bluuebunny/crossref_metadata_2025 huggingface dataset:
Active Vibration Control Method for Space Mechanical Structure with Piezostacks
Authors: Koszewnik Andrzej Piotr
Published: March 2013

Mechanical structures are spatial, three-dimensional (3D) systems of distributed parameters. They present quite complicated plants, if methods of control systems theory are applied. The design process of the vibration control system for such plants is extremely difficult and requires an extensive heuristic knowledge. The subject of the control system is to eliminate the vibrations of the free end at the plane parallel to the foundation Similar problems are met, when the stabilization of robot arms, antennas, satellite solar batteries or slender skyscrapers is considered. In the paper we have presented the 3D bar structure with sticked parallel two piezo-stacks into bars. Recall piezo-elements are actuators, but sensors are two eddy-current sensors located in near free end the structure in perpendicular directions X and Y. Thus the whole structure is TITO (Two Input Two Output) system. For such system the control law was designed with used LQR controller. Above controller was designed for coupled and decoupled system also. In both case a correct damp and very short period of the vibration were criteria to choose the controller parameters. All investigations were carried out in two steps. In the first step control laws were designed in computer simulation. In the second step these control laws were verified experimentally on the laboratory stand by using DSP. Finally, desired control laws were compared.
Diversity of Servo-Constraint Problems for Underactuated Mechanical Systems: A Case Study Illustration
Authors: Blajer Wojciech , Seifried Robert , Kołodziejczyk Krzysztof
Published: March 2013

Underactuated mechanical systems are systems with fewer control inputs than degrees of freedom. Determination of an input control strategy that forces an underactuated system to complete specified in time outputs (servo-constraints), whose number is equal to the number of inputs, can be a challenging task. Diversity of the servo-constraint problems is discussed here using a simple spring-mass system mounted on a carriage (two degrees of freedom, one control input, and one specified in time output). A formulation of underactuated system dynamics which includes the output coordinates is motivated, with the governing equations arising either as ODEs (ordinary differential equations) or DAEs (differential-algebraic equations). Solutions to the servo-constraint problem are then discussed with reference to so-called non-flat systems (with internal dynamics) and differentially flat systems (no internal dynamics). Some computational issues related to the ODE and DAE formulations are finally discussed, and relevant simulation results for the sample case study are reported.
Energy Dissipation of Synchronized Switch Damping with Piezoceramics Using Negative Capacitance
Authors: Neubauer Marcus , Han Xu , Wallaschek Jörg
Published: March 2013

This publication presents a novel piezoelectric shunt damping circuit. It consists of a negative capacitance in parallel to a synchronized switch damping on inductor (SSDI) branch. This combination utilizes the increased piezoelectric coupling due to the negative capacitance together with the adaptive ability of the SSDI technique. This novel circuit is theoretically modelled using non-dimensional parameters, and optimum network parameters and the corresponding maximum damping is obtained. The increase in damping performance due to the negative capacitance is clearly highlighted. Theoretically, the energy dissipation can be increased unlimited when tuning the system at the stability boundary, given the system would still be excited to vibrations. However, due to imperfections and practical realization using operational amplifiers the increase is limited.
Energy Parameter Control System of Strength Machine for Material Tests under Cyclic Bending and Torsion
Authors: Kasprzyczak Leszek , Macha Ewald , Marciniak Zbigniew
Published: March 2013

The paper presents strength machine control system for characterization of fatigue properties of materials based on a new, recently defined, energy fatigue damage parameter. It is used in new procedure for precise determination of the fatigue characteristics of materials with the controlled strain energy density parameter. The new parameter distinguishes positive and negative values strain energy density histories during variable loading. In case of modern, cyclically unstable materials the new closed-loop control system of strength machine allows to univocally establish the relevant stress-strain based fatigue characteristic under bending and torsion. This control system has been implemented with the use of National Instruments LabVIEW software. The mechatronic stand based on fatigue machine for material testing under bending moment and torsion moment has been described and preliminarily material tests have been done.
Genetic Fuzzy Approach for Designing a Gain Scheduling Anti-Sway Crane Control System
Authors: Smoczek Jaroslaw
Published: March 2013

The gain scheduling control scheme designing problem consists in selecting a set of appropriate operating points at which the linear controllers are determined, thus the interpolation scheme ensures expected control quality within the known range of system's parameters changes, when those parameters vary in relation to some exogenous variables used in a control system as the scheduling variables. The problem arises together with the number of scheduling variables correlated with the parameters variations, thus utilizing the iterative techniques to minimize a set of controllers can be unreliable. The problem of gain scheduling system designing is addressed in the paper to the anti-sway crane control system. The fuzzy interpolation is used to determine the gains of proportional-derivative controllers based on the scheduling variables, the rope length and mass of a payload suspended on a rope. The problem of rules base optimization and membership function parameters tuning is solved using genetic algorithm and pole placement method.
Hardware in the Loop Test Rig for Development of Control Algorithms for Electric Vehicles
Authors: Quantmeyer Florian , Liu-Henke Xiao Bo
Published: March 2013

Political pressure on the automotive industry will lead in future to an increasing electrification of the powertrain. The new components require the development of new vehicle control systems and control functions. Due to the high complexity of such systems the mechatronical development process including Model in the Loop (MIL), Software in the Loop (SIL) and Hardware in the Loop (HIL) simulation has been established. In this paper, a HiL test rig is presented, which has high flexibility and supports the model based development of control systems for battery electric vehicles at all levels.
Mathematical Models of Control Systems of Angular Speed of Steam Turbines for Diagnostic Tests of Automatic and Mechatronic Devices
Authors: Redlarski Grzegorz , Piechocki Janusz , Dąbkowski Mariusz
Published: March 2013

In many automatics and mechatronics systems accurate modeling of several physical processes is needed. In power system, one of these is the process of control of angular velocity of power blocks during their connection to parallel operation. This process is extremely dynamic and the response of control system results from continuous changes in many physical parameters (temperature, pressure and flow of the working medium, etc.). An accuracy of modeling this process influences int. al. on: quality of the automatic synchronizer diagnostic tests in the laboratory, as well as the possibility of evaluation of prospects for connection process in the power system, without the automatic synchronizer [. Automatics systems used for research and diagnosis of automatic synchronizers are known in the literature as and simulators [2, . To impose similar to real working conditions, it is required to implement an appropriate models of control systems. One of such models, representative for the larger population of objects, is model of control systems of angular velocity. Currently used models, e.g. [3, 4, 5, , allow to approximate the response of real object, or to impose higher restricted conditions of work, for example: related to the angular acceleration dω/dt, the size of overshoots and decay time of transitional characteristics, while accurate modeling the real working conditions using them is not possible. Furthermore, their use requires knowledge of the (often difficult to access) object parameters and time-consuming selection of manual procedure of certain substitute settings, occurring in these models. To eliminate inconveniences mentioned above, in the paper the proposal and mathematical modeling procedure is presented, which allow to obtain much more accurate transitional characteristics of real objects.
Solution for Inverse Kinematics of 5 DOF Serial Link MCM Machine
Authors: Kozioł Piotr , Kukliński Kamil , Wolniakowski Adam , Miatliuk Konstanty
Published: March 2013

The paper presents the forward and inverse kinematics problems solution for 5 DoF automated serial link MCM cutting and welding machine. Particularly, the solution was developed for specific application to be implemented in industry. The developing of the mathematical model for control purposes, implementing algorithms for trajectory finding and mathematical model for forward and inverse kinematics solution are described in the work. The solution is presented as simulation in RobWork Studio software [, as well as a 3D interactive animation implemented in specifically developed software environment. The result of given solution are evaluated and directions of further work concerning the implementation of obtained solution in the actual industrial application are defined.
Modelling of Ship's Heeling and Rolling for the Purpose of Gantry Control Improvement in the Course of Cargo Handling Operations in Sea Ports
Authors: Krata Przemysław , Szpytko Janusz , Weintrit Adam
Published: March 2013

The paper presents two proposals of models of interaction between a ship and cargo being loaded or discharged by a gantry in port, in terms of heeling and rolling of the vessel. The main purpose of such modelling is the need for improvement of gantry control with regard to faster operations thanks to more accurate estimation of level and moment of cargo release from a gantry hook or spreader. The study may be the contribution to the development of gantry control systems in sea ports.
Non-Collision Path Planning of a Payload in Crane Operating Space
Authors: Smoczek Jaroslaw , Szpytko Janusz , Hyla Pawel
Published: March 2013

The problem of ensuring the safe and efficient cranes operations in automated manufacturing processes involves the automation of the operating workspace identification, non-collision and time-optimal path planning, and real-time following a payload along the determined path by crane motion mechanisms with expected precision. The paper describes the stereo vision based system used for identification of workspace of the laboratory scaled overhead travelling crane. The time-optimal trajectory of a payload is determined by using the A-star graph searching algorithm, and next real-time trucking by PLC-based crane control system.
The Anti-Sway Crane Control System with Using Dynamic Vision System
Authors: Smoczek Jaroslaw , Szpytko Janusz , Hyla Pawel
Published: March 2013

The paper presents the mechatronic approach to design a robust anti-sway crane control system on the laboratory stand, physical model of an overhead traveling crane. The core of a problem in realizing the anti-sway crane closed-loop control system in industrial practice is the reliable technique of measuring swing angle of payload suspended on a rope. Thus, the contactless method utilizing dynamic vision system is proposed in the paper. The poles assignment-based method of fuzzy gain scheduling crane control system designing is applied to built the crane control scheme. The software and hardware equipment of laboratory stand allows to automate the process of prototyping the control system and built the control application based on the programmable logic controller (PLC).
Investigation of Bodies Vibrations with Elastomeric Elements
Authors: Tipans Igors , Eiduks Maris , Viba Janis , Grishchenko Marina , Grzibovska Veronika
Published: March 2013

By analyzing underwater flexible object motion, new challenges facing mechanical and engineering industry can be seen. One of typical examples is the need to solve the complex task of elastomeric (e.g. rubber or silicone) robotic objects interaction with the water boundary. Current work is an attempt to launch an investigation on elastomer dynamics of experimental and theoretical research in two directions. Experimental studies have been conducted with a sample loading on the tensile and compression machine. Theoretical research investigation proposes a new model with internal interactions inside elastomers. Model is based on common lateral and diagonal interaction links between cross-sections of a material. Results of the work are applied for vibration systems motion modeling. Additionally, a new dynamical material model may be applied for the imitation of muscle dynamics and thus to provide basis for further applications in biomechanics such as development of artificial muscles.
The Optimal Spindle Speed Map for Reduction of Chatter Vibration during Milling of Bow Thruster Blade
Authors: Kaliński Krzysztof J. , Mazur Michał R. , Galewski Marek A.
Published: March 2013

The milling process considered in the paper is a finishing milling of ship bow thruster. It is really challenging task because this kind of object can be prone to vibration, and due to certain conditions, the self-excited chatter vibration may appear [. One of the methods of the chatter reduction depends upon the selection of the spindle speed by matching it to the optimal phase shift between subsequent passes of the tool cutting edges [. However, in case of complex-shaped objects there may be different values of optimal spindle speeds for various points of the workpiece surface. The paper presents an example of implementation of the procedure of building the optimal spindle speed map [. In order to create the map for specific surface points, optimal spindle speed is obtained with the use of various modal analysis techniques. The map seems to be effective way for eliminating chatter in case of the process of milling flexible details.
Vibration Analysis of Mechanical Systems with the Discrete-Continuous Distribution of Parameters
Authors: Białas Katarzyna , Sękala Agnieszka
Published: March 2013

This paper presents an analysis of mechanical systems with the discrete-continuous distribution of parameters performing small vibrations around the adopted state of equilibrium. The modelling and analysis of discretecontinuous vibration systems with conjugations using the non-classical method is a more general approach as compared to modelling and analysis in classical terms. The method presented in this article permits a simplification and facilitates the understanding of mechanical vibrations in such class of systems.
Commitment and the emigration intentions of South African professional nurses
Authors: Bagraim Jeffrey J.
Published: March 2013

The emigration of skilled nurses from South Africa exacerbates the crisis in the provision of public health services. A descriptive, quantitative design was applied to investigate the relationship between intention to emigrate and employee commitment. Over 400 registered nurses (N = 419), working within public sector tertiary hospitals in the Western Cape, responded to a cross-sectional survey questionnaire. Three foci of employee commitment (organisational, professional and national) were examined but only national commitment significantly helped predict intention to emigrate from South Africa in the regression model (beta = -0.0525, p < 0.0001). The implications of the results obtained in this study are discussed.Die emigrasie van verpleegkundiges uit Suid-Afrika vererger die krisis in die verskaffing van gesondheidsorgdienste in die land. ’n Beskrywende, kwantitatiewe ontwerp is gebruik om die verwantskap tussen werknemertoewyding en die voorneme om te emigreer te ondersoek. Meer as 400 verpleegsters (N = 419) wat in openbare tersiêre hospitale in die Wes-Kaap werk, het op die vraelys gereageer. Drie fokusareas van toewyding (organisatories, professioneel en nasionaal) is gemeet, maar net nasionale toewyding het daartoe bygedra om emigrasievoorneme te voorspel (beta = -0.0525, p < 0.0001). Die implikasies van hierdie resultate word bespreek.
Quantifying the uncertainty in simulating global tropospheric composition due to the variability in global emission estimates of Biogenic Volatile Organic Compounds
Authors: Williams J. E. , van Velthoven P. F. J. , Brenninkmeijer C. A. M.
Published: March 2013

Abstract. The emission of organic compounds from biogenic processes acts as an important source of trace gases in remote regions away from urban conurbations, and is likely to become more important in future decades due to the further mitigation of anthropogenic emissions that affect air quality and climate forcing. In this study we examine the contribution of biogenic volatile organic compounds (BVOCs) towards global tropospheric composition using the global 3-D chemistry transport model TM5 and the recently developed modified CB05 chemical mechanism. By comparing regional BVOC emission estimates we show that biogenic processes act as dominant sources for many regions and exhibit a large variability in the annually and seasonally integrated emission fluxes. By performing sensitivity studies we find that the contribution of BVOC species containing between 1 to 3 carbon atoms has an impact on the resident mixing ratios of tropospheric O3 and CO, accounting for ~2.5% and ~10.8% of the simulated global distribution, respectively. This is approximately a third of the cumulative effect introduced by isoprene and the monoterpenes. By examining an ensemble of 3-D global chemistry transport simulations which adopt different global BVOC emission inventories we determine the associated uncertainty introduced towards simulating the composition of the troposphere for the year 2000. By comparing the model ensemble values against a composite of atmospheric measurements we show that the effects on tropospheric O3 are limited to the lower troposphere (with an uncertainty between −2% to 10%), whereas that for tropospheric CO extends up to the upper troposphere (with an uncertainty of between 10 to 45%). Comparing the mixing ratios for low molecular weight alkenes in TM5 against surface measurements taken in Europe implies that the cumulative emission estimates are too low, regardless of the chosen BVOC inventory. This variability in the global distribution of CO due to BVOC emissions introduces an associated uncertainty in the tropospheric CO burden of 11.4%, which impacts strongly on the oxidative capacity of the troposphere, introducing an uncertainty in the atmospheric lifetime of the greenhouse gas CH4 of ~3.3%. This study thus identifies the necessity of placing further constraints on non-CH4 global biogenic emission estimates in large-scale global atmospheric chemistry models.
Comparison of different real time VOC measurement techniques in a ponderosa pine forest
Authors: Kaser L. , Karl T. , Schnitzhofer R. , Graus M. , Herdlinger-Blatt I. S. , DiGangi J. P. , Sive B. , Turnipseed A. , Hornbrook R. S. , Zheng W. , Flocke F. M. , Guenther A. , Keutsch F. N. , Apel E. , Hansel A.
Published: March 2013

Abstract. Volatile organic compound (VOC) mixing ratios measured by five independent instruments are compared at a forested site dominated by ponderosa pine (Pinus Ponderosa) during the BEACHON-ROCS field study in summer 2010. The instruments included a Proton Transfer Reaction Time of Flight Mass Spectrometer (PTR-TOF-MS), a Proton Transfer Reaction Quadrupole Mass Spectrometer (PTR-MS), a Fast Online Gas-Chromatograph coupled to a Mass Spectrometer (GC/MS; TOGA), a Thermal Dissociation Chemical Ionization Mass Spectrometer (PAN-CIMS) and a Fiber Laser-Induced Fluorescence Instrument (FILIF). The species discussed in this comparison include the most important biogenic VOCs and a selected suite of oxygenated VOCs that are thought to dominate the VOC reactivity at this particular site as well as typical anthropogenic VOCs that showed low mixing ratios at this site. Good agreement was observed for methanol, the sum of the oxygenated hemiterpene 2-methyl-3-buten-2-ol (MBO) and the hemiterpene isoprene, acetaldehyde, the sum of acetone and propanal, benzene and the sum of methyl ethyl ketone (MEK) and butanal. Measurements of the above VOCs conducted by different instruments agree within 20%. The ability to differentiate the presence of toluene and cymene by PTR-TOF-MS is tested based on a comparison with GC-MS measurements, suggesting a study-average relative contribution of 74% for toluene and 26% for cymene. Similarly, 2-hydroxy-2-methylpropanal (HMPR) is found to interfere with the sum of methyl vinyl ketone and methacrolein (MVK + MAC) using PTR-(TOF)-MS at this site. A study-average relative contribution of 85% for MVK + MAC and 15% for HMPR was determined. The sum of monoterpenes measured by PTR-MS and PTR-TOF-MS was generally 20–25% higher than the sum of speciated monoterpenes measured by TOGA, which included α-pinene, β-pinene, camphene, carene, myrcene, limonene, cineole as well as other terpenes. However, this difference is consistent throughout the study, and likely points to an offset in calibration, rather than a difference in the ability to measure the sum of terpenes. The contribution of isoprene relative to MBO inferred from PTR-MS and PTR-TOF-MS was smaller than 12% while GC-MS data suggested an average of 21% of isoprene relative to MBO. This comparison demonstrates that the current capability of VOC measurements to account for OH reactivity associated with the measured VOCs is within 20%.
A decadal cirrus clouds climatology from ground-based and spaceborne lidars above south of France (43.9° N–5.7° E)
Authors: Hoareau C. , Keckhut P. , Noel V. , Chepfer H. , Baray J.-L.
Published: March 2013

Abstract. This study provides an analysis of cirrus clouds properties at midlatitude in the southern part of France from ground-based and spaceborne lidars. A climatology of cirrus clouds properties and their evolution over more than 12 yr is presented and compared to other mid-latitude climatological studies. Cirrus clouds occur ~ 37% of the total observation time and remain quasi-constant across seasons with a variation within ~ 5% around the mean occurrence. Similar results are obtained from CALIOP and the ground-based lidar, with a mean difference in occurrence of ~ 5% between both instruments. From the ground-based lidar data, a slight decrease in occurrence of ~ 3% per decade is observed but found statistically insignificant. Based on a clustering analysis of cirrus cloud parameters, three distinct classes have been identified and investigations concerning their origin are discussed. Properties of these different classes are analysed, showing that thin cirrus in the upper troposphere represent ~ 50% of cloud cover detected in summer and fall, decreasing by 15–20% for other seasons.
Evaluation of a regional air-quality model with bidirectional NH3 exchange coupled to an agroecosystem model
Authors: Bash J. O. , Cooter E. J. , Dennis R. L. , Walker J. T. , Pleim J. E.
Published: March 2013

Abstract. Atmospheric ammonia (NH3) is the primary atmospheric base and an important precursor for inorganic particulate matter and when deposited NH3 contributes to surface water eutrophication, soil acidification and decline in species biodiversity. Flux measurements indicate that the air–surface exchange of NH3 is bidirectional. However, the effects of bidirectional exchange, soil biogeochemistry and human activity are not parameterized in air quality models. The US Environmental Protection Agency's (EPA) Community Multiscale Air-Quality (CMAQ) model with bidirectional NH3 exchange has been coupled with the United States Department of Agriculture's (USDA) Environmental Policy Integrated Climate (EPIC) agroecosystem model. The coupled CMAQ-EPIC model relies on EPIC fertilization timing, rate and composition while CMAQ models the soil ammonium (NH4+) pool by conserving the ammonium mass due to fertilization, evasion, deposition, and nitrification processes. This mechanistically coupled modeling system reduced the biases and error in NHx (NH3 + NH4+) wet deposition and in ambient aerosol concentrations in an annual 2002 Continental US (CONUS) domain simulation when compared to a 2002 annual simulation of CMAQ without bidirectional exchange. Fertilizer emissions estimated in CMAQ 5.0 with bidirectional exchange exhibits markedly different seasonal dynamics than the US EPA's National Emissions Inventory (NEI), with lower emissions in the spring and fall and higher emissions in July.
A bio-optical model for remote sensing of Lena water
Authors: Örek H. , Doerffer R. , Röttgers R. , Boersma M. , Wiltshire K. H.
Published: March 2013

Abstract. Bio-optical measurements and sampling were carried out in the delta of the Lena River (Northern Siberia, Russia) during the high water run-off period between 26 June 2011 and 4 July 2011. The aim of this study was to determine the inherent optical properties of the Lena water, i.e. absorption, attenuation and scattering coefficients, during the period of maximum run-off. In this context CDOM (Colored Dissolved Organic Matter), total particle absorption, total suspended matter and phytoplankton-pigments were measured. CDOM was found to be the most dominant parameter affecting the optical properties of the river, with an absorption coefficient of 4.5–5 m−1 at 442 nm, which was almost four times higher than total particle absorption values at visible wavelength range during the first week of the campaign. This difference decreased over the following days when Total Suspended Matter (TSM) concentration increased. The wavelength dependent absorption spectra of the water constituents were characterized by determining the semi logarithmic spectral slope. Mean CDOM, and Detritus slopes, were 0.0149 nm−1(stdev = 0.0003, n = 18), and 0.0057 nm−1 (stdev = 0.0017, n = 19), respectively, values which are typical for water bodies with high concentrations of dissolved and particulate carbon. Mean total chlorophyll a, and total suspended matter, were also measured to determine the relationship between concentrations and optical properties. Mean chlorophyll a and total suspended matter were 1.821 mg m−3 (stdev = 0.734 n = 18) and 31.89 mg L−1 (stdev = 19.94) respectively. The light penetration depth (Secchi disc depth) was highly correlated with the suspended matter concentration with a maximum of 90 cm. We conclude that the bio-optical properties of the Lena River are rather complex because of the high CDOM and variable particle load which may change within a matter of days. Furthermore, the chlorophyll concentration constitutes a small fraction. Our results will improve the remote sensing protocols of the river and coastal waters in and around the Lena Delta and serve as a basis for characterizing the light climate with respect to primary production.
Carbon balance of a partially-harvested mixed conifer forest following mountain pine beetle attack and its comparison to a clearcut
Authors: Mathys A. , Black T. A. , Nesic Z. , Nishio G. , Brown M. , Spittlehouse D. L. , Fredeen A. L. , Bowler R. , Jassal R. S. , Grant N. J. , Burton P. J. , Trofymow J. A.
Published: March 2013

Abstract. The recent mountain pine beetle (MPB) outbreak has had an impact on the carbon (C) cycling of lodgepole pine forests in British Columbia. This study examines how partial harvesting as a forest management response to MPB infestation affects the net ecosystem production (NEP) of a mixed conifer forest (MPB-09) in Interior BC. MPB-09 is a 70-yr old stand that was partially harvested in 2009 after it had been attacked by MPB. Using the eddy-covariance technique, the C dynamics of the stand were studied over two years and compared to an adjacent clearcut (MPB-09C) over the growing season. The annual NEP at MPB-09 increased from −108 g C m−2 in 2010 to −57 g C m−2 in 2011. The increase of NEP was due to the associated increase in annual gross ecosystem photosynthesis (GEP) from 812 g C m−2 in 2010 to 954 g C m−2 in 2011 exceeding the increase in annual respiration (Re) from 920 g C m−2 to 1011 g C m−2 during the two years. During the growing season of 2010, NEP at MPB-09C was −132 g C m−2 indicating high C losses in the clearcut. MPB-09 was a C sink during the growing season of both years, increasing from 9 g C m−2 in 2010 to 47 g C m−2 in 2011. The increase of NEP in the partially-harvested stand amounted to a recovery corresponding to a 25% increase in the maximum assimilation rate in the second year. This study shows that retaining the healthy residual forest can result in higher C sequestration of MPB-attacked stands compared to clearcut harvesting.
Climate variability since MIS 5 in SW Balkans inferred from multiproxy analysis of Lake Prespa sediments
Authors: Panagiotopoulos K. , Böhm A. , Leng M. J. , Wagner B. , Schäbitz F.
Published: March 2013

Abstract. The transboundary Lake Prespa (AL/FYROM/GR) has been recognized as a conservation priority wetland. The catchment area has a remarkably diverse flora that points to its refugial properties. A lake sediment core retrieved from a coring location in the northern part of the lake was investigated through geophysical, sedimentological, geochemical, and palynological analyses. Based on tephrochronology, radiocarbon and electron spin resonance (ESR) dating, and cross correlation with other Northern Hemisphere records, the age model suggests that the basal part of core Co1215 reaches back to 92 ka cal BP. Here we present the response of this mid-altitude site (849 m a.s.l.) to climate oscillations during this interval and assess its sensitivity to millennial-scale variability. Endogenic calcite precipitation occurred in Marine Isotope Stages (MIS) 5 and 1 and is synchronous with periods of increased primary production (terrestrial and/or lacustrine). Periods of pronounced phytoplankton blooms (inferred from green algae and dinoflagellate concentrations) are recorded in MIS 5 and MIS 1 and suggest that the trophic state and lake levels underwent substantial fluctuations. Three major phases of vegetation development are distinguished: the forested phases of MIS 5 and MIS 1 dominated by deciduous trees with higher temperatures and moisture availability, the open landscapes of MIS 3 with significant presence of temperate trees, and the pine dominated open landscapes of MIS 4 and MIS 2 with lower temperatures and moisture availability. Forest dynamics, cover and density are discussed in an altitudinal context and the existence of temperate tree refugia is examined.
Brief communication "The aerophotogrammetric map of Greenland ice masses"
Authors: Citterio M. , Ahlstrøm A. P.
Published: March 2013

Abstract. The PROMICE (Programme for Monitoring of the Greenland Ice Sheet) aerophotogrammetric map of Greenland ice masses is the first high resolution dataset documenting the mid-1980s areal extent of the Greenland Ice Sheet and all the local glaciers and ice caps. The total glacierized area excluding nunataks was 1 804 638 km2 ± 2178 km2, of which 88 083 ± 1240 km2 belonged to local glaciers and ice caps (GIC) substantially independent from the Greenland Ice Sheet. This new result of GIC glacierized area is higher than most previous estimates, 81% greater than Weng's (1995) measurements, but is in line with contemporary findings based on independent data sources. A comparison between our map and the recently released Rastner et al. (2012) inventory and GIMP (Greenland Ice Mapping Project) Ice-Cover Mask (Howat and Negrete, 2013) shows potential for change-assessment studies.
A Comparison of the Niagara™ and Dolphin® Catheters for Continuous Renal Replacement Therapy
Authors: Kim Inbyung , Fealy Nigel , Baldwin Ian , Bellomo Rinaldo
Published: March 2013

Purpose

The choice of vascular access catheter may affect filter life during continuous renal replacement therapy (CRRT); specifically, a new surface-modified catheter has been reported to possibly prevent thrombosis and catheter malfunction.

Design and Setting

A sequential, controlled study in a tertiary ICU.

Aims

To compare circuit life when CRRT was performed with a Bard®Niagara™ catheter or the surface-modified GamCath™ Dolphin® Protect 1320 catheter.

Patients and measurements

We studied 50 patients with acute kidney injury requiring CRRT, all delivered with catheters in the femoral position. We obtained information on age, gender, disease severity score (APACHE II and APACHE III), filter life, total heparin dose, hemoglobin concentration, platelet count, INR, and aPTT during CRRT.

Results

We studied 341 circuits in 50 patients; 30 patients (140 circuits) used the Niagara and 20 patients (201 circuits) used the Dolphin catheter. Mean of circuit life in two groups was 14.9 hours and 13.1 hours, respectively (p=0.22). Patients using Niagara catheters had a more prolonged APTT (p<0.01) and lower platelet count (p=0.05), while heparin dose (p=0.22), and other anticoagulant treatment (p=0.73) were not significantly different. On Kaplan-Meier survival analysis, circuit life was not significant different between the two catheters (p=0.15).

Conclusions

The Niagara and Dolphin catheters appear to be broadly equivalent in terms of their impact on circuit life.
Growth-Promoting Effects of Quercetin on Peripheral Nerves in Rats
Authors: Wang Walter , Huang Chih-Yang , Tsai Fuu-Jen , Tsai Chin-Chuan , Yao Chun-Hsu , Chen Yueh-Sheng
Published: March 2013

Objectives

The present study evaluated in vitro and in vivo the effects of quercetin (QC), a major ingredient in various flavonoids, on peripheral nerve regeneration.

Methods

In the in vitro study, we found that QC at concentrations of 0.1, 1, and 10 μg/mL could significantly promote the survival and outgrowth of cultured Schwann cells as compared with the controls treated with culture medium only. In the in vivo study, we evaluated peripheral nerve regeneration across a 15-mm gap in the sciatic nerve of the rat, using a silicone rubber nerve chamber filled with the QC solution. In the control group, the chambers were filled with normal saline only.

Results

At the end of 8 weeks, morphometric data revealed that all 3 QC groups significantly increased the count and density of myelinated axons as compared with the controls. Electro-physiological measurements showed that the QC-treated group at 1 μg/mL had a significantly larger area of evoked muscle action potential (MAP) compared with the controls. In addition, the amplitude of the MAP in the QC-treated groups at 0.1 and 1 μg/mL was significantly larger than that in the controls.

Conclusions

All of these results indicate that QC treatment has nerve growth–promoting effects which may lead to a promising herbal medicine for the recovery of regenerating peripheral nerves.
Editorial
Authors: Palacios Daniel M.
Published: March 2013

Dedication to Dr. Robert Clarke (1919-2011)
Dr. Robert Henry Clarke, Oceanographer, M.A. (Oxon), Dr. Philos. (Oslo), 1919-2011
Authors: Paliza Obla , Clarke Aravec , Clarke Suyana , Clarke George
Published: March 2013

In Memoriam for Dr. Robert Clarke, 1919-2011
Neviditelná skupina aneb Co s postdoktorandy?
Authors: Mareš J.
Published: March 2013

Sdělení si klade za cíl: (1) upozornit na situaci, kdy vysoké školy v České republice produkují desítky absolventů doktorského studia ročně a málo se zajímají o jejich další osud; (2) charakterizovat pojem postdoktorand a přiblížit výzkumy, které tuto skupinu vysokoškoláků zkoumají; (3) předložit údaje o absolventech doktorského studia pedagogiky v České republice; (4) diskutovat domácí kontext, který ovlivňuje uplatnění postdoktorandů; (5) shrnout zahraniční poznatky o systematické práci s postdoktorandy. V první části je charakterizována současná situace v ČR i v zahraničí. Druhá část příspěvku popisuje výzkumnou sondu o počtech úspěšných absolventů doktorského studia Pedagogika. Třetí část je věnována zamyšlení nad domácím kontextem, který ovlivňuje uplatnění postdoktorandů. Čtvrtá část shrnuje zahraniční zkušenosti se systematickou prací s postdoktorandy. Ukázalo se, že v letech 1999–2011 úspěšně dokončilo doktorské studium v programu Pedagogika v ČR 549 osob. Soustavná práce s postdoktorandy je na třech velkých českých univerzitách (Univerzita Karlova, Masarykova a Palackého) teprve v počátcích. Z uvedeného vyplývá, že v ČR bude třeba pravidelně sledovat, kde postdoktorandi pracují, nakolik se věnují vědecké činnosti a jak vypadá jejich kvalifikační růst. Kromě toho bude třeba (s oporou o zahraniční zkušenost) propracovat systém, který postdoktorandům umožní různými cestami se zdokonalovat ve svých znalostech a dovednostech.
Spatial and temporal variability of oxidative stress indicators in the red crab (Pleuroncodes planipes) from the west coast of the Baja California Peninsula, Mexico
Authors: Martínez-Canto Orlando , Olguín-Monroy Norma Olimpia , De Anda-Montañez Juan Antonio , Zenteno-Savín Tania
Published: March 2013

The red crab Pleuroncodes planipes is a resource with the potential for commercial exploitation. Red crabs have an elevated antioxidant capacity, which is subject to spatial and temporal variability. The objective of this study was to evaluate the variability of the oxidative stress indicators in P. planipes collected on four research cruises off the western coast of the Baja California Peninsula (Mexico). Superoxide radical (O2•–) production, lipid peroxidation, and antioxidant enzyme activities were quantified in muscle and hepatopancreas of the collected specimens. Significantly higher O2•– production and antioxidant enzyme activities were found in hepatopancreas than in muscle (P < 0.05), which reflects the specific function of each tissue. Statistically significant differences (P < 0.05) in oxidative stress indicators were found among sampling stations. The results suggest that P. planipes is more susceptible to oxidative damage when sea temperature is warmer, particularly during El Niño conditions.
Bioorthogonal Profiling of Protein Methylation (BPPM) Using an Azido Analog of S‐Adenosyl‐L‐Methionine
Authors: Blum Gil , Islam Kabirul , Luo Minkui
Published: March 2013

Protein methyltransferases (PMTs) utilize S‐adenosyl‐L‐methionine (SAM) as a cofactor and transfer its sulfonium methyl moiety to diverse substrates. These methylation events can lead to meaningful biological outcomes, from transcriptional activation/silencing to cell cycle regulation. This article describes recently developed technology based on protein engineering in tandem with SAM analog cofactors and bioorthogonal click chemistry to unambiguously profile the substrates of a specific PMT. The protocols encapsulate the logic and methods of selectively profiling the substrates of a candidate PMT by (1) engineering the selected PMT to accommodate a bulky SAM analog; (2) generating a proteome containing the engineered PMT; (3) visualizing the proteome‐wide substrates of the designated PMT via bioorthogonal labeling with a fluorescent tag; and finally (4) pulling down the proteome‐wide substrates for mass spectrometric analysis. Curr. Protoc. Chem. Biol. 5:45‐66 © 2013 by John Wiley & Sons, Inc.
Usefulness of Computed Tomography in the Etiologic Evaluation of Adult Unilateral Vocal Fold Paralysis
Authors: Kang Byung Chul , Roh Jong‐Lyel , Lee Jeong Hyun , Jung Jae Hoon , Choi Seung‐Ho , Nam Soon Yuhl , Kim Sang Yoon
Published: March 2013

Background

Unilateral vocal fold paralysis (UVFP) may present as an uncommon complication of extralaryngeal neoplasms, requiring diagnostic scrutiny to seek occult tumors or diseases. The aim of this study was to examine the utility of computed tomography (CT) in evaluating adult UVFP of unknown etiology.

Methods

From January 2010 to December 2011, UVFP was diagnosed in 822 patients at our tertiary‐care center. In 634 patients, a readily identifiable cause of the UVFP was evident and therefore there was no need for any imaging; in the remaining 188 patients, the etiology could not be determined. Among this latter group, 153 patients underwent chest radiography (CXR) and contrast‐enhanced CT imaging from the skull base to the midchest.

Results

In 36 of the 153 (23.5 %) patients, CT revealed the cause of the UVFP: lung cancer in 12 patients, thyroid carcinoma in 7 patients, skull‐base tumor in 4 patients, aortic aneurysm in 4 patients, esophageal cancer in 3 patients, thymus tumor in 2 patients, pericardial effusion in 1 patient, and other neck lesions in 3 patients. CXR and neck ultrasonography also identified the etiology in 14 and 12 patients, respectively. During follow‐up after the initial CT, none of the patients with idiopathic UVFP was determined to have an underlying disease that would have explained the paralysis.

Conclusion

CT is a useful single‐imaging method for evaluating the etiology of adult UVFP. This approach may reveal occult tumors or previously undiagnosed diseases as the cause of the paralysis, thus improving patient care.
Neue Methoden der Mobilitätsanalyse: Die Verbindung von GPS-Tracking mit quantitativen und qualitativen Methoden im Kontext des Tourismus
Authors: Weber Hans-Jörg L. , Bauder Michael
Published: March 2013

Due to its structural complexity, the analysis of mobility patterns requires a combination of individual methods. In the first part the socio-scientific methods of mobility acquisition will be discussed in the context of tourism. It will be demonstrated, that individual methods cannot cope with the demand for socio-scientific differentiation of mobility patterns. Analysis on this new level will only be possible when using a consistent method design, composed of GPS-Tracking, questionnaire and text analysis, which unions the individual person, activity and mobility in space. In the second part of this paper, the method of differentiating mobility patterns will be explained. It will be shown, that the variable (touristic) practice in terms of Bourdieu is suitable for the explanation of individual activity and for the differentiation of mobility patterns. The combination of individual (questionnaire) and spatial data (GPS-Tracking) is based on the principal component analysis. It will be shown how the characteristic groups can be spatially represented in a Geographic Information System using the GPS-data and fed back with the results of the text analysis (guidebook). The successful combination of GPS-Tracking with quantitative and qualitative methods will be explained in the third section on the basis of practical examples. It will be provided evidence, that qualitative and quantitative methods can be successfully used together, GPS data can be differentiated based on socio-scientific variables and practices and individuals are interlinked in space.
Quillen's work in algebraicK-theory
Authors: Grayson Daniel R.
Published: March 2013

We survey the genesis and development of higher algebraicK-theory by Daniel Quillen.
Quillen's solution of Serre's Problem
Authors: Suslin Andrei
Published: March 2013

In this note we recall the history of Serre's problem and its beautiful solution given by D. Quillen in 1976
ON NEAR-PERFECT NUMBERS WITH TWO DISTINCT PRIME FACTORS
Authors: REN XIAO-ZHI , CHEN YONG-GAO
Published: March 2013

Recently, Pollack and Shevelev [‘On perfect and near-perfect numbers’, J. Number Theory 132 (2012), 3037–3046] introduced the concept of near-perfect numbers. A positive integer $n$ is called near-perfect if it is the sum of all but one of its proper divisors. In this paper, we determine all near-perfect numbers with two distinct prime factors.
Brain connectivity in body dysmorphic disorder compared with controls: a diffusion tensor imaging study
Authors: Buchanan B. G. , Rossell S. L. , Maller J. J. , Toh W. L. , Brennan S. , Castle D. J.
Published: March 2013

Background

Several neuroimaging studies have investigated brain grey matter in people with body dysmorphic disorder (BDD), showing possible abnormalities in the limbic system, orbitofrontal cortex, caudate nuclei and temporal lobes. This study takes these findings forward by investigating white matter properties in BDD compared with controls using diffusion tensor imaging. It was hypothesized that the BDD sample would have widespread significantly reduced white matter connectivity as characterized by fractional anisotropy (FA).

Method

A total of 20 participants with BDD and 20 healthy controls matched on age, gender and handedness underwent diffusion tensor imaging. FA, a measure of water diffusion within a voxel, was compared between groups on a voxel-by-voxel basis across the brain using tract-based spatial statistics within the FSL package.

Results

Results showed that, compared with healthy controls, BDD patients demonstrated significantly lower FA (p < 0.05) in most major white matter tracts throughout the brain, including in the superior longitudinal fasciculus, inferior fronto-occipital fasciculus and corpus callosum. Lower FA levels could be accounted for by increased radial diffusivity as characterized by eigenvalues 2 and 3. No area of higher FA was found in BDD.

Conclusions

This study provided the first evidence of compromised white matter integrity within BDD patients. This suggests that there are inefficient connections between different brain areas, which may explain the cognitive and emotion regulation deficits within BDD patients.
Second messenger/signal transduction pathways in major mood disorders: moving from membrane to mechanism of action, part II: bipolar disorder
Authors: Niciu Mark J. , Ionescu Dawn F. , Mathews Daniel C. , Richards Erica M. , Zarate Carlos A.
Published: March 2013

In this second of two articles on second messenger/signal transduction cascades in major mood disorders, we will review the evidence in support of intracellular dysfunction and its rectification in the etiopathogenesis and treatment of bipolar disorder (BD). The importance of these cascades is highlighted by lithium's (the gold standard in BD psychopharmacology) ability to inhibit multiple critical loci in second messenger/signal transduction cascades including protein kinase C (involved in the IP3/PIP2 pathway) and GSK-3β (canonically identified in the Wnt/Fz/Dvl/GSK-3β cascade). As a result, and like major depressive disorder (MDD), more recent pathophysiological studies and rational therapeutic targets have been directed at these and other intracellular mediators. Even in the past decade, intracellular dysfunction in numerous neuroprotective/apoptotic cascades appears important in the pathophysiology and may be a future target for pharmacological interventions of BD.
Gene network requirements for regulation of metabolic gene expression to a desired state
Authors: Berkhout Jan , Teusink Bas , Bruggeman Frank J.
Published: March 2013

Gene circuits that control metabolism should restore metabolic functions upon environmental changes. Whether gene networks are capable of steering metabolism to optimal states is an open question. Here we present a method to identify such optimal gene networks. We show that metabolic network optimisation over a range of environments results in an input-output relationship for the gene network that guarantees optimal metabolic states. Optimal control is possible if the gene network can achieve this input-output relationship. We illustrate our approach with the best-studied regulatory network in yeast, the galactose network. We find that over the entire range of external galactose concentrations, the regulatory network is able to optimally steer galactose metabolism. Only a few gene network parameters affect this optimal regulation. The other parameters can be tuned independently for optimisation of other functions, such as fast and low-noise gene expression. This study highlights gene network plasticity, evolvability and modular functionality.