blowdown, salvage logging, and wildfire in sub-boreal pine systems

USGS Publications Warehouse

D'Amato, A.W.; Fraver, S.; Palik, B.J.; Bradford, J.B.; Patty, L.

2011-01-01

The role of disturbance in structuring vegetation is widely recognized; however, we are only beginning to understand the effects of multiple interacting disturbances on ecosystem recovery and development. Of particular interest is the impact of post-disturbance management interventions, particularly in light of the global controversy surrounding the effects of salvage logging on forest ecosystem recovery. Studies of salvage logging impacts have focused on the effects of post-disturbance salvage logging within the context of a single natural disturbance event. There have been no formal evaluations of how these effects may differ when followed in short sequence by a second, high severity natural disturbance. To evaluate the impact of this management practice within the context of multiple disturbances, we examined the structural and woody plant community responses of sub-boreal Pinus banksiana systems to a rapid sequence of disturbances. Specifically, we compared responses to Blowdown (B), Fire (F), Blowdown-Fire, and Blowdown-Salvage-Fire (BSF) and compared these to undisturbed control (C) stands. Comparisons between BF and BSF indicated that the primary effect of salvage logging was a decrease in the abundance of structural legacies, such as downed woody debris and snags. Both of these compound disturbance sequences (BF and BSF), resulted in similar woody plant communities, largely dominated by Populus tremuloides; however, there was greater homogeneity in community composition in salvage logged areas. Areas experiencing solely fire (F stands) were dominated by P. banksiana regeneration, and blowdown areas (B stands) were largely characterized by regeneration from shade tolerant conifer species. Our results suggest that salvage logging impacts on woody plant communities are diminished when followed by a second high severity disturbance; however, impacts on structural legacies persist. Provisions for the retention of snags, downed logs, and surviving trees as part of salvage logging operations will minimize these structural impacts and may allow for greater ecosystem recovery following these disturbance combinations. ?? 2011 Elsevier B.V.

Effect of local magnetic field disturbances on inertial measurement units accuracy.

PubMed

Robert-Lachaine, Xavier; Mecheri, Hakim; Larue, Christian; Plamondon, André

2017-09-01

Inertial measurement units (IMUs), a practical motion analysis technology for field acquisition, have magnetometers to improve segment orientation estimation. However, sensitivity to magnetic disturbances can affect their accuracy. The objective of this study was to determine the joint angles accuracy of IMUs under different timing of magnetic disturbances of various durations and to evaluate a few correction methods. Kinematics from 12 individuals were obtained simultaneously with an Xsens system where an Optotrak cluster acting as the reference system was affixed to each IMU. A handling task was executed under normal laboratory conditions and imposed magnetic disturbances. Joint angle RMSE was used to conduct a three-way repeated measures analysis of variance in order to contrast the following disturbance factors: duration (0, 30, 60, 120 and 240 s), timing (during the disturbance, directly after it and a 30-second delay after it) and axis (X, Y and Z). The highest joint angle RMSE was observed on rotations about the Y longitudinal axis and during the longer disturbances. It stayed high directly after a disturbance, but returned close to baseline after a 30-second delay. When magnetic disturbances are experienced, waiting 30 s in a normal condition is recommended as a way to restore the IMUs' initial accuracy. The correction methods performed modestly or poorly in the reduction of joint angle RMSE. Copyright © 2017 Elsevier Ltd. All rights reserved.

Genetics Home Reference: fibromyalgia

MedlinePlus

... other catastrophic events, and low job or life satisfaction have also been associated with an increased risk of fibromyalgia . Additionally, physical inactivity, obesity, and sleep disturbances seem to increase risk. However, ... & ...

Toward blind removal of unwanted sound from orchestrated music

NASA Astrophysics Data System (ADS)

Chang, Soo-Young; Chun, Joohwan

2000-11-01

The problem addressed in this paper is to removing unwanted sounds from music sound. The sound to be removed could be disturbance such as cough. We shall present some preliminary results on this problem using statistical properties of signals. Our approach consists of three steps. We first estimate the fundamental frequencies and partials given noise-corrupted music sound. This gives us the autoregressive (AR) model of the music sound. Then we filter the noise-corrupted sound using the AR parameters. The filtered signal is then subtracted from the original noise-corrupted signal to get the disturbance. Finally, the obtained disturbance is used a reference signal to eliminate the disturbance from the noise- corrupted music signal. Above three steps are carried out in a recursive manner using a sliding window or an infinitely growing window with an appropriate forgetting factor.

Disturbance of eelgrass Zostera marina by commercial mussel Mytilus edulis harvesting in Maine: Dragging impacts and habitat recovery

USGS Publications Warehouse

Neckles, Hilary A.; Short, Frederick T.; Barker, Seth; Kopp, Blaine S.

2005-01-01

We studied the effects of commercial harvest of blue mussels Mytilus edulis on eelgrass Zostera marina L. in Maquoit Bay, Maine, USA, at a hierarchy of scales. We used aerial photography, underwater video, and eelgrass population- and shoot-based measurements to quantify dragging impacts within 4 sites that had been disturbed at different times over an approximate 7 yr interval, and to project eelgrass meadow recovery rates. Dragging had disturbed 10% of the eelgrass cover in Maquoit Bay, with dragged sites ranging from 3.4 to 31.8 ha in size. Dragging removed above- and belowground plant material from the majority of the bottom in the disturbed sites. One year following dragging, eelgrass shoot density, shoot height and total biomass of disturbed sites averaged respectively 2 to 3%, 46 to 61% and <1% that of the reference sites. Substantial differences in eelgrass biomass persisted between disturbed and reference sites up to 7 yr after dragging. Dragging did not affect physical characteristics of the sediment. The pattern and rate of eelgrass bed recovery depended strongly on initial dragging intensity; areas of relatively light dragging with many remnant eelgrass patches (i.e. patches that were missed by the mussel dredge) showed considerable revegetation in 1 yr. However, by developing recovery trajectories from measurements at sites disturbed in different years, we projected that it would require a mean of 10.6 yr for recovery of eelgrass shoot density within the areas of intense dragging characterizing most of the disturbed sites. A spatial simulation model based on measured rates of lateral patch-expansion (mean 12.5 cm yr-1) and new-patch recruitment (mean 0.19 patches m-2 yr-1) yielded a mean bed recovery time of 9 to 11 yr following dragging, depending on initial degree of plant removal. Model simulations suggested that with favorable environmental conditions, eelgrass beds might recover from dragging disturbance in 6 yr; conversely, recovery under conditions less conducive to eelgrass growth could require 20 yr or longer. This study shows that mussel dragging poses a severe threat to eelgrass in this region and that regulations to protect eelgrass from dragging impacts would maintain the integrity of a substantial amount of habitat.

Disturbance of eelgrass Zostera marina by commercial mussel Mytilus edulis harvesting in Maine: Dragging impacts and habitat recovery

USGS Publications Warehouse

Neckles, H.A.; Short, F.T.; Barker, S.; Kopp, B.S.

2005-01-01

We studied the effects of commercial harvest of blue mussels Mytilus edulis on eelgrass Zostera marina L. in Maquoit Bay, Maine, USA, at a hierarchy of scales. We used aerial photography, underwater video, and eelgrass population- and shoot-based measurements to quantify dragging impacts within 4 sites that had been disturbed at different times over an approximate 7 yr interval, and to project eelgrass meadow recovery rates. Dragging had disturbed 10% of the eelgrass cover in Maquoit Bay, with dragged sites ranging from 3.4 to 31.8 ha in size. Dragging removed above- and belowground plant material from the majority of the bottom in the disturbed sites. One year following dragging, eelgrass shoot density, shoot height and total biomass of disturbed sites averaged respectively 2 to 3 %, 46 to 61 % and <1 % that of the reference sites. Substantial differences in eelgrass biomass persisted between disturbed and reference sites up to 7 yr after dragging. Dragging did not affect physical characteristics of the sediment. The pattern and rate of eelgrass bed recovery depended strongly on initial dragging intensity; areas of relatively light dragging with many remnant eelgrass patches (i.e. patches that were missed by the mussel dredge) showed considerable revegetation in 1 yr. However, by developing recovery trajectories from measurements at sites disturbed in different years, we projected that it would require a mean of 10.6 yr for recovery of eelgrass shoot density within the areas of intense dragging characterizing most of the disturbed sites. A spatial simulation model based on measured rates of lateral patch-expansion (mean 12.5 cm yr-1) and new-patch recruitment (mean 0.19 patches m-2 yr-1) yielded a mean bed recovery time of 9 to 11 yr following dragging, depending on initial degree of plant removal. Model simulations suggested that with favorable environmental conditions, eelgrass beds might recover from dragging disturbance in 6 yr; conversely, recovery under conditions less conducive to eelgrass growth could require 20 yr or longer. This study shows that mussel dragging poses a severe threat to eelgrass in this region and that regulations to protect eelgrass from dragging impacts would maintain the integrity of a substantial amount of habitat.

Pointing control for LDR

NASA Technical Reports Server (NTRS)

Yam, Y.; Briggs, C.

1988-01-01

One important aspect of the LDR control problem is the possible excitations of structural modes due to random disturbances, mirror chopping, and slewing maneuvers. An analysis was performed to yield a first order estimate of the effects of such dynamic excitations. The analysis involved a study of slewing jitters, chopping jitters, disturbance responses, and pointing errors, making use of a simplified planar LDR model which describes the LDR dynamics on a plane perpendicular to the primary reflector. Briefly, the results indicate that the command slewing profile plays an important role in minimizing the resultant jitter, even to a level acceptable without any control action. An optimal profile should therefore be studied.

Temperate forest health in an era of emerging megadisturbance

USGS Publications Warehouse

Millar, Constance I.; Stephenson, Nathan L.

2015-01-01

Although disturbances such as fire and native insects can contribute to natural dynamics of forest health, exceptional droughts, directly and in combination with other disturbance factors, are pushing some temperate forests beyond thresholds of sustainability. Interactions from increasing temperatures, drought, native insects and pathogens, and uncharacteristically severe wildfire are resulting in forest mortality beyond the levels of 20th-century experience. Additional anthropogenic stressors, such as atmospheric pollution and invasive species, further weaken trees in some regions. Although continuing climate change will likely drive many areas of temperate forest toward large-scale transformations, management actions can help ease transitions and minimize losses of socially valued ecosystem services.

Postural Control Disturbances Produced By Exposure to HMD and Dome Vr Systems

NASA Technical Reports Server (NTRS)

Harm, D. L.; Taylor, L. C.

2005-01-01

Two critical and unresolved human factors issues in VR systems are: 1) potential "cybersickness", a form of motion sickness which is experienced in virtual worlds, and 2) maladaptive sensorimotor performance following exposure to VR systems. Interestingly, these aftereffects are often quite similar to adaptive sensorimotor responses observed in astronauts during and/or following space flight. Most astronauts and cosmonauts experience perceptual and sensorimotor disturbances during and following space flight. All astronauts exhibit decrements in postural control following space flight. It has been suggested that training in virtual reality (VR) may be an effective countermeasure for minimizing perceptual and/or sensorimotor disturbances. People adapt to consistent, sustained alterations of sensory input such as those produced by microgravity, and experimentally-produced stimulus rearrangements (e.g., reversing prisms, magnifying lenses, flight simulators, and VR systems). Adaptation is revealed by aftereffects including perceptual disturbances and sensorimotor control disturbances. The purpose of the current study was to compare disturbances in postural control produced by dome and head-mounted virtual environment displays. Individuals recovered from motion sickness and the detrimental effects of exposure to virtual reality on postural control within one hour. Sickness severity and initial decrements in postural equilibrium decreases over days, which suggests that subjects become dual-adapted over time. These findings provide some direction for developing training schedules for VR users that facilitate adaptation, and address safety concerns about aftereffects.

Temporal Variability of Suspended Sediment Load, Dissolved Load, and Bedload for Two Small Oak Forested Catchments with Contrasting Disturbance Levels in the Lesser Himalaya of North-West India

NASA Astrophysics Data System (ADS)

Qazi, N. U. Q.; Rai, S. P.; Bruijnzeel, L. A.

2014-12-01

Sediment transfer from mountainous areas to lowland areas is one of the most important geomorphological processes globally with the bulk of the sediment yield from such areas typically deriving from mass wastage processes. This study presents monthly, seasonal and annual variations in sediment transport (both suspended load and bed load) as well as dissolved loads over three consecutive water years (2008-2011) for two small forested watersheds with contrasting levels of forest disturbance in the Lesser Himalaya of Northwest India. Seasonal and annual suspended sediment yields were strongly influenced by amounts of rainfall and stream flow and showed a 23-fold range between wet and dry years. Of the annual load, some 92% was produced on average during the monsoon season (June-September). Sediment production by the disturbed forest catchment was 2.6-fold (suspended sediment) to 5.9-fold (bed load) higher than that for the well-stocked forest catchment. By contrast, dissolved loads varied much less between years, seasons (although minimal during the dry summer season), and degree of forest disturbance. Total mechanical denudation rates were 1.2 times and 4.7 times larger than chemical denudation rates for the little disturbed and the heavily disturbed forest catchment, respectively whereas overall denudation rates were estimated at 0.59 and 1.05 mm per 1000 years, respectively.

Spatial vision within egocentric and exocentric frames of reference

NASA Technical Reports Server (NTRS)

Howard, Ian P.

1989-01-01

The extent to which perceptual judgements within egocentric and exocentric frames of reference are subject to illusory disturbances and long term modifications is discussed. It is argued that well known spatial illusions, such as the oculogyral illusion and induced visual motion have usually been discussed without proper attention being paid to the frame of reference within which they occur, and that this has led to the construction of inadequate theories and inappropriate procedures for testing them.

Correction of Proton Resonance Frequency Shift Temperature Maps for Magnetic Field Disturbances Caused by Breathing

NASA Astrophysics Data System (ADS)

Shmatukha, Andriy V.; Bakker, Chris J. G.

2006-05-01

Respiratory Induced Resonance Offset (RIRO) is a periodic disturbance of the magnetic field due to breathing. Such disturbances handicap the accuracy of the Proton Resonance Frequency Shift (PRFS) method of MRI temperature mapping in anatomies situated nearby the lungs and chest wall. In this work, we propose a method capable of minimizing errors caused by RIRO in PRFS temperature maps. In this method, a set of baseline images characterizing RIRO at a variety of respiratory cycle instants is acquired before the thermal treatment starts. During the treatment, the temperature evolution is found from two successive images. Then, the calculated temperature changes are corrected for the additional contribution caused by RIRO using the pre-treatment baseline images acquired at the identical instances of the respiratory cycle. Our method is shown to improve the accuracy and stability of PRFS temperature maps in the presence of RIRO and motion in phantom and volunteer experiments.

Numerical evaluation of surface modifications at landing site due to spacecraft (soft) landing on the moon

NASA Astrophysics Data System (ADS)

Mishra, Sanjeev Kumar; Prasad, K. Durga

2018-07-01

Understanding surface modifications at landing site during spacecraft landing on planetary surfaces is important for planetary missions from scientific as well as engineering perspectives. An attempt has been made in this work to numerically investigate the disturbance caused to the lunar surface during soft landing. The variability of eject velocity of dust, eject mass flux rate, ejecta amount etc. has been studied. The effect of lander hovering time and hovering altitude on the extent of disturbance is also evaluated. The study thus carried out will help us in understanding the surface modifications during landing thereby making it easier to plan a descent trajectory that minimizes the extent of disturbance. The information about the extent of damage will also be helpful in interpreting the data obtained from experiments carried on the lunar surface in vicinity of the lander.

Precursor of transition to turbulence: spatiotemporal wave front.

PubMed

Bhaumik, S; Sengupta, T K

2014-04-01

To understand transition to turbulence via 3D disturbance growth, we report here results obtained from the solution of Navier-Stokes equation (NSE) to reproduce experimental results obtained by minimizing background disturbances and imposing deterministic excitation inside the shear layer. A similar approach was adopted in Sengupta and Bhaumik [Phys. Rev. Lett. 107, 154501 (2011)], where a route of transition from receptivity to fully developed turbulent stage was explained for 2D flow in terms of the spatio-temporal wave-front (STWF). The STWF was identified as the unit process of 2D turbulence creation for low amplitude wall excitation. Theoretical prediction of STWF for boundary layer was established earlier in Sengupta, Rao, and Venkatasubbaiah [Phys. Rev. Lett. 96, 224504 (2006)] from the Orr-Sommerfeld equation as due to spatiotemporal instability. Here, the same unit process of the STWF during transition is shown to be present for 3D disturbance field from the solution of governing NSE.

H∞ output tracking control of discrete-time nonlinear systems via standard neural network models.

PubMed

Liu, Meiqin; Zhang, Senlin; Chen, Haiyang; Sheng, Weihua

2014-10-01

This brief proposes an output tracking control for a class of discrete-time nonlinear systems with disturbances. A standard neural network model is used to represent discrete-time nonlinear systems whose nonlinearity satisfies the sector conditions. H∞ control performance for the closed-loop system including the standard neural network model, the reference model, and state feedback controller is analyzed using Lyapunov-Krasovskii stability theorem and linear matrix inequality (LMI) approach. The H∞ controller, of which the parameters are obtained by solving LMIs, guarantees that the output of the closed-loop system closely tracks the output of a given reference model well, and reduces the influence of disturbances on the tracking error. Three numerical examples are provided to show the effectiveness of the proposed H∞ output tracking design approach.

Electro-encephalographic disturbances due to chronic toxin abuse in young people, with special reference to glue-sniffing.

PubMed

Griesel, R D; Jansen, P; Richter, L M

1990-11-03

A study was carried out in order to document any abnormalities in the electro-encephalogram (EEG) that might appear in young adolescents who have deliberately inhaled the range of volatile substances loosely referred to as 'glue'. The EEGs of a group of 'street children' being assisted in a Johannesburg shelter were examined. The records were analysed for any clinical abnormalities and also subjected to spectral analysis in order to examine the overall characteristics of frequency, power and spatial distribution. The EEGs clearly revealed that, although at the time of the examination the subjects were ostensibly abstinent, both clinical and normative evidence of continuing brain disturbance was present. It was concluded that glue sniffing is likely to have long term electrocerebral sequelae.

Application of quadratic optimization to supersonic inlet control

NASA Technical Reports Server (NTRS)

Lehtinen, B.; Zeller, J. R.

1971-01-01

The application of linear stochastic optimal control theory to the design of the control system for the air intake (inlet) of a supersonic air-breathing propulsion system is discussed. The controls must maintain a stable inlet shock position in the presence of random airflow disturbances and prevent inlet unstart. Two different linear time invariant control systems are developed. One is designed to minimize a nonquadratic index, the expected frequency of inlet unstart, and the other is designed to minimize the mean square value of inlet shock motion. The quadratic equivalence principle is used to obtain the best linear controller that minimizes the nonquadratic performance index. The two systems are compared on the basis of unstart prevention, control effort requirements, and sensitivity to parameter variations.

Estimating disturbance effects from military training using developmental instability and physiological measures of plant stress

USGS Publications Warehouse

Duda, J.J.; Freeman, D.C.; Brown, M.L.; Graham, J.H.; Krzysik, A.J.; Emlen, J.M.; Zak, J.C.; Kovacic, D.A.

2004-01-01

We used developmental instability, water potential, and variable fluorescence to determine if populations of winged sumac (Rhus copallinum) were being negatively effected by military training disturbance. We established nine sites that represented a land-use disturbance gradient with three impact levels (low, medium, and high), the effects mostly due to mechanized infantry training maneuvers. Although mean values of developmental instability, water potential, and variable fluorescence differed significantly among sites, the patterns did not consistently differentiate sites relative to the disturbance gradient. At the population level, some measures of developmental instability and variable fluorescence were positively correlated. All nine sites consisted of habitat mosaics, with the abundance of higher quality habitat patches and canopy gaps closely related to habitat impacts. It may be that R. copallinum is selecting similar micro-environments at all sites and therefore minimizing inter-site variation in stress measures, despite large differences in overall habitat condition. Our results call for caution in developing ecological indicators using the response of physiological and morphological measures from a single plant species. ?? 2003 Elsevier Ltd. All rights reserved.

What are the neurocognitive correlates of basic self-disturbance in schizophrenia? Integrating phenomenology and neurocognition: Part 2 (aberrant salience).

PubMed

Nelson, B; Whitford, T J; Lavoie, S; Sass, L A

2014-01-01

Phenomenological research indicates that disturbance of the basic sense of self may be a core phenotypic marker of schizophrenia spectrum disorders. Basic self-disturbance refers to disruption of the sense of ownership of experience and agency of action and is associated with a variety of anomalous subjective experiences. Little is known about the neurocognitive underpinnings of basic self-disturbance. In these two theoretical papers (of which this is Part 2), we review some recent phenomenological and neurocognitive research and point to a convergence of these approaches around the concept of self-disturbance. Specifically, we propose that subjective anomalies associated with basic self-disturbance may be associated with: 1. source monitoring deficits, which may contribute particularly to disturbances of "ownership" and "mineness" (the phenomenological notion of presence or self-affection) and 2. aberrant salience, and associated disturbances of memory, prediction and attention processes, which may contribute to hyper-reflexivity, disturbed "grip" or "hold" on perceptual and conceptual fields, and disturbances of intuitive social understanding ("common sense"). In this paper (Part 2) we focus on aberrant salience. Part 1 (this issue) addressed source monitoring deficits. Empirical studies are required in a variety of populations in order to test these proposed associations between phenomenological and neurocognitive aspects of self-disturbance in schizophrenia. An integration of findings across the phenomenological and neurocognitive "levels" would represent a significant advance in the understanding of schizophrenia and possibly enhance early identification and intervention strategies. © 2013 Elsevier B.V. All rights reserved.

Remote sensing of forest insect disturbances: Current state and future directions

NASA Astrophysics Data System (ADS)

Senf, Cornelius; Seidl, Rupert; Hostert, Patrick

2017-08-01

Insect disturbance are important agents of change in forest ecosystems around the globe, yet their spatial and temporal distribution and dynamics are not well understood. Remote sensing has gained much attention in mapping and understanding insect outbreak dynamics. Consequently, we here review the current literature on the remote sensing of insect disturbances. We suggest to group studies into three insect types: bark beetles, broadleaved defoliators, and coniferous defoliators. By so doing, we systematically compare the sensors and methods used for mapping insect disturbances within and across insect types. Results suggest that there are substantial differences between methods used for mapping bark beetles and defoliators, and between methods used for mapping broadleaved and coniferous defoliators. Following from this, we highlight approaches that are particularly suited for each insect type. Finally, we conclude by highlighting future research directions for remote sensing of insect disturbances. In particular, we suggest to: 1) Separate insect disturbances from other agents; 2) Extend the spatial and temporal domain of analysis; 3) Make use of dense time series; 4) Operationalize near-real time monitoring of insect disturbances; 5) Identify insect disturbances in the context of coupled human-natural systems; and 6) Improve reference data for assessing insect disturbances. Since the remote sensing of insect disturbances has gained much interest beyond the remote sensing community recently, the future developments identified here will help integrating remote sensing products into operational forest management. Furthermore, an improved spatiotemporal quantification of insect disturbances will support an inclusion of these processes into regional to global ecosystem models.

Remote sensing of forest insect disturbances: Current state and future directions.

PubMed

Senf, Cornelius; Seidl, Rupert; Hostert, Patrick

2017-08-01

Insect disturbance are important agents of change in forest ecosystems around the globe, yet their spatial and temporal distribution and dynamics are not well understood. Remote sensing has gained much attention in mapping and understanding insect outbreak dynamics. Consequently, we here review the current literature on the remote sensing of insect disturbances. We suggest to group studies into three insect types: bark beetles, broadleaved defoliators, and coniferous defoliators. By so doing, we systematically compare the sensors and methods used for mapping insect disturbances within and across insect types. Results suggest that there are substantial differences between methods used for mapping bark beetles and defoliators, and between methods used for mapping broadleaved and coniferous defoliators. Following from this, we highlight approaches that are particularly suited for each insect type. Finally, we conclude by highlighting future research directions for remote sensing of insect disturbances. In particular, we suggest to: 1) Separate insect disturbances from other agents; 2) Extend the spatial and temporal domain of analysis; 3) Make use of dense time series; 4) Operationalize near-real time monitoring of insect disturbances; 5) Identify insect disturbances in the context of coupled human-natural systems; and 6) Improve reference data for assessing insect disturbances. Since the remote sensing of insect disturbances has gained much interest beyond the remote sensing community recently, the future developments identified here will help integrating remote sensing products into operational forest management. Furthermore, an improved spatiotemporal quantification of insect disturbances will support an inclusion of these processes into regional to global ecosystem models.

On the 485-day Mode in the Atmospheric Angular Momentum: Spectral Analysis of IERS Data

NASA Astrophysics Data System (ADS)

Tsurkis, I. Ya.; Kuchai, M. S.

2018-05-01

The modification of spectral analysis especially intended for studying the disturbing functions of the atmosphere and ocean, as well as the observed polar motion (Wiener-Liouville spectrum), is used. The time series of the atmospheric disturbing functions obtained by the U.S. National Centers for Environmental Prediction (NCEP) of the International Earth Rotation and Reference Systems Service (IERS) for the period from January 1, 1980 to June 20, 2014 (http://www.iers.org/.cs1?pid=43-1100116) are analyzed. It is shown that the baric disturbing function contains a regular mode with a period of 16 months; the contribution of this mode in the polar motion is estimated.

Change in spatial characteristics of forest openings in the Klamath Mountains of northwestern California, USA

Treesearch

Carl N. Skinner

1995-01-01

Change in the spatial characteristics of forest openings was investigated in three forested watersheds in northwestern Siskiyou County, California totalling approximately 24,600 hectares. Watersheds with minimal human disturbance were chosen for study. However, fi;e suppression has been pervasive throughout. Characteristics of forest openings (area, perimeter, distance...

76 FR 10564 - Takes of Marine Mammals Incidental to Specified Activities; St. George Reef Light Station...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-02-25

.... Acoustic and visual stimuli generated by: (1) Helicopter landings/takeoffs; (2) noise generated during... minimize acoustic and visual disturbances) as described in NMFS' December 22, 2010 (75 FR 80471) notice of... Activity on Marine Mammals Acoustic and visual stimuli generated by: (1) Helicopter landings/ takeoffs; (2...

76 FR 67419 - Takes of Marine Mammals Incidental to Specified Activities; Piling and Structure Removal in...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-01

... unclear how expanded monitoring, in the absence of specific experimental design, would empirically verify..., designed to minimize disturbance to harbor seals within the action area in consideration of timing... February (i.e., within the designated in-water work window designed to reduce impacts to fish species in...

77 FR 28703 - Endangered and Threatened Wildlife and Plants; Threatened Status for Eriogonum codium (Umtanum...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-15

... necessarily designed to be a response, rather than a regulatory activity. All collecting is prohibited on the... be designed to minimize surface disturbance in the vicinity of sensitive resources, and fire control... benefit Umtanum desert buckwheat, these programs do not appear to have been designed to function as...

A predictive model for anti-degradation monitoring of the Delaware River mainstem

EPA Science Inventory

The non-tidal portion of the Delaware River can be considered to be in minimally disturbed condition, but there is increasing pressure on the watershed. Thus, the primary goal of this research was to develop a monitoring tool that can be used by the Delaware River Basin Commissi...

Evaluating habitat associations of a fish assemblages at multiple scales in a minimally disturbed stream on the Edwards Plateau, Central Texas

USGS Publications Warehouse

Cheek, Brandon D.; Grabowski, Timothy B.; Bean, Preston T.; Groeschel, Jillian R.; Magnelia, Stephan J.

2016-01-01

Low-cost side-scan sonar proved to be a cost-effective means of acquiring information on the habitat availability of the entire river length and allowed the assessment of how a full suite of riverscape-level variables influenced local fish assemblage structure.

Effects of integrated polyethylene and cover crop mulch, conservation tillage, and herbicide application on weed control, yield, and economic returns in watermelon

USDA-ARS?s Scientific Manuscript database

The lack of conservation adoption in watermelon production reflects the lack of field practice recommendations addressing the challenges associated with producing vegetables in minimally disturbed cover crop residues. A three year watermelon experiment was established in fall 2013 to evaluate integr...

A concept for adaptive performance optimization on commercial transport aircraft

NASA Technical Reports Server (NTRS)

Jackson, Michael R.; Enns, Dale F.

1995-01-01

An adaptive control method is presented for the minimization of drag during flight for transport aircraft. The minimization of drag is achieved by taking advantage of the redundant control capability available in the pitch axis, with the horizontal tail used as the primary surface and symmetric deflection of the ailerons and cruise flaps used as additional controls. The additional control surfaces are excited with sinusoidal signals, while the altitude and velocity loops are closed with guidance and control laws. A model of the throttle response as a function of the additional control surfaces is formulated and the parameters in the model are estimated from the sensor measurements using a least squares estimation method. The estimated model is used to determine the minimum drag positions of the control surfaces. The method is presented for the optimization of one and two additional control surfaces. The adaptive control method is extended to optimize rate of climb with the throttle fixed. Simulations that include realistic disturbances are presented, as well as the results of a Monte Carlo simulation analysis that shows the effects of changing the disturbance environment and the excitation signal parameters.

Ab interno management of blocked Ahmed valve in the posterior segment.

PubMed

Odrich, Steven; Wald, Kenneth; Sperber, Laurence

2013-01-01

To report a case of late failure of a posterior segment placed Ahmed valve in a uveitic eye with a corneal graft and a minimally invasive, ab interno approach in restoring valve function, pressure control, and preservation of vision. Case report. A 25 gauge trans-conjunctival 3-port pars plana vitrectomy was performed to inspect and clean the ostium of the Ahmed valve of any vitreous debris. The Ahmed valve was not disturbed externally and conjunctival dissection was not performed. A 27-gauge blunt cannula was introduced through the vitrector site and used to cannulate the tube and flush it with balanced salt solution. A bleb was immediately re-established and all instruments were removed requiring no sutures. Intraocular pressure returned to target levels and a filtration bleb was re-established. Corneal graft clarity was restored with resolution of preoperative microcystic edema. Postoperative inflammation was minimal and vision was restored. A nonfunctioning tube shunt residing in the vitreous cavity may be revised ab interno without disturbing the shunt placement or the conjunctiva under which it resides to re-establish filtration.

The Space Technology-7 Disturbance Reduction Systems

NASA Technical Reports Server (NTRS)

ODonnell, James R., Jr.; Hsu, Oscar C.; Hanson, John; Hruby, Vlad

2004-01-01

The Space Technology 7 Disturbance Reduction System (DRS) is an in-space technology demonstration designed to validate technologies that are required for future missions such as the Laser Interferometer Space Antenna (LISA) and the Micro-Arcsecond X-ray Imaging Mission (MAXIM). The primary sensors that will be used by DRS are two Gravitational Reference Sensors (GRSs) being developed by Stanford University. DRS will control the spacecraft so that it flies about one of the freely-floating Gravitational Reference Sensor test masses, keeping it centered within its housing. The other GRS serves as a cross-reference for the first as well as being used as a reference for .the spacecraft s attitude control. Colloidal MicroNewton Thrusters being developed by the Busek Co. will be used to control the spacecraft's position and attitude using a six degree-of-freedom Dynamic Control System being developed by Goddard Space Flight Center. A laser interferometer being built by the Jet Propulsion Laboratory will be used to help validate the results of the experiment. The DRS will be launched in 2008 on the European Space Agency (ESA) LISA Pathfinder spacecraft along with a similar ESA experiment, the LISA Test Package.

Asbestos

MedlinePlus

... Healthy Air > Indoor > Indoor Air Pollutants and Health Asbestos What is asbestos? Asbestos refers to a group of naturally occurring, ... in others. 2 What are the sources of asbestos? Deteriorating, damaged or disturbed products—such as insulation, ...

Genetics Home Reference: sialidosis

MedlinePlus

... walking (gait disturbance) and/or a loss of sharp vision (reduced visual acuity). Individuals with sialidosis type ... d'Azzo A, Cavicchi C, Messeri A, Guerrini R, Zammarchi E, Donati MA, Morrone A. Type II ...

Forest restoration: a global dataset for biodiversity and vegetation structure.

PubMed

Crouzeilles, Renato; Ferreira, Mariana S; Curran, Michael

2016-08-01

Restoration initiatives are becoming increasingly applied around the world. Billions of dollars have been spent on ecological restoration research and initiatives, but restoration outcomes differ widely among these initiatives in part due to variable socioeconomic and ecological contexts. Here, we present the most comprehensive dataset gathered to date on forest restoration. It encompasses 269 primary studies across 221 study landscapes in 53 countries and contains 4,645 quantitative comparisons between reference ecosystems (e.g., old-growth forest) and degraded or restored ecosystems for five taxonomic groups (mammals, birds, invertebrates, herpetofauna, and plants) and five measures of vegetation structure reflecting different ecological processes (cover, density, height, biomass, and litter). We selected studies that (1) were conducted in forest ecosystems; (2) had multiple replicate sampling sites to measure indicators of biodiversity and/or vegetation structure in reference and restored and/or degraded ecosystems; and (3) used less-disturbed forests as a reference to the ecosystem under study. We recorded (1) latitude and longitude; (2) study year; (3) country; (4) biogeographic realm; (5) past disturbance type; (6) current disturbance type; (7) forest conversion class; (8) restoration activity; (9) time that a system has been disturbed; (10) time elapsed since restoration started; (11) ecological metric used to assess biodiversity; and (12) quantitative value of the ecological metric of biodiversity and/or vegetation structure for reference and restored and/or degraded ecosystems. These were the most common data available in the selected studies. We also estimated forest cover and configuration in each study landscape using a recently developed 1 km consensus land cover dataset. We measured forest configuration as the (1) mean size of all forest patches; (2) size of the largest forest patch; and (3) edge:area ratio of forest patches. Global analyses of the factors influencing ecological restoration success at both the local and landscape scale are urgently needed to guide restoration initiatives and to further develop restoration knowledge in a topic area of much contemporary interest. © 2016 by the Ecological Society of America.

Observation and Modeling of Storm Generated Acoustic Waves in the Ionosphere Revealed in a Dense Network of GPS Receivers

NASA Astrophysics Data System (ADS)

Walterscheid, R. L.; Azeem, S. I.

2017-12-01

Acoustic waves generated in the lower atmosphere may become an important source of variably in the upper atmosphere. Although they are excited with small amplitudes they are minimally subject to viscous dissipation and may reach significant amplitudes at F-region altitudes. A number of studies in the 1970s showed clear signatures in ionosonde data in the infrasonic period range attributable to thunder storm activity. We have examined Total Electron Content data from a dense network of over 4000 ground-based GPS receivers over the continental United States during an outbreak of severe weather, including tornados, over Kansas in May 2015. A sequence of GPS TEC images showed clear Traveling Ionospheric Disturbances (TIDs) in the form of concentric rings moving outward from the center of the storm region. The characteristics of the disturbance (phase speed and frequency) were consistent with acoustic waves in the infrasonic range. We have modeled the disturbance by including a tropospheric heat source representing latent heat release from a large thunderstorm. The disturbance at ionospheric altitudes resembles the observed disturbance in terms of phase speed, frequency and horizontal wavelength. We conclude that the observed TIDs in TEC were caused by an acoustic wave generated by deep convection.

Disturbance of a rare seabird by ship-based tourism in a marine protected area.

PubMed

Marcella, Timothy K; Gende, Scott M; Roby, Daniel D; Allignol, Arthur

2017-01-01

Managers of marine protected areas (MPAs) must often seek ways to allow for visitation while minimizing impacts to the resources they are intended to protect. Using shipboard observers, we quantified the "zone of disturbance" for Kittlitz's and marbled murrelets (Brachyramphus brevirostris and B. marmoratus) exposed to large cruise ships traveling through Glacier Bay National Park, one of the largest MPAs in North America. In the upper reaches of Glacier Bay, where Kittlitz's murrelets predominated, binary logistic regression models predicted that 61% of all murrelets within 850 m perpendicular distance of a cruise ship were disturbed (defined as flushing or diving), whereas in the lower reaches, where marbled murrelets predominated, this percentage increased to 72%. Using survival analysis, murrelets in both reaches were found to react at greater distances when ships approached indirectly, presumably because of the ship's larger profile, suggesting murrelets responded to visual rather than audio cues. No management-relevant covariates (e.g., ship velocity, route distance from shore) were found to be important predictors of disturbance, as distance from ship to murrelet accounted for > 90% of the explained variation in murrelet response. Utilizing previously published murrelet density estimates from Glacier Bay, and applying an average empirical disturbance probability (68%) out to 850 m from a cruise ship's typical route, we estimated that a minimum of 9.8-19.6% of all murrelets in Glacier Bay are disturbed per ship entry. Whether these disturbance levels are inconsistent with Park management objectives, which include conserving wildlife as well as providing opportunities for visitation, depends in large part on whether disturbance events caused by cruise ships have impacts on murrelet fitness, which remains uncertain.

Gas film disturbance characteristics analysis of high-speed and high-pressure dry gas seal

NASA Astrophysics Data System (ADS)

Chen, Yuan; Jiang, Jinbo; Peng, Xudong

2016-08-01

The dry gas seal(DGS) has been widely used in high parameters centrifugal compressor, but the intense vibrations of shafting, especially in high-speed condition, usually result in DGS's failure. So the DGS's ability of resisting outside interference has become a determining factor of the further development of centrifugal compressor. However, the systematic researches of which about gas film disturbance characteristics of high parameters DGS are very little. In order to study gas film disturbance characteristics of high-speed and high-pressure spiral groove dry gas seal(S-DGS) with a flexibly mounted stator, rotor axial runout and misalignment are taken into consideration, and the finite difference method and analytical method are used to analyze the influence of gas film thickness disturbance on sealing performance parameters, what's more, the effects of many key factors on gas film thickness disturbance are systematically investigated. The results show that, when sealed pressure is 10.1MPa and seal face average linear velocity is 107.3 m/s, gas film thickness disturbance has a significant effect on leakage rate, but has relatively litter effect on open force; Excessively large excitation amplitude or excessively high excitation frequency can lead to severe gas film thickness disturbance; And it is beneficial to assure a smaller gas film thickness disturbance when the stator material density is between 3.1 g/cm3 to 8.4 g/cm3; Ensuring sealing performance while minimizing support axial stiffness and support axial damping can help to improve dynamic tracking property of dry gas seal. The proposed research provides the instruction to optimize dynamic tracking property of the DGS.

Gravitational mass attraction measurement for drag-free references

NASA Astrophysics Data System (ADS)

Swank, Aaron J.

Exciting new experiments in gravitational physics are among the proposed future space science missions around the world. Such future space science experiments include gravitational wave observatories, which require extraordinarily precise instruments for gravitational wave detection. In fact, future space-based gravitational wave observatories require the use of a drag free reference sensor, which is several orders of magnitude more precise than any drag free satellite launched to date. With the analysis methods and measurement techniques described in this work, there is one less challenge associated with achieving the high-precision drag-free satellite performance levels required by gravitational wave observatories. One disturbance critical to the drag-free performance is an acceleration from the mass attraction between the spacecraft and drag-free reference mass. A direct measurement of the gravitational mass attraction force is not easily performed. Historically for drag-free satellite design, the gravitational attraction properties were estimated by using idealized equations between a point mass and objects of regular geometric shape with homogeneous density. Stringent requirements are then placed on the density distribution and fabrication tolerances for the drag-free reference mass and satellite components in order to ensure that the allocated gravitational mass attraction disturbance budget is not exceeded due to the associated uncertainty in geometry and mass properties. Yet, the uncertainty associated with mass properties and geometry generate an unacceptable uncertainty in the mass attraction calculation, which make it difficult to meet the demanding drag-free performance requirements of future gravitational wave observatories. The density homogeneity and geometrical tolerances required to meet the overall drag-free performance can easily force the use of special materials or manufacturing processes, which are impractical or not feasible. The focus of this research is therefore to develop the necessary equations for the gravitational mass attraction force and gradients between two general distributed bodies. Assuming the drag-free reference mass to be a single point mass object is no longer necessary for the gravitational attraction calculations. Furthermore, the developed equations are coupled with physical measurements in order to eliminate the mass attraction uncertainty associated with mass properties. The mass attraction formula through a second order expansion consists of the measurable quantifies of mass, mass center, and moment of inertia about the mass center. Thus, the gravitational self-attraction force on the drag free reference due to the satellite can be indirectly measured. By incorporating physical measurements into the mass attraction calculation, the uncertainty in the density distribution as well as geometrical variations due to the manufacturing process are included in the analysis. For indirect gravitational mass attraction measurements, the corresponding properties of mass, mass center, and moment of inertia must be precisely determined for the proof mass and satellite components. This work focuses on the precision measurement of the moment of inertia for the drag-free test mass. Presented here is the design of a new moment of inertia measurement apparatus utilizing a five-wire torsion pendulum design. The torsion pendulum is utilized to measure the moment of inertia tensor for a prospective drag-free test mass geometry. The measurement results presented indicate the prototype five-wire torsion has matched current state of the art precision. With only minimal work to reduce laboratory environmental disturbances, the apparatus has the prospect of exceeding state of the art precision by almost an order of magnitude. In addition, the apparatus is shown to be capable of measuring the mass center offset from the geometric center to a level better than typical measurement devices. Although the pendulum was not originally designed for mass center measurements, preliminary results indicate an apparatus with a similar design may have the potential of achieving state of the art precision.

Task I: A Computational Model for Short Wavelength Stall Inception and Development In Multi-Stage Compressors

NASA Technical Reports Server (NTRS)

Suder, Kenneth (Technical Monitor); Tan, Choon-Sooi

2003-01-01

A computational model is presented for simulating axial compressor stall inception and development via disturbances with length scales on the order of several (typically about three) blade pitches. The model was designed for multi-stage compressors in which stall is initiated by these short wavelength disturbances, also referred to as spikes. The inception process described is fundamentally nonlinear, in contrast to the essentially linear behavior seen in so-called modal stall inception . The model was able to capture the following experimentally observed phenomena: (1) development of rotating stall via short wavelength disturbances, (2) formation and evolution of localized short wavelength stall cells in the first stage of a mismatched compressor, (3) the switch from long to short wavelength stall inception resulting from the re-staggering of the inlet guide vane, (4) the occurrence of rotating stall inception on the negatively sloped portion of the compressor characteristic. Parametric investigations indicated that (1) short wavelength disturbances were supported by the rotor blade row, (2) the disturbance strength was attenuated within the stators, and (3) the reduction of inter-blade row gaps can suppress the growth of short wavelength disturbances. It is argued that each local component group (rotor plus neighboring stators) has its own instability point (i.e. conditions at which disturbances are sustained) for short wavelength disturbances, with the instability point for the compressor set by the most unstable component group.

Effectiveness of a confinement strategy for reducing campsite impacts in Shenandoah National Park

USGS Publications Warehouse

Reid, S.E.; Marion, J.L.

2004-01-01

The expansion and proliferation of backcountry campsites is a persistent problem in many parks and protected areas. Shenandoah National Park (SNP) has one of the highest backcountry overnight use densities in the USA national parks system. SNP managers implemented a multi-option backcountry camping policy in 2000 that included camping containment with established campsites. These actions were intended to reduce the number of campsites and the area of camping disturbance at each site. This paper describes a longitudinal adaptive management assessment of the new campsite policies, applying quantitative measures of campsite conditions to evaluate the efficacy of management interventions. Physical campsite measurements combined with qualitative visitor interviews indicated SNP had successfully reduced the number of campsites and aggregate measures of camping-related disturbance in the Park, while minimizing the use of regulations, site facilities and staff resources. Implications for managers of other protected areas are that an established site camping policy can minimize camping disturbance, including the number and size of campsites, provided managers can sustain rehabilitation efforts to close and restore unneeded campsites. Experiential attributes, such as the potential for solitude, can also be manipulated through control over the selection of established campsites. Integrating resource and social science methods also provided a more holistic perspective on management policy assessments. Adaptive management research provided a timely evaluation of management success while facilitating effective modifications in response to unforeseen challenges. Conclusions regarding the effectiveness of a visitor impact containment strategy involving an established site camping option are offered.

Robust Fuzzy Logic Stabilization with Disturbance Elimination

PubMed Central

Danapalasingam, Kumeresan A.

2014-01-01

A robust fuzzy logic controller is proposed for stabilization and disturbance rejection in nonlinear control systems of a particular type. The dynamic feedback controller is designed as a combination of a control law that compensates for nonlinear terms in a control system and a dynamic fuzzy logic controller that addresses unknown model uncertainties and an unmeasured disturbance. Since it is challenging to derive a highly accurate mathematical model, the proposed controller requires only nominal functions of a control system. In this paper, a mathematical derivation is carried out to prove that the controller is able to achieve asymptotic stability by processing state measurements. Robustness here refers to the ability of the controller to asymptotically steer the state vector towards the origin in the presence of model uncertainties and a disturbance input. Simulation results of the robust fuzzy logic controller application in a magnetic levitation system demonstrate the feasibility of the control design. PMID:25177713

Upper Atmosphere Research Satellite attitude disturbances during shadow entry and exit

NASA Technical Reports Server (NTRS)

Lambertson, M.; Underwood, S.; Woodruff, C.; Garber, A.

1993-01-01

The Upper Atmosphere Research Satellite (UARS), as with the Landsat-4 and Landsat-5 spacecraft, experiences large attitude disturbances when entering and exiting the Earth's shadow. Previous investigations have provided some evidence linking these disturbances to rapid bending of the solar array but have also raised questions. For example, the magnitudes of the roll attitude disturbances have shown an unmolested asymmetry, and the timing of the disturbances at sunrise appears to disagree with the modeled timing. A better understanding of this phenomenon is important in assessing the implications for UARS science gathering and for future mission design analysis. To this end, UARS attitude, sensor, and actuator data are used to evaluate the disturbances as they vary with solar beta angle and solar array drive angle. The attitude data are examined during specific periods of interest, such as the month in which the solar array was parked in its high-noon position, and are also tracked from the beginning of the mission to determine any trends that may result from changing mass properties due to cryogen boiloff and propellant usage. Attitude rate and torque profiles are derived from inertial reference until data and related to the disturbances seen in the attitude data. The timing of the disturbances with respect to spacecraft sunset and sunrise is characterized to allow event predictions. Stability during the disturbances is discussed in terms of science instrument requirements. Finally, the results are compared with the behavior predicted by models that are based on solar array bending.

Do Not Disturb Act of 2014

THOMAS, 113th Congress

Sen. Begich, Mark [D-AK

2014-11-20

Senate - 11/20/2014 Read twice and referred to the Committee on Commerce, Science, and Transportation. (All Actions) Tracker: This bill has the status IntroducedHere are the steps for Status of Legislation:

Regulation of Post-Logging N Turnover and Mobile N by Solar Insolation in a Steep Rocky Mountain Watershed

NASA Astrophysics Data System (ADS)

Stewart, D. M.; Silins, U.; Emelko, M.; Stone, M.

2016-12-01

While forest harvesting effects on nitrogen (N) cycling and watershed nitrogen export are generally well documented, the factors that govern variation in post-disturbance watershed export of N after forest disturbance across different hydro-climatic regions as less well understood. Factors that regulate the coupling of N dynamics on hillslopes with receiving streams are not well understood in steeper mountainous terrain where strong spatial variation in radiation, temperature, and nutrient turnover potentially govern post-disturbance catchment exports of N. Objectives of this study were to explore the relative influence of variation in hillslope position (upper vs lower) and radiation load among contrasting south- and north-facing hillslope positions in regulating soil nitrogen turnover and mobile nitrogen (NO-3) after clear-cut logging in the Rocky Mountains of south-west Alberta, Canada. A combined approach employing replicated measurement of key soil N species in soil solution (available N, using ion exchange membranes) and shallow hillslope pore water N (using suction lysimeters) was used to explore how variation in hillslope position and radiation load (S/N facing) after clear-cut logging of a Lodgepole pine dominated Rocky Mountain watershed in southwest Alberta. These were compared to parallel measurements in unharvested (reference) hillslopes in the same watershed. Logging was completed in 2015 with measurements of soil and shallow groundwater N at 6 week intervals from April to Oct. 2016. Compared to other types of forest disturbance (i.e. wildfire) common in this region, clear-cut harvesting did not produce a large impact on both surface and deeper available N for reference and harvested stands. In particular, early season available NO-3 is enriched in upper stands, while other factors showed less of an effect. Overall, results provide important insights into how disturbance effects on mobile N among hillslopes of contrasting energy gain, soil moisture, and thermal regimes interact in driving post-disturbance N export in steep, mountainous terrain.

Swine manure injection with low-disturbance applicator and cover crops reduce phosphorus losses.

PubMed

Kovar, J L; Moorman, T B; Singer, J W; Cambardella, C A; Tomer, M D

2011-01-01

Injection of liquid swine manure disturbs surface soil so that runoff from treated lands can transport sediment and nutrients to surface waters. We determined the effect of two manure application methods on P fate in a corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] production system, with and without a winter rye (Secale cereale L.)-oat (Avena sativa L.) cover crop. Treatments included: (i) no manure; (ii) knife injection; and (iii) low-disturbance injection, each with and without the cover crop. Simulated rainfall runoff was analyzed for dissolved reactive P (DRP) and total P (TP). Rainfall was applied 8 d after manure application (early November) and again in May after emergence of the corn crop. Manure application increased soil bioavailable P in the 20- to 30-cm layer following knife injection and in the 5- to 20-cm layer following low-disturbance injection. The low-disturbance system caused less damage to the cover crop, so that P uptake was more than threefold greater. Losses of DRP were greater in both fall and spring following low-disturbance injection; however, application method had no effect on TP loads in runoff in either season. The cover crop reduced fall TP losses from plots with manure applied by either method. In spring, DRP losses were significantly higher from plots with the recently killed cover crop, but TP losses were not affected. Low-disturbance injection of swine manure into a standing cover crop can minimize plant damage and P losses in surface runoff while providing optimum P availability to a subsequent agronomic crop.

Adaptive terminal sliding mode control for hypersonic flight vehicles with strictly lower convex function based nonlinear disturbance observer.

PubMed

Wu, Yun-Jie; Zuo, Jing-Xing; Sun, Liang-Hua

2017-11-01

In this paper, the altitude and velocity tracking control of a generic hypersonic flight vehicle (HFV) is considered. A novel adaptive terminal sliding mode controller (ATSMC) with strictly lower convex function based nonlinear disturbance observer (SDOB) is proposed for the longitudinal dynamics of HFV in presence of both parametric uncertainties and external disturbances. First, for the sake of enhancing the anti-interference capability, SDOB is presented to estimate and compensate the equivalent disturbances by introducing a strictly lower convex function. Next, the SDOB based ATSMC (SDOB-ATSMC) is proposed to guarantee the system outputs track the reference trajectory. Then, stability of the proposed control scheme is analyzed by the Lyapunov function method. Compared with other HFV control approaches, key novelties of SDOB-ATSMC are that a novel SDOB is proposed and drawn into the (virtual) control laws to compensate the disturbances and that several adaptive laws are used to deal with the differential explosion problem. Finally, it is illustrated by the simulation results that the new method exhibits an excellent robustness and a better disturbance rejection performance than the convention approach. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Genetics Home Reference: ataxia with oculomotor apraxia

MedlinePlus

... muscle twitches (myoclonus), and disturbances in nerve function (neuropathy). In type 1, ataxia beings around age 4; ... all individuals with ataxia with oculomotor apraxia develop neuropathy, which leads to absent reflexes and weakness. Neuropathy ...

Increasingly minimal bias routing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bataineh, Abdulla; Court, Thomas; Roweth, Duncan

2017-02-21

A system and algorithm configured to generate diversity at the traffic source so that packets are uniformly distributed over all of the available paths, but to increase the likelihood of taking a minimal path with each hop the packet takes. This is achieved by configuring routing biases so as to prefer non-minimal paths at the injection point, but increasingly prefer minimal paths as the packet proceeds, referred to herein as Increasing Minimal Bias (IMB).

Some aeroacoustic and aerodynamic applications of the theory of nonequilibrium thermodynamics

NASA Technical Reports Server (NTRS)

Horne, W. Clifton; Smith, Charles A.; Karamcheti, Krishnamurty

1990-01-01

An exact equation is derived for the dissipation function of a homogeneous, isotropic, Newtonian fluid, with terms associated with irreversible compression or expansion, wave radiation, and the square of the vorticity. This and other forms of the dissipation function are used to identify simple flows, such as incompressible channel flow, the potential vortex with rotational core, and incompressible, irrotational flow as minimally dissipative distributions. A comparison of the hydrodynamic and thermodynamic stability characteristics of a parallel shear flow suggests that an association exists between flow stability and the variation of net dissipation with disturbance amplitude, and that nonlinear effects, such as bounded disturbance amplitude, may be examined from a thermodynamic basis.

Evaluating the effects of alternative forest management plans under various physiographic settings using historical records as a reference

Treesearch

Yangjian Zhang; Hong S. He; Stephen R. Shifley; Jian Yang; Brian J. Palik

2011-01-01

Using historical General Land Office record as a reference, this study employed a landscape-scale disturbance and succession model to estimate the future cumulative effects of six alternative management plans on the tree species composition for various physiographic settings for the Mark Twain National Forest in Missouri. The results indicate that over a 200-year...

A seismic survey of the Manson disturbed area

NASA Technical Reports Server (NTRS)

Sendlein, L. V. A.; Smith, T. A.

1971-01-01

The region in north-central Iowa referred to as the Manson disturbed area was investigated with the seismic refraction method and the bedrock configuration mapped. The area is approximately 30 km in diameter and is not detectable from the surface topography; however, water wells that penetrate the bedrock indicate that the bedrock is composed of disturbed Cretaceous sediments with a central region approximately 6 km in diameter composed of Precambrian crystalline rock. Seismic velocity differences between the overlying glacial till and the Cretaceous sediments were so small that a statistical program was developed to analyze the data. The program developed utilizes existing 2 segment regression analyses and extends the method to fit 3 or more regression lines to seismic data.

Detecting post-fire salvage logging with Landsat change maps and national fire survey data

Treesearch

Todd A. Schroeder; Michael A. Wulder; Sean P. Healey; Gretchen G. Moisen

2012-01-01

In Canadian boreal forests, wildfire is the predominant agent of natural disturbance often with millions of hectares burning annually. In addition to fire, nearly one quarter of Canada's boreal forest is also managed for industrial wood production. Post-fire logging (or salvage harvesting) is increasingly used to minimize economic losses from fire, notwithstanding...

78 FR 12720 - Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-25

... added a 10 mile (16 km) exclusion zone around the Susitna Delta (which includes the Beluga River) to the... Delta and alert the vessels accordingly of necessary actions to avoid or minimize potential disturbance... reproduction areas, and to ensure that any displacement from the Susitna Delta region is temporary and would...

Use of pre-fabricated Parshall flumes to measure streamflow in permafrost-dominated watersheds.

Treesearch

Charles W. Slaughter

1981-01-01

The occurrence of permafrost in stream valleys of central Alaska causes problems with conventional stream-gauging installations. To minimize both thermal and physical disturbance at measurement sites, pre-fabricated Parshall flumes have been used to monitor streamflow at sites underlain with permafrost in a subarctic research watershed. Flumes ranging in capacity from...

Reduced-impact logging has little effect on temporal activity of frugivorous bats (Chiroptera) in lowland Amazonia

Treesearch

S.J. Presley; M.R. Willig; L.N. Saldanha; Jr. Wunderle; I. Castro-Arellano

2009-01-01

Reduced-impact logging (RIL) represents a viable option for sustainable use of Neotropical lowland forests while minimizing negative effects on local biodiversity. Many Neotropical bats of the family Phyllostomidae provide ecosystem services associated with pollination and seed dispersal that promote the regeneration of disturbed areas; therefore, effects of RIL on...

Leave No Trace! An Outdoor Ethic: A Program To Teach Skills for Protecting the Wilderness Environment.

ERIC Educational Resources Information Center

Forest Service (USDA), Washington, DC.

This document consists of two brochures that were developed as part of a land ethics training program for outdoor recreationists. The brochures provide information about techniques that outdoor practitioners can use to help minimize disturbance to backcountry and wilderness areas. Heavy use of popular camping areas can create problems such as…

Digital current regulator for proportional electro-hydraulic valves with unknown disturbance rejection.

PubMed

Canuto, Enrico; Acuña-Bravo, Wilber; Agostani, Marco; Bonadei, Marco

2014-07-01

Solenoid current regulation is well-known and standard in any proportional electro-hydraulic valve. The goal is to provide a wide-band transfer function from the reference to the measured current, thus making the solenoid a fast and ideal force actuator within the limits of the power supplier. The power supplier is usually a Pulse Width Modulation (PWM) amplifier fixing the voltage bound and the Nyquist frequency of the regulator. Typical analog regulators include three main terms: a feedforward channel, a proportional feedback channel and the electromotive force compensation. The latter compensation may be accomplished by integrative feedback. Here the problem is faced through a model-based design (Embedded Model Control), on the basis of a wide-band embedded model of the solenoid which includes the effect of eddy currents. To this end model parameters must be identified. The embedded model includes a stochastic disturbance dynamics capable of estimating and correcting the electromotive contribution together with parametric uncertainty, variability and state dependence. The embedded model which is fed by the measured current and the supplied voltage becomes a state predictor of the controllable and disturbance dynamics. The control law combines reference generator, state feedback and disturbance rejection to dispatch the PWM amplifier with the appropriate duty cycle. Modeling, identification and control design are outlined together with experimental result. Comparison with an existing analog regulator is also provided. © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

Origin of the ahead of tsunami traveling ionospheric disturbances during Sumatra tsunami and offshore forecasting

NASA Astrophysics Data System (ADS)

Bagiya, Mala S.; Kherani, E. A.; Sunil, P. S.; Sunil, A. S.; Sunda, S.; Ramesh, D. S.

2017-07-01

The presence of ionospheric disturbances associated with Sumatra 2004 tsunami that propagated ahead of tsunami itself has previously been identified. However, their origin remains unresolved till date. Focusing on their origin mechanism, we document these ionospheric disturbances referred as Ahead of tsunami Traveling Ionospheric Disturbances (ATIDs). Using total electron content (TEC) data from GPS Aided GEO Augmented Navigation GPS receivers located near the Indian east coast, we first confirm the ATIDs presence in TEC that appear 90 min ahead of the arrival of tsunami at the Indian east coast. We propose here a simulation study based on tsunami-atmospheric-ionospheric coupling that considers tsunamigenic acoustic gravity waves (AGWs) to excite these disturbances. We explain the ATIDs generation based on the dissipation of transverse mode of the primary AGWs. The simulation corroborates the excitation of ATIDs with characteristics similar to the observations. Therefore, we offer an alternative theoretical tool to monitor the offshore ATIDs where observations are either rare or not available and could be potentially important for the tsunami early warning.

Comparison between epiphyte assemblages of leaves and rhizomes of the seagrass Posidonia oceanica subjected to different levels of anthropogenic eutrophication

NASA Astrophysics Data System (ADS)

Balata, David; Bertocci, Iacopo; Piazzi, Luigi; Nesti, Ugo

2008-09-01

This paper aimed to compare epiphyte assemblages of leaves and rhizomes of Posidonia oceanica exposed to different levels of concentration of nutrients. The same design including a potentially impacted meadow and two reference meadows was used in each of two locations, characterized by the presence of a city or of suspended cages of a fish farm, respectively. This allowed to test for the consistency of responses of epiphytic assemblages to different sources of eutrophication. In both studies, results documented differences in patterns of composition and abundance of epiphytic assemblages on leaves between disturbed and reference meadows, while assemblages on rhizomes did not appear sensitive to this kind of disturbance. Moreover, in potentially impacted meadows, both assemblages showed different patterns of spatial variability compared to reference assemblages. Species composition and abundance of epiphyte assemblages seemed suitable for detecting moderate nutrient increases, even if adequate sampling designs are needed to separate patterns related to the large natural spatial variability of these systems from those related to changes in environmental conditions.

Exchanging honest employment references: avoiding the traps of defamation and negligent hiring.

PubMed

McConnell, Charles R

2015-01-01

In present-day reference checking, many of the same organizations that seek as much information as possible about people they wish to hire resist giving out more than a bare minimum of information to other organizations. The strongest force driving this minimal reference information release is fear of legal action taken because of something said about an individual in a reference response. Many employers seem so frightened of being sued that they share nothing of substance, usually not realizing that in supposedly protecting themselves against defamation charges they are sometimes increasing the risk of negligent hiring charges. However, truthful reference information can be provided with minimal risk if it is provided in good faith, given only to those who have a legitimate need to know, is strictly job related, and is not communicated maliciously. References must always be provided objectively with information verifiable in personnel files.

Genetics Home Reference: Vohwinkel syndrome

MedlinePlus

... 26 in cells, and may interfere with the function of other connexin proteins. This disruption could affect skin growth and also impair hearing by disturbing the conversion of sound waves to nerve impulses. The variant form of Vohwinkel ...

Qcritical as a Geomorphically and Biologically Relevant Flow Threshold for Stormwater Management and Catchment-scale Stream Restoration

NASA Astrophysics Data System (ADS)

Hawley, R. J.; Vietz, G. J.; Wooten, M. S.

2016-12-01

The threshold discharge that initiates streambed mobilization (Qcritical) is one of the most mechanistically-important flows for geomorphic function and biological integrity in stream ecosystems. Increased frequency and duration of flows that exceed Qcritical are a dominant driver of geomorphic instability and excess benthic disturbance in urban/suburban streams (i.e. the urban disturbance regime). Qcritical frequency also corresponds to measures of stream integrity in reference streams, with both geomorphic stability and biological indices significantly correlated to time since a Qcritical event in one 7-y study. Indeed, reference site macroinvertebrate communities during years with atypically frequent Qcritical events were more similar to sites draining watersheds with 30% imperviousness than to reference site communities of more typical rainfall years. Despite its biophysical relevance to stream ecosystems, Qcritical is one of the most overlooked and misunderstood flows in the stormwater management and stream restoration fields. Regional stormwater policies and stream restoration design guidance are often based on the misplaced assumption that streambed erosion does not occur at sub-bankfull events (often assumed to correspond to the 1-y recurrence discharge). Using an international database of nearly 200 sites we show that Qcritical varies by several orders of magnitude as a function of streambed particle size. Qcritical in sand-dominated streams is likely to be orders of magnitude less than the 1-yr discharge, whereas Qcritical in cobble/boulder dominated streams could be much larger than the 1-yr discharge, implying that stormwater/restoration policies focused on the 1-yr event could lack efficacy in many stream settings. Qcritical is a geomorphically- and biologically-relevant discharge threshold when developing stormwater management policies intended to protect streams from excess erosion, designing watershed-scale restoration efforts to restore a more natural disturbance regime, or reconstructing stream reaches designed to restore sediment continuity. Incorporation of Qcritical into such restoration and management efforts ensures that designs are actually tailored to the mechanisms that drive channel erosion and disturbance to the benthos.

Changes in soil hydraulic properties caused by construction of a simulated waste trench at the Idaho National Engineering Laboratory, Idaho

USGS Publications Warehouse

Shakofsky, S.M.

1995-01-01

In order to assess the effect of filled waste disposal trenches on transport-governing soil properties, comparisons were made between profiles of undisturbed soil and disturbed soil in a simulated waste trench. The changes in soil properties induced by the construction of a simulated waste trench were measured near the Radioactive Waste Management Complex at the Idaho National Engineering Laboratory (INEL) in the semi-arid southeast region of Idaho. The soil samples were collected, using a hydraulically- driven sampler to minimize sample disruption, from both a simulated waste trench and an undisturbed area nearby. Results show that the undisturbed profile has distinct layers whose properties differ significantly, whereas the soil profile in the simulated waste trench is. by comparison, homogeneous. Porosity was increased in the disturbed cores, and, correspondingly, saturated hydraulic conductivities were on average three times higher. With higher soil-moisture contents (greater than 0.32), unsaturated hydraulic conductivities for the undisturbed cores were typically greater than those for the disturbed cores. With lower moisture contents, most of the disturbed cores had greater hydraulic conductivities. The observed differences in hydraulic conductivities are interpreted and discussed as changes in the soil pore geometry.

Adaptive control of dynamical synchronization on evolving networks with noise disturbances

NASA Astrophysics Data System (ADS)

Yuan, Wu-Jie; Zhou, Jian-Fang; Sendiña-Nadal, Irene; Boccaletti, Stefano; Wang, Zhen

2018-02-01

In real-world networked systems, the underlying structure is often affected by external and internal unforeseen factors, making its evolution typically inaccessible. An adaptive strategy was introduced for maintaining synchronization on unpredictably evolving networks [Sorrentino and Ott, Phys. Rev. Lett. 100, 114101 (2008), 10.1103/PhysRevLett.100.114101], which yet does not consider the noise disturbances widely existing in networks' environments. We provide here strategies to control dynamical synchronization on slowly and unpredictably evolving networks subjected to noise disturbances which are observed at the node and at the communication channel level. With our strategy, the nodes' coupling strength is adaptively adjusted with the aim of controlling synchronization, and according only to their received signal and noise disturbances. We first provide a theoretical analysis of the control scheme by introducing an error potential function to seek for the minimization of the synchronization error. Then, we show numerical experiments which verify our theoretical results. In particular, it is found that our adaptive strategy is effective even for the case in which the dynamics of the uncontrolled network would be explosive (i.e., the states of all the nodes would diverge to infinity).

The anorectic agent, lorcaserin, disturbs estrous cyclicity and produces endometrial hyperplasia without affecting ovarian population in female rats.

PubMed

Abdel-Latif, Raghda T; Zaitone, Sawsan A; Abdel-Mottaleb, Yousra; El-Maraghy, Nabila N

2017-08-15

The present study aims to investigate the effect of the new anorectic agent, lorcaserin, on estrous cyclicity, reproductive hormones and folliculogenesis in female mature rats. Rats were divided into four groups; Group i: control group. Group ii-iv: rats treated with lorcaserin (5, 10 or 30mg/kg/day, p.o.), respectively. The treatment continued for 28days. Lorcaserin (5 or 10mg/kg) caused estrous cycle disturbance in 40% of treated rats while the high dose (30mg/kg) produced disturbances in 100% of the treated rats. Lorcaserin (5-30mg/kg) altered some of female hormones where it enhanced estradiol but reduced luteinizing hormone. Minimal edema with congested vessels was observed in the medulla of ovarian sections. Further, epithelial and uterine sections showed hyperplasia. Taken together, the present results demonstrated that lorcaserin affected some reproductive hormones, disturbed estrous cyclicity and induced histopathological changes in the ovaries and uteri without affecting the ovarian populations. Therefore, lorcaserin should be used with caution in women of child bearing potential until adequate clinical safety data are available. Copyright © 2017 Elsevier Inc. All rights reserved.

Environmental perturbations can be detected through microwear texture analysis in two platyrrhine species from Brazilian Amazonia.

PubMed

Estalrrich, Almudena; Young, Mariel B; Teaford, Mark F; Ungar, Peter S

2015-11-01

Recent dental microwear studies have shown that fossil species differ from one another in texture attributes-both in terms of central tendency and dispersion. Most comparative studies used to interpret these results have relied on poorly provenienced museum samples that are not well-suited to consideration of within species variation in diet. Here we present a study of two species of platyrrhine monkeys, Alouatta belzebul (n = 60) and Sapajus apella (n = 28) from Pará State in the Brazilian Amazon in order to assess effects of habitat variation on microwear (each species was sampled from forests that differ in the degree of disturbance from highly disturbed to minimally disturbed). Results indicate that microwear texture values vary between habitats-more for the capuchins than the howler monkeys. This is consistent with the notion that diets of the more folivorous A. belzebul are less affected by habitat disturbance than those of the more frugivorous S. apella. It also suggests that microwear holds the potential to reflect comparatively subtle differences in within-species variation in fossil taxa if sample size and control over paleohabitat allow. © 2015 Wiley Periodicals, Inc.

Control oriented concentrating solar power (CSP) plant model and its applications

NASA Astrophysics Data System (ADS)

Luo, Qi

Solar receivers in concentrating solar thermal power plants (CSP) undergo over 10,000 start-ups and shutdowns, and over 25,000 rapid rate of change in temperature on receivers due to cloud transients resulting in performance degradation and material fatigue in their expected lifetime of over 30 years. The research proposes to develop a three-level controller that uses multi-input-multi-output (MIMO) control technology to minimize the effect of these disturbances, improve plant performance, and extend plant life. The controller can be readily installed on any vendor supplied state-of-the-art control hardware. We propose a three-level controller architecture using multi-input-multi-output (MIMO) control for CSP plants that can be implemented on existing plants to improve performance, reliability, and extend the life of the plant. This architecture optimizes the performance on multiple time scalesreactive level (regulation to temperature set points), tactical level (adaptation of temperature set points), and strategic level (trading off fatigue life due to thermal cycling and current production). This controller unique to CSP plants operating at temperatures greater than 550 °C, will make CSPs competitive with conventional power plants and contribute significantly towards the Sunshot goal of 0.06/kWh(e), while responding with agility to both market dynamics and changes in solar irradiance such as due to passing clouds. Moreover, our development of control software with performance guarantees will avoid early stage failures and permit smooth grid integration of the CSP power plants. The proposed controller can be implemented with existing control hardware infrastructure with little or no additional equipment. In the thesis, we demonstrate a dynamics model of CSP, of which different components are modelled with different time scales. We also show a real time control strategy of CSP control oriented model in steady state. Furthermore, we shown different controllers design for disturbance rejection and reference tracking to handle complex receiver dynamics under system disturbance and measurement noise. At last, we show different applications of this control oriented CSP model including life cycle enhancement and electricity load forecasting using both neural network and regression tree.

Active disturbance rejection control based robust output feedback autopilot design for airbreathing hypersonic vehicles.

PubMed

Tian, Jiayi; Zhang, Shifeng; Zhang, Yinhui; Li, Tong

2018-03-01

Since motion control plant (y (n) =f(⋅)+d) was repeatedly used to exemplify how active disturbance rejection control (ADRC) works when it was proposed, the integral chain system subject to matched disturbances is always regarded as a canonical form and even misconstrued as the only form that ADRC is applicable to. In this paper, a systematic approach is first presented to apply ADRC to a generic nonlinear uncertain system with mismatched disturbances and a robust output feedback autopilot for an airbreathing hypersonic vehicle (AHV) is devised based on that. The key idea is to employ the feedback linearization (FL) and equivalent input disturbance (EID) technique to decouple nonlinear uncertain system into several subsystems in canonical form, thus it would be much easy to directly design classical/improved linear/nonlinear ADRC controller for each subsystem. It is noticed that all disturbances are taken into account when implementing FL rather than just omitting that in previous research, which greatly enhances controllers' robustness against external disturbances. For autopilot design, ADRC strategy enables precise tracking for velocity and altitude reference command in the presence of severe parametric perturbations and atmospheric disturbances only using measurable output information. Bounded-input-bounded-output (BIBO) stable is analyzed for closed-loop system. To illustrate the feasibility and superiority of this novel design, a series of comparative simulations with some prominent and representative methods are carried out on a benchmark longitudinal AHV model. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

United States Population-Based Estimates of Patient-Reported Outcomes Measurement Information System Symptom and Functional Status Reference Values for Individuals With Cancer.

PubMed

Jensen, Roxanne E; Potosky, Arnold L; Moinpour, Carol M; Lobo, Tania; Cella, David; Hahn, Elizabeth A; Thissen, David; Smith, Ashley Wilder; Ahn, Jaeil; Luta, George; Reeve, Bryce B

2017-06-10

Purpose To estimate cancer population-based reference values in the United States for eight PROMIS (Patient-Reported Outcomes Measurement Information System) domains by age and stage of disease. Patients and Methods For the Measuring Your Health (MY-Health) study, persons newly diagnosed with cancer (prostate, colorectal, non-small-cell lung, non-Hodgkin lymphoma, breast, uterine, or cervical) from 2010 to 2012 (N = 5,284) were recruited through the National Cancer Institute's SEER Program. Participants were mailed surveys 6 to 13 months after diagnosis. Raking by race/ethnicity, age, and stage generated weighted average PROMIS scores for pain interference, fatigue, anxiety, depression, sleep disturbance, physical function, ability to participate in social roles, and cognitive function. PROMIS measures are standardized to a T-score metric, with a score of 50 representing the general US population mean. Clinically meaningful differences were defined as a 3-point difference in scores. Results Several reference values (means) for patients with cancer were worse than the general United States population norms of 50. These include pain interference (52.4), fatigue (52.2), and physical function (44.1). Reference values were highest (ie, showed greatest symptom burden) in lung cancer (pain interference, 55.5; fatigue, 57.3; depression, 51.4) and cervical cancer (anxiety, 53.2; sleep disturbance, 53.4). Reference values for patients age 65 to 84 years reported lower sleep disturbance, anxiety, and depression, and better cognitive function than younger patients. Cancer reference values were poorer among those with advanced disease compared with patients with limited or no evidence of disease, specifically physical function (41.1 v 46.6, respectively), fatigue (55.8 v 50.2, respectively), and pain interference (55.2 v 50.9, respectively). Conclusion In a large, population-based sample of patients with recently diagnosed cancer, we observed symptom severity and functional deficits by age, stage, and cancer type consistent with the expected impact of cancer diagnosis and treatment. These United States cancer reference values can help facilitate interpretation of the PROMIS domain scores in research studies or in clinical applications that measure and evaluate the symptom and functional burden patients with cancer experience after initial treatment.

New modeling method and mechanism analyses for active control of interior noise in an irregular enclosure using piezoelectric actuators.

PubMed

Geng, Hou C; Rao, Zhu S; Han, Zu S

2003-03-01

A new modeling method is developed in this paper for the active minimization of noise within a three-dimensional irregular enclosure using distributed lead zirconate titanate piezoelectric (PZT) actuators, and the control mechanisms for irregular enclosure are analyzed. The irregular enclosure is modeled with four rigid walls and two simply supported flexible panels, and PZT actuators are bound to one of the flexible panels. The process of the new modeling method is as follows. First, the modal coupling method is used to establish the motion equations, which contain important coefficients such as modal masses and modal coupling coefficients, etc., of acoustic-structural-piezoelectric coupling system. Then, the acoustic modes and the modal masses of irregular enclosure are calculated by numerical methods. Last, the modal coupling coefficients in motion equations are calculated according to the numerical results of the acoustic modes of irregular enclosure and the modes of two panels. The validity of this modeling method is verified by a regular hexahedron enclosure. Two cost functions are applied to this model. With the two cost functions, good results are obtained in minimizing the sound-pressure level (SPL) within irregular enclosure according to numerical investigations. By comparing the results obtained under controlled and uncontrolled states, the control mechanisms of the system are discussed. It is found that the control mechanisms vary with disturbance frequencies. At most disturbance frequencies, the SPL within enclosure is reduced by restructuring the modes of two panels simultaneously. When the disturbance frequency comes close to one of the natural frequencies of panel a, the dominant mode of panel a is suppressed, while the modes of panel b are reconstructed. While the disturbance frequency is near one of the natural frequencies of panel b, the modes of two panels are restructured at the same time.

Reinforcement-learning-based output-feedback control of nonstrict nonlinear discrete-time systems with application to engine emission control.

PubMed

Shih, Peter; Kaul, Brian C; Jagannathan, Sarangapani; Drallmeier, James A

2009-10-01

A novel reinforcement-learning-based output adaptive neural network (NN) controller, which is also referred to as the adaptive-critic NN controller, is developed to deliver the desired tracking performance for a class of nonlinear discrete-time systems expressed in nonstrict feedback form in the presence of bounded and unknown disturbances. The adaptive-critic NN controller consists of an observer, a critic, and two action NNs. The observer estimates the states and output, and the two action NNs provide virtual and actual control inputs to the nonlinear discrete-time system. The critic approximates a certain strategic utility function, and the action NNs minimize the strategic utility function and control inputs. All NN weights adapt online toward minimization of a performance index, utilizing the gradient-descent-based rule, in contrast with iteration-based adaptive-critic schemes. Lyapunov functions are used to show the stability of the closed-loop tracking error, weights, and observer estimates. Separation and certainty equivalence principles, persistency of excitation condition, and linearity in the unknown parameter assumption are not needed. Experimental results on a spark ignition (SI) engine operating lean at an equivalence ratio of 0.75 show a significant (25%) reduction in cyclic dispersion in heat release with control, while the average fuel input changes by less than 1% compared with the uncontrolled case. Consequently, oxides of nitrogen (NO(x)) drop by 30%, and unburned hydrocarbons drop by 16% with control. Overall, NO(x)'s are reduced by over 80% compared with stoichiometric levels.

Harmonization of Multiple Forest Disturbance Data to Create a 1986-2011 Database for the Conterminous United States

NASA Astrophysics Data System (ADS)

Soulard, C. E.; Acevedo, W.; Yang, Z.; Cohen, W. B.; Stehman, S. V.; Taylor, J. L.

2015-12-01

A wide range of spatial forest disturbance data exist for the conterminous United States, yet inconsistencies between map products arise because of differing programmatic objectives and methodologies. Researchers on the Land Change Research Project (LCRP) are working to assess spatial agreement, characterize uncertainties, and resolve discrepancies between these national level datasets, in regard to forest disturbance. Disturbance maps from the Global Forest Change (GFC), Landfire Vegetation Disturbance (LVD), National Land Cover Dataset (NLCD), Vegetation Change Tracker (VCT), Web-enabled Landsat Data (WELD), and Monitoring Trends in Burn Severity (MTBS) were harmonized using a pixel-based data fusion process. The harmonization process reconciled forest harvesting, forest fire, and remaining forest disturbance across four intervals (1986-1992, 1992-2001, 2001-2006, and 2006-2011) by relying on convergence of evidence across all datasets available for each interval. Pixels with high agreement across datasets were retained, while moderate-to-low agreement pixels were visually assessed and either manually edited using reference imagery or discarded from the final disturbance map(s). National results show that annual rates of forest harvest and overall fire have increased over the past 25 years. Overall, this study shows that leveraging the best elements of readily-available data improves forest loss monitoring relative to using a single dataset to monitor forest change, particularly by reducing commission errors.

Disturbance of a rare seabird by ship-based tourism in a marine protected area

USGS Publications Warehouse

Marcella, Timothy K.; Gende, Scott M.; Roby, Daniel D.; Allignol, Arthur

2017-01-01

Managers of marine protected areas (MPAs) must often seek ways to allow for visitation while minimizing impacts to the resources they are intended to protect. Using shipboard observers, we quantified the “zone of disturbance” for Kittlitz’s and marbled murrelets (Brachyramphus brevirostris and B. marmoratus) exposed to large cruise ships traveling through Glacier Bay National Park, one of the largest MPAs in North America. In the upper reaches of Glacier Bay, where Kittlitz’s murrelets predominated, binary logistic regression models predicted that 61% of all murrelets within 850 m perpendicular distance of a cruise ship were disturbed (defined as flushing or diving), whereas in the lower reaches, where marbled murrelets predominated, this percentage increased to 72%. Using survival analysis, murrelets in both reaches were found to react at greater distances when ships approached indirectly, presumably because of the ship’s larger profile, suggesting murrelets responded to visual rather than audio cues. No management-relevant covariates (e.g., ship velocity, route distance from shore) were found to be important predictors of disturbance, as distance from ship to murrelet accounted for > 90% of the explained variation in murrelet response. Utilizing previously published murrelet density estimates from Glacier Bay, and applying an average empirical disturbance probability (68%) out to 850 m from a cruise ship’s typical route, we estimated that a minimum of 9.8–19.6% of all murrelets in Glacier Bay are disturbed per ship entry. Whether these disturbance levels are inconsistent with Park management objectives, which include conserving wildlife as well as providing opportunities for visitation, depends in large part on whether disturbance events caused by cruise ships have impacts on murrelet fitness, which remains uncertain.

Disturbance of a rare seabird by ship-based tourism in a marine protected area

PubMed Central

Allignol, Arthur

2017-01-01

Managers of marine protected areas (MPAs) must often seek ways to allow for visitation while minimizing impacts to the resources they are intended to protect. Using shipboard observers, we quantified the “zone of disturbance” for Kittlitz’s and marbled murrelets (Brachyramphus brevirostris and B. marmoratus) exposed to large cruise ships traveling through Glacier Bay National Park, one of the largest MPAs in North America. In the upper reaches of Glacier Bay, where Kittlitz’s murrelets predominated, binary logistic regression models predicted that 61% of all murrelets within 850 m perpendicular distance of a cruise ship were disturbed (defined as flushing or diving), whereas in the lower reaches, where marbled murrelets predominated, this percentage increased to 72%. Using survival analysis, murrelets in both reaches were found to react at greater distances when ships approached indirectly, presumably because of the ship’s larger profile, suggesting murrelets responded to visual rather than audio cues. No management-relevant covariates (e.g., ship velocity, route distance from shore) were found to be important predictors of disturbance, as distance from ship to murrelet accounted for > 90% of the explained variation in murrelet response. Utilizing previously published murrelet density estimates from Glacier Bay, and applying an average empirical disturbance probability (68%) out to 850 m from a cruise ship’s typical route, we estimated that a minimum of 9.8–19.6% of all murrelets in Glacier Bay are disturbed per ship entry. Whether these disturbance levels are inconsistent with Park management objectives, which include conserving wildlife as well as providing opportunities for visitation, depends in large part on whether disturbance events caused by cruise ships have impacts on murrelet fitness, which remains uncertain. PMID:28489902

Deriving the Hirshfeld partitioning using distance metrics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heidar-Zadeh, Farnaz; Ayers, Paul W., E-mail: ayers@mcmaster.ca; Bultinck, Patrick

2014-09-07

The atoms in molecules associated with the Hirshfeld partitioning minimize the generalized Hellinger-Bhattacharya distance to the reference pro-atom densities. Moreover, the reference pro-atoms can be chosen by minimizing the distance between the pro-molecule density and the true molecular density. This provides an alternative to both the heuristic “stockholder” and the mathematical information-theoretic interpretations of the Hirshfeld partitioning. These results extend to any member of the family of f-divergences.

Arousal from sleep - The physiological and subjective effects of a 15 dB/A/ reduction in aircraft flyover noise

NASA Technical Reports Server (NTRS)

Levere, T. E.; Davis, N.

1977-01-01

The present research was concerned with whether or not a 15 dB(A) reduction in overall noise level would lessen the sleep disturbing properties of jet aircraft flyover noise and, if less disturbing, whether this would be subjectively appreciated by the sleeping individual. The results indicate that a reduction of 15 dB (A) does result in less sleep disruption but only during sleep characterized by fast-wave electroencephalographic activity. During sleep characterized by slow-wave electroencephalographic activity, such a reduction in the sleep-disturbing properties of jet aircraft noise has little effect. Moreover, even when effective during fast-wave sleep, the decreased arousal produced by the lower noise levels is not subjectively appreciated by the individual in terms of his estimate of the quality of his night's sleep. Thus, reducing the overall noise level of jet aircraft flyovers by some 15 dB(A), is, at best, minimally beneficial to sleep.

The microgravity environment of the D1 mission

NASA Technical Reports Server (NTRS)

Hamacher, H.; Merbold, U.; Jilg, R.

1990-01-01

Some characteristic features and results of D1 microgravity measurements are discussed as performed in the Material Science Double Rack (MSDR) and the Materials Science Double Rack for Experiment Modules and Apparatus (MEDEA). Starting with a brief review of the main potential disturbances, the payload aspects of interest to the analysis and the accelerometer measuring systems are described. The microgravity data are analyzed with respect to selected mission events such as thruster firings for attitude control, operations of Spacelab experiment facilities, vestibular experiments and crew activities. The origins are divided into orbit, vehicle, and experiment induced perturbations. It has been found that the microgravity-environment is dictated mainly by payload-induced perturbations. To reduce the microgravity-level, the design of some experiment facilities has to be improved by minimizing the number of moving parts, decoupling of disturbing units from experiment facilities, by taking damping measures, etc. In addition, strongly disturbing experiments and very sensitive investigations should be performed in separate mission phases.

Characteristics of Sediment Transportation in Two Contrasting Oak Forested Watersheds in the Lesser Central Himalaya, India

NASA Astrophysics Data System (ADS)

Qazi, N. U. Q.; Bruijnzeel, S., Sr.; Rai, S. P., Sr.

2015-12-01

Sediment transfer from mountainous areas to lowland areas is one of the most important geomorphological processes globally with the bulk of the sediment yield from such areas typically deriving from mass wastage processes. This study presents monthly, seasonal and annual variations in sediment transport (both suspended load and bedload) as well as dissolved loads over three consecutive water years (2008-2011) for two small forested watersheds with contrasting levels of forest disturbance in the Lesser Himalaya of Northwest India. Seasonal and annual suspended sediment yields were strongly influenced by amounts of rainfall and streamflow and showed a 10-63 fold range between wet and dry years. Of the annual load, some 93% was produced on average during the monsoon season (June-September). Sediment production by the disturbed forest catchment was 1.9-fold (suspended sediment) to 5.9-fold (bedload) higher than that for the well-stocked forest catchment. By contrast, dissolved loads varied much less between years, seasons (although minimal during the dry summer season), and degree of forest disturbance. Total mechanical denudation rates were 1.6 times and 4.6 times larger than chemical denudation rates for the little disturbed and the heavily disturbed forest catchment, respectively whereas overall denudation rates were estimated at 0.69 and 1.04 mm per 1000 years, respectively.

Root distributions of Eurotia lanata in association with two species of agropyron on disturbed soils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bonham, C.D.; Mack, S.E.

1990-12-01

Root distributions of Eurotia lanata in association with Agropyron inerme and A. smithii on soils that were mechanically disturbed were studied. Root diagrams and measurements were made for plants in competitive pairs from soils representing two depths of soil disturbance (30 cm and 1 m) and control areas. Soil disturbance was observed to reduce significantly depth of root penetration and root concentration of E. lanata. Root depth, maximum lateral spread of roots, and zone of root concentration of E. lanata plants were greatest in pure stand pairs. Eurotia lanata associated with A. inerme had the smallest root concentration. The areamore » occupied by E. lanata roots was 59% greater in pure stands than when found adjacent to A. inerme. Agropyron inerme apparently used more available soil water in the top 20 cm of soil than did the shrub and resulted in reduced root growth for E. lanata. On the other hand, the asexual reproductive strategy of A. smithii, where roots and rhizomes were distributed both vertically and laterally, enables the grass species to minimize detrimental effects of its association with E. lanata. The results have important implications for selection of species combinations to reseed disturbed soils in semiarid or arid environments. In particular, attention should be given to use of species that have differing specializations as indicated by their growth and morphology.« less

Disturbance metrics predict a wetland Vegetation Index of Biotic Integrity

USGS Publications Warehouse

Stapanian, Martin A.; Mack, John; Adams, Jean V.; Gara, Brian; Micacchion, Mick

2013-01-01

Indices of biological integrity of wetlands based on vascular plants (VIBIs) have been developed in many areas in the USA. Knowledge of the best predictors of VIBIs would enable management agencies to make better decisions regarding mitigation site selection and performance monitoring criteria. We use a novel statistical technique to develop predictive models for an established index of wetland vegetation integrity (Ohio VIBI), using as independent variables 20 indices and metrics of habitat quality, wetland disturbance, and buffer area land use from 149 wetlands in Ohio, USA. For emergent and forest wetlands, predictive models explained 61% and 54% of the variability, respectively, in Ohio VIBI scores. In both cases the most important predictor of Ohio VIBI score was a metric that assessed habitat alteration and development in the wetland. Of secondary importance as a predictor was a metric that assessed microtopography, interspersion, and quality of vegetation communities in the wetland. Metrics and indices assessing disturbance and land use of the buffer area were generally poor predictors of Ohio VIBI scores. Our results suggest that vegetation integrity of emergent and forest wetlands could be most directly enhanced by minimizing substrate and habitat disturbance within the wetland. Such efforts could include reducing or eliminating any practices that disturb the soil profile, such as nutrient enrichment from adjacent farm land, mowing, grazing, or cutting or removing woody plants.

Genetics Home Reference: Bart-Pumphrey syndrome

MedlinePlus

... 26 in cells, and may interfere with the function of other connexin proteins. This disruption could affect skin growth and also impair hearing by disturbing the conversion of sound waves to nerve impulses. Learn more about the gene ...

Genetics Home Reference: palmoplantar keratoderma with deafness

MedlinePlus

... 26 in cells, and may interfere with the function of other connexin proteins. This disruption could affect skin growth and also impair hearing by disturbing the conversion of sound waves to nerve impulses. Palmoplantar keratoderma with deafness can ...

Integrated model reference adaptive control and time-varying angular rate estimation for micro-machined gyroscopes

NASA Astrophysics Data System (ADS)

Tsai, Nan-Chyuan; Sue, Chung-Yang

2010-02-01

Owing to the imposed but undesired accelerations such as quadrature error and cross-axis perturbation, the micro-machined gyroscope would not be unconditionally retained at resonant mode. Once the preset resonance is not sustained, the performance of the micro-gyroscope is accordingly degraded. In this article, a direct model reference adaptive control loop which is integrated with a modified disturbance estimating observer (MDEO) is proposed to guarantee the resonant oscillations at drive mode and counterbalance the undesired disturbance mainly caused by quadrature error and cross-axis perturbation. The parameters of controller are on-line innovated by the dynamic error between the MDEO output and expected response. In addition, Lyapunov stability theory is employed to examine the stability of the closed-loop control system. Finally, the efficacy of numerical evaluation on the exerted time-varying angular rate, which is to be detected and measured by the gyroscope, is verified by intensive simulations.

Application of quadratic optimization to supersonic inlet control.

NASA Technical Reports Server (NTRS)

Lehtinen, B.; Zeller, J. R.

1972-01-01

This paper describes the application of linear stochastic optimal control theory to the design of the control system for the air intake, the inlet, of a supersonic air-breathing propulsion system. The controls must maintain a stable inlet shock position in the presence of random airflow disturbances and prevent inlet unstart. Two different linear time invariant controllers are developed. One is designed to minimize a nonquadratic index, the expected frequency of inlet unstart, and the other is designed to minimize the mean square value of inlet shock motion. The quadratic equivalence principle is used to obtain a linear controller that minimizes the nonquadratic index. The two controllers are compared on the basis of unstart prevention, control effort requirements, and frequency response. It is concluded that while controls designed to minimize unstarts are desirable in that the index minimized is physically meaningful, computation time required is longer than for the minimum mean square shock position approach. The simpler minimum mean square shock position solution produced expected unstart frequency values which were not significantly larger than those of the nonquadratic solution.

Reaction Wheel Disturbance Model Extraction Software - RWDMES

NASA Technical Reports Server (NTRS)

Blaurock, Carl

2009-01-01

The RWDMES is a tool for modeling the disturbances imparted on spacecraft by spinning reaction wheels. Reaction wheels are usually the largest disturbance source on a precision pointing spacecraft, and can be the dominating source of pointing error. Accurate knowledge of the disturbance environment is critical to accurate prediction of the pointing performance. In the past, it has been difficult to extract an accurate wheel disturbance model since the forcing mechanisms are difficult to model physically, and the forcing amplitudes are filtered by the dynamics of the reaction wheel. RWDMES captures the wheel-induced disturbances using a hybrid physical/empirical model that is extracted directly from measured forcing data. The empirical models capture the tonal forces that occur at harmonics of the spin rate, and the broadband forces that arise from random effects. The empirical forcing functions are filtered by a physical model of the wheel structure that includes spin-rate-dependent moments (gyroscopic terms). The resulting hybrid model creates a highly accurate prediction of wheel-induced forces. It accounts for variation in disturbance frequency, as well as the shifts in structural amplification by the whirl modes, as the spin rate changes. This software provides a point-and-click environment for producing accurate models with minimal user effort. Where conventional approaches may take weeks to produce a model of variable quality, RWDMES can create a demonstrably high accuracy model in two hours. The software consists of a graphical user interface (GUI) that enables the user to specify all analysis parameters, to evaluate analysis results and to iteratively refine the model. Underlying algorithms automatically extract disturbance harmonics, initialize and tune harmonic models, and initialize and tune broadband noise models. The component steps are described in the RWDMES user s guide and include: converting time domain data to waterfall PSDs (power spectral densities); converting PSDs to order analysis data; extracting harmonics; initializing and simultaneously tuning a harmonic model and a wheel structural model; initializing and tuning a broadband model; and verifying the harmonic/broadband/structural model against the measurement data. Functional operation is through a MATLAB GUI that loads test data, performs the various analyses, plots evaluation data for assessment and refinement of analysis parameters, and exports the data to documentation or downstream analysis code. The harmonic models are defined as specified functions of frequency, typically speed-squared. The reaction wheel structural model is realized as mass, damping, and stiffness matrices (typically from a finite element analysis package) with the addition of a gyroscopic forcing matrix. The broadband noise model is realized as a set of speed-dependent filters. The tuning of the combined model is performed using nonlinear least squares techniques. RWDMES is implemented as a MATLAB toolbox comprising the Fit Manager for performing the model extraction, Data Manager for managing input data and output models, the Gyro Manager for modifying wheel structural models, and the Harmonic Editor for evaluating and tuning harmonic models. This software was validated using data from Goodrich E wheels, and from GSFC Lunar Reconnaissance Orbiter (LRO) wheels. The validation testing proved that RWDMES has the capability to extract accurate disturbance models from flight reaction wheels with minimal user effort.

Effects of local land-use planning on development and disturbance in riparian areas

Treesearch

Judith A. Dempsey; Andrew J. Plantinga; Jeffrey D. Kline; Joshua J. Lawler; Sebastian Martinuzzi; Volker C. Radeloff; Daniel P. Bigelow

2017-01-01

Land-use change can significantly affect the provision of ecosystem services. On a local scale, zoning laws and other land-use regulations are commonly used to influence land-use change, but their effectiveness is often unclear. We evaluate the effectiveness of local land-use planning in concentrating development and minimizing impacts in riparian areas. We use...

Foreign Military Sales Pricing Principles for Electronic Technical Manuals

DTIC Science & Technology

2004-06-01

companies provide benefits such as flexible hours, flexible days, and telecommuting . This information is useful because facilities costs and overhead can...personnel are listed below: Occupation Title Employment (1) Median Hourly Mean Hourly Mean Annual (2) Computer and Mathematical Science...be minimized or significantly reduced for companies providing this benefit . There was one disturbing statistic from this survey. Despite the

Substituting root numbers for length: Improving the use of minirhizotrons to study fine root dynamics

Treesearch

Tracey L. Crocker; Ron L. Hendrick; Roger W. Ruess; Kurt S. Pregitzer; Andrew J. Burton; Michael F. Allen; Jianping Shan; Lawrence A. Morris

2003-01-01

Minirhizotrons provide a unique way to repeatedly measure the production and fate of individual root segments, while minimizing soil disturbance and the confounding of spatial-temporal variation. However, the time associated with processing videotaped minirhizotron images limits the amount of data that can be extracted in a reasonable amount of time. We found that this...

Sediment movement from forest road systems-roads: a major contributor to erosion and stream sedimentation

Treesearch

Johnny M. Grace

2002-01-01

Nonpoint source pollution is a major concern related to natural resource management throughout the United States. Undisturbed forest lands typically have minimal erosion, less than 0.13 ton/acre (0.30 ton/hectare), due to the increased cover and surface roughness found in these areas. However, disturbances caused by forest management practices can result in...

Addressing Lead-Based Paint Hazards During Renovation, Remodeling, and Rehabilitation in Federally Owned and Assisted Housing. Student Manual for Use in HUD-Sponsored Lead-Safe Work Practices Training.

ERIC Educational Resources Information Center

Department of Housing and Urban Development, Washington, DC.

This student manual comprises the United States Environmental Protection Agency's model renovation training course designed for renovation, remodeling, and painting contractors. It provides information regarding the containment, minimization, and cleanup of lead hazards during activities that disturb lead painted surfaces. Introductory material…

[Contemporary place of the electroconvulsive therapy. Part 2. Clinical aspect].

PubMed

Zyssi, Tomasz; Rachel, Wojciech; Datka, Wojciech; Hese, Robert T; Gorczyca, Piotr; Szwajca, Krzysztof; Piekoszewski, Wojciech; Zięba, Andrzej

2015-01-01

Electroconvulsive therapy (ECT) is an important method of biological treatment in serious psychic disturbances. Similarly to drug therapy it is marked by a determined schematics of applying including the list of indications, contraindications, procedures of the performance, as well as the list of adverse invents. Applying defined schemas allows for minimizing the risk and influences the final effectiveness of therapy.

Performance of the Forest Vegetation Simulator in managed white spruce plantations influenced by eastern spruce budworm in northern Minnesota

Treesearch

Matthew B. Russell; Anthony W. D' Amato; Michael A. Albers; Christopher W. Woodall; Klaus J. Puettmann; Michael R. Saunders; Curtis L. VanderSchaaf

2015-01-01

Silvicultural strategies such as thinning may minimize productivity losses from a variety of forest disturbances, including forest insects. This study analyzed the 10-year postthinning response of stands and individual trees in thinned white spruce (Picea glauca [Moench] Voss) plantations in northern Minnesota, USA, with light to moderate defoliation...

Flood tolerance evaluation of bottomland oaks in a multi-channel field laboratory

Treesearch

Mark V. Coggeshall; J. W. Van Sambeek; Scott E. Schlarbaum

2005-01-01

A multi-channel field laboratory was designed and constructed by the University of Missouri Center for Agroforestry at the Horticulture and Agroforestry Research Center to assess the flood tolerance of forages and hardwood seedlings. This facility located in the Missouri River floodplain consists of twelve 6-m wide x 180-m long channels that had minimal disturbance to...

Effects of shallow natural gas well structures and associated roads on grassland songbird reproductive success in Alberta, Canada

PubMed Central

Koper, Nicola

2017-01-01

Grassland songbird populations across North America have experienced dramatic population declines due to habitat loss and degradation. In Canada, energy development continues to fragment and disturb prairie habitat, but effects of oil and gas development on reproductive success of songbirds in North American mixed-grass prairies remains largely unknown. From 2010–2012, in southeastern Alberta, Canada, we monitored 257 nests of two ground-nesting grassland songbird species, Savannah sparrow (Passerculus sandwichensis) and chestnut-collared longspur (Calcarius ornatus). Nest locations varied with proximity to and density of conventional shallow gas well structures and associated roads in forty-two 258-ha mixed-grass prairie sites. We estimated the probabilities of nest success and clutch size relative to gas well structures and roads. There was little effect of distance to or density of gas well structure on nest success; however, Savannah sparrow experienced lower nest success near roads. Clutch sizes were lower near gas well structures and cattle water sources. Minimizing habitat disturbance surrounding gas well structures, and reducing abundance of roads and trails, would help minimize impacts on reproductive success for some grassland songbirds. PMID:28355241

Abyssal ostracods from the South and Equatorial Atlantic Ocean: Biological and paleoceanographic implications

USGS Publications Warehouse

Yasuhara, Moriaki; Cronin, T. M.; Martinez, Arbizu P.

2008-01-01

We report the distribution of ostracods from ???5000 m depth from the Southeast and Equatorial Atlantic Ocean recovered from the uppermost 10 cm of minimally disturbed sediments taken by multiple-corer during the R/V Meteor DIVA2 expedition M63.2. Five cores yielded the following major deep-sea genera: Krithe, Henryhowella, Poseidonamicus, Legitimocythere, Pseudobosquetina, and Pennyella. All genera are widely distributed in abyssal depths in the world's oceans and common in Cenozoic deep-sea sediments. The total number of ostracod specimens is higher and ostracod shell preservation is better near the sediment-water interface, especially at the 0-1 cm core depths. Core slices from ???5 to 10 cm were barren or yielded a few poorly preserved specimens. The DIVA2 cores show that deep-sea ostracod species inhabit corrosive bottom water near the carbonate compensation depth (CCD) even though their calcareous valves are rarely preserved as fossils in sediment cores due to postmortem dissolution. Their occurrence at great water depths may partially explain the well-known global distributions of major deep-sea taxa in the world's oceans, although further expeditions using minimal-disturbance sampling devices are needed to fill geographic gaps. ?? 2008 Elsevier Ltd. All rights reserved.

Effects of shallow natural gas well structures and associated roads on grassland songbird reproductive success in Alberta, Canada.

PubMed

Yoo, Jenny; Koper, Nicola

2017-01-01

Grassland songbird populations across North America have experienced dramatic population declines due to habitat loss and degradation. In Canada, energy development continues to fragment and disturb prairie habitat, but effects of oil and gas development on reproductive success of songbirds in North American mixed-grass prairies remains largely unknown. From 2010-2012, in southeastern Alberta, Canada, we monitored 257 nests of two ground-nesting grassland songbird species, Savannah sparrow (Passerculus sandwichensis) and chestnut-collared longspur (Calcarius ornatus). Nest locations varied with proximity to and density of conventional shallow gas well structures and associated roads in forty-two 258-ha mixed-grass prairie sites. We estimated the probabilities of nest success and clutch size relative to gas well structures and roads. There was little effect of distance to or density of gas well structure on nest success; however, Savannah sparrow experienced lower nest success near roads. Clutch sizes were lower near gas well structures and cattle water sources. Minimizing habitat disturbance surrounding gas well structures, and reducing abundance of roads and trails, would help minimize impacts on reproductive success for some grassland songbirds.

The association between working hours and sleep disturbances according to occupation and gender.

PubMed

Kim, Bo Hwan; Lee, Hye-Eun

2015-01-01

We attempted to explore the relationship between working hours and sleep disturbance according to occupation and gender among Korean workers. Data were derived from the third Korean Working Conditions Survey, conducted in 2011 by the Korea Occupational Safety and Health Agency. From a total of 50,032 workers, 34,783 salaried contract workers were selected. Work hours were categorized as <40, 40-48 (reference), 49-60, and >60 h/week. The outcome variable was sleep disturbance, which was assessed by a single question item (During the past 12 months, have you experienced sleep disturbance or insomnia?). Multiple survey logistic regression models were performed after adjusting with age, education level, marital status, self-rated health, salary, shift work, smoking and alcohol drinking. Gender and occupation were stratified in these models. The adjusted odds ratio (OR) for sleep disturbance in male non-manual workers with long work hours (>60 h/week) was 3.017 [95% confidence interval (CI) 1.956-4.653]. In female non-manual workers who work 49-60 working hour per week, the OR was 1.525 (95% CI 1.034-2.249). Long working hours can be a risk factor for sleep disturbance in Korean workers. The association was especially prominent in male non-manual workers.

Monitoring Forest Degradation for a Case Study in Cambodia: Comparison of Landsat 8 and Sentinel-2 Imagery

NASA Astrophysics Data System (ADS)

Langner, Andreas; Miettinen, Jukka; Stibig, Hans-Jurgen

2016-08-01

We use a Normalized Burned Ratio (NBR) differential approach for detecting forest canopy disturbance caused by selective logging in evergreen tropical moist forests of central Cambodia. The general disturbance pattern obtained from Landsat 8 (30 m) imagery is largely compatible to Sentinel-2 (10 m), showing good conformity to high resolution RapidEye reference data. However, the 10 m spatial resolution of Sentinel-2 provides notably higher spatial detail and purer pixel values, increasing the potential for detecting fine and subtle forest canopy changes as indicators for potential forest degradation. We can expect further improvement for detecting short-lived disturbance signals in tropical forest canopies due to an increased revisit frequency (5 days) after the Sentinel-2B launch.

Crossflow Stability and Transition Experiments in Swept-Wing Flow

NASA Technical Reports Server (NTRS)

Dagenhart, J. Ray; Saric, William S.

1999-01-01

An experimental examination of crossflow instability and transition on a 45deg swept wing was conducted in the Arizona State University Unsteady Wind Tunnel. The stationary-vortex pattern and transition location are visualized by using both sublimating chemical and liquid-crystal coatings. Extensive hot-wire measurements were obtained at several measurement stations across a single vortex track. The mean and travelling wave disturbances were measured simultaneously. Stationary crossflow disturbance profiles were determined by subtracting either a reference or a span-averaged velocity profile from the mean velocity data. Mean, stationary crossflow, and traveling wave velocity data were presented as local boundary layer profiles and contour plots across a single stationary crossflow vortex track. Disturbance mode profiles and growth rates were determined. The experimental data are compared with predictions from linear stability theory.

Geomagnetic transmission disturbances and heavy-ion fluences observed in low Earth orbit during the solar energetic particle events of October 1989.

PubMed

Boberg, P R; Tylka, A J; Adams, J H; Beahm, L P; Fluckiger, E O; Kleis, T; Kobel, E

1996-01-01

The large solar energetic particle (SEP) events and simultaneous large geomagnetic disturbances observed during October 1989 posed a significant, rapidly evolving space radiation hazard. Using data from the GOES-7, NOAA-10, IMP-8 and LDEF satellites, we determined the geomagnetic transmission, heavy ion fluences, mean Fe ionic charge state, and effective radiation hazard observed in low Earth orbit (LEO) for these SEPs. We modeled the geomagnetic transmission by tracing particles through the combination of the internal International Geomagnetic Reference Field (IGRF) and the Tsyganenko (1989) magnetospheric field models, extending the modeling to large geomagnetic disturbances. We used our results to assess the radiation hazard such very large SEP events would pose in the anticipated 52 degrees inclination space station orbit.

Design of a Nested Eight-Channel Sodium and Four-Channel Proton Coil for 7 Tesla Knee Imaging

PubMed Central

Brown, Ryan; Madelin, Guillaume; Lattanzi, Riccardo; Chang, Gregory; Regatte, Ravinder R.; Sodickson, Daniel K.; Wiggins, Graham C.

2012-01-01

The critical design aim for a dual-tuned sodium/proton coil is to maximize sodium sensitivity and transmit field (B1+) homogeneity while simultaneously providing adequate proton sensitivity and homogeneity. While most dual-frequency coils utilize lossy high-impedance trap circuits or PIN diodes to allow dual-resonance, we explored a nested-coil design for sodium/proton knee imaging at 7T. A stand-alone eight-channel sodium receive array was implemented without standard dual-resonance circuitry to provide improved sodium signal-to-noise ratio (SNR) over a volume coil. A detunable sodium birdcage was added for homogeneous sodium excitation and a four-channel proton transmit-receive array was added to provide anatomical reference imaging and B0 shimming capability. Both modules were implemented with minimal disturbance to the eight-channel sodium array by managing their respective resonances and geometrical arrangement. In vivo sodium SNR was 1.2 to 1.7 times greater in the developed eight-channel array than in a mono-nuclear sodium birdcage coil, while the developed four-channel proton array provided SNR similar to that of a commercial mono-nuclear proton birdcage coil. PMID:22887123

Incremental Housing Development; An Approach In Meeting the Needs Of Low Cost Housing In Indonesia

NASA Astrophysics Data System (ADS)

Wibowo, A. H.; Larasati, D.

2018-05-01

As a country with a rapid population growth, there is a very high shortage of homes and need a quick solution to build houses for the community. The emerging solution is mass housing with industrialization system. As time goes by, this mass housing solution raises a new problem, the mass housing users are not satisfied with the existing home. Incremental development approach is considered as one of the solutions for solving the mass housing problem. Incremental development is a constructive approach that allows the separation of dwellings to be built, altered and dismantled without disturbing others. With this approach, dwelling is not seen as a finished product, but it’s a process where residents can participate in designing their own house according to the needs and economy capabilities. Furthermore, Housing provision is built according to minimal needs and it’s designed as a ‘permanent longlife’ and adaptable base. This paper will discuss the criteria of incremental house for low-income communities provided by the government. Literature studies and case studies are used to find the criteria for incremental house. Some criteria can be used as a reference for incremental house construction as a housing solution in Indonesia.

Quaternion-Based Unscented Kalman Filter for Accurate Indoor Heading Estimation Using Wearable Multi-Sensor System

PubMed Central

Yuan, Xuebing; Yu, Shuai; Zhang, Shengzhi; Wang, Guoping; Liu, Sheng

2015-01-01

Inertial navigation based on micro-electromechanical system (MEMS) inertial measurement units (IMUs) has attracted numerous researchers due to its high reliability and independence. The heading estimation, as one of the most important parts of inertial navigation, has been a research focus in this field. Heading estimation using magnetometers is perturbed by magnetic disturbances, such as indoor concrete structures and electronic equipment. The MEMS gyroscope is also used for heading estimation. However, the accuracy of gyroscope is unreliable with time. In this paper, a wearable multi-sensor system has been designed to obtain the high-accuracy indoor heading estimation, according to a quaternion-based unscented Kalman filter (UKF) algorithm. The proposed multi-sensor system including one three-axis accelerometer, three single-axis gyroscopes, one three-axis magnetometer and one microprocessor minimizes the size and cost. The wearable multi-sensor system was fixed on waist of pedestrian and the quadrotor unmanned aerial vehicle (UAV) for heading estimation experiments in our college building. The results show that the mean heading estimation errors are less 10° and 5° to multi-sensor system fixed on waist of pedestrian and the quadrotor UAV, respectively, compared to the reference path. PMID:25961384

Disorders Induced by Direct Occupational Exposure to Noise: Systematic Review

PubMed Central

Domingo-Pueyo, Andrea; Sanz-Valero, Javier; Wanden-Berghe, Carmina

2016-01-01

Background: To review the available scientific literature about the effects on health by occupational exposure to noise. Materials and Methods: A systematic review of the retrieved scientific literature from the databases MEDLINE (via PubMed), ISI-Web of Knowledge (Institute for Scientific Information), Cochrane Library Plus, SCOPUS, and SciELO (collection of scientific journals) was conducted. The following terms were used as descriptors and were searched in free text: “Noise, Occupational,” “Occupational Exposure,” and “Occupational Disease.” The following limits were considered: “Humans,” “Adult (more than 18 years),” and “Comparative Studies.” Results: A total of 281 references were retrieved, and after applying inclusion/exclusion criteria, 25 articles were selected. Of these selected articles, 19 studies provided information about hearing disturbance, four on cardiovascular disorders, one regarding respiratory alteration, and one on other disorders. Conclusions: It can be interpreted that the exposure to noise causes alterations in humans with different relevant outcomes, and therefore appropriate security measures in the work environment must be employed to minimize such an exposure and thereby to reduce the number of associated disorders. PMID:27762251

Aquaculture disturbance impacts the diet but not ecological linkages of a ubiquitous predatory fish

USGS Publications Warehouse

McPeek, Kathleen C.; McDonald, P. Sean; VanBlaricom, Glenn

2015-01-01

Aquaculture operations are a frequent and prominent cause of anthropogenic disturbance to marine and estuarine communities and may alter species composition and abundance. However, little is known about how such disturbances affect trophic linkages or ecosystem functions. In Puget Sound, Washington, aquaculture of the Pacific geoduck clam (Panopea generosa) is increasing and involves placing nets and polyvinyl chloride (PVC) tubes in intertidal areas to protect juvenile geoducks from predators. Initial studies of the structured phase of the farming cycle have documented limited impacts on the abundance of some species. To examine the effect of geoduck aquaculture on ecological linkages, the trophic relationships of a local ubiquitous consumer, Pacific staghorn sculpin (Leptocottus armatus), to its invertebrate prey were compared between geoduck aquaculture sites and nearby reference areas with no aquaculture. Mark-recapture data indicated that sculpin exhibit local site fidelity to cultured and reference areas. The stomach contents of sculpin and stable isotope signatures of sculpin and their prey were examined to study the trophic ecology of cultured and reference areas. Results showed that the structured phase of geoduck aquaculture initiated some changes to staghorn sculpin ecology, as reflected in sculpin diet through stomach content analysis. However, carbon and nitrogen stable isotopes revealed that the general food web function of sculpin remained unchanged. The source of carbon at the base of the food web and the trophic position of sculpin were not impacted by geoduck aquaculture. The study has important implications for geoduck aquaculture management and will inform regulatory decisions related to shellfish aquaculture policy.

[Cognitive performance in schizophrenia (paranoid vs residual subtype)].

PubMed

Dillon, Carol; Taragano, Fernando; Sarasola, Diego; Iturry, Mónica; Serrano, Cecilia; Raczkowski, Amalia; Allegri, Ricardo

2007-01-01

Several studies refer to the relationship between schizophrenia and cognitive dysfunctions. The most frequent disturbances accepted are the deficits in the executive, memory and verbal tests. However, there are few comparative data about the cognitive functioning of the different subtypes of schizophrenia. Analyze and compare the neuropsychological disturbances present in patients with paranoid and residual schizophrenia. Eleven patients with paranoid schizophrenia, eleven patients with residual schizophrenia (DSM-IV criteria), and thirty one normal subjects matched by age, educational level, and general cognitive level (Mini Mental State Examination (Folstein, 1975), were assessed with a semistructured psychiatric examination and an extensive neuropsychological battery. Significant differences were found in memory, language, and executive functions when schizophrenics were compared with normal subjects. Differences in similarities were found between paranoid and residual schizophrenics. Residual schizophrenics had more disturbances in neuropsychological tests in comparison with paranoid schizophrenics. Schizophrenics demonstrated disturbances in memory, language, executive functions and attention. Residual schizophrenics had more impairment in neuropsychological tests than paranoid schizophrenics.

Distributed finite-time trajectory tracking control for multiple nonholonomic mobile robots with uncertainties and external disturbances

NASA Astrophysics Data System (ADS)

Ou, Meiying; Sun, Haibin; Gu, Shengwei; Zhang, Yangyi

2017-11-01

This paper investigates the distributed finite-time trajectory tracking control for a group of nonholonomic mobile robots with time-varying unknown parameters and external disturbances. At first, the tracking error system is derived for each mobile robot with the aid of a global invertible transformation, which consists of two subsystems, one is a first-order subsystem and another is a second-order subsystem. Then, the two subsystems are studied respectively, and finite-time disturbance observers are proposed for each robot to estimate the external disturbances. Meanwhile, distributed finite-time tracking controllers are developed for each mobile robot such that all states of each robot can reach the desired value in finite time, where the desired reference value is assumed to be the trajectory of a virtual leader whose information is available to only a subset of the followers, and the followers are assumed to have only local interaction. The effectiveness of the theoretical results is finally illustrated by numerical simulations.

Invited article: advanced drag-free concepts for future space-based interferometers: acceleration noise performance.

PubMed

Gerardi, D; Allen, G; Conklin, J W; Sun, K-X; DeBra, D; Buchman, S; Gath, P; Fichter, W; Byer, R L; Johann, U

2014-01-01

Future drag-free missions for space-based experiments in gravitational physics require a Gravitational Reference Sensor with extremely demanding sensing and disturbance reduction requirements. A configuration with two cubical sensors is the current baseline for the Laser Interferometer Space Antenna (LISA) and has reached a high level of maturity. Nevertheless, several promising concepts have been proposed with potential applications beyond LISA and are currently investigated at HEPL, Stanford, and EADS Astrium, Germany. The general motivation is to exploit the possibility of achieving improved disturbance reduction, and ultimately understand how low acceleration noise can be pushed with a realistic design for future mission. In this paper, we discuss disturbance reduction requirements for LISA and beyond, describe four different payload concepts, compare expected strain sensitivities in the "low-frequency" region of the frequency spectrum, dominated by acceleration noise, and ultimately discuss advantages and disadvantages of each of those concepts in achieving disturbance reduction for space-based detectors beyond LISA.

Proposed CMG momentum management scheme for space station

NASA Technical Reports Server (NTRS)

Bishop, L. R.; Bishop, R. H.; Lindsay, K. L.

1987-01-01

A discrete control moment gyro (CMG) momentum management scheme (MMS) applicable to spacecraft with principal axes misalignments, such as the proposed NASA dual keel space station, is presented in this paper. The objective of the MMS is to minmize CMG angular momentum storage requirements for maintaining the space station near local vertical in the presence of environmental disturbances. It utilizes available environmental disturbances, namely gravity gradient torques, to minimize CMG momentum storage. The MMS is executed once per orbit and generates a commanded torque equilibrium attitude (TEA) time history which consists of a yaw, pitch and roll angle command profile. Although the algorithm is called only once per orbit to compute the TEA profile, the space station will maneuver several discrete times each orbit.

Robust blood-glucose control using Mathematica.

PubMed

Kovács, Levente; Paláncz, Béla; Benyó, Balázs; Török, László; Benyó, Zoltán

2006-01-01

A robust control design on frequency domain using Mathematica is presented for regularization of glucose level in type I diabetes persons under intensive care. The method originally proposed under Mathematica by Helton and Merino, --now with an improved disturbance rejection constraint inequality--is employed, using a three-state minimal patient model. The robustness of the resulted high-order linear controller is demonstrated by nonlinear closed loop simulation in state-space, in case of standard meal disturbances and is compared with H infinity design implemented with the mu-toolbox of Matlab. The controller designed with model parameters represented the most favorable plant dynamics from the point of view of control purposes, can operate properly even in case of parameter values of the worst-case scenario.

Forest legacies, climate change, altered disturbance regimes, invasive species and water

USGS Publications Warehouse

Stohlgren, T.; Jarnevich, C.; Kumar, S.

2007-01-01

The factors that must be considered in seeking to predict changes in water availability has been examined. These factors are the following: forest legacies including logging, mining, agriculture, grazing, elimination of large carnivores, human-caused wildfire, and pollution; climate change and stream flow; altered disturbances such as frequency intensity and pattern of wildfires and insect outbreaks as well as flood control; lastly, invasive species like forest pests and pathogens. An integrated approach quantifying the current and past condition trends can be combined with spatial and temporal modeling to develop future change in forest structures and water supply. The key is a combination of geographic information system technologies with climate and land use scenarios, while preventing and minimizing the effects of harmful invasive species.

Anomalously Soft Non-Euclidean Springs

NASA Astrophysics Data System (ADS)

Levin, Ido; Sharon, Eran

2016-01-01

In this work we study the mechanical properties of a frustrated elastic ribbon spring—the non-Euclidean minimal spring. This spring belongs to the family of non-Euclidean plates: it has no spontaneous curvature, but its lateral intrinsic geometry is described by a non-Euclidean reference metric. The reference metric of the minimal spring is hyperbolic, and can be embedded as a minimal surface. We argue that the existence of a continuous set of such isometric minimal surfaces with different extensions leads to a complete degeneracy of the bulk elastic energy of the minimal spring under elongation. This degeneracy is removed only by boundary layer effects. As a result, the mechanical properties of the minimal spring are unusual: the spring is ultrasoft with a rigidity that depends on the thickness t as t7 /2 and does not explicitly depend on the ribbon's width. Moreover, we show that as the ribbon is widened, the rigidity may even decrease. These predictions are confirmed by a numerical study of a constrained spring. This work is the first to address the unusual mechanical properties of constrained non-Euclidean elastic objects.

Effects of industrial and investigator disturbance on Arctic-nesting geese

USGS Publications Warehouse

Meixell, Brandt W.; Flint, Paul L.

2017-01-01

Oil and gas development on the Arctic Coastal Plain (ACP) of Alaska, USA may have effects on Arctic-nesting birds. To estimate effects of industrial activity and investigator disturbance on avian productivity, we monitored nests of greater white-fronted geese (Anser albifrons) with digital cameras and periodic nest visits during 2013–2014 at 2 sites on the ACP. A disturbed site was adjacent to human-made infrastructure and industrial clean-up activities initiated at the onset of the study and a control site was >2 km from sources of industrial disturbance. We assessed variation in estimates of incubation constancy, nest survival, and predator behavior relative to site, year, and distance from industrial activity using nest photographs obtained at 1-minute intervals. We compared analysis of hourly nest survival informed by intensive monitoring with cameras to analysis of daily nest survival informed by traditional nest visit data obtained at intervals of 5–7 days to assess how method and time scale of sampling affect ecological inference. Geese in both sites exhibited high levels of nest attendance and initiated incubation breaks less than once per day. Observer-caused incubation breaks associated with nest visits ( = 37.8 min) were longer than other types of incubation breaks ( = 8.7 min), demonstrating a differential response by nesting geese to direct human encroachment versus indirect vehicular and aircraft traffic. During both years, geese were absent from nests more frequently in the disturbed ( = 0.9 breaks/day) than control ( = 0.6 breaks/day) site, and this break frequency was slightly higher for nests closer to industrial activity. In the year with high rates of depredation, nest survival was positively related to distance from industrial activity and abandoned infrastructure, consistent with predictions of industry-caused effects. This relationship, however, was not evident in the year with reduced predation pressure, likely because of annual variation in arctic fox (Vulpes lagopus) behavior. Analysis of nest survival probability informed by camera data allowed for detection of detailed patterns of variation that were not supported when using only visit data for the same nests. Observer visits were responsible for reductions of 7–35% in nest survival probability, highlighting the importance of minimizing, and controlling for, observer effects in studies of avian productivity. Indirect vehicular and aircraft disturbance posed less risk to nest survival than direct encroachment by observers at nest sites. Therefore, effects of industrial activities on avian productivity in the Arctic can be minimized through practices that limit direct encounters with nests. 

Metal detector system

NASA Technical Reports Server (NTRS)

Lee, R. D.

1970-01-01

Signal voltage resulting from the disturbance of an electromagnetic field within the volume of a sensitive area is compared with a reference ac voltage for polarity information, which identifies the material. System output amplitude and polarity indicate approximate size and type of metal, respectively.

75 FR 42432 - Northern Natural Gas Company, Southern Natural Gas Company, Florida Gas Transmission Company, LLC...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-21

... instructions on connecting to eLibrary, refer to the last page of this notice. Land Requirements for.... However, there would be some ground disturbance associated with offshore disconnects within federal waters...

Exchanging honest employment references: tiptoeing between defamation and negligent hiring.

PubMed

McConnell, Charles R

2007-01-01

In present day reference checking, many of the same organizations that seek as much information as possible about people they wish to hire resist giving out more than a bare minimum of information to other organizations. The strongest force driving this minimal reference information release is fear of legal action taken because of something said about an individual ("defamation," supposedly). Many employers seem so frightened of being sued for libel or slander that they share nothing of substance, usually not realizing that in supposedly protecting themselves against defamation charges, they are increasing the risk of negligent hiring charges. However, truthful reference information can be provided with minimal risk if it is provided in good faith, given only to those who have a legitimate need to know, is strictly job related, and is not communicated maliciously. References must always be provided objectively with information verifiable in personnel files.

Resilience: Concepts and Measures. Chapter 2

NASA Technical Reports Server (NTRS)

Westman, Walter E.

1986-01-01

Inertia, the resistance of an ecosystem property to change under stress, is distinguished from resilience, which refers to the degree, manner. and pace of change or recovery in ecosystem properties following disturbance. In turn, these two terms are differentiated from 'stability'. which is used here to refer to the pattern of natural fluctuation in ecosystem properties in the absence of major exogenous disturbance. Four component attributes of resilience are reviewed in the context of Mediterranean-climate examples. The elasticity component concerns the rate of recovery of an ecosystem property following disturbance; amplitude, the threshold of stress beyond which recovery to the initial state does not occur; hysteresis, the degree to which the pattern of recovery after stress differs from that of deterioration under chronic stress, and malleability the ease with which the ecosystem can become permanently altered. Each ecosystem property will typically reveal a different level of resilience to a given stress and stressor. The degree of recovery should not be expected to be complete in any event, due to sample variability and stochastic events. In cyclicallystable ecosystems, the pattern of recovery should be measured in light of this periodicity, and short-term (within-cycle) recovery distinguished from long-term (between-cycle) recovery. The prediction of resilience properties of ecosystems can be approached through a knowledge of the modular structure of foodwebs, through knowledge of the autecological adaptations of key species to the stressor, or through cumulative experience of the response to disturbance at the community level. At present there is much room for investigation of each of these approaches in Mediterranean-climate ecosystems.

Survey on eating disorder-related thoughts, behaviors, and their relationship with food intake and nutritional status in female high school students in Taiwan.

PubMed

Chang, Yu-Jhen; Lin, Wei; Wong, Yueching

2011-02-01

Eating disorders are now a global health problem for adolescents and young female adults. The level of eating disorders among young female adults is growing in Asian countries. Therefore, the purpose of this study was to investigate body image, weight concerns, eating attitudes, dietary intake, and nutritional status related to eating disorders of female high school students in Taiwan. A total of 1605 female high school students participated in this study. The written questionnaire included respondents' demographics and weight concerns, the Eating Attitudes Test-26 (EAT-26), and 24-hour dietary recall. Blood chemistry data were also collected. The data were analyzed using a Student t test, χ(2) analysis, and logistic regression. Disturbed eating attitudes and behaviors were found in 17.11% of participants (measured by an EAT-26 score ≥20). Logistic regression analyses showed that disturbed eating attitudes/behaviors were significantly associated with overestimation of body weight, unrealistic body weight goal, dissatisfaction with body weight, and weight loss experiences. The reported intakes of energy, protein, carbohydrate, zinc, and vitamins B6 and B12 were significantly lower in participants with disturbed eating patterns than in participants without disturbance issues. Conversely, participants with disturbed eating patterns had higher dietary and crude fiber intake than participants without disturbed eating issues. The percentage of participants with abnormal values of total iron-binding capacity and serum iron was significantly higher in those with disturbed eating patterns than in those without disturbed eating patterns. Disturbed eating attitudes/behaviors exist among female adolescents in Taiwan, and these behaviors jeopardize their nutritional status. The possibility of using the EAT-26 as a reference to predict the quality and quantity of food intake among female adolescents is worthy of further study.

Scaling Stream Flow Response to Forest Disturbance: the SID Project

NASA Astrophysics Data System (ADS)

Buttle, J. M.; Beall, F. D.; Creed, I. F.; Gordon, A. M.; Mackereth, R.; McLaughlin, J. W.; Sibley, P. K.

2004-05-01

We do not have a good understanding of the hydrologic implications of forest harvesting in Ontario, either for current or alternative management approaches. Attempts to address these implications face a three-fold problem: data on hydrologic response to forest disturbance in Ontario are lacking; most studies of these responses have been in regions with forest cover and hydrologic conditions that differ from the Ontario context; and these studies have generally been conducted at relatively small scales (<1 km2). It is generally assumed that hydrologic changes induced by forest disturbance should diminish with increasing scale due to the buffering capacity of large drainage basins. Recent modeling exercises and reanalysis of paired-basin results call this widespread applicability of this assumption into question, with important implications for assessing the cumulative impacts of forest disturbance on basin stream flow. The SID (Scalable Indicators of Disturbance) project combines stream flow monitoring across basin scales with the RHESSys modeling framework to identify forest disturbance impacts on stream flow characteristics in Ontario's major forest ecozones. As a precursor to identifying stream flow response to forest disturbance, we are examining the relative control of basin geology, topography, typology and topology on stream flow characteristics under undisturbed conditions. This will assist in identifying the dominant hydrologic processes controlling basin stream flow that must be incorporated into the RHESSys model framework in order to emulate forest disturbance and its hydrologic impacts. We present preliminary results on stream flow characteristics in a low-relief boreal forest landscape, and explore how the dominant processes influencing these characteristics change with basin scale in this landscape under both reference and disturbance conditions.

Basic self-disturbance predicts psychosis onset in the ultra high risk for psychosis "prodromal" population.

PubMed

Nelson, Barnaby; Thompson, Andrew; Yung, Alison R

2012-11-01

Phenomenological research indicates that disturbance of the basic sense of self may be a core phenotypic marker of schizophrenia spectrum disorders. Basic self-disturbance refers to a disruption of the sense of ownership of experience and agency of action and is associated with a variety of anomalous subjective experiences. In this study, we investigated the presence of basic self-disturbance in an "ultra high risk" (UHR) for psychosis sample compared with a healthy control sample and whether it predicted transition to psychotic disorder. Forty-nine UHR patients and 52 matched healthy control participants were recruited to the study. Participants were assessed for basic self-disturbance using the Examination of Anomalous Self-Experience (EASE) instrument. UHR participants were followed for a mean of 569 days. Levels of self-disturbance were significantly higher in the UHR sample compared with the healthy control sample (P < .001). Cox regression indicated that total EASE score significantly predicted time to transition (P < .05) when other significant predictors were controlled for. Exploratory analyses indicated that basic self-disturbance scores were higher in schizophrenia spectrum cases, irrespective of transition to psychosis, than nonschizophrenia spectrum cases. The results indicate that identifying basic self-disturbance in the UHR population may provide a means of further "closing in" on individuals truly at high risk of psychotic disorder, particularly of schizophrenia spectrum disorders. This may be of practical value by reducing inclusion of "false positive" cases in UHR samples and of theoretical value by shedding light on core phenotypic features of schizophrenia spectrum pathology.

Effects of harvest, fire, and pest/pathogen disturbances on the West Cascades ecoregion carbon balance.

PubMed

Turner, David P; Ritts, William D; Kennedy, Robert E; Gray, Andrew N; Yang, Zhiqiang

2015-12-01

Disturbance is a key influence on forest carbon dynamics, but the complexity of spatial and temporal patterns in forest disturbance makes it difficult to quantify their impacts on carbon flux over broad spatial domains. Here we used a time series of Landsat remote sensing images and a climate-driven carbon cycle process model to evaluate carbon fluxes at the ecoregion scale in western Oregon. Thirteen percent of total forest area in the West Cascades ecoregion was disturbed during the reference interval (1991-2010). The disturbance regime was dominated by harvesting (59 % of all area disturbed), with lower levels of fire (23 %), and pest/pathogen mortality (18 %). Ecoregion total Net Ecosystem Production was positive (a carbon sink) in all years, with greater carbon uptake in relatively cool years. Localized carbon source areas were associated with recent harvests and fire. Net Ecosystem Exchange (including direct fire emissions) showed greater interannual variation and became negative (a source) in the highest fire years. Net Ecosystem Carbon Balance (i.e. change in carbon stocks) was more positive on public that private forestland, because of a lower disturbance rate, and more positive in the decade of the 1990s than in the warmer and drier 2000s because of lower net ecosystem production and higher direct fire emissions in the 2000s. Despite recurrent disturbances, the West Cascades ecoregion has maintained a positive carbon balance in recent decades. The high degree of spatial and temporal resolution in these simulations permits improved attribution of regional carbon sources and sinks.

Quantitative exposure metrics for sleep disturbance and their association with breast cancer risk.

PubMed

Girschik, Jennifer; Fritschi, Lin; Erren, Thomas C; Heyworth, Jane

2013-05-01

It has been acknowledged by those in the field of sleep epidemiology that the current measures of sleep used in many epidemiological studies do not adequately capture the complexity and variability of sleep. A number of ways to improve the measurement of sleep have been proposed. This study aimed to assess the relationship between novel 'sleep disturbance' metrics, as expanded measures of sleep, and breast cancer risk. Data for this study were derived from a population-based case-control study conducted in Western Australia between 2009 and 2011. Participants completed a self-administered questionnaire that included questions about demographic, reproductive, and lifestyle factors in addition to questions on sleep. Four metrics of exposure to sleep disturbance (cumulative, average, duration, and peak) were developed. Unconditional logistic regression was used to examine the association between metrics of sleep disturbance and breast cancer risk. There was no evidence to support an association between any of the sleep disturbance metrics and breast cancer risk. Compared with the reference group of unexposed women, the fully adjusted ORs for cumulative sleep disturbance (harm) metric were as follows: 1st tertile 0.90 (95 % CI: 0.72-1.13); OR for the 2nd tertile 1.04 (95 % CI: 0.84-1.29); and OR for the 3rd tertile 1.02 (95 % CI: 0.82-1.27). This study found no association between several metrics of sleep disturbance and risk of breast cancer. Our experience with developing metrics of sleep disturbance may be of use to others in sleep epidemiology wishing to expand their scope of sleep measurement.

Vegetation component of geothermal EIS studies: Introduced plants, ecosystem stability, and geothermal development

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

This paper contributes new information about the impacts from introduced plant invasions on the native Hawaiian vegetation as consequences of land disturbance and geothermal development activities. In this regard, most geothermal development is expected to act as another recurring source of physical disturbance which favors the spread and maintenance of introduced organisms throughout the region. Where geothermal exploration and development activities extend beyond existing agricultural and residential development, they will become the initial or sole source of disturbance to the naturalized vegetation of the area. Kilauea has a unique ecosystem adapted to the dynamics of a volcanically active landscape. Themore » characteristics of this ecosystem need to be realized in order to understand the major threats to the ecosystem and to evaluate the effects of and mitigation for geothermal development in Puna. The native Puna vegetation is well adapted to disturbances associated with volcanic eruption, but it is ill-adapted to compete with alien plant species in secondary disturbances produced by human activities. Introduced plant and animal species have become a major threat to the continued presence of the native biota in the Puna region of reference.« less

Addressing neuropsychiatric disturbances during rehabilitation after traumatic brain injury: current and future methods

PubMed Central

Arciniegas, David B.

2011-01-01

Cognitive, emotional, behavioral, and sensorimotor disturbances are the principal clinical manifestations of traumatic brain injury (TBI) throughout the early postinjury period. These post-traumatic neuropsychiatric disturbances present substantial challenges to patients, their families, and clinicians providing their rehabilitative care, the optimal approaches to which remain incompletely developed. In this article, a neuropsychiairically informed, neurobiologically anchored approach to understanding and meeting challenges is described. The foundation for thai approach is laid, with a review of clinical case definitions of TBI and clarification of their intended referents. The differential diagnosis of event-related neuropsychiatric disturbances is considered next, after which the clinical and neurobiological heterogeneity within the diagnostic category of TBI are discussed. The clinical manifestations of biomechanical force-induced brain dysfunction are described as a state of post-traumatic encephalopathy (PTE) comprising several phenomenologically distinct stages, PTE is then used as a framework for understanding and clinically evaluating the neuropsychiatric sequelae of TBI encountered commonly during the early post-injury rehabilitation period, and for considering the types and timings of neurorehabilitative interventions. Finally, directions for future research that may address productively the challenges to TBI rehabilitation presented by neuropsychiatric disturbances are considered. PMID:22034400

Insomnia during pregnancy: Diagnosis and Rational Interventions.

PubMed

Hashmi, Ali M; Bhatia, Shashi K; Bhatia, Subhash K; Khawaja, Imran S

2016-01-01

Sleep disturbances are common in pregnancy. Insomnia is a frequent sleep disturbance experienced by pregnant women which can be primary or due to co-morbid conditions. The differential diagnosis of insomnia in pregnancy includes anxiety disorders, mood disorders, breathing related sleep disorders and restless legs syndrome. Early interventions to treat the sleep disturbance are recommended to avoid adverse pregnancy outcomes. Management strategies include improving sleep hygiene, behavioral therapies, and pharmacotherapy. The risks of pharmacotherapy must be weighed against their benefits due to the possible risk of teratogenicity associated with some medications. We searched PubMed and Google Scholar employing a combination of key words: pregnancy, sleep disturbances, Obstructive Sleep Apnea, Sleep disorders and insomnia. We included original studies, review articles, meta-analysis and systematic reviews in our search prioritizing articles from the last 10-15 years. Articles older than 15 years were only included if their findings had not been superseded by more recent data. Further selection of articles was done from bibliographies and references of selected articles. Sleep disturbances in pregnancy are common and cause considerable morbidity. Management includes a combination of non-pharmacological and pharmacological treatments carefully weighing the risks and benefits of each for the expectant mother and fetus.

Insomnia during pregnancy: Diagnosis and Rational Interventions

PubMed Central

Hashmi, Ali M.; Bhatia, Shashi K.; Bhatia, Subhash K.; Khawaja, Imran S.

2016-01-01

Sleep disturbances are common in pregnancy. Insomnia is a frequent sleep disturbance experienced by pregnant women which can be primary or due to co-morbid conditions. The differential diagnosis of insomnia in pregnancy includes anxiety disorders, mood disorders, breathing related sleep disorders and restless legs syndrome. Early interventions to treat the sleep disturbance are recommended to avoid adverse pregnancy outcomes. Management strategies include improving sleep hygiene, behavioral therapies, and pharmacotherapy. The risks of pharmacotherapy must be weighed against their benefits due to the possible risk of teratogenicity associated with some medications. Methods: We searched PubMed and Google Scholar employing a combination of key words: pregnancy, sleep disturbances, Obstructive Sleep Apnea, Sleep disorders and insomnia. We included original studies, review articles, meta-analysis and systematic reviews in our search prioritizing articles from the last 10-15 years. Articles older than 15 years were only included if their findings had not been superseded by more recent data. Further selection of articles was done from bibliographies and references of selected articles. Conclusion: Sleep disturbances in pregnancy are common and cause considerable morbidity. Management includes a combination of non-pharmacological and pharmacological treatments carefully weighing the risks and benefits of each for the expectant mother and fetus. PMID:27648062

Sea-dumped chemical weapons: environmental risk, occupational hazard.

PubMed

Greenberg, M I; Sexton, K J; Vearrier, D

2016-01-01

Chemical weapons dumped into the ocean for disposal in the twentieth century pose a continuing environmental and human health risk. In this review we discuss locations, quantity, and types of sea-dumped chemical weapons, related environmental concerns, and human encounters with sea-dumped chemical weapons. We utilized the Ovid (http://ovidsp.tx.ovid.com) and PubMed (http://www.pubmed.org) search engines to perform MEDLINE searches for the terms 'sea-dumped chemical weapons', 'chemical warfare agents', and 'chemical munitions'. The searches returned 5863 articles. Irrelevant and non-English articles were excluded. A review of the references for these articles yielded additional relevant sources, with a total of 64 peer-reviewed articles cited in this paper. History and geography of chemical weapons dumping at sea: Hundreds of thousands of tons of chemical munitions were disposed off at sea following World War II. European, Russian, Japanese, and United States coasts are the areas most affected worldwide. Several areas in the Baltic and North Seas suffered concentrated large levels of dumping, and these appear to be the world's most studied chemical warfare agent marine dumping areas. Chemical warfare agents: Sulfur mustard, Lewisite, and the nerve agents appear to be the chemical warfare agents most frequently disposed off at sea. Multiple other type of agents including organoarsenicals, blood agents, choking agents, and lacrimators were dumped at sea, although in lesser volumes. Environmental concerns: Numerous geohydrologic variables contribute to the rate of release of chemical agents from their original casings, leading to difficult and inexact modeling of risk of release into seawater. Sulfur mustard and the organoarsenicals are the most environmentally persistent dumped chemical agents. Sulfur mustard in particular has a propensity to form a solid or semi-solid lump with a polymer coating of breakdown products, and can persist in this state on the ocean floor for decades. Rates of solubility and hydrolysis and levels of innate toxicity of a chemical agent are used to predict the risk to the marine environments. The organoarsenicals eventually breakdown into arsenic, and thus present an indefinite timeline for contamination. Generally, studies assaying sediment and water levels of parent chemical agents and breakdown products at dumpsites have found minimal amounts of relevant chemicals, although arsenic levels are typically higher in dumpsites than reference areas. Studies of marine organisms have not shown concerning amounts of chemical agents or breakdown products in tissue, but have shown evidence of chronic toxicity. There is believed to be minimal risk posed by seafood consumption. Microbiota assays of dumpsites are significantly altered in species composition compared to reference sites, which may imply unseen but significant changes to ecosystems of dumpsites. Human health concerns: The major human health risk at this time appears to arise from acute exposure to an agent by either accidental recovery of a chemical weapon on a fishing vessel, or by munitions washed ashore onto beaches. Improving technology continues to make the deep sea more accessible, thus increasing the risk of disturbing munitions lying on or buried in the seabed. Pipe laying, cable burying, drilling, scuba diving, trawling, and undersea scientific research are the activities posing the most risk. The long-term threat to the benthic habitat via increased arsenic concentrations, shifts in microbiota speciation, and chronic toxicity to vertebrates and invertebrates is not currently understood. The risk to the environment of massive release via disturbance remains a distinct possibility. Terrorist recovery and re-weaponization of chemical agents is a remote possibility.

Measurement of coarse gravel and cobble transport using portable bedload traps

Treesearch

Kristin Bunte; Steven R. Abt; John P. Potyondy; Sandra E. Ryan

2004-01-01

Portable bedload traps (0.3 by 0.2 m opening) were developed for sampling coarse bedload transport in mountain gravel-bed rivers during wadable high flows. The 0.9 m long trailing net can capture about 20 kg of gravel and cobbles. Traps are positioned on ground plates anchored in the streambed to minimize disturbance of the streambed during sampling. This design...

Adaptive-Wall Wind-Tunnel Investigations

DTIC Science & Technology

1981-02-01

boundary condition for unconfined flow. In this way, theory and experiment are combined to minimize wall interference. The concept of an adaptive wall...should be noted that although shock waves extend to the walls, the exterior-flow calculation was based on subcritical-flow theory . Goodyer’s configuration...and v by aerodynamic probes. Both subsonic and transonic small- disturbance theory were used, as appropriate, to evaluate the functional rela

Setting nutrient thresholds to support an ecological assessment based on nutrient enrichment, potential primary production and undesirable disturbance.

PubMed

Devlin, Michelle; Painting, Suzanne; Best, Mike

2007-01-01

The EU Water Framework Directive recognises that ecological status is supported by the prevailing physico-chemical conditions in each water body. This paper describes an approach to providing guidance on setting thresholds for nutrients taking account of the biological response to nutrient enrichment evident in different types of water. Indices of pressure, state and impact are used to achieve a robust nutrient (nitrogen) threshold by considering each individual index relative to a defined standard, scale or threshold. These indices include winter nitrogen concentrations relative to a predetermined reference value; the potential of the waterbody to support phytoplankton growth (estimated as primary production); and detection of an undesirable disturbance (measured as dissolved oxygen). Proposed reference values are based on a combination of historical records, offshore (limited human influence) nutrient concentrations, literature values and modelled data. Statistical confidence is based on a number of attributes, including distance of confidence limits away from a reference threshold and how well the model is populated with real data. This evidence based approach ensures that nutrient thresholds are based on knowledge of real and measurable biological responses in transitional and coastal waters.

First steps in developing a multimetric macroinvertebrate index for the Ohio River

USGS Publications Warehouse

Applegate, J.M.; Baumann, P.C.; Emery, E.B.; Wooten, M.S.

2007-01-01

The causes of degradation of aquatic systems are often complex and stem from a variety of human influences. Comprehensive, multimetric biological indices have been developed to quantify this degradation and its effect on aquatic communities, and measure subsequent recovery from anthropogenic stressors. Traditionally, such indices have concentrated on small-to medium-sized streams. Recently, however, the Ohio River Fish Index (ORFIn) was created to assess biotic integrity in the Ohio River. The goal of the present project was to begin developing a companion Ohio River multimetric index using benthic macroinvertebrates. Hester-Dendy multiplate samplers were used to evaluate benthic macroinvertebrate assemblages in relation to a gradient of water quality disturbance, represented by varying distances downstream of industrial and municipal wastewater outfalls in the Ohio River. In August 1999 and 2000, samplers were set every 100 m downstream of outfalls (12 outfalls in 1999, 22 in 2000) for 300-1000 m, as well as at upstream reference sites. Candidate metrics (n = 55) were examined to determine which have potential to detect changes in water quality downstream of outfalls. These individual measures of community structure were plotted against distance downstream of each outfall to determine their response to water quality disturbance. Values at reference and outfall sites were also compared. Metrics that are ecologically relevant and showed a response to outfall disturbance were identified as potentially valuable in a multimetric index. Multiple box plots of index scores indicated greater response to outfall disturbance during periods of low-flow, and longitudinal river-wide trends. Evaluation of other types of anthropogenic disturbance, as well as continued analysis of the effects of chemical water quality on macroinvertebrate communities in future years will facilitate further development of a multimetric benthic macroinvertebrate index to evaluate biotic integrity in the Ohio River. Copyright ?? 2007 John Wiley & Sons, Ltd.

Effects of disturbances caused by coastal constructions on spatial structure, growth dynamics and photosynthesis of the seagrass Posidonia oceanica.

PubMed

Ruiz, J M; Romero, J

2003-12-01

The light-limitation hypothesis was tested to assess whether water turbidity had caused the decline of a Mediterranean Posidonia oceanica (L.) Delile meadow in an area affected by a harbor. The annual growth, photosynthesis and rhizome starch concentrations of seagrass were measured and related to changes in light availability and dissolved nutrient concentration along a gradient of meadow degradation from areas close to the harbor outwards. Environmental and plant variables were measured in three stations placed along this gradient and compared with a reference station at an undisturbed meadow. The light attenuation coefficient (k) increased toward the inner harbor area, mainly due to sediment resuspension. The shoot density and leaf productivity of P. oceanica shoots were much lower in disturbed stations of the inner harbor area than in the outer, less disturbed station and the reference meadow. However, daily leaf carbon gains, calculated from the photosynthetic rates at saturating irradiance (P(max)) and the daily period in which seagrass receives light higher than its saturating irradiance (H(sat)), suggested positive C-balance in all stations. This was partly explained by photo-acclimatization of seagrass to the reduced light availability at the disturbed harbor stations (inner and intermediate), as indicated by the lengthening of H(sat) and the decrease in saturating irradiance (I(sat)) and respiratory demands. Despite photo-acclimatization, disturbed harbor stations showed less positive C-balance, seen not only in their lower leaf growth and biomass but also in a decrease in rhizome carbohydrate reserves (starch). Our results suggest that light reduction account for the reduced seagrass productivity and abundance. However, meadow decline (in terms of shoot mortality) in the harbor area is well above that predicted from similar light environments of nearby meadows or simulated in shading experiments. Thus, there are other factors than light limitation involved in seagrass mortality, most probably through more complex interactions (e.g. nutrient-epiphytes-grazers, water quality--siltation).

Soil and biomass carbon re-accumulation after landslide disturbances

NASA Astrophysics Data System (ADS)

Schomakers, Jasmin; Jien, Shih-Hao; Lee, Tsung-Yu; Huang-Chuan, Jr.; Hseu, Zeng-Yei; Lin, Zan Liang; Lee, Li-Chin; Hein, Thomas; Mentler, Axel; Zehetner, Franz

2017-07-01

In high-standing islands of the Western Pacific, typhoon-triggered landslides occasionally strip parts of the landscape of its vegetative cover and soil layer and export large amounts of biomass and soil organic carbon (OC) from land to the ocean. After such disturbances, new vegetation colonizes the landslide scars and OC starts to re-accumulate. In the subtropical mountains of Taiwan and in other parts of the world, bamboo (Bambusoideae) species may invade at a certain point in the succession of recovering landslide scars. Bamboo has a high potential for carbon sequestration because of its fast growth and dense rooting system. However, it is still largely unknown how these properties translate into soil OC re-accumulation rates after landslide disturbance. In this study, a chronosequence was established on four former landslide scars in the Central Mountain Range of Taiwan, ranging in age from 6 to 41 years post disturbance as determined by landslide mapping from remote sensing. The younger landslide scars were colonized by Miscanthus floridulus, while after approx. 15 to 20 years of succession, bamboo species (Phyllostachys) were dominating. Biomass and soil OC stocks were measured on the recovering landslide scars and compared to an undisturbed Cryptomeria japonica forest stand in the area. After initially slow re-vegetation, biomass carbon accumulated in Miscanthus stands with mean annual accretion rates of 2 ± 0.5 Mg C ha- 1 yr- 1. Biomass carbon continued to increase after bamboo invasion and reached 40% of that in the reference forest site after 41 years of landslide recovery. Soil OC accumulation rates were 2.0 Mg C ha- 1 yr- 1, 6 to 41 years post disturbance reaching 64% of the level in the reference forest. Our results from this in-situ study suggest that recovering landslide scars are strong carbon sinks once an initial lag period of vegetation re-establishment is overcome.

Crossflow Stability and Transition Experiments in a Swept-Wing Flow. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Dagenhart, John Ray

1992-01-01

An experimental examination of crossflow instability and transition on a 45 degree swept wing is conducted in the Arizona State University Unsteady Wind Tunnel. The stationary-vortex pattern and transition location are visualized using both sublimating-chemical and liquid-crystal coatings. Extensive hot-wire measurements are conducted at several measurement stations across a single vortex track. The mean and travelling-wave disturbances are measured simultaneously. Stationary-crossflow disturbance profiles are determined by subtracting either a reference or a span-averaged velocity profile from the mean-velocity data. Mean, stationary-crossflow, and travelling-wave velocity data are presented as local boundary-layer profiles and as contour plots across a single stationary-crossflow vortex track. Disturbance-mode profiles and growth rates are determined. The experimental data are compared to predictions from linear stability theory.

Attitude control system conceptual design for the GOES-N spacecraft series

NASA Technical Reports Server (NTRS)

Markley, F. L.; Bauer, F. H.; Deily, J. J.; Femiano, M. D.

1991-01-01

The attitude determination sensing and processing of the system are considered, and inertial reference units, star trackers, and beacons and landmarks are discussed as well as an extended Kalman filter and expected attitude-determination performance. The baseline controller is overviewed, and a spacecraft motion compensation (SMC) algorithm, disturbance environment, and SMC performance expectations are covered. Detailed simulation results are presented, and emphasis is placed on dynamic models, attitude estimation and control, and SMC disturbance accommmodation. It is shown that the attitude control system employing gyro/star tracker sensing and active three-axis control with reaction wheels is capable of maintaining attitude errors of 1.7 microrad or less on all axes in the absence of attitude disturbances, and that the sensor line-of-sight pointing errors can be reduced to 0.1 microrad by SMC.

Hybrid Feedforward-Feedback Noise Control Using Virtual Sensors

NASA Technical Reports Server (NTRS)

Bean, Jacob; Fuller, Chris; Schiller, Noah

2016-01-01

Several approaches to active noise control using virtual sensors are evaluated for eventual use in an active headrest. Specifically, adaptive feedforward, feedback, and hybrid control structures are compared. Each controller incorporates the traditional filtered-x least mean squares algorithm. The feedback controller is arranged in an internal model configuration to draw comparisons with standard feedforward control theory results. Simulation and experimental results are presented that illustrate each controllers ability to minimize the pressure at both physical and virtual microphone locations. The remote microphone technique is used to obtain pressure estimates at the virtual locations. It is shown that a hybrid controller offers performance benefits over the traditional feedforward and feedback controllers. Stability issues associated with feedback and hybrid controllers are also addressed. Experimental results show that 15-20 dB reduction in broadband disturbances can be achieved by minimizing the measured pressure, whereas 10-15 dB reduction is obtained when minimizing the estimated pressure at a virtual location.

Cascade control of superheated steam temperature with neuro-PID controller.

PubMed

Zhang, Jianhua; Zhang, Fenfang; Ren, Mifeng; Hou, Guolian; Fang, Fang

2012-11-01

In this paper, an improved cascade control methodology for superheated processes is developed, in which the primary PID controller is implemented by neural networks trained by minimizing error entropy criterion. The entropy of the tracking error can be estimated recursively by utilizing receding horizon window technique. The measurable disturbances in superheated processes are input to the neuro-PID controller besides the sequences of tracking error in outer loop control system, hence, feedback control is combined with feedforward control in the proposed neuro-PID controller. The convergent condition of the neural networks is analyzed. The implementation procedures of the proposed cascade control approach are summarized. Compared with the neuro-PID controller using minimizing squared error criterion, the proposed neuro-PID controller using minimizing error entropy criterion may decrease fluctuations of the superheated steam temperature. A simulation example shows the advantages of the proposed method. Copyright © 2012 ISA. Published by Elsevier Ltd. All rights reserved.

Classic Peripheral Signs of Subacute Bacterial Endocarditis

PubMed Central

Chong, Yooyoung; Han, Sung Joon; Rhee, Youn Ju; Kang, Shin Kwang; Yu, Jae Hyeon; Na, Myung Hoon

2016-01-01

A 50-year-old female patient with visual disturbances was referred for further evaluation of a heart murmur. Fundoscopy revealed a Roth spot in both eyes. A physical examination showed peripheral signs of infective endocarditis, including Osler nodes, Janeway lesions, and splinter hemorrhages. Our preoperative diagnosis was subacute bacterial endocarditis with severe aortic regurgitation. The patient underwent aortic valve replacement and was treated with intravenous antibiotics for 6 weeks postoperatively. The patient made a remarkable recovery and was discharged without complications. We report this case of subacute endocarditis with all 4 classic peripheral signs in a patient who presented with visual disturbance. PMID:27734006

Effect of Wall Temperature on Roughness Induced Attachment-Line Transition

NASA Technical Reports Server (NTRS)

Dietz, Anthony; Coleman, Colin; Laub, Jim; Poll, D. I. A.; Nixon, David (Technical Monitor)

1999-01-01

An experiment on a cooled swept cylinder in a low-disturbance Mach 1.6 wind tunnel is described. The flow attachment line is disturbed by trip wires of varying size and the laminar/turbulent state of the downstream boundary layer is determined with a hot wire. The results demonstrate that although cooling the wall increases the stability of the boundary layer, it promotes roughness induced transition. Analysis of the data suggests that the attachment- line Reynolds number can account for the effect of wall cooling if the viscosity is evaluated at a particular reference temperature.

Productivity of Black Oystercatchers: Effects of recreational disturbance in a National Park

USGS Publications Warehouse

Morse, J.A.; Powell, A.N.; Tetreau, M.D.

2006-01-01

National parks in Alaska are generally assumed to be high-quality, undisturbed wildlife habitats. However, these parks attract recreational users, whose presence may reduce the suitability of key habitats for nesting shorebirds. In Kenai Fjords National Park, Black Oystercatchers (Haematopus bachmani) often breed on gravel beaches that are also popular campsites. In this study, we examined the effects of recreational activities in coastal Alaska on reproductive performance of Black Oystercatchers. We monitored survival of nests and chicks on 35 to 39 breeding territories annually during four breeding seasons (2001-2004). Most recreational disturbance on these territories occurred after the peak hatching date of first clutches. Annual productivity was low (average of 0.35 chicks per pair), but was not strongly affected by recreational disturbance. Daily survival of nests varied annually and declined over the season. Our results suggest that nest survival was lower during periods of extreme high tides. Daily survival rate of broods increased over the season and was higher on island than mainland territories, likely due to differences in predator communities. Territory occupancy rate and site fidelity were high; 95% of color-banded oystercatchers returned to the same breeding territory in the subsequent year. We conclude that Black Oystercatchers are resilient to low levels of recreational disturbance. However, in light of projected increases in recreation, we suggest managers move campsites away from the traditional nest sites identified in this study to minimize future disturbances. ?? The Cooper Ornithological Society 2006.

Alerts of forest disturbance from MODIS imagery

NASA Astrophysics Data System (ADS)

Hammer, Dan; Kraft, Robin; Wheeler, David

2014-12-01

This paper reports the methodology and computational strategy for a forest cover disturbance alerting system. Analytical techniques from time series econometrics are applied to imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor to detect temporal instability in vegetation indices. The characteristics from each MODIS pixel's spectral history are extracted and compared against historical data on forest cover loss to develop a geographically localized classification rule that can be applied across the humid tropical biome. The final output is a probability of forest disturbance for each 500 m pixel that is updated every 16 days. The primary objective is to provide high-confidence alerts of forest disturbance, while minimizing false positives. We find that the alerts serve this purpose exceedingly well in Pará, Brazil, with high probability alerts garnering a user accuracy of 98 percent over the training period and 93 percent after the training period (2000-2005) when compared against the PRODES deforestation data set, which is used to assess spatial accuracy. Implemented in Clojure and Java on the Hadoop distributed data processing platform, the algorithm is a fast, automated, and open source system for detecting forest disturbance. It is intended to be used in conjunction with higher-resolution imagery and data products that cannot be updated as quickly as MODIS-based data products. By highlighting hotspots of change, the algorithm and associated output can focus high-resolution data acquisition and aid in efforts to enforce local forest conservation efforts.

A new energy-efficient control approach for astronomical telescope drive system

NASA Astrophysics Data System (ADS)

Zhou, W.; Wang, Y.

2012-12-01

Drive control makes the astronomical telescope accurately tracking celestial bodies in spite of external and internal disturbances, which is a key technique to the performance of telescopes. In this paper, we propose a nonlinear ad, aptive observer based on power reversible approach for high precision telescope position tracking. The nonlinear adaptive observer automatically estimates the disturbances in drive system, and the observed value is applied to compensate for the real disturbances. With greatly reduced disturbances, the control precision can be evidently improved. In conventional drive control, the brake device is often used to slow down the reaction wheel and may waste enormous energy. To avoid those disadvantages, an H-bridge is put forward for wheel speed regulation. Such H-bridge has four independent sections, and each section mainly consists of a power electronic switch and an anti-parallel diode. During the period of the mount slowing down, the armature current of drive motor goes through the two path-wise diodes to charge the battery. Thus, energy waste is avoided. Based on the disturbance compensation, an optimal controller is designed to minimize an evaluation function which is made up of a weighted sum of position errors and energy consumption.The outputs of the controller are applied to control the H-bridge. Simulations are performed in MATLAB language. The results show that high precision control can be obtained by the proposed approach. And the energy consumption will be remarkably reduced.

Robust model reference adaptive output feedback tracking for uncertain linear systems with actuator fault based on reinforced dead-zone modification.

PubMed

Bagherpoor, H M; Salmasi, Farzad R

2015-07-01

In this paper, robust model reference adaptive tracking controllers are considered for Single-Input Single-Output (SISO) and Multi-Input Multi-Output (MIMO) linear systems containing modeling uncertainties, unknown additive disturbances and actuator fault. Two new lemmas are proposed for both SISO and MIMO, under which dead-zone modification rule is improved such that the tracking error for any reference signal tends to zero in such systems. In the conventional approach, adaption of the controller parameters is ceased inside the dead-zone region which results tracking error, while preserving the system stability. In the proposed scheme, control signal is reinforced with an additive term based on tracking error inside the dead-zone which results in full reference tracking. In addition, no Fault Detection and Diagnosis (FDD) unit is needed in the proposed approach. Closed loop system stability and zero tracking error are proved by considering a suitable Lyapunov functions candidate. It is shown that the proposed control approach can assure that all the signals of the close loop system are bounded in faulty conditions. Finally, validity and performance of the new schemes have been illustrated through numerical simulations of SISO and MIMO systems in the presence of actuator faults, modeling uncertainty and output disturbance. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

TOWARDS A SUSTAINABILITY INDEX USING INFORMATION THEORY

EPA Science Inventory

We explore the use of Fisher Information as a basis for an index of sustainability. Sustainability of an ecosystem refers to the robustness of a preferred dynamic regime to human and natural disturbances. Ecosystems under perturbations of varying regularity and intensity can ei...

Genetics Home Reference: cerebral folate transport deficiency

MedlinePlus

... a treatable neurodegenerative disorder associated with disturbed myelin metabolism. Am J Hum Genet. 2009 Sep;85(3):354-63. doi: 10.1016/j.ajhg.2009.08.005. Citation on PubMed or Free article on PubMed Central Toelle SP, Wille D, Schmitt ...

Regional recovery of the disturbing gravitational potential by inverting satellite gravitational gradients

NASA Astrophysics Data System (ADS)

Pitoňák, Martin; Šprlák, Michal; Hamáčková, Eliška; Novák, Pavel

2016-04-01

Regional recovery of the disturbing gravitational potential in the area of Central Europe from satellite gravitational gradients data is discussed in this contribution. The disturbing gravitational potential is obtained by inverting surface integral formulas which transform the disturbing gravitational potential onto disturbing gravitational gradients in the spherical local north-oriented frame. Two numerical approaches that solve the inverse problem are considered. In the first approach, the integral formulas are rigorously decomposed into two parts, that is, the effects of the gradient data within near and distant zones. While the effect of the near zone data is sought as an inverse problem, the effect of the distant zone data is synthesized from the global gravitational model GGM05S using spectral weights given by truncation error coefficients up to the degree 150. In the second approach, a reference gravitational field up to the degree 180 is applied to reduce and smooth measured gravitational gradients. In both cases we recovered the disturbing gravitational potential from each of the four well-measured gravitational gradients of the GOCE satellite separately as well as from their combination. Obtained results are compared with the EGM2008, DIR-r2, TIM-r2 and SPW-r2 global gravitational models. The best fit was achieved for EGM2008 and the second approach combining all four well-measured gravitational gradients with rms of 1.231 m2 s-2.

Secondary succession of arthropods and plants in the Arizona Sonoran Desert in response to transmission-line construction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, C.D.; Beley, J.R.; Ditsworth, T.M.

1983-03-01

At a site about 16 km south of Black Canyon City, Arizona, density of arthropods on an undisturbed plot after an access road was built for powerline construction was much greater than on a disturbed plot. Mites, springtails, leafhoppers, scale insects, ants and thrips were significantly reduced on the disturbed area. Diversity increased on the disturbed plot after construction, but density decreased. A slight increase in similarity (H', Clambda) of the arthropod communities of the two plots appears to be related to the modest increase in cover on the disturbed area. Globe-mallow, goosefoot and a four-o'clock were pioneer species andmore » occurred only on the disturbed area. There was a significant reduction in cover of all plant species on the disturbed plot after construction, but there was a steady increase of annual forbs at the end of the study. The results indicate that restoration of numbers of arthropods on the disturbed area is dependent on the total plant cover on the plot, apparently regardless of the composition of the plant species involved. It is obvious in this area that the plant communities will remain dissimilar, with the pioneering herbaceous plants on the disturbed plot dominating. Construction of a powerline apparently has had little impact on the structure of the arthropod community on the disturbed area, as proportions of three trophic categories of arthropods have not been radically altered. The results of this study, when compared to other studies in the Sonoran Desert and in desert grasslands disturbed by powerline construction, indicate that lengthy secondary succession does occur in the Sonoran Desert. Early arthropod invaders were found to be mainly herbivores, with few parasites or predators, and an equilibrium was eventually reached between colonizers and space requirements. 35 references, 3 figures, 3 tables« less

Effects of human activity of breeding American Oystercatchers, Cumberland Island National Seashore, Georgia, USA

USGS Publications Warehouse

Sabine, J.B.; Meyers, J.M.; Moore, C.T.; Schweitzer, Sara H.

2008-01-01

Abstract.-Increased human use of coastal areas threatens the United States population of American Oystercatchers (Haematopus palliatus), a species of special concern. Biologists often attribute its low numbers and reproductive success to human disturbance, but the mechanism by which human presence reduces reproductive success is not well understood. During the 2003 and 2004 breeding seasons, 32 nesting attempts of American Oystercatchers were studied on Cumberland Island National Seashore (CINS). Behavior was examined with and without human activity in the area to determine how human activity affected behavior. The oystercatchers' behavioral responses (proportion time) were analyzed with and without human or intraspecific disturbances using mixed models regression analysis. Proportions of time human activities were present (137 m and vehicular activity should be minimized at current levels or less.

Use of Current 2010 Forest Disturbance Monitoring Products for the Conterminous United States in Aiding a National Forest Threat Early Warning System

NASA Technical Reports Server (NTRS)

Spruce, Joseph P.; Hargrove, William; Gasser, J.; Smoot, J.; Kuper, P.

2010-01-01

This presentation discusses contributions of near real time (NRT) MODIS forest disturbance detection products for the conterminous United States to an emerging national forest threat early warning system (EWS). The latter is being developed by the USDA Forest Service s Eastern and Western Environmental Threat Centers with help from NASA Stennis Space Center and the Oak Ridge National Laboratory. Building off work done in 2009, this national and regional forest disturbance detection and viewing capability of the EWS employs NRT MODIS NDVI data from the USGS eMODIS group and historical NDVI data from standard MOD13 products. Disturbance detection products are being computed for 24 day composites that are refreshed every 8 days. Products for 2010 include 42 dates of the 24 day composites. For each compositing date, we computed % change in forest maximum NDVI products for 2010 with respect to each of three historical baselines of 2009, 2007-2009, and 2003-2009,. The three baselines enable one to view potential current, recent, and longer term forest disturbances. A rainbow color table was applied to each forest change product so that potential disturbances (NDVI drops) were identified in hot color tones and growth (NDVI gains) in cold color tones. Example products were provided to end-users responsible for forest health monitoring at the Federal and State levels. Large patches of potential forest disturbances were validated based on comparisons with available reference data, including Landsat and field survey data. Products were posted on two internet mapping systems for US Forest Service internal and collaborator use. MODIS forest disturbance detection products were computed and posted for use in as little as 1 day after the last input date of the compositing period. Such products were useful for aiding aerial disturbance detection surveys and for assessing disturbance persistence on both inter- and intra-annual scales. Multiple 2010 forest disturbance events were detected across the nation, including damage from ice storms, tornadoes, caterpillars, bark beetles, and wildfires. This effort enabled improved NRT forest disturbance monitoring capabilities for this nation-wide forest threat EWS.

Use of Current 2010 Forest Disturbance Monitoring Products for the Conterminous United States in Aiding a National Forest Threat Early Warning System

NASA Astrophysics Data System (ADS)

Spruce, J.; Hargrove, W. W.; Gasser, J.; Smoot, J.; Kuper, P.

2010-12-01

This presentation discusses contributions of near real time (NRT) MODIS forest disturbance detection products for the conterminous United States to an emerging national forest threat early warning system (EWS). The latter is being developed by the USDA Forest Service’s Eastern and Western Environmental Threat Centers with help from NASA Stennis Space Center and the Oak Ridge National Laboratory. Building off work done in 2009, this national and regional forest disturbance detection and viewing capability of the EWS employs NRT MODIS NDVI data from the USGS eMODIS group and historical NDVI data from standard MOD13 products. Disturbance detection products are being computed for 24 day composites that are refreshed every 8 days. Products for 2010 include 42 dates of the 24 day composites. For each compositing date, we computed % change in forest maximum NDVI products for 2010 with respect to each of three historical baselines of 2009, 2007-2009, and 2003-2009. The three baselines enable one to view potential current, recent, and longer term forest disturbances. A rainbow color table was applied to each forest change product so that potential disturbances (NDVI drops) were identified in hot color tones and growth (NDVI gains) in cold color tones. Example products were provided to end-users responsible for forest health monitoring at the Federal and State levels. Large patches of potential forest disturbances were validated based on comparisons with available reference data, including Landsat and field survey data. Products were posted on two internet mapping systems for US Forest Service internal and collaborator use. MODIS forest disturbance detection products were computed and posted for use in as little as 1 day after the last input date of the compositing period. Such products were useful for aiding aerial disturbance detection surveys and for assessing disturbance persistence on both inter- and intra-annual scales. Multiple 2010 forest disturbance events were detected across the nation, including damage from ice storms, tornados, caterpillars, bark beetles, and wildfires. This effort enabled improved NRT forest disturbance monitoring capabilities for this nation-wide forest threat EWS.

Magnitude of daily energy deficit predicts frequency but not severity of menstrual disturbances associated with exercise and caloric restriction.

PubMed

Williams, Nancy I; Leidy, Heather J; Hill, Brenna R; Lieberman, Jay L; Legro, Richard S; De Souza, Mary Jane

2015-01-01

We assessed the impact of energy deficiency on menstrual function using controlled feeding and supervised exercise over four menstrual cycles (1 baseline and 3 intervention cycles) in untrained, eumenorrheic women aged 18-30 yr. Subjects were randomized to either an exercising control (EXCON) or one of three exercising energy deficit (ED) groups, i.e., mild (ED1; -8 ± 2%), moderate (ED2; -22 ± 3%), or severe (ED3; -42 ± 3%). Menstrual cycle length and changes in urinary concentrations of estrone-1-glucuronide, pregnanediol glucuronide, and midcycle luteinizing hormone were assessed. Thirty-four subjects completed the study. Weight loss occurred in ED1 (-3.8 ± 0.2 kg), ED2 (-2.8 ± 0.6 kg), and ED3 (-2.6 ± 1.1 kg) but was minimal in EXCON (-0.9 ± 0.7 kg). The overall sum of disturbances (luteal phase defects, anovulation, and oligomenorrhea) was greater in ED2 compared with EXCON and greater in ED3 compared with EXCON AND ED1. The average percent energy deficit was the main predictor of the frequency of menstrual disturbances (f = 10.1, β = -0.48, r(2) = 0.23, P = 0.003) even when weight loss was included in the model. The estimates of the magnitude of energy deficiency associated with menstrual disturbances ranged from -22 (ED2) to -42% (ED3), reflecting an energy deficit of -470 to -810 kcal/day, respectively. This is the first study to demonstrate a dose-response relationship between the magnitude of energy deficiency and the frequency of exercise-related menstrual disturbances; however, the severity of menstrual disturbances was not dependent on the magnitude of energy deficiency. Copyright © 2015 the American Physiological Society.

Analysis of TMT primary mirror control-structure interaction

NASA Astrophysics Data System (ADS)

MacMynowski, Douglas G.; Thompson, Peter M.; Sirota, Mark J.

2008-07-01

The primary mirror control system (M1CS) keeps the 492 segments of the Thirty Meter Telescope primary mirror aligned in the presence of disturbances. A global position control loop uses feedback from inter-segment edge sensors to three actuators behind each segment that control segment piston, tip and tilt. If soft force actuators are used (e.g. voice-coil), then in addition to the global position loop there will be a local servo loop to provide stiffness. While the M1 control system at Keck compensates only for slow disturbances such as gravity and thermal variations, the M1CS for TMT will need to provide some compensation for higher frequency wind disturbances in order to meet stringent error budget targets. An analysis of expected high-wavenumber wind forces on M1 suggests that a 1Hz control bandwidth is required for the global feedback of segment edge-sensorbased position information in order to minimize high spatial frequency segment response for both seeing-limited and adaptive optics performance. A much higher bandwidth is required from the local servo loop to provide adequate stiffness to wind or acoustic disturbances. A related paper presents the control designs for the local actuator servo loops. The disturbance rejection requirements would not be difficult to achieve for a single segment, but the structural coupling between segments mounted on a flexible mirror cell results in controlstructure interaction (CSI) that limits the achievable bandwidth. Using a combination of simplified modeling to build intuition and the full telescope finite element model for verification, we present designs and analysis for both the local servo loop and global loop demonstrating sufficient bandwidth and resulting wind-disturbance rejection despite the presence of CSI.

[Impact of heavy snow storm and freezing rain disasters on soil fauna in Chinese fir plantation in southern China].

PubMed

Yan, Shao-kui; Zhang, Wei-dong; Liu, Yan-xin; Fu, Sheng-lei; Li, Yuan-liang; Wang, Si-long

2009-01-01

In January 2008, southern China suffered an unusual heavy snowstorm and freezing rain over a large area for almost a month long. This catastrophic event was the worst one in past 50 years, which brought the area a serious impact on the infrastructure, ecology, and environment. To understand the long-term impact of this catastrophic event on the forest ecosystems in this area, a field investigation was conducted on the soil fauna in a pure Chinese fir plantation and a mixed Chinese fir plantation-alder plantation in Huitong County of Hunan Province on March 23, 2008, the date 40 days after the heavy snowstorm and freezing rain. With the abundance and community composition as the main parameters and the monitoring data from the two plantations on March 23, 2007 as the reference, the flexibility and resistance of soil fauna to the disturbances of the catastrophic event was preliminarily evaluated. The results showed that there was a significant deviation of soil fauna communities in the two plantations from the reference. An outbreak increase in microfauna nematode abundance was found from 12216.9 ind x m(-2) to 118343.9 ind x m(-2) in pure Chinese fir plantation and from 25435.9 ind x m(-2) to 84573.0 ind x m(-2) in mixed Chinese fir plantation-alder plantation, while a 27.0% and 85.6% decrease of macrofauna abundance was found in the two plantations, respectively, compared with the reference. Mesofauna abundance also had a significant decrease in litter layer but not in soil. The abundance recovery displayed a trend from quick rate for microfauna to slow rate for macrofauna, which indicated that the soil fauna functional groups, in terms of body size, could be used as a vulnerable indicator in evaluating disturbance event and post-disturbance recovery. By using community ordinations, no shift in soil fauna community composition was detected 40 days after the catastrophic event, suggesting that the community composition of soil invertebrate had a high resistance to catastrophic snowstorm and freezing rain disturbances.

[Gluten Ataxia: Anti-Transglutaminase-6 Antibody as a New Biomarker].

PubMed

Sato, Kenji; Nanri, Kazunori

2017-08-01

Gluten-related disorders (GRDs) are conditions that develop in response to the common trigger of gluten ingestion and manifest as a variety of clinical symptoms. GRDs have been considered rare in Asian countries, including Japan, because of lower consumption of wheat products than in Europe and the U.S.A. and differences in genetic background. Recently, however, GRDs, such as celiac disease and gluten ataxia, have been reported in Japan, albeit sporadically and their presence is now recognized in this country. Gluten ataxia is defined as an anti-gliadin antibody positive sporadic ataxia. Recently, it was reported that the presence of anti-transglutaminase-6 (TG6) antibody can be used to diagnose gluten ataxia. Herein, we will review evidence relating to gluten ataxia and report two cases of anti-TG6 antibody positive gluten ataxia. In patients with gluten ataxia, sensory disturbance is generally considered to be so mild that it contributes minimally to ataxia. However, our patients showed a positive Romberg sign. Deep sensory disturbance, in addition to cerebellar disturbance, may have been involved in the clinical symptoms of our cases.

Orbital Disturbance Analysis due to the Lunar Gravitational Potential and Deviation Minimization through the Trajectory Control in Closed Loop

NASA Astrophysics Data System (ADS)

Gonçalves, L. D.; Rocco, E. M.; de Moraes, R. V.

2013-10-01

A study evaluating the influence due to the lunar gravitational potential, modeled by spherical harmonics, on the gravity acceleration is accomplished according to the model presented in Konopliv (2001). This model provides the components x, y and z for the gravity acceleration at each moment of time along the artificial satellite orbit and it enables to consider the spherical harmonic degree and order up to100. Through a comparison between the gravity acceleration from a central field and the gravity acceleration provided by Konopliv's model, it is obtained the disturbing velocity increment applied to the vehicle. Then, through the inverse problem, the Keplerian elements of perturbed orbit of the satellite are calculated allowing the orbital motion analysis. Transfer maneuvers and orbital correction of lunar satellites are simulated considering the disturbance due to non-uniform gravitational potential of the Moon, utilizing continuous thrust and trajectory control in closed loop. The simulations are performed using the Spacecraft Trajectory Simulator-STRS, Rocco (2008), which evaluate the behavior of the orbital elements, fuel consumption and thrust applied to the satellite over the time.

ostglacial rebound from VLBI Geodesy: On Establishing Vertical Reference

NASA Technical Reports Server (NTRS)

Argus, Donald .

1996-01-01

I propose that a useful reference frame for vertical motions is that found by minimizing differences between vertical motions observed with VLBI [Ma and Ryan, 1995] and predictions from postglacial rebound predictions [Peltier, 1995].

METHODS MODULE

EPA Science Inventory

The ultimate goal of classification is to reduce variation within classes to enable detection of differences between reference and impacted condition within classes as cost-effectively as possible, while minimizing the number of classes for which reference conditions must be defi...

Solar flare emissions and geophysical disturbances

NASA Technical Reports Server (NTRS)

Sakurai, K.

1973-01-01

Various geophysical phenomena are produced by both wave and particle emissions from solar flares. Using the observed data for these emissions, a review is given on the nature of solar flares and their development. Geophysical phenomena are discussed by referring to the results for solar flare phenomena.

77 FR 27747 - Applications for New Awards; Personnel Development To Improve Services and Results for Children...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-11

... disabilities, that result in improvements in learning and developmental outcomes (e.g., academic, social...-incidence disabilities'' refers to learning disabilities, emotional disturbance, or intellectual... Results for Children With Disabilities--Personnel Preparation in Special Education, Early Intervention...

A global meta-analysis on the ecological drivers of forest restoration success

PubMed Central

Crouzeilles, Renato; Curran, Michael; Ferreira, Mariana S.; Lindenmayer, David B.; Grelle, Carlos E. V.; Rey Benayas, José M.

2016-01-01

Two billion ha have been identified globally for forest restoration. Our meta-analysis encompassing 221 study landscapes worldwide reveals forest restoration enhances biodiversity by 15–84% and vegetation structure by 36–77%, compared with degraded ecosystems. For the first time, we identify the main ecological drivers of forest restoration success (defined as a return to a reference condition, that is, old-growth forest) at both the local and landscape scale. These are as follows: the time elapsed since restoration began, disturbance type and landscape context. The time elapsed since restoration began strongly drives restoration success in secondary forests, but not in selectively logged forests (which are more ecologically similar to reference systems). Landscape restoration will be most successful when previous disturbance is less intensive and habitat is less fragmented in the landscape. Restoration does not result in full recovery of biodiversity and vegetation structure, but can complement old-growth forests if there is sufficient time for ecological succession. PMID:27193756

Sleep disorders in US military personnel: a high rate of comorbid insomnia and obstructive sleep apnea.

PubMed

Mysliwiec, Vincent; Gill, Jessica; Lee, Hyunhwa; Baxter, Tristin; Pierce, Roslyn; Barr, Taura L; Krakow, Barry; Roth, Bernard J

2013-08-01

Sleep disturbances are among the most common symptoms of military personnel who return from deployment. The objective of our study was to determine the presence of sleep disorders in US military personnel referred for evaluation of sleep disturbances after deployment and examine associations between sleep disorders and service-related diagnoses of depression, mild traumatic brain injury, pain, and posttraumatic stress disorder (PTSD). This was a cross-sectional study of military personnel with sleep disturbances who returned from combat within 18 months of deployment. Sleep disorders were assessed by clinical evaluation and polysomnogram with validated instruments to diagnose service-related illnesses. Of 110 military personnel included in our analysis, 97.3% were men (mean age, 33.6 ± 8.0 years; mean BMI, 30.0 ± 4.3 kg/m2), and 70.9% returned from combat within 12 months. Nearly one-half (47.3%) met diagnostic criteria for two or more service-related diagnoses. Sleep disorders were diagnosed in 88.2% of subjects; 11.8% had a normal sleep evaluation and served as control subjects. Overall, 62.7% met diagnostic criteria for obstructive sleep apnea (OSA) and 63.6% for insomnia. The exclusive diagnoses of insomnia and OSA were present in 25.5% and 24.5% of subjects, respectively; 38.2% had comorbid insomnia and OSA. Military personnel with comorbid insomnia and OSA were significantly more likely to meet criteria for depression (P < .01) and PTSD (P < .01) compared with control subjects and those with OSA only. Comorbid insomnia and OSA is a frequent diagnosis in military personnel referred for evaluation of sleep disturbances after deployment. This diagnosis, which is difficult to treat, may explain the refractory nature of many service-related diagnoses.

Delirium in elderly people: a study of a psychiatric liaison service in north India.

PubMed

Grover, Sandeep; Kate, Natasha; Agarwal, Munish; Mattoo, Surendra Kumar; Avasthi, Ajit; Malhotra, Savita; Kulhara, Parmanand; Chakrabarti, Subho; Basu, Debasish

2012-01-01

Very few studies from India have studied the phenomenology of delirium. The aim of the present study was to study the phenomenology as measured using the Delirium Rating Scale-Revised-98 (DRS-R98), the associated etiologies and the outcome of delirium among the elderly participants seen by the consultation-liaison psychiatric service in India. In addition, an attempt was made to study the factor structure of symptoms using principal components analysis. The case notes of 109 elderly patients referred to psychiatry liaison services were reviewed. The mean age of the sample was 73.35 years (SD: 7.44; range 65-95 years) and two-thirds of the sample had hospital emergent delirium. The mean DRS-R98 severity score was 18.77 and the DRS-R98 total score was 24.81. In 15 patients the DRS-R98 scores were in the subsyndromal range. Among the various symptoms present, most patients had sleep-wake cycle disturbance, disturbance in orientation, attention and short-term memory impairments, fluctuation of symptoms, temporal onset of symptoms and a physical disorder. Principal components analysis identified three factors which explained 43.5% of variance of symptomatology and it yielded a three-factor structure. Endocrine/metabolic disturbances were the commonest associated etiological category with delirium. The mean hospital stay after being referred to psychiatry referral services was 8.89 days, after which delirium improved in 58.7% of cases. The mortality rate during the inpatient stay was 16.5%. Results suggest that the symptoms of delirium as assessed by DRS-R98 separate out into a three-factor structure. Delirium is commonly associated with metabolic endocrine disturbances and about one-sixth of the patients die during the short inpatient stay.

Sleep Disorders in US Military Personnel

PubMed Central

Gill, Jessica; Lee, Hyunhwa; Baxter, Tristin; Pierce, Roslyn; Barr, Taura L.; Krakow, Barry; Roth, Bernard J.

2013-01-01

Background: Sleep disturbances are among the most common symptoms of military personnel who return from deployment. The objective of our study was to determine the presence of sleep disorders in US military personnel referred for evaluation of sleep disturbances after deployment and examine associations between sleep disorders and service-related diagnoses of depression, mild traumatic brain injury, pain, and posttraumatic stress disorder (PTSD). Methods: This was a cross-sectional study of military personnel with sleep disturbances who returned from combat within 18 months of deployment. Sleep disorders were assessed by clinical evaluation and polysomnogram with validated instruments to diagnose service-related illnesses. Results: Of 110 military personnel included in our analysis, 97.3% were men (mean age, 33.6 ± 8.0 years; mean BMI, 30.0 ± 4.3 kg/m2), and 70.9% returned from combat within 12 months. Nearly one-half (47.3%) met diagnostic criteria for two or more service-related diagnoses. Sleep disorders were diagnosed in 88.2% of subjects; 11.8% had a normal sleep evaluation and served as control subjects. Overall, 62.7% met diagnostic criteria for obstructive sleep apnea (OSA) and 63.6% for insomnia. The exclusive diagnoses of insomnia and OSA were present in 25.5% and 24.5% of subjects, respectively; 38.2% had comorbid insomnia and OSA. Military personnel with comorbid insomnia and OSA were significantly more likely to meet criteria for depression (P < .01) and PTSD (P < .01) compared with control subjects and those with OSA only. Conclusions: Comorbid insomnia and OSA is a frequent diagnosis in military personnel referred for evaluation of sleep disturbances after deployment. This diagnosis, which is difficult to treat, may explain the refractory nature of many service-related diagnoses. PMID:23681455

Sensitivity of mountain ecosystems to human-accelerated soil erosion. Contrasting geomorphic response between tropical and semi-arid ecosystems.

NASA Astrophysics Data System (ADS)

Vanacker, Veerle; Bellin, Nicolas; Schoonejans, Jerome; Molina, Armando; Kubik, Peter W.

2014-05-01

Human-induced land cover changes are causing important adverse effects on the ecological services rendered by mountain ecosystems, and the number of case-studies of the impact of humans on soil erosion and sediment yield has mounted rapidly. A modelling framework that is specifically adapted to mountain environments is currently lacking. Most studies make use of general river basin models that were originally parameterized and calibrated for temperate, low relief landscapes. Transposing these modelling concepts directly to steep environments with shallow and stony soils often leads to unrealistic model predictions, as model input parameters are rarely calibrated for the range of environmental conditions found in mountain regions. Here, we present a conceptual model that evaluates erosion regulation as a function of human disturbances in vegetation cover. The basic idea behind this model is that soil erosion mechanisms are independent of human impact, but that the frequency-magnitude distributions of erosion rates change as a response to human disturbances. Pre-disturbance (or natural) erosion rates are derived from in-situ produced 10Be concentrations in river sediment, while post-disturbance (or modern) erosion rates are derived from sedimentation rates in small catchments. In its simplicity, the model uses vegetation cover change as a proxy of human disturbance in a given vegetation system. The model is then calibrated with field measurements from two mountainous sites with strongly different vegetation dynamics, climatic and geological settings: the Tropical Andes, and the Spanish Betic Cordillera. Natural erosion processes are important in mountainous sites, and natural erosion benchmarks are primordial to assess human-induced changes in erosion rates. While the Spanish Betic Cordillera is commonly characterized as a degraded landscape, there is no significant change in erosion due to human disturbance for uncultivated sites. The opposite is true for the Tropical Andes where the share of natural erosion in the modern erosion rate is minimal for most disturbed sites. When pooling pre- and post-disturbance erosion data from both sites, it becomes evident that the human acceleration of erosion is significantly related to vegetation disturbance. It may therefore be expected that the potential for erosion regulation is larger in well-vegetated ecosystem where strong differences may exist in vegetation cover between human disturbed and undisturbed or restored sites.

H∞ output tracking control of uncertain and disturbed nonlinear systems based on neural network model

NASA Astrophysics Data System (ADS)

Li, Chengcheng; Li, Yuefeng; Wang, Guanglin

2017-07-01

The work presented in this paper seeks to address the tracking problem for uncertain continuous nonlinear systems with external disturbances. The objective is to obtain a model that uses a reference-based output feedback tracking control law. The control scheme is based on neural networks and a linear difference inclusion (LDI) model, and a PDC structure and H∞ performance criterion are used to attenuate external disturbances. The stability of the whole closed-loop model is investigated using the well-known quadratic Lyapunov function. The key principles of the proposed approach are as follows: neural networks are first used to approximate nonlinearities, to enable a nonlinear system to then be represented as a linearised LDI model. An LMI (linear matrix inequality) formula is obtained for uncertain and disturbed linear systems. This formula enables a solution to be obtained through an interior point optimisation method for some nonlinear output tracking control problems. Finally, simulations and comparisons are provided on two practical examples to illustrate the validity and effectiveness of the proposed method.

Effects of common seagrass restoration methods on ecosystem structure in subtropical seagrass meadows.

PubMed

Bourque, Amanda S; Fourqurean, James W

2014-06-01

Seagrass meadows near population centers are subject to frequent disturbance from vessel groundings. Common seagrass restoration methods include filling excavations and applying fertilizer to encourage seagrass recruitment. We sampled macrophytes, soil structure, and macroinvertebrate infauna at unrestored and recently restored vessel grounding disturbances to evaluate the effects of these restoration methods on seagrass ecosystem structure. After a year of observations comparing filled sites to both undisturbed reference and unrestored disturbed sites, filled sites had low organic matter content, nutrient pools, and primary producer abundance. Adding a nutrient source increased porewater nutrient pools at disturbed sites and in undisturbed meadows, but not at filled sites. Environmental predictors of infaunal community structure across treatments included soil texture and nutrient pools. At the one year time scale, the restoration methods studied did not result in convergence between restored and unrestored sites. Particularly in filled sites, soil conditions may combine to constrain rapid development of the seagrass community and associated infauna. Our study is important for understanding early recovery trajectories following restoration using these methods. Published by Elsevier Ltd.

Hard tissue pediatric facial trauma: a review.

PubMed

Hogg, Nicholas J V; Horswell, Bruce B

2006-01-01

Although hard tissue injuries are uncommon in the pediatric patient, dentists may be involved in the initial assessment of these patients. In this paper, we review fractures of the facial skeleton with a focus on dentoalveolar injuries. Minimally displaced fractures in pediatric patients can be managed conservatively, while displaced fractures may require open approaches and rigid fixation. New fixation stratagems are presented, and possible facial growth disturbances resulting from trauma are discussed.

Numerical and experimental evaluation of microfluidic sorting devices.

PubMed

Taylor, Jay K; Ren, Carolyn L; Stubley, G D

2008-01-01

The development of lab-on-a-chip devices calls for the isolation or separation of specific bioparticles or cells. The design of a miniaturized cell-sorting device for handheld operation must follow the strict parameters associated with lab-on-a-chip technology. The limitations include applied voltage, high efficiency of cell-separation, reliability, size, flow control, and cost, among others. Currently used designs have achieved successful levels of cell isolation; however, further improvements in the microfluidic chip design are important to incorporate into larger systems. This study evaluates specific design modifications that contribute to the reduction of required applied potential aiming for developing portable devices, improved operation reliability by minimizing induced pressure disturbance when electrokinetic pumping is employed, and improved flow control by incorporating directing streams achieving dynamic sorting and counting. The chip designs fabricated in glass and polymeric materials include asymmetric channel widths for sample focusing, nonuniform channel depth for minimizing induced pressure disturbance, directing streams to assist particle flow control, and online filters for reducing channel blockage. Fluorescence-based visualization experimental results of electrokinetic focusing, flow field phenomena, and dynamic sorting demonstrate the advantages of the chip design. Numerical simulations in COMSOL are validated by the experimental data and used to investigate the effects of channel geometry and fluid properties on the flow field.

Employment references: walking scared between the minefield of defamation and the specter of negligent hiring.

PubMed

McConnell, C R

2000-12-01

In present day reference checking, many of the same organizations that seek as much information as possible about people they wish to hire resist giving out more than a bare minimum of information to other organizations. The strongest force driving this minimal reference information release is fear of legal action taken because of something said about an individual (defamation, supposedly). Many employers appear so frightened of being sued for libel or slander that they share nothing of substance, usually not realizing that in trying to protect themselves against defamation charges they are increasing their legal risk associated with negligent hiring charges. However, truthful reference information can be provided with minimal risk if it is provided in good faith, given only to someone who has a legitimate need to know, is related strictly to job in character, and is not communicated maliciously. Also, reference always must be answered completely objectively with information verifiable in the individual's personnel file.

Optimized spatial priorities for biodiversity conservation in China: a systematic conservation planning perspective.

PubMed

Wu, Ruidong; Long, Yongcheng; Malanson, George P; Garber, Paul A; Zhang, Shuang; Li, Diqiang; Zhao, Peng; Wang, Longzhu; Duo, Hairui

2014-01-01

By addressing several key features overlooked in previous studies, i.e. human disturbance, integration of ecosystem- and species-level conservation features, and principles of complementarity and representativeness, we present the first national-scale systematic conservation planning for China to determine the optimized spatial priorities for biodiversity conservation. We compiled a spatial database on the distributions of ecosystem- and species-level conservation features, and modeled a human disturbance index (HDI) by aggregating information using several socioeconomic proxies. We ran Marxan with two scenarios (HDI-ignored and HDI-considered) to investigate the effects of human disturbance, and explored the geographic patterns of the optimized spatial conservation priorities. Compared to when HDI was ignored, the HDI-considered scenario resulted in (1) a marked reduction (∼9%) in the total HDI score and a slight increase (∼7%) in the total area of the portfolio of priority units, (2) a significant increase (∼43%) in the total irreplaceable area and (3) more irreplaceable units being identified in almost all environmental zones and highly-disturbed provinces. Thus the inclusion of human disturbance is essential for cost-effective priority-setting. Attention should be targeted to the areas that are characterized as moderately-disturbed, <2,000 m in altitude, and/or intermediately- to extremely-rugged in terrain to identify potentially important regions for implementing cost-effective conservation. We delineated 23 primary large-scale priority areas that are significant for conserving China's biodiversity, but those isolated priority units in disturbed regions are in more urgent need of conservation actions so as to prevent immediate and severe biodiversity loss. This study presents a spatially optimized national-scale portfolio of conservation priorities--effectively representing the overall biodiversity of China while minimizing conflicts with economic development. Our results offer critical insights for current conservation and strategic land-use planning in China. The approach is transferable and easy to implement by end-users, and applicable for national- and local-scale systematic conservation prioritization practices.

Chronic human disturbance affects plant trait distribution in a seasonally dry tropical forest

NASA Astrophysics Data System (ADS)

Sfair, Julia C.; de Bello, Francesco; de França, Thaysa Q.; Baldauf, Cristina; Tabarelli, Marcelo

2018-02-01

The effects of human disturbance on biodiversity can be mediated by environmental conditions, such as water availability, climate and nutrients. In general, disturbed, dry or nutrient-depleted soils areas tend to have lower taxonomic diversity. However, little is known about how these environmental conditions affect functional composition and intraspecific variability in tropical dry forests. We studied a seasonally dry tropical forest (SDTF) under chronic anthropogenic disturbance (CAD) along rainfall and soil nutrient gradients to understand how these factors influence the taxonomic and functional composition. Specifically we evaluated two aspects of CAD, wood extraction and livestock pressure (goat and cattle grazing), along soil fertility and rainfall gradients on shrub and tree traits, considering species turnover and intraspecific variability. In addition, we also tested how the traits of eight populations of the most frequent species are affected by wood extraction, livestock pressure, rainfall and soil fertility. In general, although CAD and environmental gradients affected each trait of the most widespread species differently, the most abundant species also had a greater variation of traits. Considering species turnover, wood extraction is associated with species with a smaller leaf area and lower investment in leaf mass, probably due to the indirect effects of this disturbance type on the vegetation, i.e. the removal of branches and woody debris clears the vegetation, favouring species that minimize water loss. Livestock pressure, on the other hand, affected intraspecific variation: the herbivory caused by goats and cattle promoted individuals which invest more in wood density and leaf mass. In this case, the change of functional composition observed is a direct effect of the disturbance, such as the decrease of palatable plant abundance by goat and cattle herbivory. In synthesis, CAD, rainfall and soil fertility can affect trait distribution at community and species levels, which can have significant implications for the ecosystem functioning of SDTF under increasing levels of disturbance, climate change and soil nutrient depletion.

Optimized Spatial Priorities for Biodiversity Conservation in China: A Systematic Conservation Planning Perspective

PubMed Central

Wu, Ruidong; Long, Yongcheng; Malanson, George P.; Garber, Paul A.; Zhang, Shuang; Li, Diqiang; Zhao, Peng; Wang, Longzhu; Duo, Hairui

2014-01-01

By addressing several key features overlooked in previous studies, i.e. human disturbance, integration of ecosystem- and species-level conservation features, and principles of complementarity and representativeness, we present the first national-scale systematic conservation planning for China to determine the optimized spatial priorities for biodiversity conservation. We compiled a spatial database on the distributions of ecosystem- and species-level conservation features, and modeled a human disturbance index (HDI) by aggregating information using several socioeconomic proxies. We ran Marxan with two scenarios (HDI-ignored and HDI-considered) to investigate the effects of human disturbance, and explored the geographic patterns of the optimized spatial conservation priorities. Compared to when HDI was ignored, the HDI-considered scenario resulted in (1) a marked reduction (∼9%) in the total HDI score and a slight increase (∼7%) in the total area of the portfolio of priority units, (2) a significant increase (∼43%) in the total irreplaceable area and (3) more irreplaceable units being identified in almost all environmental zones and highly-disturbed provinces. Thus the inclusion of human disturbance is essential for cost-effective priority-setting. Attention should be targeted to the areas that are characterized as moderately-disturbed, <2,000 m in altitude, and/or intermediately- to extremely-rugged in terrain to identify potentially important regions for implementing cost-effective conservation. We delineated 23 primary large-scale priority areas that are significant for conserving China's biodiversity, but those isolated priority units in disturbed regions are in more urgent need of conservation actions so as to prevent immediate and severe biodiversity loss. This study presents a spatially optimized national-scale portfolio of conservation priorities – effectively representing the overall biodiversity of China while minimizing conflicts with economic development. Our results offer critical insights for current conservation and strategic land-use planning in China. The approach is transferable and easy to implement by end-users, and applicable for national- and local-scale systematic conservation prioritization practices. PMID:25072933

Nonlinear modeling of wave-topography interactions, shear instabilities and shear induced wave breaking using vortex method

NASA Astrophysics Data System (ADS)

Guha, Anirban

2017-11-01

Theoretical studies on linear shear instabilities as well as different kinds of wave interactions often use simple velocity and/or density profiles (e.g. constant, piecewise) for obtaining good qualitative and quantitative predictions of the initial disturbances. Moreover, such simple profiles provide a minimal model to obtain a mechanistic understanding of shear instabilities. Here we have extended this minimal paradigm into nonlinear domain using vortex method. Making use of unsteady Bernoulli's equation in presence of linear shear, and extending Birkhoff-Rott equation to multiple interfaces, we have numerically simulated the interaction between multiple fully nonlinear waves. This methodology is quite general, and has allowed us to simulate diverse problems that can be essentially reduced to the minimal system with interacting waves, e.g. spilling and plunging breakers, stratified shear instabilities (Holmboe, Taylor-Caulfield, stratified Rayleigh), jet flows, and even wave-topography interaction problem like Bragg resonance. We found that the minimal models capture key nonlinear features (e.g. wave breaking features like cusp formation and roll-ups) which are observed in experiments and/or extensive simulations with smooth, realistic profiles.

Concentrating anthropogenic disturbance to balance ecological and economic values: applications to forest management.

PubMed

Tittler, Rebecca; Messier, Christian; Fall, Andrew

2012-06-01

To maintain healthy ecosystems, natural-disturbance-based management aims to minimize differences between unmanaged and managed landscapes. Two related approaches may help accomplish this goal, either applied together or in isolation: (1) concentrating anthropogenic disturbance through zoning (with protected areas and intensive management); and (2) emulating natural disturbances. The purpose of this paper is to examine the effects of these two approaches, applied both in isolation and in combination, on the structure of the forest landscape. To do so, we use a spatially explicit landscape simulation model on a large fire-dominated landscape in eastern Canada. Specifically, we examine the effects of (1) increasing the maximum size of logged stands (cutblocks) to better emulate the full range of fire sizes in a fire-dominated landscape, (2) increasing protected areas, and (3) adding aggregated or dispersed intensive wood production areas to the landscape in addition to protected areas (triad management). We focus on maximizing the amount and minimizing the fragmentation of old-growth forest and on reducing road construction. Increasing maximum cutblock size and adding protected areas led to reduced road construction, while the latter also resulted in less fragmentation and more old growth. Although protected areas led to reduced harvest volume, the addition of an intensive production zone (triad management) counterbalanced this loss and resulted in more old growth than equivalent scenarios with protected areas but no intensive production zone. However, we found no differences between aggregated and dispersed intensive wood production. Our results imply that differences between unmanaged and managed landscapes can be reduced by concentrating logging efforts through a combination of protected areas and intensive wood production, and by creating some larger cutblocks. We conclude that the forest industry and regulators should therefore seek to increase protected areas through triad management and consider increasing maximum cutblock size. These results add to a growing body of literature indicating that intensive management on a small part of the landscape may be better than less intensive management spread out over a much larger part of the landscape, whether this is in the context of forestry, agriculture, or urban development.

Evaluation of the effect of erythropoietin + corticosteroid versus corticosteroid alone in methanol-induced optic nerve neuropathy.

PubMed

Zamani, Nasim; Hassanian-Moghaddam, Hossein; Shojaei, Maziar; Rahimian, Sara

2018-06-01

Following methanol intoxication, optic nerve neuropathy may occur, which is currently treated by different therapeutic regimens. Erythropoietin (EPO) has recently been introduced as a good therapeutic option in methanol-induced optic neuropathy. The aim of the current study was to evaluate the efficacy of EPO in improvement of the visual disturbances in methanol-intoxicated patients. In a case-control study, all patients who had referred to our toxicology centre with confirmed diagnosis of methanol toxicity were considered to be included. Of them, those who had referred with visual disturbances, survived, and their visual disturbances had not improved after haemodialysis were entered. Cases received EPO and corticosteroids while controls only received corticosteroids. They were then compared regarding their visual outcome. All five patients in the control group mentioned that after discharge, their visual acuity had improved while in the cases, three mentioned visual improvement, two mentioned their visual acuity had deteriorated after discharge, two mentioned no change in their visual acuity and three mentioned that their visual acuity had first improved but then deteriorated with a mean two-month interval period. In fundoscopic evaluations, two controls had normal fundospcopy while eight cases had abnormal fundoscopy (p = 0.055). Protective effect of EPO on methanol-induced optic nerve may be strong at the beginning of the intervention but is probably transient.

Free Energy Minimization Calculation of Complex Chemical Equilibria. Reduction of Silicon Dioxide with Carbon at High Temperature.

ERIC Educational Resources Information Center

Wai, C. M.; Hutchinson, S. G.

1989-01-01

Discusses the calculation of free energy in reactions between silicon dioxide and carbon. Describes several computer programs for calculating the free energy minimization and their uses in chemistry classrooms. Lists 16 references. (YP)

Eigenmodes of Ducted Flows With Radially-Dependent Axial and Swirl Velocity Components

NASA Technical Reports Server (NTRS)

Kousen, Kenneth A.

1999-01-01

This report characterizes the sets of small disturbances possible in cylindrical and annular ducts with mean flow whose axial and tangential components vary arbitrarily with radius. The linearized equations of motion are presented and discussed, and then exponential forms for the axial, circumferential, and time dependencies of any unsteady disturbances are assumed. The resultant equations form a generalized eigenvalue problem, the solution of which yields the axial wavenumbers and radial mode shapes of the unsteady disturbances. Two numerical discretizations are applied to the system of equations: (1) a spectral collocation technique based on Chebyshev polynomial expansions on the Gauss-Lobatto points, and (2) second and fourth order finite differences on uniform grids. The discretized equations are solved using a standard eigensystem package employing the QR algorithm. The eigenvalues fall into two primary categories: a discrete set (analogous to the acoustic modes found in uniform mean flows) and a continuous band (analogous to convected disturbances in uniform mean flows) where the phase velocities of the disturbances correspond to the local mean flow velocities. Sample mode shapes and eigensystem distributions are presented for both sheared axial and swirling flows. The physics of swirling flows is examined with reference to hydrodynamic stability and completeness of the eigensystem expansions. The effect of assuming exponential dependence in the axial direction is discussed.

WHO Environmental Noise Guidelines for the European Region: A Systematic Review on Environmental Noise and Effects on Sleep

PubMed Central

McGuire, Sarah

2018-01-01

To evaluate the quality of available evidence on the effects of environmental noise exposure on sleep a systematic review was conducted. The databases PSYCINFO, PubMed, Science Direct, Scopus, Web of Science and the TNO Repository were searched for non-laboratory studies on the effects of environmental noise on sleep with measured or predicted noise levels and published in or after the year 2000. The quality of the evidence was assessed using GRADE criteria. Seventy four studies predominately conducted between 2000 and 2015 were included in the review. A meta-analysis of surveys linking road, rail, and aircraft noise exposure to self-reports of sleep disturbance was conducted. The odds ratio for the percent highly sleep disturbed for a 10 dB increase in Lnight was significant for aircraft (1.94; 95% CI 1.61–2.3), road (2.13; 95% CI 1.82–2.48), and rail (3.06; 95% CI 2.38–3.93) noise when the question referred to noise, but non-significant for aircraft (1.17; 95% CI 0.54–2.53), road (1.09; 95% CI 0.94–1.27), and rail (1.27; 95% CI 0.89–1.81) noise when the question did not refer to noise. A pooled analysis of polysomnographic studies on the acute effects of transportation noise on sleep was also conducted and the unadjusted odds ratio for the probability of awakening for a 10 dBA increase in the indoor Lmax was significant for aircraft (1.35; 95% CI 1.22–1.50), road (1.36; 95% CI 1.19–1.55), and rail (1.35; 95% CI 1.21–1.52) noise. Due to a limited number of studies and the use of different outcome measures, a narrative review only was conducted for motility, cardiac and blood pressure outcomes, and for children’s sleep. The effect of wind turbine and hospital noise on sleep was also assessed. Based on the available evidence, transportation noise affects objectively measured sleep physiology and subjectively assessed sleep disturbance in adults. For other outcome measures and noise sources the examined evidence was conflicting or only emerging. According to GRADE criteria, the quality of the evidence was moderate for cortical awakenings and self-reported sleep disturbance (for questions that referred to noise) induced by traffic noise, low for motility measures of traffic noise induced sleep disturbance, and very low for all other noise sources and investigated sleep outcomes. PMID:29538344

Intelligent systems for strategic power infrastructure defense

NASA Astrophysics Data System (ADS)

Jung, Ju-Hwan

A fault or disturbance in a power system can be severe due to the sources of vulnerability such as human errors, protection and control system failures, a failure of communication networks to deliver critical control signals, and market and load uncertainties. There have been several catastrophic failures resulting from disturbances involving the sources of vulnerability while power systems are designed to withstand disturbances or faults. To avoid catastrophic failures or minimize the impact of a disturbance(s), the state of the power system has to be analyzed correctly and preventive or corrective self-healing control actions have to be deployed. This dissertation addresses two aspects of power systems: Defense system and diagnosis, both concerned with the power system analysis and operation during events involving faults or disturbances. This study is intended to develop a defense system that is able to assess power system vulnerability and to perform self-healing control actions based on the system-wide analysis. In order to meet the requirements of the system-wide analysis, the defense system is designed with multi-agent system technologies. Since power systems are dynamic and uncertain the self-healing control actions need to be adaptive. This study applies the reinforcement learning technique to provide a theoretical basis for adaptation. One of the important issues in adaptation is the convergence of the learning algorithm. An appropriate convergence criterion is derived and an application with a load-shedding scheme is demonstrated in this study. This dissertation also demonstrates the feasibility of the defense system and self-healing control actions through multi-agent system technologies. The other subject of this research is to investigate the methodology for on-line fault diagnosis using the information from Sequence-of-Events Recorders (SER). The proposed multiple-hypothesis analysis generates one or more hypothetical fault scenarios to interpret the SER information. In order to avoid ambiguity of the hypotheses, this study proposes a new method to determine the credibility of each hypothesis. Even if there is not enough SER information, the proposed method is able to perform an accurate fault and malfunction analysis. To avoid exhaustive testing, a minimal set of test scenarios is derived, which is able to handle missing information and SERs. During extreme contingencies or cascading events, fault diagnosis is the first step in the operation of the power system. On-line fault diagnosis provides necessary and correct information for the defense system to make correct and efficient decisions on self-healing control actions. It has been shown in previous studies that incorrect fault diagnosis can lead to catastrophic failures in power systems. Fault diagnosis is an important issue for strategic power infrastructure defense.

Redundancy management of electrohydraulic servoactuators by mathematical model referencing

NASA Technical Reports Server (NTRS)

Campbell, R. A.

1971-01-01

A description of a mathematical model reference system is presented which provides redundancy management for an electrohydraulic servoactuator. The mathematical model includes a compensation network that calculates reference parameter perturbations induced by external disturbance forces. This is accomplished by using the measured pressure differential data taken from the physical system. This technique was experimentally verified by tests performed using the H-1 engine thrust vector control system for Saturn IB. The results of these tests are included in this report. It was concluded that this technique improves the tracking accuracy of the model reference system to the extent that redundancy management of electrohydraulic servosystems may be performed using this method.

Optimal trajectories of aircraft and spacecraft

NASA Technical Reports Server (NTRS)

Miele, A.

1990-01-01

Work done on algorithms for the numerical solutions of optimal control problems and their application to the computation of optimal flight trajectories of aircraft and spacecraft is summarized. General considerations on calculus of variations, optimal control, numerical algorithms, and applications of these algorithms to real-world problems are presented. The sequential gradient-restoration algorithm (SGRA) is examined for the numerical solution of optimal control problems of the Bolza type. Both the primal formulation and the dual formulation are discussed. Aircraft trajectories, in particular, the application of the dual sequential gradient-restoration algorithm (DSGRA) to the determination of optimal flight trajectories in the presence of windshear are described. Both take-off trajectories and abort landing trajectories are discussed. Take-off trajectories are optimized by minimizing the peak deviation of the absolute path inclination from a reference value. Abort landing trajectories are optimized by minimizing the peak drop of altitude from a reference value. Abort landing trajectories are optimized by minimizing the peak drop of altitude from a reference value. The survival capability of an aircraft in a severe windshear is discussed, and the optimal trajectories are found to be superior to both constant pitch trajectories and maximum angle of attack trajectories. Spacecraft trajectories, in particular, the application of the primal sequential gradient-restoration algorithm (PSGRA) to the determination of optimal flight trajectories for aeroassisted orbital transfer are examined. Both the coplanar case and the noncoplanar case are discussed within the frame of three problems: minimization of the total characteristic velocity; minimization of the time integral of the square of the path inclination; and minimization of the peak heating rate. The solution of the second problem is called nearly-grazing solution, and its merits are pointed out as a useful engineering compromise between energy requirements and aerodynamics heating requirements.

Linguistic Vitality, Endangerment, and Resilience

ERIC Educational Resources Information Center

Roche, Gerald

2017-01-01

The concept of "resilience" originated in both ecology and psychology, and refers to the propensity of a system or entity to "bounce back" from a disturbance. Recently, the concept has found increasing application within linguistics, particularly the study of endangered languages. In this context, resilience is used to describe…

Convective Water Vapor Energy for Lower Urinary Tract Symptoms/Benign Prostatic Hyperplasia.

PubMed

DeLay, Kenneth Jackson; McVary, Kevin T

2016-08-01

Benign prostatic hyperplasia (BPH) refers to proliferation of smooth muscle and epithelial cells within the transition zone of the prostate. Half of men over 40 develop histologic BPH. About half of men with BPH develop an enlarged prostate gland, called benign prostatic enlargement; among these, about half develop some degree of bladder outlet obstruction. Bladder outlet obstruction and changes in smooth muscle tone and resistance may result in lower urinary tract symptoms, including storage disturbances (such as daytime urinary urgency, frequency, and nocturia) and voiding disturbances (such as urinary hesitancy, weak urinary stream, straining to void, and prolonged voiding). Copyright © 2016 Elsevier Inc. All rights reserved.

Intelligent control of a multi-degree-of freedom reaction compensating platform system using fuzzy logic

NASA Technical Reports Server (NTRS)

Choi, Benjamin B.; Lawrence, Charles; Lin, Yueh-Jaw

1994-01-01

This paper presents the development of a general-purpose fuzzy logic (FL) control methodology for isolating the external vibratory disturbances of space-based devices. According to the desired performance specifications, a full investigation regarding the development of an FL controller was done using different scenarios, such as variances of passive reaction-compensating components and external disturbance load. It was shown that the proposed FL controller is robust in that the FL-controlled system closely follows the prespecified ideal reference model. The comparative study also reveals that the FL-controlled system achieves significant improvement in reducing vibrations over passive systems.

[Circadian rhythm disruption and human development].

PubMed

Kohyama, Jun

2013-12-01

Ontogenetic developments of rest-activity, sleep-wakefulness, temperature and several hormone rhythms in humans were reviewed. The reported effects of environment on these alterations were also summarized. Then, disorders or conditions which often encounter during early stage of life and reveal circadian rhythm disruptions were described. These disorders or conditions included severe brain damage, visual disturbance, developmental disorders(autistic spectrum disorder and attention deficit/hyperactivity disorder), Rett syndrome, Angelman syndrome, Smith-Magenis syndrome, epilepsy, Yonaki, and inadequate sleep hygiene. Finally, it was emphasized that we should pay special attention on the development of youngsters who showed sleep disturbance during early stage of life with special reference to the later occurrence of developmental disorders.

Modern control techniques in active flutter suppression using a control moment gyro

NASA Technical Reports Server (NTRS)

Buchek, P. M.

1974-01-01

Development of organized synthesis techniques, using concepts of modern control theory was studied for the design of active flutter suppression systems for two and three-dimensional lifting surfaces, utilizing a control moment gyro (CMG) to generate the required control torques. Incompressible flow theory is assumed, with the unsteady aerodynamic forces and moments for arbitrary airfoil motion obtained by using the convolution integral based on Wagner's indicial lift function. Linear optimal control theory is applied to find particular optimal sets of gain values which minimize a quadratic performance function. The closed loop system's response to impulsive gust disturbances and the resulting control power requirements are investigated, and the system eigenvalues necessary to minimize the maximum value of control power are determined.

Aggregatibacter actinomycetemcomitans osteomyelitis in a 12 year old boy: case report emphasizing the importance of tissue culture, and review of literature.

PubMed

Sharma, Ketaki; Mudgil, Poonam; Whitehall, John S; Gosbell, Iain

2017-03-14

Aggregatibacter actinomycetemcomitans most commonly causes periodontitis but has been reported to infect heart valves, soft tissue, brain and lungs, and distal bones. Osteomyelitis distal to the jaw is rarely described. We report an unusual and rare case of chronic osteomyelitis caused by A. actinomycetemcomitans in the toe of a paediatric patient, and review the available literature. The infection was managed with intravenous antibiotics followed by oral antibiotics. This is an unusual presentation of A. actinomycetemcomitans causing chronic osteomyelitis presumed due to nidation in a minimally damaged bone, associated with bacteraemia of an oral commensal. It occurred in the toe, without obvious dental predisposition; associated with minimal clinical disturbance and with muted immune response.

Characterizing invertebrate traits in wadeable streams of the contiguous US: differences among ecoregions and land uses

USGS Publications Warehouse

Zuellig, Robert E.; Schmidt, Travis S.

2012-01-01

Much is known about invertebrate community traits in basins across Europe, but no comprehensive description of traits exists for the continental US. Little is known about the trait composition of invertebrates in reference or least-disturbed basins of the US, how trait composition varies among ecoregions, or how consistently traits respond to land use. These elements are essential to development of trait-based tools for conservation and assessment of biological integrity. We compared invertebrate traits of least-disturbed basins among ecoregions of the US. Benthic invertebrate data (presence/absence) from 1987 basins were translated into 56 binary traits (e.g., bivoltine, clinger). Basins were classified as least-disturbed, agricultural, or urban, and grouped into 9 ecoregions. Landuse, climatic, physiographic, and hydrologic data were used to describe ecoregions and to evaluate least-disturbed basin quality. The unique habitat template of each ecoregion selected for trait compositions in least-disturbed basins that differed among ecoregions. Among the traits examined, life-history (e.g., voltinism, development) and ecological traits (e.g., rheophily, thermal preference) differed most among ecoregions. Agricultural and urban land uses selected for trait compositions that differed from least-disturbed, but the extent of the differences depended on ecoregion and quality of the least-disturbed basins. No trait compositions unique to specific land uses were found. However, a disturbance syndrome was observed in that the magnitude and direction of trait responses to urban and agricultural land uses were consistent among ecoregions. Each ecoregion had a unique trait composition, but trait compositions could be used to aggregate ecoregions into 3 broad regions: Western Mountains, Plains and Lowlands, and Eastern Highlands. Our results indicate that large-scale trait-based assessment tools for the US will require calibration to account for regional differences in the trait composition of basins and in the quality of least-disturbed basins.

Of lemurs and louse flies: The biogeochemical and biotic effects of forest disturbance on Propithecus edwardsi and its obligate ectoparasite Allobosca crassipes in Ranomafana National Park, southeastern Madagascar.

PubMed

McGee, Elizabeth; Vaughn, Stanley

2017-08-01

From alleles to ecosystems and landscapes, anthropogenic activity continues to affect the environment, with particularly adverse effects on biodiversity hotspots such as Madagascar. Selective logging has been proposed as a "win-win" conservation strategy, yet its effects on different components of biodiversity are still not fully understood. Here we examine biotic factors (i.e., dietary differences) that may be driving differences in biogeochemical stocks between disturbed and undisturbed forests. We present the stable nitrogen (δ 15 N) and carbon (δ 13 C) isotope composition of hair from the lemur Propithecus edwardsi and of whole bodies of its obligate ectoparasite, the louse-fly Allobosca crassipes, from sites in Ranomafana National Park (RNP) that are comparable except for the history of logging and subsequent forest regeneration. P. edwardsi and A. crassipes from the disturbed (i.e., heavily selectively logged) site are lower in 15 N and 13 C relative to P. edwardsi and A. crassipes from sites that were minimally selectively logged or not commercially logged at all. There is a ∼3‰ decrease in 15 N between disturbed and undisturbed sites that corresponds to a difference of nearly a full trophic level. Flowers from Bakerella clavata, a staple food source for P. edwardsi in disturbed habitats and a fallback food for P. edwardsi in primary forests, were also analyzed isotopically. B. clavata is δ 15 N-depleted in both disturbed and undisturbed sites. Data from longitudinal behavioral surveys of P. edwardsi in RNP and other forests in eastern Madagascar point to significant differences in consumption patterns of B. clavata, with P. edwardsi in disturbed forests consuming almost twice as much of this plant. Depletion of 15 N in animal tissues is a complex issue, but likely the result of the interaction of physiological and ecological factors. Anthropogenic disturbance in RNP from selective logging has had both biotic and biogeochemical effects that are observable trophically. © 2017 Wiley Periodicals, Inc.

Menstruation disturbances: prevalence, characteristics, and effects on the activities of daily living among adolescent girls from Brazil.

PubMed

Pitangui, Ana Carolina R; Gomes, Mayra Ruana de A; Lima, Alaine Souza; Schwingel, Paulo Adriano; Albuquerque, Ana Paula dos S; de Araújo, Rodrigo Cappato

2013-06-01

To determine the prevalence, characteristics and effects on the activities of daily living of menstruation disturbances among adolescent girls. Descriptive, cross-sectional study. A public school in the city of Petrolina, Brazil. 218 female adolescents of ages between 12 and 17 years. We used a structured questionnaire addressing the socio-demographic and menstrual characteristics of the adolescents. The intensity of menstrual pain and its effect on the activities of daily living were measured using an 11-point numeric rating scale. The mean age of adolescent girls was 13.7 ± 1.5 years. The menstrual cycles of 67% were regular, while 33% were irregular. Dysmenorrhea had a prevalence of 73%, and school absenteeism was observed among 31% of the adolescents. In addition, 66% of the participants considered that dysmenorrhea affected their activities of daily living. Associations were found between the intensity of pain and the variables: school absenteeism; affected activities of daily living; need to use medications; and between affected activities of daily living and school absenteeism (P < .05). Among the menstrual disturbances observed dysmenorrhea stood out due to its high prevalence among adolescents with a negative effect on adolescents' activities of daily living. Early diagnosis and knowledge about menstrual disturbances are essential because in addition to reiterating the importance of implementing health education actions, they also help to choose appropriate treatments, thus minimizing the negative effects of these disturbances on the lives of adolescents. Copyright © 2013 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.

A new energy-efficient control approach for space telescope drive system

NASA Astrophysics Data System (ADS)

Zhou, Wangping; Wang, Yong

Drive control makes the telescope accurately track celestial bodies in spite of external and in-ternal disturbances, and is a key technique to the performance of telescopes. In this paper, we propose a nonlinear adaptive observer based on power reversible approach for high preci-sion position tracking, i.e., space telescopes. The nonlinear adaptive observer automatically estimates the disturbances in drive system, and the observed value is applied to compensate for the real disturbances. With greatly reduced disturbances, the control precision can be ev-idently improved. In conventional drive control, the brake device is often used to slow down the reaction wheel and may waste enormous energy. To avoid those disadvantages, an H-bridge is put forward for wheel speed regulation. Such H-bridge has four independent sections, and each section mainly consists of a power electronic switch and an anti-parallel diode. A pair of diagonal sections is switched on for speeding up the reaction wheel and the other pair act in reverse. During the period of the wheel slowing down, the armature current of drive motor goes through the two path-wise diodes to discharge the battery. Thusly, energy waste is avoided. Based on the disturbance compensation, an optimal controller is designed to minimize an eval-uation function which is made up of a weighted sum of position errors and energy consumption. The outputs of the controller are amplified to control the H-bridge. Simulations are performed in MATLAB language. The results show that high precision control can be obtained by the proposed approach. And the energy consumption will be remarkably reduced.

Long-term community dynamics of small landbirds with and without exposure to extensive disturbance from military training activities.

PubMed

Rivers, James W; Gipson, Philip S; Althoff, Donald P; Pontius, Jeffrey S

2010-02-01

Military training activities are known to impact individual species, yet our understanding of how such activities influence animal communities is limited. In this study, we used long-term data in a case study approach to examine the extent to which the local small landbird community differed between a site in northeast Kansas that experienced intensive disturbance from military training activities (Ft. Riley Military Installation) and a similar, nearby site that experienced minimal human disturbance (Konza Prairie Biological Station). In addition, we characterized how the regional pool of potential colonizers influenced local community dynamics using Breeding Bird Survey data. From 1991 to 2001, most species of small terrestrial landbirds (73%) recorded during breeding surveys were found at both sites and the mean annual richness at Ft. Riley (39.0 +/- 2.86 [SD]) was very similar to that of Konza Prairie (39.4 +/- 2.01). Richness was maintained at relatively constant levels despite compositional changes because colonizations compensated local extinctions at both sites. These dynamics were driven primarily by woodland species that exhibited stochastic losses and gains and were present at a low local and regional abundance. Our results suggest that military training activities may mimic natural disturbances for some species in this area because the small landbird community did not differ markedly between sites with and sites without extensive human disturbance. Although our results suggest that military training is not associated with large changes in the avian community, additional studies are needed to determine if this pattern is found in other ecological communities.

Asymptotic tracking and disturbance rejection of the blood glucose regulation system.

PubMed

Ashley, Brandon; Liu, Weijiu

2017-07-01

Type 1 diabetes patients need external insulin to maintain blood glucose within a narrow range from 65 to 108 mg/dl (3.6 to 6.0 mmol/l). A mathematical model for the blood glucose regulation is required for integrating a glucose monitoring system into insulin pump technology to form a closed-loop insulin delivery system on the feedback of the blood glucose, the so-called "artificial pancreas". The objective of this paper is to treat the exogenous glucose from food as a glucose disturbance and then develop a closed-loop feedback and feedforward control system for the blood glucose regulation system subject to the exogenous glucose disturbance. For this, a mathematical model for the glucose disturbance is proposed on the basis of experimental data, and then incorporated into an existing blood glucose regulation model. Because all the eigenvalues of the disturbance model have zero real parts, the center manifold theory is used to establish blood glucose regulator equations. We then use their solutions to synthesize a required feedback and feedforward controller to reject the disturbance and asymptotically track a constant glucose reference of 90  mg/dl. Since the regulator equations are nonlinear partial differential equations and usually impossible to solve analytically, a linear approximation solution is obtained. Our numerical simulations show that, under the linear approximate feedback and feedforward controller, the blood glucose asymptotically tracks its desired level of 90 mg/dl approximately. Copyright © 2017 Elsevier Inc. All rights reserved.

Identification of the feedforward component in manual control with predictable target signals.

PubMed

Drop, Frank M; Pool, Daan M; Damveld, Herman J; van Paassen, Marinus M; Mulder, Max

2013-12-01

In the manual control of a dynamic system, the human controller (HC) often follows a visible and predictable reference path. Compared with a purely feedback control strategy, performance can be improved by making use of this knowledge of the reference. The operator could effectively introduce feedforward control in conjunction with a feedback path to compensate for errors, as hypothesized in literature. However, feedforward behavior has never been identified from experimental data, nor have the hypothesized models been validated. This paper investigates human control behavior in pursuit tracking of a predictable reference signal while being perturbed by a quasi-random multisine disturbance signal. An experiment was done in which the relative strength of the target and disturbance signals were systematically varied. The anticipated changes in control behavior were studied by means of an ARX model analysis and by fitting three parametric HC models: two different feedback models and a combined feedforward and feedback model. The ARX analysis shows that the experiment participants employed control action on both the error and the target signal. The control action on the target was similar to the inverse of the system dynamics. Model fits show that this behavior can be modeled best by the combined feedforward and feedback model.

Full path compensation laser feedback interferometry for remote sensing with recovered nanometer resolutions

NASA Astrophysics Data System (ADS)

Xu, Ling; Tan, Yidong; Zhang, Shulian

2018-03-01

The accuracy of the existing laser feedback interferometry for measuring the remote target is limited to several microns due to environmental disturbances. A novel approach is presented in this paper based on the double-beam frequency-shift feedback of the laser, which can completely eliminate the dead path errors and measure the displacement or vibration with accuracy at nanometer scale even at a far measurement distance. The two beams emitted from one Nd:YVO4 crystal are incident on the measurement target and its adjacent reference surface, respectively. The reference surface could be taken from the nearby stationary object, without the need to put a reference mirror. The feedback paths and shift frequencies of the two beams are the same, so the air disturbances and the thermal effects in the way could be fully compensated. Under common room conditions, the displacement of a steel block at a distance of 10 m is measured, which proved that the system's stability is ±12 nm in 100 s and ±50 nm in 1000 s, the short-term resolution is better than 3 nm, and the linearity within the 300 mm range is 5 × 10-6 and within the 100 μm range is 1 × 10-4.

Forecasting and evaluating patterns of energy development in southwestern Wyoming

USGS Publications Warehouse

Garman, Steven L.

2015-01-01

The effects of future oil and natural gas development in southwestern Wyoming on wildlife populations are topical to conservation of the sagebrush steppe ecosystem. To aid in understanding these potential effects, the U.S. Geological Survey developed an Energy Footprint simulation model that forecasts the amount and pattern of energy development under different assumptions of development rates and well-drilling methods. The simulated disturbance patterns produced by the footprint model are used to assess the potential effects on wildlife habitat and populations. A goal of this modeling effort is to use measures of energy production (number of simulated wells), well-pad and road-surface disturbance, and potential effects on wildlife to identify build-out designs that minimize the physical and ecological footprint of energy development for different levels of energy production and development costs.

Application of the CAP-TSD unsteady transonic small disturbance program to wing flutter. [Computational Aeroelasticity Program

NASA Technical Reports Server (NTRS)

Bennett, Robert M.; Batina, John T.

1989-01-01

The application and assessment of a computer program called CAP-TSD (Computational Aeroelasticity Program - Transonic Small Disturbance) for flutter predictions are described. Flutter calculations are presented for two thin swept-and-tapered wing planforms with well-defined modal properties. One planform is a series of 45-degree swept wings and the other planform is a clipped delta wing. Comparisons are made between the results of CAP-TSD using the linear equation and no airfoil thickness and the results obtained from a subsonic kernel function analysis. The calculations cover a Mach number range from low subsonic to low supersonic values, including the transonic range, and are compared with subsonic linear theory and experimental data. It is noted that since both wings have very thin airfoil sections, the effects of thickness are minimal.

Off-Body Boundary-Layer Measurement Techniques Development for Supersonic Low-Disturbance Flows

NASA Technical Reports Server (NTRS)

Owens, Lewis R.; Kegerise, Michael A.; Wilkinson, Stephen P.

2011-01-01

Investigations were performed to develop accurate boundary-layer measurement techniques in a Mach 3.5 laminar boundary layer on a 7 half-angle cone at 0 angle of attack. A discussion of the measurement challenges is presented as well as how each was addressed. A computational study was performed to minimize the probe aerodynamic interference effects resulting in improved pitot and hot-wire probe designs. Probe calibration and positioning processes were also developed with the goal of reducing the measurement uncertainties from 10% levels to less than 5% levels. Efforts were made to define the experimental boundary conditions for the cone flow so comparisons could be made with a set of companion computational simulations. The development status of the mean and dynamic boundary-layer flow measurements for a nominally sharp cone in a low-disturbance supersonic flow is presented.

Anomalously soft non-Euclidean spring

NASA Astrophysics Data System (ADS)

Levin, Ido; Sharon, Eran

In this work we study the mechanical properties of a frustrated elastic ribbon spring - the non-Euclidean minimal spring. This spring belongs to the family of non-Euclidean plates: it has no spontaneous curvature, but its lateral intrinsic geometry is described by a non-Euclidean reference metric. The reference metric of the minimal spring is hyperbolic, and can be embedded as a minimal surface. We argue that the existence of a continuous set of such isometric minimal surfaces with different extensions leads to a complete degeneracy of the bulk elastic energy of the minimal spring under elongation. This degeneracy is removed only by boundary layer effects. As a result, the mechanical properties of the minimal spring are unusual: the spring is ultra-soft with rigidity that depends on the thickness, t , as t raise 0 . 7 ex 7 7 2 lower 0 . 7 ex 2, and does not explicitly depend on the ribbon's width. These predictions are confirmed by a numerical study of a constrained spring. This work is the first to address the unusual mechanical properties of constrained non-Euclidean elastic objects. We also present a novel experimental system that is capable of constructing such objects, along with many other non-Euclidean plates.

Adolescent Problematic Social Networking and School Experiences: The Mediating Effects of Sleep Disruptions and Sleep Quality.

PubMed

Vernon, Lynette; Barber, Bonnie L; Modecki, Kathryn L

2015-07-01

An important developmental task for adolescents is to become increasingly responsible for their own health behaviors. Establishing healthy sleep routines and controlling media use before bedtime are important for adequate, quality sleep so adolescents are alert during the day and perform well at school. Despite the prevalence of adolescent social media use and the large percentage of computers and cell phones in adolescents' bedrooms, no studies to date have investigated the link between problematic adolescent investment in social networking, their sleep practices, and associated experiences at school. A sample of 1,886 students in Australia aged between 12 and 18 years of age completed self-report data on problematic social networking use, sleep disturbances, sleep quality, and school satisfaction. Structural equation modeling (SEM) substantiated the serial mediation hypothesis: for adolescents, problematic social networking use significantly increased sleep disturbances, which adversely affected perceptions of sleep quality that, in turn, lowered adolescents' appraisals of their school satisfaction. This significant pattern was largely driven by the indirect effect of sleep disturbances. These findings suggest that adolescents are vulnerable to negative consequences from social networking use. Specifically, problematic social networking is associated with poor school experiences, which result from poor sleep habits. Promoting better sleep routines by minimizing sleep disturbances from social media use could improve school experiences for adolescents with enhanced emotional engagement and improved subjective well-being.

Control of Advanced Reactor-Coupled Heat Exchanger System: Incorporation of Reactor Dynamics in System Response to Load Disturbances

DOE PAGES

Skavdahl, Isaac; Utgikar, Vivek; Christensen, Richard; ...

2016-05-24

We present an alternative control schemes for an Advanced High Temperature Reactor system consisting of a reactor, an intermediate heat exchanger, and a secondary heat exchanger (SHX) in this paper. One scheme is designed to control the cold outlet temperature of the SHX (T co) and the hot outlet temperature of the intermediate heat exchanger (T ho2) by manipulating the hot-side flow rates of the heat exchangers (F h/F h2) responding to the flow rate and temperature disturbances. The flow rate disturbances typically require a larger manipulation of the flow rates than temperature disturbances. An alternate strategy examines the controlmore » of the cold outlet temperature of the SHX (T co) only, since this temperature provides the driving force for energy production in the power conversion unit or the process application. The control can be achieved by three options: (1) flow rate manipulation; (2) reactor power manipulation; or (3) a combination of the two. The first option has a quicker response but requires a large flow rate change. The second option is the slowest but does not involve any change in the flow rates of streams. The final option appears preferable as it has an intermediate response time and requires only a minimal flow rate change.« less

Optimal migration energetics of humpback whales and the implications of disturbance.

PubMed

Braithwaite, Janelle E; Meeuwig, Jessica J; Hipsey, Matthew R

2015-01-01

Whales migrate long distances and reproduce on a finite store of energy. Budgeting the use of this limited energy reserve is an important factor to ensure survival over the period of migration and to maximize reproductive investment. For some whales, migration routes are closely associated with coastal areas, exposing animals to high levels of human activity. It is currently unclear how various forms of human activity may disturb whales during migration, how this might impact their energy balance and how this could translate into long-term demographic changes. Here, we develop a theoretical bioenergetic model for migrating humpback whales to investigate the optimal migration strategy that minimizes energy use. The average migration velocity was an important driver of the total energy used by a whale, and an optimal velocity of 1.1 m s(-1) was determined. This optimal velocity is comparable to documented observed migration speeds, suggesting that whales migrate at a speed that conserves energy. Furthermore, the amount of resting time during migration was influenced by both transport costs and feeding rates. We simulated hypothetical disturbances to the optimal migration strategy in two ways, by altering average velocity to represent changes in behavioural activity and by increasing total travelled distance to represent displacement along the migration route. In both cases, disturbance increased overall energy use, with implications for the growth potential of calves.

Optimal migration energetics of humpback whales and the implications of disturbance

PubMed Central

Braithwaite, Janelle E.; Meeuwig, Jessica J.; Hipsey, Matthew R.

2015-01-01

Whales migrate long distances and reproduce on a finite store of energy. Budgeting the use of this limited energy reserve is an important factor to ensure survival over the period of migration and to maximize reproductive investment. For some whales, migration routes are closely associated with coastal areas, exposing animals to high levels of human activity. It is currently unclear how various forms of human activity may disturb whales during migration, how this might impact their energy balance and how this could translate into long-term demographic changes. Here, we develop a theoretical bioenergetic model for migrating humpback whales to investigate the optimal migration strategy that minimizes energy use. The average migration velocity was an important driver of the total energy used by a whale, and an optimal velocity of 1.1 m s−1 was determined. This optimal velocity is comparable to documented observed migration speeds, suggesting that whales migrate at a speed that conserves energy. Furthermore, the amount of resting time during migration was influenced by both transport costs and feeding rates. We simulated hypothetical disturbances to the optimal migration strategy in two ways, by altering average velocity to represent changes in behavioural activity and by increasing total travelled distance to represent displacement along the migration route. In both cases, disturbance increased overall energy use, with implications for the growth potential of calves. PMID:27293686

Individual Differences in Diabetes Risk: Role of Sleep Disturbances

DTIC Science & Technology

2009-08-01

In acromegaly, hypothyroidism and Cushing syndrome, the prevalence of OSA is 19%–23%, 50%–100%, and 18%–32%, respec- tively.43 The pathophysiology... hypothyroidism ”, “polycystic ovary syndrome”, and “PCOS”. We also searched the reference lists of identified articles for further papers. Articles were

Dance/Movement Therapy with Emotionally Disturbed Adolescents.

ERIC Educational Resources Information Center

Bannon, Veronica

This outline profiles two programs that use dance/movement therapy to help students with low self-esteem, poor body image, poor self-control, lack of trust in others, difficulty identifying and expressing feelings, and poor interpersonal relating skills. Students referred for dance/movement therapy services are assessed for appropriateness, and…

Temperate and boreal forest mega-fires: characteristics and challenges

Treesearch

Scott L. Stephens; Neil Burrows; Alexander Buyantuyev; Robert W. Gray; Robert E. Keane; Rick Kubian; Shirong Liu; Francisco Seijo; Lifu Shu; Kevin G. Tolhurst; Jan W. van Wagtendonk

2014-01-01

Mega-fires are often defined according to their size and intensity but are more accurately described by their socioeconomic impacts. Three factors - climate change, fire exclusion, and antecedent disturbance, collectively referred to as the "mega-fire triangle" - likely contribute to today's mega-fires. Some characteristics of mega-fires may emulate...

A Proposed Regional Hierarchy in Recovery of Post-Stroke Aphasia

ERIC Educational Resources Information Center

Heiss, W.-D.; Thiel, A.

2006-01-01

Activation studies in patients with aphasia due to stroke or tumours in the dominant hemisphere have revealed effects of disinhibition in ipsilateral perilesional and in contralateral homotopic cortical regions, referred to as collateral and transcallosal disinhibition. These findings were supported by studies with selective disturbance of…

Orbital construction demonstration study. Volume 2: Technical

NASA Technical Reports Server (NTRS)

1977-01-01

The following items are discussed in reference to OCDA requirements; (1) flight mechanics and control, (2) effects of sun angle, (3) disturbance torques, (4) control system requirements, (5) OCDA orbit decay profile, and (6) aerodynamic drag forces. Structural design requirements are also given as well as basic design definition.

Evaluation of the automated reference toolset for oil and gas reclamation on Colorado rangelands

USDA-ARS?s Scientific Manuscript database

Rangelands are characterized by low precipitation and low biomass, making them susceptible to disturbance and difficult to reclaim. Considering the widespread and significant impact of oil and gas development on rangelands, effective reclamation is vital. Thus, it is important that land managers und...

Affordable/Acceptable Supersonic Flight: Is It Near?

NASA Technical Reports Server (NTRS)

Darden, Christine M.

2003-01-01

The author takes a historical look at supersonic flight and humankind's first encounter with the sonic boom. A review is given from the 1950s to the present of the quest to understand the sonic boom, quantify its disturbance on humans and structures, and minimize its effect through aircraft design and operation. Finally, the author reminds readers that sonic boom is only one factor, though critical, in enabling an economically viable commercial supersonic aircraft.

Does homeostasis or disturbance of homeostasis in minimum leaf water potential explain the isohydric versus anisohydric behavior of Vitis vinifera L. cultivars?

Treesearch

Jean-Christophe Domec; Daniel M. Johnson

2012-01-01

Due to the diurnal and seasonal fluctuations in leaf-to-air vapor pressure deficit (D), one of the key regulatory roles played by stomata is to limit transpiration-induced leaf water deficit. Different types of plants are known to vary in the sensitivity of stomatal conductance (gs) to D with important consequences for their survival and growth. Plants that minimize...

Experimental Comparison of Speed : Fuel-flow and Speed-area Controls on a Turbojet Engine for Small Step Disturbances

NASA Technical Reports Server (NTRS)

Wenzel, L M; Hart, C E; Craig, R T

1957-01-01

Optimum proportional-plus-integral control settings for speed - fuel-flow control, determined by minimization of integral criteria, correlated well with analytically predicted optimum settings. Engine response data are given for a range of control settings around the optimum. An inherent nonlinearity in the speed-area loop necessitated the use of nonlinear controls. Response data for two such nonlinear control schemes are presented.

Energy, time, and channel evolution in catastrophically disturbed fluvial systems

USGS Publications Warehouse

Simon, A.

1992-01-01

Specific energy is shown to decrease nonlinearly with time during channel evolution and provides a measure of reductions in available energy at the channel bed. Data from two sites show convergence towards a minimum specific energy with time. Time-dependent reductions in specific energy at a point act in concert with minimization of the rate of energy dissipation over a reach during channel evolution as the fluvial systems adjust to a new equilibrium.

Endoscope-assisted resection of cavernous angioma at the foramen of Monro: a case report.

PubMed

Matsumoto, Yuji; Kurozumi, Kazuhiko; Shimazu, Yousuke; Ichikawa, Tomotsugu; Date, Isao

2016-01-01

Intraventricular cavernous angiomas are rare pathological entities, and those located at the foramen of Monro are even rarer. We herein present a case of cavernous angioma at the foramen of Monro that was successfully treated by neuroendoscope-assisted surgical removal, and review the relevant literature. A 65-year-old woman had experienced headache and vomiting for 10 days before admission to another hospital. Magnetic resonance imaging (MRI) showed a mass at the foramen of Monro, and obstructive hydrocephalus of both lateral ventricles. The patient was then referred to our hospital. Neurological examination on admission to our hospital showed memory disturbance (Mini-Mental State Examination 20/30) and wide-based gait. A cavernous angioma at the foramen of Monro was diagnosed based on the typical popcorn-like appearance of the lesion on MRI. The lesion was completely removed by neuroendoscope-assisted transcortical surgery with the Viewsite Brain Access System (Vycor Medical Inc., Boca Raton, FL), leading to a reduction in the size of the ventricles. The resected mass was histologically confirmed to be cavernous angioma. The patient's symptoms resolved immediately and there were no postoperative complications. Minimally invasive neuroendoscope-assisted surgery was used to successfully treat a cavernous angioma at the foramen of Monro.

Organic matter quantity and source affects microbial community structure and function following volcanic eruption on Kasatochi Island, Alaska

USGS Publications Warehouse

Zeglin, Lydia H.; Wang, Bronwen; Waythomas, Christopher F.; Rainey, Frederick; Talbot, Sandra L.

2016-01-01

In August 2008, Kasatochi volcano erupted and buried a small island in pyroclastic deposits and fine ash; since then, microbes, plants and birds have begun to re-colonize the initially sterile surface. Five years post-eruption, bacterial 16S rRNA gene and fungal internal transcribed spacer (ITS) copy numbers and extracellular enzyme activity (EEA) potentials were one to two orders of magnitude greater in pyroclastic materials with organic matter (OM) inputs relative to those without, despite minimal accumulation of OM (< 0.2%C). When normalized by OM levels, post-eruptive surfaces with OM inputs had the highest β-glucosidase, phosphatase, NAGase and cellobiohydrolase activities, and had microbial population sizes approaching those in reference soils. In contrast, the strongest factor determining bacterial community composition was the dominance of plants versus birds as OM input vectors. Although soil pH ranged from 3.9 to 7.0, and %C ranged 100×, differentiation between plant- and bird-associated microbial communities suggested that cell dispersal or nutrient availability are more likely drivers of assembly than pH or OM content. This study exemplifies the complex relationship between microbial cell dispersal, soil geochemistry, and microbial structure and function; and illustrates the potential for soil microbiota to be resilient to disturbance.

Patient, surgeon, and hospital disparities associated with benign hysterectomy approach and perioperative complications.

PubMed

Mehta, Ambar; Xu, Tim; Hutfless, Susan; Makary, Martin A; Sinno, Abdulrahman K; Tanner, Edward J; Stone, Rebecca L; Wang, Karen; Fader, Amanda N

2017-05-01

Hysterectomy is among the most common major surgical procedures performed in women. Approximately 450,000 hysterectomy procedures are performed each year in the United States for benign indications. However, little is known regarding contemporary US hysterectomy trends for women with benign disease with respect to operative technique and perioperative complications, and the association between these 2 factors with patient, surgeon, and hospital characteristics. We sought to describe contemporary hysterectomy trends and explore associations between patient, surgeon, and hospital characteristics with surgical approach and perioperative complications. Hysterectomies performed for benign indications by general gynecologists from July 2012 through September 2014 were analyzed in the all-payer Maryland Health Services Cost Review Commission database. We excluded hysterectomies performed by gynecologic oncologists, reproductive endocrinologists, and female pelvic medicine and reconstructive surgeons. We included both open hysterectomies and those performed by minimally invasive surgery, which included vaginal hysterectomies. Perioperative complications were defined using the Agency for Healthcare Research and Quality patient safety indicators. Surgeon hysterectomy volume during the 2-year study period was analyzed (0-5 cases annually = very low, 6-10 = low, 11-20 = medium, and ≥21 = high). We utilized logistic regression and negative binomial regression to identify patient, surgeon, and hospital characteristics associated with minimally invasive surgery utilization and perioperative complications, respectively. A total of 5660 hospitalizations were identified during the study period. Most patients (61.5%) had an open hysterectomy; 38.5% underwent a minimally invasive surgery procedure (25.1% robotic, 46.6% laparoscopic, 28.3% vaginal). Most surgeons (68.2%) were very low- or low-volume surgeons. Factors associated with a lower likelihood of undergoing minimally invasive surgery included older patient age (reference 45-64 years; 20-44 years: adjusted odds ratio, 1.16; 95% confidence interval, 1.05-1.28), black race (reference white; adjusted odds ratio, 0.70; 95% confidence interval, 0.63-0.78), Hispanic ethnicity (adjusted odds ratio, 0.62; 95% confidence interval, 0.48-0.80), smaller hospital (reference large; small: adjusted odds ratio, 0.26; 95% confidence interval, 0.15-0.45; medium: adjusted odds ratio, 0.87; 95% confidence interval, 0.79-0.96), medium hospital hysterectomy volume (reference ≥200 hysterectomies; 100-200: adjusted odds ratio, 0.78; 95% confidence interval, 0.71-0.87), and medium vs high surgeon volume (reference high; medium: adjusted odds ratio, 0.87; 95% confidence interval, 0.78-0.97). Complications occurred in 25.8% of open and 8.2% of minimally invasive hysterectomies (P < .0001). Minimally invasive hysterectomy (adjusted odds ratio, 0.22; 95% confidence interval, 0.17-0.27) and large hysterectomy volume hospitals (reference ≥200 hysterectomies; 1-100: adjusted odds ratio, 2.26; 95% confidence interval, 1.60-3.20; 101-200: adjusted odds ratio, 1.63; 95% confidence interval, 1.23-2.16) were associated with fewer complications, while patient payer, including Medicare (reference private; adjusted odds ratio, 1.86; 95% confidence interval, 1.33-2.61), Medicaid (adjusted odds ratio, 1.63; 95% confidence interval, 1.30-2.04), and self-pay status (adjusted odds ratio, 2.41; 95% confidence interval, 1.40-4.12), and very-low and low surgeon hysterectomy volume (reference ≥21 cases; 1-5 cases: adjusted odds ratio, 1.73; 95% confidence interval, 1.22-2.47; 6-10 cases: adjusted odds ratio, 1.60; 95% confidence interval, 1.11-2.23) were associated with perioperative complications. Use of minimally invasive hysterectomy for benign indications remains variable, with most patients undergoing open, more morbid procedures. Older and black patients and smaller hospitals are associated with open hysterectomy. Patient race and payer status, hysterectomy approach, and surgeon volume were associated with perioperative complications. Hysterectomies performed for benign indications by high-volume surgeons or by minimally invasive techniques may represent an opportunity to reduce preventable harm. Copyright © 2017 Elsevier Inc. All rights reserved.

A Serials Holdings List Using UNIX Refer.

ERIC Educational Resources Information Center

Boyce, Judith I.; Boyce, Bert R.

1987-01-01

Describes the production of an automated union list of serials holdings at minimal cost by a small consortium of state government libraries in Louisiana. Use of the UNIX Refer system without any modifications for data entry and production is described. (EM)

Analysis of the Motion Control Methods for Stratospheric Balloon-Borne Gondola Platform

NASA Astrophysics Data System (ADS)

Wang, H. H.; Yuan, Z. H.; Wu, J.

2006-10-01

At present, gondola platform is one of the stratospheric balloon-borne platforms being in research focus at home and overseas. Comparing to other stratospheric balloon-borne platforms, such as airship platform, gondola platform has advantages of higher stability, rapid in motion regulation and lower energy cost but disadvantages of less supporting capacity and be incapable of fixation. While all platforms have the same goal of keeping them at accurate angle and right pose for the requirements of instruments and objects installed in the platforms, when platforms rotate round the ground level perpendicular. That is accomplishing motion control. But, platform control system has factors of low damper, excessive and uncertain disturbances by the reason of its being hung over balloon in the air, it is hard to achieve the desired control precision because platform is ease to deviate its benchmark motion. Thus, in the controlling procedure in order to get higher precision, it is crucial to perceive the platform's swing synchronously and rapidly, and restrain the influence of disturbances effectively, keep the platform's pose steadily. Furthermore, while the platform in the air regard control center in the ground as reference object, it is ultimate to select a appropriate reference frame and work out the coordinates and implement the adjustment by the PC104 controller. This paper introduces the methods of the motion control based on stratospheric balloon-borne gondola platform. Firstly, this paper compares the characteristic of the flywheel and CMG and specifies the key methods of obtaining two significant states which are 'orientation stability' state and 'orientation tracking' state for platform motion control procedure using CMG as the control actuator. These two states reduce the deviation amplitude of rotation and swing of gondola's motion relative to original motion due to stratospheric intense atmosphere disturbance. We define it as the first procedure. In next procedure, we use the transfer matrix of earth reference frame to geographic reference frame to transform the data measured by the magnetic orientation sensors and the gyroscope to the space orientations, then the PC104 controller use the space orientations value as feedback to complete revises.

[Application of electrogastrography in pediatrics. Part II. The incidence of disturbed gastric myoelectrical activity in children suffering from recurrent abdominal pain].

PubMed

Maliszewska, Iwona; Krusiec-Swidergoł, Beata; Kasicka-Jonderko, Anna; Jonderko, Krzysztof; Błońska-Fajfrowska, Barbara

2007-01-01

The study was devoted to determine the incidence of an abnormal gastric myoelectrical activity (GMA) in children suffering from recurrent abdominal pain. Surface electrogastrograms were taken in the interdigestive state and after a meal stimulation in 187 children referred to the laboratory with the diagnosis of recurrent abdominal pain. The cohort comprised the following subgroups: age 6-11 years (33 boys and 36 girls), age 12-18 years (28 boys and 90 girls). Continuous variables characterizing quantitatively an electrogastrogram were recoded into categorical data sets, which were used further for construction of an arbitrary scale reflecting disturbances of an electrogastrographic recording: score 0--normal, score 1-2, 3-4, and 5-6 corresponding to a light, moderate, and severe disturbance of the GMA. Abnormal electrogastrograms were found in just over a half of the examined children (54.5%). Nevertheless, light abnormalities (score 1-2) were predominant--42.8% of the whole cohort. Moderate abnormalities were revealed in almost every eight patient (11.8%), whereas no case of severely disturbed GMA was disclosed. On the other hand as much as 45.5% children did not exhibit any abnormality of the electrogastrogram. No statistically significant differences were found when the frequency distributions of particular degrees of the GMA disturbance were compared among groups of different age and gender. A disclosure that an abnormal electrogastrogram is encountered in just over a half of the patients and the predominance of light disturbances within this group, implies that disturbed GMA is neither an inherent nor a pathognomonic pathological finding of the clinical picture of recurrent abdominal pain in children.

Posture Control-Human-Inspired Approaches for Humanoid Robot Benchmarking: Conceptualizing Tests, Protocols and Analyses.

PubMed

Mergner, Thomas; Lippi, Vittorio

2018-01-01

Posture control is indispensable for both humans and humanoid robots, which becomes especially evident when performing sensorimotor tasks such as moving on compliant terrain or interacting with the environment. Posture control is therefore targeted in recent proposals of robot benchmarking in order to advance their development. This Methods article suggests corresponding robot tests of standing balance, drawing inspirations from the human sensorimotor system and presenting examples from robot experiments. To account for a considerable technical and algorithmic diversity among robots, we focus in our tests on basic posture control mechanisms, which provide humans with an impressive postural versatility and robustness. Specifically, we focus on the mechanically challenging balancing of the whole body above the feet in the sagittal plane around the ankle joints in concert with the upper body balancing around the hip joints. The suggested tests target three key issues of human balancing, which appear equally relevant for humanoid bipeds: (1) four basic physical disturbances (support surface (SS) tilt and translation, field and contact forces) may affect the balancing in any given degree of freedom (DoF). Targeting these disturbances allows us to abstract from the manifold of possible behavioral tasks. (2) Posture control interacts in a conflict-free way with the control of voluntary movements for undisturbed movement execution, both with "reactive" balancing of external disturbances and "proactive" balancing of self-produced disturbances from the voluntary movements. Our proposals therefore target both types of disturbances and their superposition. (3) Relevant for both versatility and robustness of the control, linkages between the posture control mechanisms across DoFs provide their functional cooperation and coordination at will and on functional demands. The suggested tests therefore include ankle-hip coordination. Suggested benchmarking criteria build on the evoked sway magnitude, normalized to robot weight and Center of mass (COM) height, in relation to reference ranges that remain to be established. The references may include human likeness features. The proposed benchmarking concept may in principle also be applied to wearable robots, where a human user may command movements, but may not be aware of the additionally required postural control, which then needs to be implemented into the robot.

Posture Control—Human-Inspired Approaches for Humanoid Robot Benchmarking: Conceptualizing Tests, Protocols and Analyses

PubMed Central

Mergner, Thomas; Lippi, Vittorio

2018-01-01

Posture control is indispensable for both humans and humanoid robots, which becomes especially evident when performing sensorimotor tasks such as moving on compliant terrain or interacting with the environment. Posture control is therefore targeted in recent proposals of robot benchmarking in order to advance their development. This Methods article suggests corresponding robot tests of standing balance, drawing inspirations from the human sensorimotor system and presenting examples from robot experiments. To account for a considerable technical and algorithmic diversity among robots, we focus in our tests on basic posture control mechanisms, which provide humans with an impressive postural versatility and robustness. Specifically, we focus on the mechanically challenging balancing of the whole body above the feet in the sagittal plane around the ankle joints in concert with the upper body balancing around the hip joints. The suggested tests target three key issues of human balancing, which appear equally relevant for humanoid bipeds: (1) four basic physical disturbances (support surface (SS) tilt and translation, field and contact forces) may affect the balancing in any given degree of freedom (DoF). Targeting these disturbances allows us to abstract from the manifold of possible behavioral tasks. (2) Posture control interacts in a conflict-free way with the control of voluntary movements for undisturbed movement execution, both with “reactive” balancing of external disturbances and “proactive” balancing of self-produced disturbances from the voluntary movements. Our proposals therefore target both types of disturbances and their superposition. (3) Relevant for both versatility and robustness of the control, linkages between the posture control mechanisms across DoFs provide their functional cooperation and coordination at will and on functional demands. The suggested tests therefore include ankle-hip coordination. Suggested benchmarking criteria build on the evoked sway magnitude, normalized to robot weight and Center of mass (COM) height, in relation to reference ranges that remain to be established. The references may include human likeness features. The proposed benchmarking concept may in principle also be applied to wearable robots, where a human user may command movements, but may not be aware of the additionally required postural control, which then needs to be implemented into the robot. PMID:29867428

Carbon stocks and fluxes in fire disturbed landscapes of Colorado, U.S.A.

NASA Astrophysics Data System (ADS)

Barnes, R. T.; Wolf, K.; Whittinghill, K. A.; Gilbertson, A.; Buma, B.

2016-12-01

In terrestrial ecosystems, ecological disturbances can strongly regulate material and energy flows. This often results from the reduction in biomass and associated ecological relationships and physiological processes. Researchers have noted an increase in the size and severity of disturbances, such as wildfire, in recent decades. While there is significant research examining post-disturbance carbon stocks and recovery, there is less known about the fate and quality of post-disturbance carbon pools. In an effort to understand the recovery and resilience of forest carbon stocks to severe wildfire we examined the carbon and black carbon (pyrogenic) stocks (e.g. above ground biomass, coarse woody debris, charcoal, soils) and export fluxes (stream export, soil leachate, soil respiration) within the burn scars and nearby reference sites of five 2002 Colorado fires. The fires encompass large precipitation and ecosystem gradients (relatively dry montane Ponderosa forests to relatively wet subalpine Lodgepole forests), allowing us to control for various state factors in our analyses. With the exception of the Hinman fire (subalpine, Lodgepole dominated), there is little forest regrowth more than a decade later, with only a few saplings found in burned plots; instead forbes and grasses dominate. Fire also reduces soil C stocks (by 16 to 68%) across all sites. In addition, with the shifts in vegetation we hypothesize that there will be corresponding changes in soil organic matter (SOM), altering the residence time of C in soil. Soil incubation experiments reveal that organic matter bioavailability is significantly greater in three of the burned sites, suggesting that the new sources of SOM are more bioavailable. Stable isotopic analyses of SOM and the evolved CO2 from the incubation studies will allow us to test this hypothesis. Fire also affects the amount and nature of dissolved and particulate organic matter (DOM and POM, respectively) leaving the watershed. For example, the dissolved organic matter exported from burned watersheds is less aromatic and has lower C:N than DOM exported from reference watersheds. In addition to measuring these fluxes, we assessed the fate of leached DOM via laboratory bioassays to determine the likelihood of additional CO2 losses to the atmosphere.

Living status, economic hardship and sleep disturbance were associated with subjective shoulder pain in survivors of the Great East Japan Earthquake: A cross sectional study.

PubMed

Hagiwara, Yoshihiro; Sekiguchi, Takuya; Yabe, Yutaka; Sugawara, Yumi; Watanabe, Takashi; Kanazawa, Kenji; Koide, Masashi; Itaya, Nobuyuki; Tsuchiya, Masahiro; Tsuji, Ichiro; Itoi, Eiji

2017-05-01

The Great East Japan Earthquake and devastating Tsunami hit hard everything on the northeastern coast of Japan. This study aimed to determine socio-psychological factors for "subjective shoulder pain" of the survivors at 2 years evaluated by a self-report questionnaire. Between November 2012 to February 2013, survivors replied to the self-report questionnaire, and 2275 people consented to join this study. Living status was divided into 5 categories (1. same house as before the earthquake (reference group), 2. temporary small house, 3. apartment, 4. house of relatives or acquaintance, 5. new house) and economic hardship was divided into 4 categories (1. normal (reference group), 2. a little bit hard, 3. hard, 4. very hard). Gender, age, body mass index, living areas, smoking and drinking habits, complications of diabetes mellitus and cerebral stroke, working status, and walking time were considered as the confounding factors. Kessler Psychological Distress Scale of ≥10/24 and Athens Insomnia Scale of ≥6/24 points were defined as a presence of psychological distress and sleep disturbance, respectively. We used multiple logistic regression analysis to examine the association of shoulder pain with living environment, economic hardship, psychological distress, and sleep disturbance at 2 years after the earthquake. There were significant differences in the risk of having shoulder pain in those with "apartment" (OR = 1.74, 95% CI = 1.03-2.96), "house of relatives or acquaintance" (OR = 2.98, 95% CI = 1.42-6.25), economic hardship of "hard" (OR = 1.71, 95% CI = 1.08-2.7) and "very hard" (OR = 2.51, 95% CI = 1.47-4.29), and sleep disturbance (OR = 2.96, 95% CI = 2.05-4.27). Living status of "apartment" and "house of relatives or acquaintance", economic hardship of "hard" and "very hard", and "sleep disturbance" were significantly associated with shoulder pain. Copyright © 2017 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.

Minimal Impact Education: A New Approach To Walking Softly.

ERIC Educational Resources Information Center

Bauchop, Deborah; Parkin, Danny

2000-01-01

Introduces protected areas as opportunities for outdoor education and considers the possibility that outdoor education may contribute to the ecological degradation of these areas through overuse or poor outdoor practices. Provides a new approach to minimal impact education through the promotion of individual change. (Contains 24 references.)…

Changes in the referent body location and configuration may underlie human gait, as confirmed by findings of multi-muscle activity minimizations and phase resetting.

PubMed

Feldman, Anatol G; Krasovsky, Tal; Baniña, Melanie C; Lamontagne, Anouk; Levin, Mindy F

2011-04-01

Locomotion is presumably guided by feed-forward shifts in the referent body location in the desired direction in the environment. We propose that the difference between the actual and the referent body locations is transmitted to neurons that virtually diminish this difference by appropriately changing the referent body configuration, i.e. the body posture at which muscles reach their recruitment thresholds. Muscles are activated depending on the gap between the actual and the referent body configurations resulting in a step being made to minimize this gap. This hypothesis implies that the actual and the referent leg configurations can match each other at certain phases of the gait cycle, resulting in minimization of leg muscle activity. We found several leg configurations at which EMG minima occurred, both during forward and backward gait. It was also found that the set of limb configurations associated with EMG minima can be changed by modifying the pattern of forward and backward gait. Our hypothesis predicts that, in response to perturbations of gait, the rate of shifts in the referent body location can temporarily be changed to avoid falling. The rate influences the phase of rhythmic limb movements during gait. Therefore, following the change in the rate of the referent body location, the whole gait pattern, for all four limbs, will irreversibly be shifted in time (long-lasting and global phase resetting) with only transient changes in the gait speed, swing and stance timing and cycle duration. Aside from transient changes in the duration of the swing and/or stance phase in response to perturbation, few previous studies have documented long-lasting and global phase resetting of human gait in response to perturbation. Such resetting was a robust finding in our study. By confirming the notion that feed-forward changes in the referent body location and configuration underlie human locomotion, this study solves the classical problem in the relationship between stability of posture and gait and advances the understanding of how human locomotion involves the whole body and is accomplished in a spatial frame of reference associated with the environment.

Modular Gravitational Reference Sensor (MGRS) For Astrophysics and Astronomy

NASA Astrophysics Data System (ADS)

Sun, Ke-Xun; Buchman, S.; Byer, R. L.; DeBra, D.; Goebel, J.; Allen, G.; Conklin, J.; Gerardi, D.; Higuchi, S.; Leindecker, N.; Lu, P.; Swank, A.; Torres, E.; Trillter, M.; Zoellner, A.

2009-01-01

The study of space-time for gravitational wave detection and cosmology beyond Einstein will be an important theme for astrophysics and astronomy in decades to come. Laser Interferometric Space Antenna (LISA) is designed for detecting gravitational wave in space. The Modular Gravitational Reference Sensor (MGRS) is developed as the next generation core instrument for space-time research, including gravitational wave detection beyond LISA, and an array of precision experiments in space. The MGRS provide a stable gravitational cardinal point in space-time by using a test sphere, which eliminates the need for orientation control, minimizing disturbances. The MGRS measures the space-time variation via a two step process: measurement between test mass and housing, and between housings of two spacecraft. Our Stanford group is conducting systematic research and development on the MGRS. Our initial objectives are to gain a system perspective of the MGRS, to develop component technologies, and to establish test platforms. We will review our recent progress in system technologies, optical displacement and angle sensing, diffractive optics, proof mass characterization, UV LED charge management system and space qualification, thermal control and sensor development. Some highlights of our recent results are: Demonstration of the extreme radiation hardness of UV LED which sustained 2 trillion protons per square centimeter; measurement of mass center offset down to 300 nm, and measurement of small angle 0.2 nrad per root hertz using a compact grating angular sensor. The Stanford MGRS program has made exceptional contribution to education of next generation scientists and engineers. We have undergraduate and graduate students in aeronautical and astronautic engineering, applied physics, cybernetics, electrical engineering, mechanical engineering, and physics. We have also housed a number of high school students in our labs for education and public outreach.

Landuse legacies and small streams: Identifying relationships between historical land use and contemporary stream conditions

USGS Publications Warehouse

Maloney, K.O.; Feminella, J.W.; Mitchell, R.M.; Miller, S.A.; Mulholland, P.J.; Houser, J.N.

2008-01-01

The concept of landscape legacies has been examined extensively in terrestrial ecosystems and has led to a greater understanding of contemporary ecosystem processes. However, although stream ecosystems are tightly coupled with their catchments and, thus, probably are affected strongly by historical catchment conditions, few studies have directly examined the importance of landuse legacies on streams. We examined relationships between historical land use (1944) and contemporary (2000-2003) stream physical, chemical, and biological conditions after accounting for the influences of contemporary land use (1999) and natural landscape (catchment size) variation in 12 small streams at Fort Benning, Georgia, USA. Most stream variables showed strong relationships with contemporary land use and catchment size; however, after accounting for these factors, residual variation in many variables remained significantly related to historical land use. Residual variation in benthic particulate organic matter, diatom density, % of diatoms in Eunotia spp., fish density in runs, and whole-stream gross primary productivity correlated negatively, whereas streamwater pH correlated positively, with residual variation in fraction of disturbed land in catchments in 1944 (i.e., bare ground and unpaved road cover). Residual variation in % recovering land (i.e., early successional vegetation) in 1944 was correlated positively with residual variation in streambed instability, a macroinvertebrate biotic index, and fish richness, but correlated negatively with residual variation in most benthic macroinvertebrate metrics examined (e.g., Chironomidae and total richness, Shannon diversity). In contrast, residual variation in whole-stream respiration rates was not explained by historical land use. Our results suggest that historical land use continues to influence important physical and chemical variables in these streams, and in turn, probably influences associated biota. Beyond providing insight into biotic interactions and their associations with environmental conditions, identification of landuse legacies also will improve understanding of stream impairment in contemporary minimally disturbed catchments, enabling more accurate assessment of reference conditions in studies of biotic integrity and restoration. ?? 2008 by The North American Benthological Society.

Artificial neural networks for control of a grid-connected rectifier/inverter under disturbance, dynamic and power converter switching conditions.

PubMed

Li, Shuhui; Fairbank, Michael; Johnson, Cameron; Wunsch, Donald C; Alonso, Eduardo; Proaño, Julio L

2014-04-01

Three-phase grid-connected converters are widely used in renewable and electric power system applications. Traditionally, grid-connected converters are controlled with standard decoupled d-q vector control mechanisms. However, recent studies indicate that such mechanisms show limitations in their applicability to dynamic systems. This paper investigates how to mitigate such restrictions using a neural network to control a grid-connected rectifier/inverter. The neural network implements a dynamic programming algorithm and is trained by using back-propagation through time. To enhance performance and stability under disturbance, additional strategies are adopted, including the use of integrals of error signals to the network inputs and the introduction of grid disturbance voltage to the outputs of a well-trained network. The performance of the neural-network controller is studied under typical vector control conditions and compared against conventional vector control methods, which demonstrates that the neural vector control strategy proposed in this paper is effective. Even in dynamic and power converter switching environments, the neural vector controller shows strong ability to trace rapidly changing reference commands, tolerate system disturbances, and satisfy control requirements for a faulted power system.

Rapid Shifts in Soil Nutrients and Decomposition Enzyme Activity in Early Succession Following Forest Fire

DOE PAGES

Knelman, Joseph E.; Graham, Emily B.; Ferrenberg, Scott; ...

2017-09-15

In post-disturbance landscapes nutrient availability has proven a major control on ecological succession. In this study, we examined variation in connections between soil nutrient availability and decomposition extracellular enzyme activity (EEA) across post fire secondary succession in forest soils as well as after a secondary flood disturbance. We also examined possible linkages between edaphic properties and bacterial communities based on 16S rRNA gene analysis. We found that with advancing succession in a post-fire landscape, the relationship between soil nutrients and EEA became stronger over time. In general, late successional soils showed stronger connections between EEA and soil nutrient status, whilemore » early successional soils were marked by a complete decoupling of nutrients and EEA. We also found that soil moisture and bacterial communities of post-fire disturbance soils were susceptible to change following the secondary flood disturbance, while undisturbed, reference forest soils were not. Our results demonstrate that nutrient pools correlating with EEA change over time. While past work has largely focused on ecosystem succession on decadal timescales, our work suggests that nutrients shift in their relative importance as a control of decomposition EEA in the earliest stages of secondary succession. Furthermore, this work emphasizes the relevance of successional stage, even on short timescales, in predicting rates of carbon and nitrogen cycling, especially as disturbances become more frequent in a rapidly changing world.« less

Quercus rubra-associated ectomycorrhizal fungal communities of disturbed urban sites and mature forests.

PubMed

Karpati, Amy S; Handel, Steven N; Dighton, John; Horton, Thomas R

2011-08-01

The presence and quality of the belowground mycorrhizal fungal community could greatly influence plant community structure and host species response. This study tests whether mycorrhizal fungal communities in areas highly impacted by anthropogenic disturbance and urbanization are less species rich or exhibit lower host root colonization rates when compared to those of less disturbed systems. Using a soil bioassay, we sampled the ectomycorrhizal fungal (EMF) communities associating with Quercus rubra (northern red oak) seedlings in soil collected from seven sites: two mature forest reference sites and five urban sites of varying levels of disturbance. Morphological and polymerase chain reaction-restriction fragment length polymorphism analyses of fungi colonizing root tips revealed that colonization rates and fungal species richness were significantly lower on root systems of seedlings grown in disturbed site soils. Analysis of similarity showed that EMF community composition was not significantly different among several urban site soils but did differ significantly between mature forest sites and all but one urban site. We identified a suite of fungal species that occurred across several urban sites. Lack of a diverse community of belowground mutualists could be a constraint on urban plant community development, especially of late-successional woodlands. Analysis of urban EMF communities can add to our understanding of urban plant community structure and should be addressed during ecological assessment before pragmatic decisions to restore habitats are framed.

Rapid Shifts in Soil Nutrients and Decomposition Enzyme Activity in Early Succession Following Forest Fire

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knelman, Joseph E.; Graham, Emily B.; Ferrenberg, Scott

In post-disturbance landscapes nutrient availability has proven a major control on ecological succession. In this study, we examined variation in connections between soil nutrient availability and decomposition extracellular enzyme activity (EEA) across post fire secondary succession in forest soils as well as after a secondary flood disturbance. We also examined possible linkages between edaphic properties and bacterial communities based on 16S rRNA gene analysis. We found that with advancing succession in a post-fire landscape, the relationship between soil nutrients and EEA became stronger over time. In general, late successional soils showed stronger connections between EEA and soil nutrient status, whilemore » early successional soils were marked by a complete decoupling of nutrients and EEA. We also found that soil moisture and bacterial communities of post-fire disturbance soils were susceptible to change following the secondary flood disturbance, while undisturbed, reference forest soils were not. Our results demonstrate that nutrient pools correlating with EEA change over time. While past work has largely focused on ecosystem succession on decadal timescales, our work suggests that nutrients shift in their relative importance as a control of decomposition EEA in the earliest stages of secondary succession. Furthermore, this work emphasizes the relevance of successional stage, even on short timescales, in predicting rates of carbon and nitrogen cycling, especially as disturbances become more frequent in a rapidly changing world.« less

Decentralized adaptive robust control based on sliding mode and nonlinear compensator for the control of ankle movement using functional electrical stimulation of agonist-antagonist muscles

NASA Astrophysics Data System (ADS)

Kobravi, Hamid-Reza; Erfanian, Abbas

2009-08-01

A decentralized control methodology is designed for the control of ankle dorsiflexion and plantarflexion in paraplegic subjects with electrical stimulation of tibialis anterior and calf muscles. Each muscle joint is considered as a subsystem and individual controllers are designed for each subsystem. Each controller operates solely on its associated subsystem, with no exchange of information between the subsystems. The interactions between the subsystems are taken as external disturbances for each isolated subsystem. In order to achieve robustness with respect to external disturbances, unmodeled dynamics, model uncertainty and time-varying properties of muscle-joint dynamics, a robust control framework is proposed which is based on the synergistic combination of an adaptive nonlinear compensator with a sliding mode control and is referred to as an adaptive robust control. Extensive simulations and experiments on healthy and paraplegic subjects were performed to demonstrate the robustness against the time-varying properties of muscle-joint dynamics, day-to-day variations, subject-to-subject variations, fast convergence, stability and tracking accuracy of the proposed method. The results indicate that the decentralized robust control provides excellent tracking control for different reference trajectories and can generate control signals to compensate the muscle fatigue and reject the external disturbance. Moreover, the controller is able to automatically regulate the interaction between agonist and antagonist muscles under different conditions of operating without any preprogrammed antagonist activities.

Performance of ionospheric maps in support of long baseline GNSS kinematic positioning at low latitudes

NASA Astrophysics Data System (ADS)

Park, J.; Sreeja, V.; Aquino, M.; Cesaroni, C.; Spogli, L.; Dodson, A.; De Franceschi, G.

2016-05-01

Ionospheric scintillation occurs mainly at high and low latitude regions of the Earth and may impose serious degradation on GNSS (Global Navigation Satellite System) functionality. The Brazilian territory sits on one of the most affected areas of the globe, where the ionosphere behaves very unpredictably, with strong scintillation frequently occurring in the local postsunset hours. The correlation between scintillation occurrence and sharp variations in the ionospheric total electron content (TEC) in Brazil is demonstrated in Spogli et al. (2013). The compounded effect of these associated ionospheric disturbances on long baseline GNSS kinematic positioning is studied in this paper, in particular when ionospheric maps are used to aid the positioning solution. The experiments have been conducted using data from GNSS reference stations in Brazil. The use of a regional TEC map generated under the CALIBRA (Countering GNSS high-Accuracy applications Limitations due to Ionospheric disturbances in BRAzil) project, referred to as CALIBRA TEC map (CTM), was compared to the use of the Global Ionosphere Map (GIM), provided by the International GNSS Service (IGS). Results show that the use of the CTM greatly improves the kinematic positioning solution as compared with that using the GIM, especially under disturbed ionospheric conditions. Additionally, different hypotheses were tested regarding the precision of the TEC values obtained from ionospheric maps, and its effect on the long baseline kinematic solution evaluated. Finally, this study compares two interpolation methods for ionospheric maps, namely, the Inverse Distance Weight and the Natural Neighbor.

Decentralized adaptive robust control based on sliding mode and nonlinear compensator for the control of ankle movement using functional electrical stimulation of agonist-antagonist muscles.

PubMed

Kobravi, Hamid-Reza; Erfanian, Abbas

2009-08-01

A decentralized control methodology is designed for the control of ankle dorsiflexion and plantarflexion in paraplegic subjects with electrical stimulation of tibialis anterior and calf muscles. Each muscle joint is considered as a subsystem and individual controllers are designed for each subsystem. Each controller operates solely on its associated subsystem, with no exchange of information between the subsystems. The interactions between the subsystems are taken as external disturbances for each isolated subsystem. In order to achieve robustness with respect to external disturbances, unmodeled dynamics, model uncertainty and time-varying properties of muscle-joint dynamics, a robust control framework is proposed which is based on the synergistic combination of an adaptive nonlinear compensator with a sliding mode control and is referred to as an adaptive robust control. Extensive simulations and experiments on healthy and paraplegic subjects were performed to demonstrate the robustness against the time-varying properties of muscle-joint dynamics, day-to-day variations, subject-to-subject variations, fast convergence, stability and tracking accuracy of the proposed method. The results indicate that the decentralized robust control provides excellent tracking control for different reference trajectories and can generate control signals to compensate the muscle fatigue and reject the external disturbance. Moreover, the controller is able to automatically regulate the interaction between agonist and antagonist muscles under different conditions of operating without any preprogrammed antagonist activities.

The Water Erosion Prediction Project (WEPP) model for saturation excess conditions: application to an agricultural and a forested watershed.

NASA Astrophysics Data System (ADS)

Crabtree, B.; Brooks, E.; Ostrowski, K.; Elliot, W. J.; Boll, J.

2006-12-01

We incorporated saturation excess overland flow processes in the Water Erosion Prediction Project (WEPP) model for the evaluation of human disturbances in watersheds. In this presentation, we present results of the modified WEPP model to two watersheds: an agricultural watershed with mixed land use, and a forested watershed. The agricultural watershed is Paradise Creek, an intensively monitored watershed with continuous climate, flow and sediment data collection at multiple locations. Restoration efforts in Paradise Creek watershed include changing to minimal tillage or no-tillage sytems, and implementation of structural practices. The forested watershed is the 28 km2 Mica Creek Experimental Watershed (MCEW) where disturbances include clear and partial cutting, and road building. The MCEW has a nested study design, which allows for the analysis of cumulative effects as well as the traditional comparison of treatment versus control. Mica Creek watershed is a high elevation watershed where streamflow is generated mostly by snowmelt. Treatments include road building in 1997, and clearcut and partial-cut logging in 2001. Our results include the simulation of streamflow and sediment delivery at multiple locations within each watershed, and evaluation of the human disturbances.

[Posturographic study of total prostheses in the leg. Apropos of 88 patients examined].

PubMed

Lord, G; Gentaz, R; Gagey, P M; Baron, J B

1976-01-01

By suppressing certain articular sensory receptors, the reconstructive surgery of joints using total prostheses modifies tonic postural activity and, by this means, alters the regulation of balance in the subjects of operation. This doubtless explains certain discrepancies between the apparently excellent results in respect of joint movement and muscle strength and poor utilisation of the joint in every day life (instability, use of sticks or failure to use the joint in walking). Drawing on the experience and basic work of specialists in posture, the authors have undertaken a study of tonic postural activity in patients who had received a total prosthesis in the lower limb, both from the clinical aspect and by graphic measurement using an electronic apparatus, the statokinesiometer. Fourteen normal subjects were tested to calibrate the apparatus and 8 patients suffering from established osteoarthritis of the hip were studied as controls. Analysis of tonic postural activity was made in 66 patients who had received total prostheses in the lower limb. The results showed significant disturbance in balance in ankle prostheses, minimal disturbance in knee prostheses and not significant disturbance in hip prostheses. Certain therapeutic implications are derived from this study.

Intentionality as a link between the neuropsychology and the symptoms of schizophrenia.

PubMed

Kaiser, Stefan; Weisbrod, Matthias

2007-01-01

Cognitive deficits are an important feature of schizophrenia, particularly in the areas of working memory and executive function. However, their relationship to other clinical dimensions of the illness has remained elusive. We suggest that a phenomenological exploration of disordered intentionality in schizophrenia symptoms might provide us with a framework for understanding the role of cognitive deficits. We propose an understanding of intentionality as having a layered structure, which facilitates a mapping onto neuropsychological concepts. A disturbance of basic intentional processes can explain some of the 'positive' symptoms of schizophrenia. We focus on the temporal aspect of intentionality, which will be related to recent conceptions of prefrontal cortical function as the temporal organization of thought and behavior. A compensation of these basic disturbances leads to a 'minimization of change', which can explain some of the 'negative' symptoms. The compensatory strategies are thought to rely on the higher-order executive functions of the prefrontal cortex. These are also disturbed in schizophrenia, which often renders the process of compensation ineffective, leading to a fragmentation of thought and behavior. Thus the concept of intentionality might help us relate different aspects of prefrontal dysfunction to specific schizophrenic symptom clusters. (c) 2007 S. Karger AG, Basel.

Immune-mediated extrapyramidal movement disorders, including Sydenham chorea.

PubMed

Dale, Russell C

2013-01-01

Immune-mediated extrapyramidal movement disorders typically occur in previously healthy children. Immune-mediated movement disorders may occur as a postinfectious, paraneoplastic, or idiopathic process. Sydenham chorea (SC) is the classical poststreptococcal movement and psychiatric disorder, and may be associated with other features of rheumatic fever. The outcome is typically good, although residual chorea, psychiatric disturbance, and relapses are possible. Pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS) is a syndrome of streptococcal-induced tics and obsessive-compulsive disorder. Although a number of investigators have reported an association between streptococcal infection and neuropsychiatric syndromes, the PANDAS hypothesis is controversial. Encephalitis lethargica is an encephalitic illness with parkinsonism, dyskinesias, and psychiatric disturbance as dominant features. The exact disease mechanism is not understood, although an autoimmune process is suspected. NMDA-R encephalitis is a new entity characterized by encephalitis with dramatic psychiatric disturbance, dyskinesias, cognitive alteration, and seizures. Patients have autoantibodies against the NMDA-R that appear to be pathogenic: immune therapies appear warranted to minimize disability. Movement disorders are also described associated with systemic lupus erythematosus and antiphospholipid syndrome. The differential diagnosis and investigation approach of acute-onset movement disorders are also discussed. Copyright © 2013 Elsevier B.V. All rights reserved.

Hearing Loss, Dizziness, and Carbohydrate Metabolism

PubMed Central

Albernaz, Pedro L. Mangabeira

2015-01-01

Introduction  Metabolic activity of the inner ear is very intense, and makes it sensitive to changes in the body homeostasis. This study involves a group of patients with inner ear disorders related to carbohydrate metabolism disturbances, including hearing loss, tinnitus, dizziness, and episodes of vertigo. Objectives  To describe the symptoms of metabolic inner ear disorders and the examinations required to establish diagnoses. These symptoms are often the first to allow for an early diagnosis of metabolic disorders and diabetes. Methods  Retrospective study of 376 patients with inner ear symptoms suggestive of disturbances of carbohydrate metabolism. The authors present patientś clinical symptoms and clinical evaluations, with emphasis on the glucose and insulin essays. Results  Authors based their conclusions on otolaryngological findings, diagnostic procedures and treatment principles. They found that auditory and vestibular symptoms usually occur prior to other manifestations of metabolic changes, leading to an early diagnosis of hyperinsulinemia, intestinal sugar malabsorption or diabetes. Previously undiagnosed diabetes mellitus type II was found in 39 patients. Conclusions  The identification of carbohydrate metabolism disturbances is important not only to minimize the patients' clinical symptoms, but also to help maintain their general health. PMID:27413410

Methods and devices used in the wildfire localization for the protection of forest ecosystems

NASA Astrophysics Data System (ADS)

Kasymov, D. P.; Fateyev, V. N.; Zima, V. P.

2017-11-01

The development of devices for localization and extinguishing of wildland fires based on knowledge of the flame structure, including the drying zone, heating, pyrolysis, mixing with oxygen in the air, using relatively small energy disturbances (shock waves), which minimizes the damage caused to the environment have been represented. Using of the considered technical solutions leading to increase the effectiveness and efficiency of activities to combat wildland fires has been shown.

Using remote sensing data to predict road fill areas and areas affected by fill erosion with planned forest road construction: a case study in Kastamonu Regional Forest Directorate (Turkey).

PubMed

Aricak, Burak

2015-07-01

Forest roads are essential for transport in managed forests, yet road construction causes environmental disturbance, both in the surface area the road covers and in erosion and downslope deposition of road fill material. The factors affecting the deposition distance of eroded road fill are the slope gradient and the density of plant cover. Thus, it is important to take these factors into consideration during road planning to minimize their disturbance. The aim of this study was to use remote sensing and field surveying to predict the locations that would be affected by downslope deposition of eroding road fill and to compile the data into a geographic information system (GIS) database. The construction of 99,500 m of forest roads is proposed for the Kastamonu Regional Forest Directorate in Turkey. Using GeoEye satellite images and a digital elevation model (DEM) for the region, the location and extent of downslope deposition of road fill were determined for the roads as planned. It was found that if the proposed roads were constructed by excavators, the fill material would cover 910,621 m(2) and the affected surface area would be 1,302,740 m(2). Application of the method used here can minimize the adverse effects of forest roads.

Microvascular Decompression for Trigeminal Neuralgia: Technical Refinement for Complication Avoidance.

PubMed

Tomasello, Francesco; Esposito, Felice; Abbritti, Rosaria V; Angileri, Filippo F; Conti, Alfredo; Cardali, Salvatore M; La Torre, Domenico

2016-10-01

Microvascular decompression (MVD) represents the most effective and safe surgical option for the treatment of trigeminal neuralgia since it was first popularized by Jannetta 50 years ago. Despite several advances, complications such as cerebellar and vascular injury, hearing loss, muscular atrophy, cerebrospinal fluid (CSF) leak, postoperative cutaneous pain, and sensory disturbances still occur and may negatively affect the outcome. We propose some technical nuances of the surgical procedure that were used in our recent series. We used a novel hockey stick-shaped retromastoid skin incision, preserving the major nerves of the occipital and temporal areas. Microsurgical steps were performed without the use of retractors. CSF leakage was prevented with a watertight dural closure and multilayer osteodural reconstruction. The refined surgical steps were perfected in the last consecutive 15 cases of our series. In these cases we did not record any cutaneous pain, sensory disturbances, or CSF leakage. The average diameter of the craniectomy was 18 mm. No patient reported major complications related to the intradural microsurgical maneuvers. In all cases the neurovascular conflict was found and solved with a good outcome in terms of pain disappearance. Our minimally invasive approach was demonstrated to guarantee an optimal exposure of the cerebellopontine angle and minimize the rate of complications related to skin incision and muscular dissection, microsurgical steps, and closure. Copyright © 2016 Elsevier Inc. All rights reserved.

A real-time and closed-loop control algorithm for cascaded multilevel inverter based on artificial neural network.

PubMed

Wang, Libing; Mao, Chengxiong; Wang, Dan; Lu, Jiming; Zhang, Junfeng; Chen, Xun

2014-01-01

In order to control the cascaded H-bridges (CHB) converter with staircase modulation strategy in a real-time manner, a real-time and closed-loop control algorithm based on artificial neural network (ANN) for three-phase CHB converter is proposed in this paper. It costs little computation time and memory. It has two steps. In the first step, hierarchical particle swarm optimizer with time-varying acceleration coefficient (HPSO-TVAC) algorithm is employed to minimize the total harmonic distortion (THD) and generate the optimal switching angles offline. In the second step, part of optimal switching angles are used to train an ANN and the well-designed ANN can generate optimal switching angles in a real-time manner. Compared with previous real-time algorithm, the proposed algorithm is suitable for a wider range of modulation index and results in a smaller THD and a lower calculation time. Furthermore, the well-designed ANN is embedded into a closed-loop control algorithm for CHB converter with variable direct voltage (DC) sources. Simulation results demonstrate that the proposed closed-loop control algorithm is able to quickly stabilize load voltage and minimize the line current's THD (<5%) when subjecting the DC sources disturbance or load disturbance. In real design stage, a switching angle pulse generation scheme is proposed and experiment results verify its correctness.

Controller design approach based on linear programming.

PubMed

Tanaka, Ryo; Shibasaki, Hiroki; Ogawa, Hiromitsu; Murakami, Takahiro; Ishida, Yoshihisa

2013-11-01

This study explains and demonstrates the design method for a control system with a load disturbance observer. Observer gains are determined by linear programming (LP) in terms of the Routh-Hurwitz stability criterion and the final-value theorem. In addition, the control model has a feedback structure, and feedback gains are determined to be the linear quadratic regulator. The simulation results confirmed that compared with the conventional method, the output estimated by our proposed method converges to a reference input faster when a load disturbance is added to a control system. In addition, we also confirmed the effectiveness of the proposed method by performing an experiment with a DC motor. © 2013 ISA. Published by ISA. All rights reserved.

COLD-SAT dynamic model

NASA Technical Reports Server (NTRS)

Adams, Neil S.; Bollenbacher, Gary

1992-01-01

This report discusses the development and underlying mathematics of a rigid-body computer model of a proposed cryogenic on-orbit liquid depot storage, acquisition, and transfer spacecraft (COLD-SAT). This model, referred to in this report as the COLD-SAT dynamic model, consists of both a trajectory model and an attitudinal model. All disturbance forces and torques expected to be significant for the actual COLD-SAT spacecraft are modeled to the required degree of accuracy. Control and experimental thrusters are modeled, as well as fluid slosh. The model also computes microgravity disturbance accelerations at any specified point in the spacecraft. The model was developed by using the Boeing EASY5 dynamic analysis package and will run on Apollo, Cray, and other computing platforms.

The Narcissism of Depression or the Depression of Narcissism and Adolescence

ERIC Educational Resources Information Center

Anastasopoulos, Dimitris

2007-01-01

Despite the fact that it has long been recognised that narcissism can contribute to depression, we have become accustomed to referring to depression mostly in terms of a neurotic disturbance. The author highlights the difference between the narcissistic elements in depression, which is based on guilt, and the graver narcissistic depression, which…

Interactions of School Bonding, Disturbed Family Relationships, and Risk Behaviors among Adolescents

ERIC Educational Resources Information Center

Rovis, Darko; Bezinovic, Petar; Basic, Josipa

2015-01-01

Background: Substance use, gambling, and violence represent a great risk for adolescent health. Schools are often referred to as the "best" places for health promotion and prevention, where positive school bonding serves as a strong protective factor for the development of risk behaviors and poor school bonding is associated with various…

Specialized Inpatient Psychiatry for Serious Behavioral Disturbance in Autism and Intellectual Disability

ERIC Educational Resources Information Center

Siegel, Matthew; Milligan, Briana; Chemelski, Bruce; Payne, David; Ellsworth, Beth; Harmon, Jamie; Teer, Olivia; Smith, Kahsi A.

2014-01-01

Psychiatric hospitalization of children with autism spectrum disorder and/or intellectual disability is common, however, the effectiveness of this intervention is largely unknown. Thirty-eight clinically-referred children 8-19 years old admitted to a specialized inpatient psychiatry unit were assessed by a consistent caregiver on the Aberrant…

Using Landscape Hierarchies To Guide Restoration Of Disturbed Ecosystems

Treesearch

Brian J. Palik; Charles P. Goebel; Katherine L. Kirkman; Larry West

2000-01-01

Reestablishing native plant communities is an important focus of ecosystem restoration. In complex landscapes containing a diversity of ecosystem types, restoration requires a set of reference vegetation conditions for the ecosystems of concern, and a predictive model to relate plant community composition to physical variables. Restoration also requires an approach for...

Temporal Variability of Stream Macroinvertebrate Abundance and Biomass Following Pesticide Disturbance

Treesearch

John J. Hutchens; Keun Chung; J. Bruce Wallace

1998-01-01

We determined the extent of macroinvertebrate recovery in a former pesticide-treated stream (FTS) relative to a reference stream (RS) by examining macroinvertebrate colonizing red maple (Acer rubrum L.) litter bags between 5 to 10 y following pesticide treatment. Mean abundance and biomass, varibility in abundance and biomass (using the coefficient...

The neurology in Shakespeare.

PubMed

Fogan, L

1989-08-01

William Shakespeare's 37 plays and poetry contain many references of interest for almost all of the medical specialties. To support that the Bard could be considered a Renaissance neurologist, the following important neurological phenomena have been selected from his repertoire for discussion: tremors, paralysis and stroke, sleep disturbances, epilepsy, dementia, encephalopathies, and the neurology of syphilis.

The use of time-series data in the assessment of macrobenthic community change after the cessation of sewage-sludge disposal in Liverpool Bay (UK).

PubMed

Whomersley, P; Schratzberger, M; Huxham, M; Bates, H; Rees, H

2007-01-01

Sewage sludge was disposed of in Liverpool Bay for over 100 years. Annual amounts increased from 0.5 million tonnes per annum in 1900 to approximately 2 million tonnes per annum by 1995. Macrofauna and a suite of environmental variables were collected at a station adjacent to, and a reference station distant from, the disposal site over 13 years, spanning a pre- (1990-1998) and post- (1999-2003) cessation period. Univariate and multivariate analyses of the time-series data showed significant community differences between reference and disposal site stations and multivariate analyses revealed station-specific community development post-disposal. Temporal variability of communities collected at the disposal station post-cessation was higher than during years of disposal, when temporally stable dominance patterns of disturbance-tolerant species had established. Alterations of community structure post-disturbance reflected successional changes possibly driven by facilitation. Subtle faunistic changes at the Liverpool Bay disposal site indicate that the near-field effects of the disposal of sewage sludge were small and therefore could be considered environmentally acceptable.

Robust linear quadratic designs with respect to parameter uncertainty

NASA Technical Reports Server (NTRS)

Douglas, Joel; Athans, Michael

1992-01-01

The authors derive a linear quadratic regulator (LQR) which is robust to parametric uncertainty by using the overbounding method of I. R. Petersen and C. V. Hollot (1986). The resulting controller is determined from the solution of a single modified Riccati equation. It is shown that, when applied to a structural system, the controller gains add robustness by minimizing the potential energy of uncertain stiffness elements, and minimizing the rate of dissipation of energy through uncertain damping elements. A worst-case disturbance in the direction of the uncertainty is also considered. It is proved that performance robustness has been increased with the robust LQR when compared to a mismatched LQR design where the controller is designed on the nominal system, but applied to the actual uncertain system.

Effective Solar Indices for Ionospheric Modeling: A Review and a Proposal for a Real-Time Regional IRI

NASA Astrophysics Data System (ADS)

Pignalberi, A.; Pezzopane, M.; Rizzi, R.; Galkin, I.

2018-01-01

The first part of this paper reviews methods using effective solar indices to update a background ionospheric model focusing on those employing the Kriging method to perform the spatial interpolation. Then, it proposes a method to update the International Reference Ionosphere (IRI) model through the assimilation of data collected by a European ionosonde network. The method, called International Reference Ionosphere UPdate (IRI UP), that can potentially operate in real time, is mathematically described and validated for the period 9-25 March 2015 (a time window including the well-known St. Patrick storm occurred on 17 March), using IRI and IRI Real Time Assimilative Model (IRTAM) models as the reference. It relies on foF2 and M(3000)F2 ionospheric characteristics, recorded routinely by a network of 12 European ionosonde stations, which are used to calculate for each station effective values of IRI indices IG_{12} and R_{12} (identified as IG_{{12{eff}}} and R_{{12{eff}}}); then, starting from this discrete dataset of values, two-dimensional (2D) maps of IG_{{12{eff}}} and R_{{12{eff}}} are generated through the universal Kriging method. Five variogram models are proposed and tested statistically to select the best performer for each effective index. Then, computed maps of IG_{{12{eff}}} and R_{{12{eff}}} are used in the IRI model to synthesize updated values of foF2 and hmF2. To evaluate the ability of the proposed method to reproduce rapid local changes that are common under disturbed conditions, quality metrics are calculated for two test stations whose measurements were not assimilated in IRI UP, Fairford (51.7°N, 1.5°W) and San Vito (40.6°N, 17.8°E), for IRI, IRI UP, and IRTAM models. The proposed method turns out to be very effective under highly disturbed conditions, with significant improvements of the foF2 representation and noticeable improvements of the hmF2 one. Important improvements have been verified also for quiet and moderately disturbed conditions. A visual analysis of foF2 and hmF2 maps highlights the ability of the IRI UP method to catch small-scale changes occurring under disturbed conditions which are not seen by IRI.

Reconciliation of the excess 176Hf conundrum in meteorites: Recent disturbances of the Lu-Hf and Sm-Nd isotope systematics

NASA Astrophysics Data System (ADS)

Bast, Rebecca; Scherer, Erik E.; Sprung, Peter; Mezger, Klaus; Fischer-Gödde, Mario; Taetz, Stephan; Böhnke, Mischa; Schmid-Beurmann, Hinrich; Münker, Carsten; Kleine, Thorsten; Srinivasan, Gopalan

2017-09-01

The long-lived 176Lu-176Hf and 147Sm-143Nd radioisotope systems are commonly used chronometers, but when applied to meteorites, they can reveal disturbances. Specifically, Lu-Hf isochrons commonly yield dates up to ∼300 Myr older than the solar system and varying initial 176Hf/177Hf values. We investigated this problem by attempting to construct mineral and whole rock isochrons for eucrites and angrites. Meteorites from different parent bodies exhibit similar disturbance features suggesting that a common process is responsible. Minerals scatter away from isochron regressions for both meteorite classes, with low-Hf phases such as plagioclase and olivine typically being most displaced above (or left of) reference isochrons. Relatively Hf-rich pyroxene is less disturbed but still to the point of steepening Lu-Hf errorchrons. Using our Lu-Hf and Sm-Nd data, we tested various Hf and Lu redistribution scenarios and found that decoupling of Lu/Hf from 176Hf/177Hf must postdate the accumulation of significant radiogenic 176Hf. Therefore early irradiation or diffusion cannot explain the excess 176Hf. Instead, disturbed meteorite isochrons are more likely caused by terrestrial weathering, contamination, or common laboratory procedures. The partial dissolution of phosphate minerals may predominantly remove rare earth elements including Lu, leaving relatively immobile and radiogenic Hf behind. Robust Lu-Hf (and improved Sm-Nd) meteorite geochronology will require the development of chemical or physical methods for removing unsupported radiogenic Hf and silicate-hosted terrestrial contaminants without disturbing parent-daughter ratios.

Functional evaluation of anterolateral thigh flap donor sites: isokinetic torque comparisons for knee function.

PubMed

Tsuji, Naoko; Suga, Hirotaka; Uda, Koichi; Sugawara, Yasushi

2008-01-01

The anterolateral thigh flap is thought to have minor donor site morbidity, but muscle dissection is unavoidable when skin perforator vessels run through the vastus lateralis muscle. The purpose of this study was to investigate the functional problems associated with the anterolateral thigh flap donor site. We evaluated 12 patients who underwent free anterolateral thigh flap transfer between March 2003 and November 2005. A questionnaire and dynamic functional evaluation of the knee joint using the Biodex System were performed preoperatively and 6 months postoperatively. No patients reported any disturbance in their daily life. No significant differences were found between donor and normal thighs on isokinetic power tests of the quadriceps muscle. The function of the donor site after harvesting the anterolateral thigh flap was maintained. Damage to or functional disturbance of the donor site is minimal even if muscle is injured when harvesting the flap. (c) 2008 Wiley-Liss, Inc. Microsurgery, 2008

GOES-R Dual Isolation

NASA Technical Reports Server (NTRS)

Freesland, Doug; Carter, Delano; Chapel, Jim; Clapp, Brian; Howat, John; Krimchansky, Alexander

2015-01-01

The Geostationary Operational Environmental Satellite-R Series (GOES-R) is the first of the next generation geostationary weather satellites, scheduled for delivery in late 2015. GOES-R represents a quantum increase in Earth and solar weather observation capabilities, with 4 times the resolution, 5 times the observation rate, and 3 times the number of spectral bands for Earth observations. With the improved resolution, comes the instrument suite's increased sensitive to disturbances over a broad spectrum 0-512 Hz. Sources of disturbance include reaction wheels, thruster firings for station keeping and momentum management, gimbal motion, and internal instrument disturbances. To minimize the impact of these disturbances, the baseline design includes an Earth Pointed Platform (EPP), a stiff optical bench to which the two nadir pointed instruments are collocated together with the Guidance Navigation & Control (GN&C) star trackers and Inertial Measurement Units (IMUs). The EPP is passively isolated from the spacecraft bus with Honeywell D-Strut isolators providing attenuation for frequencies above approximately 5 Hz in all six degrees-of-freedom. A change in Reaction Wheel Assembly (RWA) vendors occurred very late in the program. To reduce the risk of RWA disturbances impacting performance, a secondary passive isolation system manufactured by Moog CSA Engineering was incorporated under each of the six 160 Nms RWAs, tuned to provide attenuation at frequencies above approximately 50 Hz. Integrated wheel and isolator testing was performed on a Kistler table at NASA Goddard Space Flight Center. High fidelity simulations were conducted to evaluate jitter performance for four topologies: 1) hard mounted no isolation, 2) EPP isolation only, 2) RWA isolation only, and 4) dual isolation. Simulation results demonstrate excellent performance relative to the pointing stability requirements, with dual isolated Line of Sight (LOS) jitter less than 1 micron rad.

Effects of human trampling on populations of soil fauna in the McMurdo Dry Valleys, Antarctica.

PubMed

Ayres, Edward; Nkem, Johnson N; Wall, Diana H; Adams, Byron J; Barrett, J E; Broos, Emma J; Parsons, Andrew N; Powers, Laura E; Simmons, Breana L; Virginia, Ross A

2008-12-01

Antarctic ecosystems are often considered nearly pristine because levels of anthropogenic disturbance are extremely low there. Nevertheless, over recent decades there has been a rapid increase in the number of people, researchers and tourists, visiting Antarctica. We evaluated, over 10 years, the direct impact of foot traffic on the abundance of soil animals and soil properties in Taylor Valley within the McMurdo Dry Valleys region of Antarctica. We compared soils from minimally disturbed areas with soils from nearby paths that received intermediate and high levels of human foot traffic (i.e., up to approximately 80 passes per year). The nematodes Scottnema lindsayae and Eudorylaimus sp. were the most commonly found animal species, whereas rotifers and tardigrades were found only occasionally. On the highly trampled footpaths, abundance of S. lindsayae and Eudorylaimus sp. was up to 52 and 76% lower, respectively, than in untrampled areas. Moreover, reduction in S. lindsayae abundance was more pronounced after 10 years than 2 years and in the surface soil than in the deeper soil, presumably because of the longer period of disturbance and the greater level of physical disturbance experienced by the surface soil. The ratio of living to dead Eudorylaimus sp. also declined with increased trampling intensity, which is indicative of increased mortality or reduced fecundity. At one site there was evidence that high levels of trampling reduced soil CO(2) fluxes, which is related to total biological activity in the soil. Our results show that even low levels of human traffic can significantly affect soil biota in this ecosystem and may alter ecosystem processes, such as carbon cycling. Consequently, management and conservation plans for Antarctic soils should consider the high sensitivity of soil fauna to physical disturbance as human presence in this ecosystem increases.

Magnitude of daily energy deficit predicts frequency but not severity of menstrual disturbances associated with exercise and caloric restriction

PubMed Central

Leidy, Heather J.; Hill, Brenna R.; Lieberman, Jay L.; Legro, Richard S.; Souza, Mary Jane De

2014-01-01

We assessed the impact of energy deficiency on menstrual function using controlled feeding and supervised exercise over four menstrual cycles (1 baseline and 3 intervention cycles) in untrained, eumenorrheic women aged 18–30 yr. Subjects were randomized to either an exercising control (EXCON) or one of three exercising energy deficit (ED) groups, i.e., mild (ED1; −8 ± 2%), moderate (ED2; −22 ± 3%), or severe (ED3; −42 ± 3%). Menstrual cycle length and changes in urinary concentrations of estrone-1-glucuronide, pregnanediol glucuronide, and midcycle luteinizing hormone were assessed. Thirty-four subjects completed the study. Weight loss occurred in ED1 (−3.8 ± 0.2 kg), ED2 (−2.8 ± 0.6 kg), and ED3 (−2.6 ± 1.1 kg) but was minimal in EXCON (−0.9 ± 0.7 kg). The overall sum of disturbances (luteal phase defects, anovulation, and oligomenorrhea) was greater in ED2 compared with EXCON and greater in ED3 compared with EXCON AND ED1. The average percent energy deficit was the main predictor of the frequency of menstrual disturbances (f = 10.1, β = −0.48, r2 = 0.23, P = 0.003) even when weight loss was included in the model. The estimates of the magnitude of energy deficiency associated with menstrual disturbances ranged from −22 (ED2) to −42% (ED3), reflecting an energy deficit of −470 to −810 kcal/day, respectively. This is the first study to demonstrate a dose-response relationship between the magnitude of energy deficiency and the frequency of exercise-related menstrual disturbances; however, the severity of menstrual disturbances was not dependent on the magnitude of energy deficiency. PMID:25352438

Non-linear Feedbacks Between Forest Mortality and Climate Change: Implications for Snow Cover, Water Resources, and Ecosystem Recovery in Western North America (Invited)

NASA Astrophysics Data System (ADS)

Brooks, P. D.; Harpold, A. A.; Biederman, J. A.; Gochis, D. J.; Litvak, M. E.; Ewers, B. E.; Broxton, P. D.; Reed, D. E.

2013-12-01

Unprecedented levels of tree mortality from insect infestation and wildfire are dramatically altering forest structure and composition in Western North America. Warming temperatures and increased drought stress have been implicated as major factors in the increasing spatial extent and frequency of these forest disturbances, but it is unclear how these changes in forest structure will interact with ongoing climate change to affect snowmelt water resources either for society or for ecosystem recovery following mortality. Because surface discharge, groundwater recharge, and ecosystem productivity all depend on seasonal snowmelt, a critical knowledge gap exists not only in predicting discharge, but in quantifying spatial and temporal variability in the partitioning of snowfall into abiotic vapor loss, plant available water, recharge, and streamflow within the complex mosaic of forest disturbance and topography that characterizes western mountain catchments. This presentation will address this knowledge gap by synthesizing recent work on snowpack dynamics and ecosystem productivity from seasonally snow-covered forests along a climate gradient from Arizona to Wyoming; including undisturbed sites, recently burned forests, and areas of extensive insect-induced forest mortality. Both before-after and control-impacted studies of forest disturbance on snow accumulation and ablation suggest that the spatial scale of snow distribution increases following disturbance, but net snow water input in a warming climate will increase only in topographically sheltered areas. While forest disturbance changes spatial scale of snowpack partitioning, the amount and especially the timing of snow cover accumulation and ablation are strongly related to interannual variability in ecosystem productivity with both earlier snowmelt and later snow accumulation associated with decreased carbon uptake. Empirical analyses and modeling are being developed to identify landscapes most sensitive to climate change as well as to develop management alternatives that minimize the effects of disturbance on high elevation forests and the services of water provision and carbon storage they provide.

Decision Making and the Avoidance of Cognitive Demand

ERIC Educational Resources Information Center

Kool, Wouter; McGuire, Joseph T.; Rosen, Zev B.; Botvinick, Matthew M.

2010-01-01

Behavioral and economic theories have long maintained that actions are chosen so as to minimize demands for exertion or work, a principle sometimes referred to as the "law of less work". The data supporting this idea pertain almost entirely to demands for physical effort. However, the same minimization principle has often been assumed also to…

Individual and cumulative effects of agriculture, forestry and metal mining activities on the metal and phosphorus content of fluvial fine-grained sediment; Quesnel River Basin, British Columbia, Canada.

PubMed

Smith, Tyler B; Owens, Philip N

2014-10-15

The impact of agriculture, forestry and metal mining on the quality of fine-grained sediment (<63 μm) was investigated in the Quesnel River Basin (QRB) (~11,500 km(2)) in British Columbia, Canada. Samples of fine-grained sediment were collected monthly during the snow-free season in 2008 using time-integrated samplers at replicate sites representative of agriculture, forestry and mining activities in the basin (i.e. "impacted" sites). Samples were also collected from replicate reference sites and also from the main stem of the Quesnel River at the downstream confluence with the Fraser River. Generally, metal(loid) and phosphorus (P) concentrations for "impacted" sites were greater than for reference sites. Furthermore, concentrations of copper (forestry and mining sites), manganese (agriculture and forestry sites) and selenium (agriculture, forestry and mining sites) exceeded upper sediment quality guideline (SQG) thresholds. These results suggest that agriculture, forestry and metal mining activities are having an influence on the concentrations of sediment-associated metal(loid)s and P in the Quesnel basin. Metal(loid) and P concentrations of sediment collected from the downstream site were not significantly greater than values for the reference sites, and were typically lower than the values for the impacted sites. This suggests that the cumulative effects of agriculture, forestry and mining activities in the QRB are presently not having a measureable effect at the river basin-scale. The lack of a cumulative effect at the basin-scale is thought to reflect: (i) the relatively recent occurrence of land use disturbances in this basin; (ii) the dominance of sediment contributions from natural forest and agriculture; and (iii) the potential for storage of contaminants on floodplains and other storage elements between the locations of disturbance activities and the downstream sampling site, which may be attenuating the disturbance signal. Copyright © 2014 Elsevier B.V. All rights reserved.

Report of 121 Cases of Bell's Palsy Referred to the Emergency Department

PubMed Central

Zohrevandi, Behzad; Monsef Kasmaee, Vahid; Asadi, Payman; Tajik, Hosna

2014-01-01

Introduction: According to the high incidence of Bell's palsy (IFP) and lack of clinical data regarding different aspects of disease, the present study investigated 121 Iranian patients with peripheral facial paralysis referred to the emergency department. Methods: In this retrospective study, all patients with peripheral facial paralysis, referred to the emergency department of Poursina hospital, Rasht, Iran, from August 2012 to August 2013, were enrolled. For all patients with diagnosis of Bell's palsy variables such as age, sex, occupation, clinical symptoms, comorbid disease, grade of paralysis, and the severity of the facial palsy were reviewed and analyzed using STATA version 11.0. Results: 121 patients with peripheral facial paralysis were assessed with a mean age of 47.14±18.45 years (52.9% male). The majority of patients were observed in the summer (37.2%) and autumn (33.1%) and the recurrence rate was 22.3%. The most common grades of nerve damage were IV and V based on House-Brackman grading scale (47.1%). Also, the most frequent signs and symptoms were ear pain (43.8%), taste disturbance (38.8%), hyperacusis (15.7%) and increased tearing (11.6%). There were not significant correlations between the severity of palsy with age (p= 0.08), recurrence rate (p=0.18), season (p=0.9), and comorbid disease including hypertension (p=0.18), diabetes (p=0.29), and hyperlipidemia (p=0.94). The patients with any of following symptoms such as ear pain (p<0.001), taste disturbance (p<0.001), increased tearing (p=0.03), and Hyperacusis (p<0.001) have more severe palsy. Conclusion: There was equal gender and occupational distribution, higher incidence in fourth decade of life, higher incidence in summer and autumn, higher grade of nerve damage (grade V and VI), and higher incidence of ear pain and taste disturbance in patients suffered from IFP. In addition, there was significant association between severity of nerve damage and presence of any simultaneous symptoms. PMID:26495349

Assessment of Power Quality based on Fuzzy Logic and Discrete Wavelet Transform for Nonstationary Disturbances

NASA Astrophysics Data System (ADS)

Sinha, Pampa; Nath, Sudipta

2010-10-01

The main aspects of power system delivery are reliability and quality. If all the customers of a power system get uninterrupted power through the year then the system is considered to be reliable. The term power quality may be referred to as maintaining near sinusoidal voltage at rated frequency at the consumers end. The power component definitions are defined according to the IEEE Standard 1459-2000 both for single phase and three phase unbalanced systems based on Fourier Transform (FFT). In the presence of nonstationary power quality (PQ) disturbances results in accurate values due to its sensitivity to the spectral leakage problem. To overcome these limitations the power quality components are calculated using Discrete Wavelet Transform (DWT). In order to handle the uncertainties associated with electric power systems operations fuzzy logic has been incorporated in this paper. A new power quality index has been introduced here which can assess the power quality under nonstationary disturbances.

Error mechanism analyses of an ultra-precision stage for high speed scan motion over a large stroke

NASA Astrophysics Data System (ADS)

Wang, Shaokai; Tan, Jiubin; Cui, Jiwen

2015-02-01

Reticle Stage (RS) is designed to complete scan motion with high speed in nanometer-scale over a large stroke. Comparing with the allowable scan accuracy of a few nanometers, errors caused by any internal or external disturbances are critical and must not be ignored. In this paper, RS is firstly introduced in aspects of mechanical structure, forms of motion, and controlling method. Based on that, mechanisms of disturbances transferred to final servo-related error in scan direction are analyzed, including feedforward error, coupling between the large stroke stage (LS) and the short stroke stage (SS), and movement of measurement reference. Especially, different forms of coupling between SS and LS are discussed in detail. After theoretical analysis above, the contributions of these disturbances to final error are simulated numerically. The residual positioning error caused by feedforward error in acceleration process is about 2 nm after settling time, the coupling between SS and LS about 2.19 nm, and the movements of MF about 0.6 nm.

Nonlinear control of linear parameter varying systems with applications to hypersonic vehicles

NASA Astrophysics Data System (ADS)

Wilcox, Zachary Donald

The focus of this dissertation is to design a controller for linear parameter varying (LPV) systems, apply it specifically to air-breathing hypersonic vehicles, and examine the interplay between control performance and the structural dynamics design. Specifically a Lyapunov-based continuous robust controller is developed that yields exponential tracking of a reference model, despite the presence of bounded, nonvanishing disturbances. The hypersonic vehicle has time varying parameters, specifically temperature profiles, and its dynamics can be reduced to an LPV system with additive disturbances. Since the HSV can be modeled as an LPV system the proposed control design is directly applicable. The control performance is directly examined through simulations. A wide variety of applications exist that can be effectively modeled as LPV systems. In particular, flight systems have historically been modeled as LPV systems and associated control tools have been applied such as gain-scheduling, linear matrix inequalities (LMIs), linear fractional transformations (LFT), and mu-types. However, as the type of flight environments and trajectories become more demanding, the traditional LPV controllers may no longer be sufficient. In particular, hypersonic flight vehicles (HSVs) present an inherently difficult problem because of the nonlinear aerothermoelastic coupling effects in the dynamics. HSV flight conditions produce temperature variations that can alter both the structural dynamics and flight dynamics. Starting with the full nonlinear dynamics, the aerothermoelastic effects are modeled by a temperature dependent, parameter varying state-space representation with added disturbances. The model includes an uncertain parameter varying state matrix, an uncertain parameter varying non-square (column deficient) input matrix, and an additive bounded disturbance. In this dissertation, a robust dynamic controller is formulated for a uncertain and disturbed LPV system. The developed controller is then applied to a HSV model, and a Lyapunov analysis is used to prove global exponential reference model tracking in the presence of uncertainty in the state and input matrices and exogenous disturbances. Simulations with a spectrum of gains and temperature profiles on the full nonlinear dynamic model of the HSV is used to illustrate the performance and robustness of the developed controller. In addition, this work considers how the performance of the developed controller varies over a wide variety of control gains and temperature profiles and are optimized with respect to different performance metrics. Specifically, various temperature profile models and related nonlinear temperature dependent disturbances are used to characterize the relative control performance and effort for each model. Examining such metrics as a function of temperature provides a potential inroad to examine the interplay between structural/thermal protection design and control development and has application for future HSV design and control implementation.

Anadromous sea lampreys (Petromyzon marinus) are ecosystem engineers in a spawning tributary

USGS Publications Warehouse

Hogg, Robert S.; Coghlan, Stephen M.; Zydlewski, Joseph D.; Simon, Kevin S.

2014-01-01

Sea lampreys (Petromyzon marinus) disturb the substratum during nest construction and alter the physical habitat, potentially affecting other stream organisms. We quantified differences in depth, velocity, fine-sediment coverage, embeddedness, intragravel permeability and benthic invertebrate assemblages (density and diversity) among nest mounds, nest pits and undisturbed reference locations over a 4-month period after June spawning. In 2010 and 2011, immediate and persistent effects of nest construction were assessed in summer (July) and in autumn (late September to early October), respectively. Randomly selected nests were sampled annually (25 each in summer and autumn). Nest construction increased stream-bed complexity by creating and juxtaposing shallow, swift, rocky habitat patches with deep, slow, sandy habitat patches. Mounds had a 50–143% less cover of fine sediment, and a 30–62% reduction in embeddedness, compared to pits and reference locations. These physical changes persisted into the autumn (almost 4 months). Five insect families contributed 74% of the benthic invertebrate abundance: Chironomidae (27%), Hydropsychidae (26%), Heptageniidae (8%), Philopotamidae (7%) and Ephemerellidae (6%). Densities of Hydropsychidae, Philopotamidae and Heptageniidae were up to 10 times greater in mounds than in pits and adjacent reference habitat. In summer, mounds had twice the density of Chironomidae than did pits, and 1.5 times more than reference habitats, but densities were similar among the habitats in autumn. These results suggest that spawning sea lampreys are ecosystem engineers. The physical disturbance caused by nest-building activity was significant and persistent, increasing habitat heterogeneity and favouring pollution-sensitive benthic invertebrates and, possibly, drift-feeding fish.

Infants Encode Phonetic Detail during Cross-Situational Word Learning

PubMed Central

Escudero, Paola; Mulak, Karen E.; Vlach, Haley A.

2016-01-01

Infants often hear new words in the context of more than one candidate referent. In cross-situational word learning (XSWL), word-object mappings are determined by tracking co-occurrences of words and candidate referents across multiple learning events. Research demonstrates that infants can learn words in XSWL paradigms, suggesting that it is a viable model of real-world word learning. However, these studies have all presented infants with words that have no or minimal phonological overlap (e.g., BLICKET and GAX). Words often contain some degree of phonological overlap, and it is unknown whether infants can simultaneously encode fine phonological detail while learning words via XSWL. We tested 12-, 15-, 17-, and 20-month-olds’ XSWL of eight words that, when paired, formed non-minimal pairs (MPs; e.g., BON–DEET) or MPs (e.g., BON–TON, DEET–DIT). The results demonstrated that infants are able to learn word-object mappings and encode them with sufficient phonetic detail as to identify words in both non-minimal and MP contexts. Thus, this work suggests that infants are able to simultaneously discriminate phonetic differences between words and map words to referents in an implicit learning paradigm such as XSWL. PMID:27708605

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Hao; Garzoglio, Gabriele; Ren, Shangping

FermiCloud is a private cloud developed in Fermi National Accelerator Laboratory to provide elastic and on-demand resources for different scientific research experiments. The design goal of the FermiCloud is to automatically allocate resources for different scientific applications so that the QoS required by these applications is met and the operational cost of the FermiCloud is minimized. Our earlier research shows that VM launching overhead has large variations. If such variations are not taken into consideration when making resource allocation decisions, it may lead to poor performance and resource waste. In this paper, we show how we may use an VMmore » launching overhead reference model to minimize VM launching overhead. In particular, we first present a training algorithm that automatically tunes a given refer- ence model to accurately reflect FermiCloud environment. Based on the tuned reference model for virtual machine launching overhead, we develop an overhead-aware-best-fit resource allocation algorithm that decides where and when to allocate resources so that the average virtual machine launching overhead is minimized. The experimental results indicate that the developed overhead-aware-best-fit resource allocation algorithm can significantly improved the VM launching time when large number of VMs are simultaneously launched.« less

Pointing control system design and performance evaluation of TPF coronagraph

NASA Astrophysics Data System (ADS)

Liu, Kuo-Chia; Blaurock, Carl; Mosier, Gary E.

2004-09-01

The Terrestrial Planet Finder (TPF) project aims to detect and characterize extra-solar Earth-like planets. The coronagraph telescope is one of the two mission concepts being studied. To reject the star flux and detect the planet flux in the visible light range, the coronagraph telescope must achieve a rejection ratio on the order of a billion to one. Dynamic jitter, introduced by environmental and on-board mechanical disturbances, degrades the optical performance, as characterized primarily by contrast ratio. The feasibility of using passive vibration isolation combined with active attitude and line-of-sight (LOS) control systems to stabilize the spacecraft and the optical components to the requisite level is being studied. The telescope is also required to slew between targets or rotate around the LOS. The slew mode control law must be designed to balance the need for efficient large-angle maneuvers while simultaneously avoiding the excitation of flexible modes in order to minimize settling time. This paper provides an overview of the current control design concept and sensor/actuator topology for TPF Coronagraph and illustrates the fine pointing performance of the telescope. This performance is primarily a function of the rejection of high-frequency dynamic disturbances, in this case due to reaction wheel disturbance forces/torques transmitted through the passive isolation stage. Trade studies between isolator force rejection and disturbance level reduction via wheel redesign are also presented to illustrate the requirements imposed on current technologies. Finally, the paper summarizes preliminary results on the slew/settle performance of the telescope.

Unmanned aircraft systems as a new source of disturbance for wildlife: A systematic review

PubMed Central

Jenni-Eiermann, Susanne; Strebel, Nicolas; Sattler, Thomas; Negro, Juan José; Tablado, Zulima

2017-01-01

The use of small Unmanned Aircraft Systems (UAS; also known as “drones”) for professional and personal-leisure use is increasing enormously. UAS operate at low altitudes (<500 m) and in any terrain, thus they are susceptible to interact with local fauna, generating a new type of anthropogenic disturbance that has not been systematically evaluated. To address this gap, we performed a review of the existent literature about animals’ responses to UAS flights and conducted a pooled analysis of the data to determine the probability and intensity of the disturbance, and to identify the factors influencing animals’ reactions towards the small aircraft. We found that wildlife reactions depended on both the UAS attributes (flight pattern, engine type and size of aircraft) and the characteristics of animals themselves (type of animal, life-history stage and level of aggregation). Target-oriented flight patterns, larger UAS sizes, and fuel-powered (noisier) engines evoked the strongest reactions in wildlife. Animals during the non-breeding period and in large groups were more likely to show behavioral reactions to UAS, and birds are more prone to react than other taxa. We discuss the implications of these results in the context of wildlife disturbance and suggest guidelines for conservationists, users and manufacturers to minimize the impact of UAS. In addition, we propose that the legal framework needs to be adapted so that appropriate actions can be undertaken when wildlife is negatively affected by these emergent practices. PMID:28636611

Unmanned aircraft systems as a new source of disturbance for wildlife: A systematic review.

PubMed

Mulero-Pázmány, Margarita; Jenni-Eiermann, Susanne; Strebel, Nicolas; Sattler, Thomas; Negro, Juan José; Tablado, Zulima

2017-01-01

The use of small Unmanned Aircraft Systems (UAS; also known as "drones") for professional and personal-leisure use is increasing enormously. UAS operate at low altitudes (<500 m) and in any terrain, thus they are susceptible to interact with local fauna, generating a new type of anthropogenic disturbance that has not been systematically evaluated. To address this gap, we performed a review of the existent literature about animals' responses to UAS flights and conducted a pooled analysis of the data to determine the probability and intensity of the disturbance, and to identify the factors influencing animals' reactions towards the small aircraft. We found that wildlife reactions depended on both the UAS attributes (flight pattern, engine type and size of aircraft) and the characteristics of animals themselves (type of animal, life-history stage and level of aggregation). Target-oriented flight patterns, larger UAS sizes, and fuel-powered (noisier) engines evoked the strongest reactions in wildlife. Animals during the non-breeding period and in large groups were more likely to show behavioral reactions to UAS, and birds are more prone to react than other taxa. We discuss the implications of these results in the context of wildlife disturbance and suggest guidelines for conservationists, users and manufacturers to minimize the impact of UAS. In addition, we propose that the legal framework needs to be adapted so that appropriate actions can be undertaken when wildlife is negatively affected by these emergent practices.

Electrochemistry in ethanol. I. Reference electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zara, A.J.; de S. Bulhoes, L.O.

1982-01-01

The silver/silver nitrate electrode was found to be a suitable reference electrode in ethanolic solutions (2% v/v in water). The concentration of Ag/sup +/ inside the reference electrode is satisfactory in teh 0.1 to 10 mM concentration range. The liquid junction potential is minimized with sufficient supporting electrolyte (e.g., 0.1 to 0.5 M sodium perchlorate). The electrode is suitable for use as reference electrode in potentiometry and in polarography. Preparation is uncomplicated and the product is stable. 4 figures.

Determination of real machine-tool settings and minimization of real surface deviation by computerized inspection

NASA Technical Reports Server (NTRS)

Litvin, Faydor L.; Kuan, Chihping; Zhang, YI

1991-01-01

A numerical method is developed for the minimization of deviations of real tooth surfaces from the theoretical ones. The deviations are caused by errors of manufacturing, errors of installment of machine-tool settings and distortion of surfaces by heat-treatment. The deviations are determined by coordinate measurements of gear tooth surfaces. The minimization of deviations is based on the proper correction of initially applied machine-tool settings. The contents of accomplished research project cover the following topics: (1) Descriptions of the principle of coordinate measurements of gear tooth surfaces; (2) Deviation of theoretical tooth surfaces (with examples of surfaces of hypoid gears and references for spiral bevel gears); (3) Determination of the reference point and the grid; (4) Determination of the deviations of real tooth surfaces at the points of the grid; and (5) Determination of required corrections of machine-tool settings for minimization of deviations. The procedure for minimization of deviations is based on numerical solution of an overdetermined system of n linear equations in m unknowns (m much less than n ), where n is the number of points of measurements and m is the number of parameters of applied machine-tool settings to be corrected. The developed approach is illustrated with numerical examples.

The Evolution of the Reference Librarian

ERIC Educational Resources Information Center

Johnson, Wendell G.

2011-01-01

The job of the contemporary reference librarian has a virtual component unimaginable a generation ago. Today's library professional can obtain an MLS (or equivalent) online with a minimal residency requirement. Not only the degree, but also library sources, and indeed patrons, have become virtual. Both books and periodicals can be consulted by…

Cross-Situational Learning of Minimal Word Pairs

ERIC Educational Resources Information Center

Escudero, Paola; Mulak, Karen E.; Vlach, Haley A.

2016-01-01

"Cross-situational statistical learning" of words involves tracking co-occurrences of auditory words and objects across time to infer word-referent mappings. Previous research has demonstrated that learners can infer referents across sets of very phonologically distinct words (e.g., WUG, DAX), but it remains unknown whether learners can…

Comparison on different repetition rate locking methods in Er-doped fiber laser

NASA Astrophysics Data System (ADS)

Yang, Kangwen; Zhao, Peng; Luo, Jiang; Huang, Kun; Hao, Qiang; Zeng, Heping

2018-05-01

We demonstrate a systematic comparative research on the all-optical, mechanical and opto-mechanical repetition rate control methods in an Er-doped fiber laser. A piece of Yb-doped fiber, a piezoelectric transducer and an electronic polarization controller are simultaneously added in the laser cavity as different cavity length modulators. By measuring the cavity length tuning ranges, the output power fluctuations, the temporal and frequency repetition rate stability, we show that all-optical method introduces the minimal disturbances under current experimental condition.

Canine distemper virus-associated hypocalcemia.

PubMed

Weisbrode, S E; Krakowka, S

1979-01-01

A retrospective study was done to correlate serum calcium concentrations and parathyroid gland ultrastructure to clinical, immunologic, and pathologic changes experimentally induced in gnotobiotic dogs by canine distemper virus (CDV). Dogs infected with CDV had significantly reduced serum calcium concentrations associated with ultrastructural evidence of parathyroid gland inactivity, degeneration, and viral inclusions. Although CDV-infected dogs exhibited neurologic signs, minimal lesions were present in the central nervous system. It is suggested that viral-induced parathyroid dysfunction may contribute to neutrologic disturbance of CDV infection.

Infanticide and moral consistency.

PubMed

McMahan, Jeff

2013-05-01

The aim of this essay is to show that there are no easy options for those who are disturbed by the suggestion that infanticide may on occasion be morally permissible. The belief that infanticide is always wrong is doubtfully compatible with a range of widely shared moral beliefs that underlie various commonly accepted practices. Any set of beliefs about the morality of abortion, infanticide and the killing of animals that is internally consistent and even minimally credible will therefore unavoidably contain some beliefs that are counterintuitive.

Robustness and Actuator Bandwidth of MRP-Based Sliding Mode Control for Spacecraft Attitude Control Problems

NASA Astrophysics Data System (ADS)

Keum, Jung-Hoon; Ra, Sung-Woong

2009-12-01

Nonlinear sliding surface design in variable structure systems for spacecraft attitude control problems is studied. A robustness analysis is performed for regular form of system, and calculation of actuator bandwidth is presented by reviewing sliding surface dynamics. To achieve non-singular attitude description and minimal parameterization, spacecraft attitude control problems are considered based on modified Rodrigues parameters (MRP). It is shown that the derived controller ensures the sliding motion in pre-determined region irrespective of unmodeled effects and disturbances.

Survival and movements of molting male black ducks in Labrador

USGS Publications Warehouse

Bowman, Timothy D.; Longcore, J.R.

1989-01-01

We marked 26 flightless male American black ducks with transmitters during the post-nuptial molt in northern Labrabor to determine survival and movements. Twelve ducks remained in the watershed where marked and 11 ducks moved to different watersheds. The period survival rate (PSR) for these flightless males was 0.89 using the Kaplan-Meier estimator. Only 2 ducks were killed by predators. Death of these 2 ducks might have been influenced by our disturbance, thus we considered the PSR minimal.

Invasive Plants Field and Reference Guide: An Ecological Perspective of Plant Invaders of Forests and Woodlands

Treesearch

Cynthia D. Huebner; Cassandra Olson; Heather C. Smith; Heather C. Smith

2005-01-01

There are many field guides available about invasive plants and their identification. The purpose of this particular field guide is to give a scientific synthesis of what is known about the behavior of such species in managed, disturbed, and pristine forested systems in addition to key information for accurate identification.