bluuebunny/crossref_metadata_2025 huggingface dataset:
Multitemporal radar backscattering measurement of wheat fields using multifrequency (L, S, C, and X) and full‐polarization
Authors: Jia Mingquan , Tong Ling , Zhang Yuanzhi , Chen Yan
Published: July 2013

This paper presents the measurements of the backscattering coefficients over the wheat fields using an L‐, S‐, C‐, and X‐band scatterometer system during a whole period of wheat growth. The wheat field located at Qionglai County of China was measured during a wheat growing season from November 2010 to May 2011. Twelve experimental acquisitions (ground and radar data) were measured over the wheat field in a flat area at VV‐, VH‐, HV‐, and HH‐polarizations of L‐, S‐, C‐, and X‐bands, with the incidence angles ranging from 0° to 80°. Wheat biomass, canopy structure, leaf area index (LAI), soil moisture, and eco‐physiological canopy variables were also collected to investigate the radar sensitivity. It shows that the HH measurements for wheat are higher than VV at each band after jointing, and the value of HH/VV is larger for lower frequency. The temporal variations of each band at selected incidence angles were compared with the wheat biomass, canopy height, LAI, and soil moisture. The correlations were analyzed between backscattering coefficients and wheat crop variables at 23°, 38°, 53°, and 68°, respectively. The results show that the backscattering coefficient has a strong correlation with biomass and LAI, especially for the HH‐ and cross‐polarizations of L‐band, and the radar backscatter signatures at high frequency (X‐ and C‐bands) are sensitive to detect newly transplanted thin wheat seedlings at the high incident angle. These data can provide experimental evidence to allow for determining the growth status and/or condition of wheat by use of measured radar backscatters.
Polymer‐Based Stimuli‐Responsive Recyclable Catalytic Systems for Organic Synthesis
Authors: Zhang Jingli , Zhang Mingxi , Tang Kangjian , Verpoort Francis , Sun Taolei
Published: July 2013

The introduction of stimuli‐responsive polymers into the study of organic catalysis leads to the generation of a new kind of polymer‐based stimuli‐responsive recyclable catalytic system. Owing to their reversible switching properties in response to external stimuli, these systems are capable of improving the mass transports of reactants/products in aqueous solution, modulating the chemical reaction rates, and switching the catalytic process on and off. Furthermore, their stimuli‐responsive properties facilitate the separation and recovery of the active catalysts from the reaction mixtures. As a fascinating approach of the controllable catalysis, these stimuli‐responsive catalytic systems including thermoresponsive, pH‐responsive, chemo‐mechano‐chemical, ionic strength‐responsive, and dual‐responsive, are reviewed in terms of their nanoreactors and mechanisms.
Teriflunomide reduces relapse-related neurological sequelae, hospitalizations and steroid use
Authors: O’Connor Paul W. , Lublin Fred D. , Wolinsky Jerry S. , Confavreux Christian , Comi Giancarlo , Freedman Mark S. , Olsson Tomas P. , Miller Aaron E. , Dive-Pouletty Catherine , Bégo-Le-Bagousse Gaëlle , Kappos Ludwig
Published: July 2013

Multiple sclerosis (MS) relapses impose a substantial clinical and economic burden. Teriflunomide is a new oral disease-modifying therapy approved for the treatment of relapsing MS. We evaluated the effects of teriflunomide treatment on relapse-related neurological sequelae and healthcare resource use in a post hoc analysis of the Phase III TEMSO study. Confirmed relapses associated with neurological sequelae [defined by an increase in Expanded Disability Status Scale/Functional System (sequelae-EDSS/FS) ≥30 days post relapse or by the investigator (sequelae-investigator)] were analyzed in the modified intention-to-treat population (n = 1086). Relapses requiring hospitalization or intravenous (IV) corticosteroids, all hospitalizations, emergency medical facility visits (EMFV), and hospitalized nights for relapse were also assessed. Annualized rates were derived using a Poisson model with treatment, baseline EDSS strata, and region as covariates. Risks of sequelae and hospitalization per relapse were calculated as percentages and groups were compared with a χ2 test. Compared with placebo, teriflunomide reduced annualized rates of relapses with sequelae-EDSS/FS [7 mg by 32 % (p = 0.0019); 14 mg by 36 % (p = 0.0011)] and sequelae-investigator [25 % (p = 0.071); 53 % (p < 0.0001)], relapses leading to hospitalization [36 % (p = 0.015); 59 % (p < 0.0001)], and relapses requiring IV corticosteroids [29 % (p = 0.001); 34 % (p = 0.0003)]. Teriflunomide-treated patients spent fewer nights in hospital for relapse (p < 0.01). Teriflunomide 14 mg also decreased annualized rates of all hospitalizations (p = 0.01) and EMFV (p = 0.004). The impact of teriflunomide on relapse-related neurological sequelae and relapses requiring healthcare resources may translate into reduced healthcare costs.
Synthesis of Thumba, Castor and Sal Fatty Ethanolamide‐Based Anionic Surfactants
Authors: Kamalakar Kotte , Satyavani Tenneti , Mohini Yarra , Prasad Rachapudi B. N. , Karuna Mallampalli S. L.
Published: July 2013

The study involved the preparation and evaluation of anionic surfactants from non‐edible oil based thumba (containing unsaturated‐rich fatty acids, 80.9 %), castor (containing ricinoleic acid, a hydroxy fatty acid 89.3 %) and sal (containing saturated‐rich fatty acids, 56.5 %). The oils extracted from these seeds (using Soxhlet) were reacted with monoethanolamine and diethanolamine to get corresponding fatty mono‐ and diethanolamides. The ethanolamides were sulfated using chlorosulfonic acid and the sulfated sodium salts were evaluated for surfactant properties namely surface tension, critical micelle concentration (CMC), emulsifying property, wetting, foaming power and calcium tolerance. The properties were compared with sodium dodecyl sulfate (SDS) a well known anionic surfactant. Among the different sulfated sodium salts of ethanolamides, thumba showed superior surfactant properties compared to castor and sal. Sulfated sodium salt of thumba monoethanolamide showed better properties (CMC, 0.035 mmol/L, surface tension 30.2 mN/m and calcium tolerance >1,000 ml, 0.5 % calcium acetate solution) compared to sulfated sodium salts of thumba diethanolamides, followed by sulfated sodium salts of castor monoethanolamide (CMC 0.037 mmol/L, surface tension 35.3 mN/m and calcium tolerance >1,000 ml, 0.5 % calcium acetate solution). Sal being saturated rich was not properly soluble in water and showed poor surfactant properties compared to the other two. Also the sulfated sodium salts of thumba and castor ethanolamides exhibited superior properties compared to SDS.
Understanding loneliness during adolescence: Developmental changes that increase the risk of perceived social isolation
Authors: Laursen Brett , Hartl Amy C.
Published: July 2013

Loneliness is typically defined in terms of feeling states. In this review, we take a somewhat different approach, describing loneliness in terms of perceived social isolation. Vulnerabilities to perceived social isolation differ across the lifespan. Unique properties of adolescence are identified that carry special risk for perceived social isolation. These include (but are not limited to) developmental changes in companions, developmental changes in autonomy and individuation, identity exploration, cognitive maturation, developmental changes in social perspective taking, and physical maturation. Scholars are encouraged to consider loneliness through the lens of perceived social isolation so as to better understand how the experience of physical isolation varies across adolescence.
A review of global access to emergency contraception
Authors: Westley Elizabeth , Kapp Nathalie , Palermo Tia , Bleck Jennifer
Published: July 2013

Background

Emergency contraception has been known for several decades, and dedicated products have been on the market for close to 20 years. Yet it is unclear whether women, particularly in low‐resource countries, have access to this important second‐chance method of contraception.

Objectives

To review relevant policies, regulations, and other factors related to access to emergency contraception worldwide.

Search strategy

A wide range of gray literature was reviewed, several specific studies were commissioned, and a number of online databases were searched.

Main results

Several positive policies and regulations are in place: emergency contraception products are registered in the majority of countries around the world, listed in many countries' essential medicines lists, included in widely used guidance, and supported by most donors. Yet analysis of demographic data shows that the majority of women in low‐income countries have never heard of emergency contraception, and surveys find that many providers have negative attitudes toward providing emergency contraception.

Conclusions

Despite more than a decade of concerted international and country‐level efforts to ensure that women have access to emergency contraception, accessibility remains limited.
Women's ability to self‐screen for contraindications to combined oral contraceptive pills in Tanzanian drug shops
Authors: Chin‐Quee Dawn , Ngadaya Esther , Kahwa Amos , Mwinyiheri Thomas , Otterness Conrad , Mfinanga Sayoki , Nanda Kavita
Published: July 2013

Objective

To estimate the accuracy of self‐screening for contraindications to combined oral contraceptive pills (COCs) and to estimate the proportion of women with contraindications to hormonal methods among those using drug shops in Tanzania.

Methods

Trained nurses interviewed 1651 women aged 18–39 years who self‐screened for contraindications to COCs with the help of a poster at drug shops in Tanzania. Nurse assessment of the women served as the gold standard for comparison with self‐assessment. Blood pressure was also measured onsite.

Results

Nurses reported that 437 (26.5%) women were not eligible to use COCs, compared with 485 (29.4%) according to self‐report. Overall, 133 (8.1%) women who said that they were eligible were deemed ineligible by nurses. The rate of ineligibility was artificially high owing to participant and nurse assessments that were incorrectly based on adverse effects of pill use and cultural reasons, and because of the sampling procedure, which intercepted women regardless of their reasons for visiting the drug shop. Adjusted rates of ineligibility were 8.6% and 12.7%, respectively, according to nurse and participant assessment. Both nurses and women underestimated the prevalence of hypertension in the present group.

Conclusion

Self‐screening among women in rural and peri‐urban Tanzania with regard to contraindications to COC use was comparable to assessment by trained nurses.
How to diagnose and manage patients with cardiac implantable electronic device infections
Authors: Tarakji Khaldoun G. , Wilkoff Bruce L.
Published: July 2013

Over the last two decades, there has been a surge in the number of Cardiac Implantable Electronic Device (CIED) implantation. These devices improve the quality of life and survival among certain cardiac patients. However, this benefit might be affected by device complications and one of the most important ones is CIED infection as it carries significant morbidity and mortality. CIED infection can present as a device pocket infection or endovascular infection and its diagnosis could be challenging. In general, management of CIED infection involves device removal and antibiotic therapy and requires collaboration between different clinical teams. Future efforts and research should focus on measures to prevent the occurrence of this outcome.
Pre-Columbian landscape impact and agriculture in the Monumental Mound region of theLlanos de Moxos, lowland Bolivia
Authors: Whitney Bronwen S. , Dickau Ruth , Mayle Francis E. , Soto J. Daniel , Iriarte José
Published: July 2013

We present a multiproxy study of land use by a pre-Columbian earth mounds culture in the Bolivian Amazon. The Monumental Mounds Region (MMR) is an archaeological sub-region characterized by hundreds of pre-Columbian habitation mounds associated with a complex network of canals and causeways, and situated in the forest–savanna mosaic of theLlanos de Moxos. Pollen, phytolith, and charcoal analyses were performed on a sediment core from a large lake (14 km2), Laguna San José (14°56.97′S, 64°29.70′W). We found evidence of high levels of anthropogenic burning from AD 400 to AD 1280, corroborating dated occupation layers in two nearby excavated habitation mounds. The charcoal decline pre-dates the arrival of Europeans by at least 100 yr, and challenges the notion that the mounds culture declined because of European colonization. We show that the surrounding savanna soils were sufficiently fertile to support crops, and the presence of maize throughout the record shows that the area was continuously cultivated despite land-use change at the end of the earth mounds culture. We suggest that burning was largely confined to the savannas, rather than forests, and that pre-Columbian deforestation was localized to the vicinity of individual habitation mounds, whereas the inter-mound areas remained largely forested.
Drops bouncing on a vibrating bath
Authors: Moláček Jan , Bush John W. M.
Published: July 2013

We present the results of a combined experimental and theoretical investigation of millimetric droplets bouncing on a vertically vibrating fluid bath. We first characterize the system experimentally, deducing the dependence of the droplet dynamics on the system parameters, specifically the drop size, driving acceleration and driving frequency. As the driving acceleration is increased, depending on drop size, we observe the transition from coalescing to vibrating or bouncing states, then period-doubling events that may culminate in either walking drops or chaotic bouncing states. The drop’s vertical dynamics depends critically on the ratio of the forcing frequency to the drop’s natural oscillation frequency. For example, when the data describing the coalescence–bouncing threshold and period-doubling thresholds are described in terms of this ratio, they collapse onto a single curve. We observe and rationalize the coexistence of two non-coalescing states, bouncing and vibrating, for identical system parameters. In the former state, the contact time is prescribed by the drop dynamics; in the latter, by the driving frequency. The bouncing states are described by theoretical models of increasing complexity whose predictions are tested against experimental data. We first model the drop–bath interaction in terms of a linear spring, then develop a logarithmic spring model that better captures the drop dynamics over a wider range of parameter space. While the linear spring model provides a faster, less accurate option, the logarithmic spring model is found to be more accurate and consistent with all existing data.
Spontaneous generation of inertial waves from boundary turbulence in a librating sphere
Authors: Sauret Alban , Cébron David , Le Bars Michael
Published: July 2013

In this work, we report the excitation of inertial waves in a librating sphere even for libration frequencies where these waves are not directly forced. This spontaneous generation comes from the localized turbulence induced by the centrifugal instabilities in the Ekman boundary layer near the equator and does not depend on the libration frequency. We characterize the key features of these inertial waves in analogy with previous studies of the generation of internal waves in stratified flows from localized turbulent patterns. In particular, the temporal spectrum exhibits preferred values of excited frequency. This first-order phenomenon is generic to any rotating flow in the presence of localized turbulence and is fully relevant for planetary applications.
Welchen Nutzen haben die Erkenntnisse der Hirnforschung für die Pädagogik?
Authors: Roth Gerhard
Published: July 2013

Empirische Studien zeigen, dass der schulische Lernerfolg wesentlich von der Persönlichkeit des Lehrenden, der Strukturierung des Unterrichts, Intelligenz, Motivation und Fleiß des Lernenden, Vorwissen und Anschlussfähigkeit des Stoffes, systematischer Fehlerrückmeldung und aktivem Wiederholen abhängt. Die Hirnforschung kann zusammen mit der Kognitions- und Lernpsychologie begründen, warum diese Faktoren so wichtig sind und wie sie auf die Verankerung von Wissen im Langzeitgedächtnis einwirken. Dies betrifft insbesondere die Glaubwürdigkeit, Kompetenz und Feinfühligkeit der Lehrenden sowie die kritischen Eigenschaften des Arbeitsgedächtnisses und seiner Verbindung mit Aufmerksamkeit, Motivation, der Begrenztheit aktuell verarbeitbarer Stoffmenge und einer entsprechenden «hirngerechten» Darbietung des Stoffes. Die Hirnforschung kann allein keine neue Pädagogik begründen, aber dazu beitragen, empirisch besser fundierte pädagogische Konzepte zu entwickeln.
Evaluation eines videobasierten Trainingsseminars zur Förderung der professionellen Wahrnehmung von Klassenführung im Grundschulunterricht*
Authors: Gold Bernadette , Förster Stephan , Holodynski Manfred
Published: July 2013

Zur erfolgreichen Gestaltung einer angemessenen Lernumgebung gehört eine effiziente Klassenführung. Eine wesentliche Voraussetzung dafür ist die Fähigkeit, klassenführungsrelevante Ereignisse im Unterricht erkennen, angemessen einschätzen und mögliche Handlungsalternativen benennen zu können. In der vorliegenden Evaluationsstudie wird untersucht, inwiefern sich solch eine professionelle Wahrnehmung in der universitären Lehramtsausbildung anhand der angeleiteten Analyse von Unterrichtsvideos vermitteln lässt. In Lehrseminaren trainierten Studierende im Umfang von 60 Stunden in Partnerarbeit die Analyse ausgewählter Unterrichtsausschnitte hinsichtlich der Klassenführungsdimensionen Allgegenwärtigkeit, Strukturierung des Unterrichtsverlaufs und Gruppenfokus. Es nahmen insgesamt 120 Studierende an der Studie mit einem Prä-Post-Kontrollgruppendesign teil. In Kovarianzanalysen zeigten sich signifikante Effekte der Gruppe in der erwarteten Richtung, wobei sich für die Facette Strukturierung des Unterrichtsverlaufs eine kleine und für die Facette Gruppenfokus eine mittlere Effektstärke ergab, während für die Facette Allgegenwärtigkeit keine Effekte gefunden wurden. Der Einfluss des Fachsemesters, aber auch Erfahrungen mit Unterrichtsanalysen und Klassenführung hatten keinen signifikanten Einfluss auf die professionelle Wahrnehmung klassenführungsrelevanter Unterrichtsereignisse.
Entwicklung der Mathematikleistung von Ganztagsschulkindern: kompensatorische Wirkung der Ganztagsschule?*
Authors: Schüpbach Marianne , Herzog Walter , Ignaczewska Julia
Published: July 2013

Im vorliegenden Beitrag wird die Schulleistungsentwicklung in Mathematik von Schülern in Ganztagsschulen, welche die Angebote intensiv nutzen, im Vergleich zu Schülern, die nur den Unterricht besuchen (Kontrollgruppe) untersucht. Zudem wird der Frage nach einer kompensatorischen Wirkung der Ganztagsschule hinsichtlich sozialer Disparitäten nachgegangen. Die Substichprobe umfasst N = 295 Schüler aus 35 Schulen in der Deutschschweiz, die im Rahmen einer quasiexperimentellen Längsschnittstudie in den ersten drei Primarschuljahren untersucht wurden. Die Ergebnisse zeigen, dass es der Ganztagsschule insgesamt gelingt, die Entwicklung der Mathematikleistung in den ersten drei Schuljahren bei intensiver Nutzung positiver – relativ zu Halbtagsunterricht – zu beeinflussen. Im Weiteren weisen die Befunde der vorliegenden Studie keine kompensatorische Wirkung der Ganztagsschule hinsichtlich einer geringen familialen Entwicklungsförderung zwischen Ende des ersten und Ende des dritten Schuljahres nach.
Leseselbstkonzept und Textart: Lassen sich literarisches und faktuales Leseselbstkonzept trennen?*
Authors: Henschel Sofie , Roick Thorsten , Brunner Martin , Stanat Petra
Published: July 2013

Das allgemeine Leseselbstkonzept ist ein bedeutsamer Prädiktor für die allgemeine Lesekompetenz. Unklar ist jedoch, ob eine weitere Differenzierung in Abhängigkeit von der Textart (literarisch vs. informatorisch) sinnvoll ist. Untersucht wurde deshalb, ob ein auf faktuale Textsorten bezogenes Leseselbstkonzept von einem auf literarische Textsorten bezogenen Leseselbstkonzept abgrenzbar ist. Die psychometrischen Eigenschaften der neu konstruierten Skalen zur Erfassung des faktualen und literarischen Leseselbstkonzeptes wurden an 1004 Jugendlichen aus neunten Klassen an Realschulen und Gymnasien untersucht. Faktoranalysen zeigen, dass sich das literarische und das faktuale Leseselbstkonzept voneinander und vom allgemeinen Leseselbstkonzept unterscheiden sowie differenziell mit der intrinsischen Lesemotivation, Schulnoten und Geschlecht assoziiert sind. Während das literarische Leseselbstkonzept ausschliesslich mit dem literarischen Textverstehen zusammenhängt, ist das faktuale Leseselbstkonzept nur mit dem faktualen Textverstehen assoziiert. Damit stellen unsere Skalen zum faktualen und literarischen Leseselbstkonzept eine solide Grundlage für differenzierte Analysen zum Verstehen literarischer und faktualer Texte dar.
A survey of underactuated mechanical systems
Authors: Liu Yang , Yu Hongnian
Published: July 2013

An underactuated mechanical system (UMS) is a system which has fewer independent control actuators than degrees of freedom to be controlled. Control of UMS is considered as one of the most active fields of research because of its diverse engineering applications. This survey reviews UMS from its history to the state‐of‐the‐art research on modelling, classification, control, and to some extent, provides some unique insights for bottleneck issues and future research directions.
Finite‐time stability and finite‐time weighted L2 ‐gain analysis for switched systems with time‐varying delay
Authors: Lin Xiangze , Du Haibo , Li Shihua , Zou Yun
Published: July 2013

Finite‐time stability and finite‐time boundedness for a class of switched linear systems with time‐varying delay are studied. Sufficient conditions which guarantee switched linear systems with time‐varying delay finite‐time stable or finite‐time bounded are presented. These conditions are delay‐dependent and are given in terms of linear matrix inequalities. Average dwell time of switching signals is also given such that switched linear systems are finite‐time stable or finite‐time bounded. Moreover, finite‐time weighted L2 ‐gain of switched linear systems with time‐varying delay are also given to measure its disturbance tolerance capability in the fixed time interval. Detail proofs are accomplished by using multiple Lyapunov‐like functions. An example is employed to verify the efficiency of the proposed method.
Structured non‐linear noise behaviour and the use of median averaging in non‐linear systems with m ‐sequence inputs
Authors: Wong Hin Kwan , Schoukens Johan , Godfrey Keith R.
Published: July 2013

In non‐linear system identification, results from traditional non‐parametric identification techniques contain both linear and non‐linear contributions. When Gaussian excitation signals (including random‐phased multisines) are used, the non‐linear contributions are noise‐like and therefore not easy to distinguish from environment noise and measurement noise. In contrast, when excitation signals based on binary maximum‐length sequences (m ‐sequences) are used, a particular property of the sequences results in the non‐linear contributions being structured. It is shown in this study that it is possible to take advantage of this structure by using a median‐based averaging technique, rather than the more traditional arithmetic mean‐based averaging, to obtain better identification performance.
Game‐theoretic linear parameter‐varying control with multiple L2 ‐gain objectives upon energy‐motion regulation of electric bikes propulsion
Authors: Hong Boe‐Shong , Su Wen‐Jui , Lin Tsu‐Yu , Chen Liang‐kuang , Chen Yong‐Song
Published: July 2013

For electric bikes, this work develops linear parameter‐varying (LPV) game‐theoretic synthesis to regulate the trade‐off between energy consumption per distance and propulsion capability in transience. Such a regulation plays like the transmission in transient state, compared to the gear transmission in steady state. Here, the propulsion dynamics is identified with LPV parameterisation that perfectly captures the non‐linearity of the dynamics. Incorporation of this LPV plant with per‐distance energy‐motion performance forms a generalised plant with multiple L2 ‐gain objectives. This generalised plant is specially constructed such that energy and motion objectives can share the same control and estimation storages without bringing conservatism to numerical solutions. Embedding the transient transmission into a dsPIC microcontroller, the authors simulate and experiment to credit such a LPV parameterisation and game‐theoretic control for DC electric propulsion.
Improved bounds for the spectrum of interval matrices
Authors: Firouzbahrami Majid , Babazadeh Maryam , Nobakhti Amin , Karimi Houshang
Published: July 2013

This study presents new sufficient conditions for Hurwitz and Schur stability of interval matrices. Tight bounds for the spectrum of interval matrices are estimated using computationally simple optimisation problems. The conservativeness is reduced further by application of ordinary similarity transformation. A necessary and sufficient vertex based criterion for the stability of a subclass of interval systems in continuous and discrete‐time cases is also proposed. This enables the spectra for this class of interval systems to be determined exactly. A selection of various examples adopted from existing literature is used to demonstrate the utility of the proposed criteria.
Some applications of passivity‐based control and invariance principles
Authors: de Ruiter Anton H. J.
Published: July 2013

This study examines the control of a passive plant utilising strictly passive feedback as motivated by the passivity theorem. A state representation of the plant is assumed with very few conditions imposed. No assumptions are made on the state representation of the feedback control law. However, some mild additional input–output properties of the feedback control law are assumed. Global stability of the closed‐loop system and asymptotic convergence of a subset of the states is proven using invariance principles. The theoretical results in the study are applied to a number of application examples, demonstrating that a much broader class of controllers can deliver closed‐loop global stability and asymptotic convergence, unlike the previous works in the literature where the examples are taken from. In one of the examples, it is demonstrated that actuator saturation constraints can readily be handled using the theory presented in this study.
Trajectory tracking of a mobile robot with frictions and uncertainties using hierarchical sliding‐mode under‐actuated control
Authors: Hwang Chih‐Lyang , Wu Hsiu‐Ming
Published: July 2013

At beginning, the kinematic model and dynamic model of a differential mobile robot (DMR), and the dynamic model of left‐ and right‐wheel DC motors are combined to be the controlled system. The control inputs of the proposed controlled system are the input voltages for the left‐ and right‐wheel motors. The (indirect) outputs are the two‐dimensional (2D) position and orientation of a DMR. Owing to the under‐actuated characteristic, the direct reference input (i.e. two desired motor currents) using the first sliding surface is designed, so that the 2D position and orientation of the DMR are simultaneously controlled by two motor currents (i.e. the direct output). On the other hand, the second sliding surface is designed as the linear dynamics of tracking error of motor currents. Under completely (or partially) known frictions and uncertainties, the hierarchical sliding‐mode under‐actuated control with suitable conditions is designed, such that two motor currents asymptotically track two desired motor currents, respectively. Then the asymptotic tracking for the 2D position and orientation of a DMR is achieved. The simulations for various trajectories, completely and partially known frictions and uncertainties, and control parameters are presented to evaluate the effectiveness and robustness of the proposed method.
Adaptive predictive control of periodic non‐linear auto‐regressive moving average systems using nearest‐neighbour compensation
Authors: Yang Chenguang , Ma Hongbin , Fu Mengyin
Published: July 2013

Many practical non‐linear systems can be described by non‐linear auto‐regressive moving average (NARMA) system models, whose stabilisation problem is challenging in the presence of large parametric uncertainties and non‐parametric uncertainties. In this work, to address this challenging problem for a wide class of discrete‐time NARMA systems, in which there are uncertain periodic parameters as well as uncertain non‐linear part with unknown periodic time delays, we develop adaptive predictive control laws using the key ideas of ‘future outputs prediction’ and ‘nearest‐neighbour compensation’, among which the former is carried out to overcome the non‐causalness problem and the latter novel idea is proposed to completely compensate for the effect of non‐linear uncertainties as well as unknown time delays. To achieve the desired asymptotic tracking performance in the presence of semi‐parametric uncertainties with time delays, an ‘n ‐step parameter update law’ is first designed, based on which an ‘one‐step update law’ is then elaborately constructed to obtain smoother closed‐loop signals. This study in general develops a systematic adaptive control framework for periodic NARMA systems with guaranteed boundedness stability and asymptotic tracking performance, which are established by rigorous theoretic proof and verified by simulation studies.
Stable‐protocol output consensus for high‐order linear swarm systems with time‐varying delays
Authors: Xi Jianxiang , Xu Zhe , Liu Guangbin , Zhong Yisheng
Published: July 2013

Stable‐protocol (SP) output consensus analysis and design problems for high‐order linear time‐invariant swarm systems with time‐varying delays are investigated. First, a dynamic output feedback consensus protocol is proposed on the basis of the observable decomposition, and a necessary and sufficient condition for SP output consensus is given, which transforms the SP output consensus problem into asymptotical stability problems of multiple lower‐dimensional subsystems. Then, in terms of linear matrix inequalities (LMIs), a sufficient condition for SP output consensualisation is presented, which can guarantee the scalability of swarm systems since it includes only five LMI constrains independent of the number of agents. Furthermore, an explicit expression of the output consensus function, which is independent of the time‐varying delay, is shown and the impacts of initial states of agents and consensus protocols on the output consensus function are determined, respectively. Finally, a numerical example is given to demonstrate theoretical results.
Geometric approach for observability and accessibility of discrete‐time non‐linear switched impulsive systems
Authors: Zhao Shouwei , Sun Jitao
Published: July 2013

This study is concerned with observability and accessibility of discrete‐time non‐linear switched impulsive systems, for which the problem is more complicated than that for general discrete systems and has novel features. A new method from the combination of differential geometric theory and Lie group analysis is developed. Specifically, under the geometric framework of the system, infinitesimal invariance for the observability and accessibility is investigated, respectively. Based on the invariance investigation, explicit criteria for local observability and local accessibility are derived. Numerical examples are discussed to show the effectiveness of the proposed methods, and the features of observability and accessibility for discrete switched impulsive systems.
Dynamic output feedback H∞ control for continuous‐time networked control systems
Authors: Wang Tian‐Bao , Wu Cheng‐Dong , Wang Yu‐Long , Zhang Yun‐Zhou
Published: July 2013

This study is concerned with dynamic output feedback (DOF) H∞ control for continuous‐time networked control systems (NCSs). The packet dropouts and network‐induced delays in the sensor‐to‐controller channel, and network‐induced delays in the controller‐to‐actuator channel are taken into account. A linear estimation‐based method is proposed to estimate the measurement output, and the non‐uniform distribution characteristic of the measurement output arrival instant is taken into full consideration to establish a new model for the considered NCSs. Based on the newly established model and a new Lyapunov functional, the problem of DOF controller design is studied. A numerical example is given to illustrate the effectiveness of the proposed DOF controller design.
Multiple interpretations by using pixel resonance concept
Authors: Hsieh Chi‐Wen , Chen Chih‐Yen , Tiu Chui‐Mei , Jong Tai‐Lang , Liu Tzu‐Chiang
Published: July 2013

Human vision is highly sensitive to perceive the contrast for interpreting images, so that the neurons of the brain will be excited to make recognition of the surroundings. In this study, the test patterns were inspired to reach the neurons excitation via the proposed pixel resonance concept, and then the quantum concept of physics was employed with random walk behaviour to analyse the test patterns for multiple interpretations. In simulation, similar alphabetic letters (C, O) and Chinese characters (玉, 王) are selected. Subsequently, various extents of noise are added including the different mean values and related standard deviations for the two test patterns. The results showed that the corresponding resonance maps with various morphologies can generate multiple resonance outputs. Furthermore, the simulation results indicated that the peak signal‐to‐noise ratio curves match those of the resonance maps perceived by using human vision. Based on this approach, it is concluded that the proposed pixel resonance algorithm can effectively simulate the multiple interpretations of the human vision system. Further, a novel physical model was presented to generate multi‐output patterns for a single image.
Image watermark detection in the wavelet domain using Bessel K densities
Authors: Bian Yong , Liang Steve
Published: July 2013

In this study, the authors propose a wavelet domain still image watermark detection method which uses the Bessel K probability density function to describe the distribution of wavelet coefficients. In this study, watermark detection is formulated as a binary statistical decision problem which is to detect a signal submerged in the noise that follows a Bessel K distribution. Using this formulation, an optimal watermark detector using likelihood ratio test is proposed. The experimental results of the proposed method in a variety of situations demonstrate that the proposed method has a robust detection performance for additive spread spectrum watermarks.
Pornographic image region detection based on visual attention model in compressed domain
Authors: Zhang Jing , Sui Lei , Zhuo Li , Li Zhenwei
Published: July 2013

According to biological attention mechanism, a region of interest (ROI) detection based on visual attention model is closer to human visual system. Taken into account the characteristics of pornographic image during regions detection, a pornographic image region detection method based on visual attention model in compressed domain is proposed in this study, which includes the following four steps: (i) the skin colour regions of pornographic images are detected in compressed domain; (ii) visual saliency map in compressed domain is computed to construct visual attention model; (iii) threshold segmentation method is used for visual saliency map, and then the torso information is retained as pornographic regions; and (iv) four features of colour, texture, intensity and skin are extracted to represent pornographic region. The experimental results show that the proposed method can perform well on the speed/accuracy of pornographic regions detection and representation.
Retinal vessel segmentation by improved matched filtering: evaluation on a new high‐resolution fundus image database
Authors: Odstrcilik Jan , Kolar Radim , Budai Attila , Hornegger Joachim , Jan Jiri , Gazarek Jiri , Kubena Tomas , Cernosek Pavel , Svoboda Ondrej , Angelopoulou Elli
Published: July 2013

Automatic assessment of retinal vessels plays an important role in the diagnosis of various eye, as well as systemic diseases. A public screening is highly desirable for prompt and effective treatment, since such diseases need to be diagnosed at an early stage. Automated and accurate segmentation of the retinal blood vessel tree is one of the challenging tasks in the computer‐aided analysis of fundus images today. We improve the concept of matched filtering, and propose a novel and accurate method for segmenting retinal vessels. Our goal is to be able to segment blood vessels with varying vessel diameters in high‐resolution colour fundus images. All recent authors compare their vessel segmentation results to each other using only low‐resolution retinal image databases. Consequently, we provide a new publicly available high‐resolution fundus image database of healthy and pathological retinas. Our performance evaluation shows that the proposed blood vessel segmentation approach is at least comparable with recent state‐of‐the‐art methods. It outperforms most of them with an accuracy of 95% evaluated on the new database.
Automatic and quick blood vessels extraction algorithm in retinal images
Authors: Shahbeig Saleh
Published: July 2013

There is an everyday increase of retinal images in different application such as human recognition and diagnosing the eye diseases. Therefore, the need for an automatic method which can recognise the eye parts of retinal images as eye features is unavoidable. This paper offers an automatic and quick morphological‐based blood vessel extraction algorithm from the coloured retinal images using Curvelet transform (CT) and principle component analysis (PCA) is proposed. In this algorithm, by estimating the illumination of background and the distribution of contrast in the retinal images, the brightness of images is considerably uniformed. Furthermore, CT is used to enhance the contrast of retinal images by highlighting the edge images in various, scales and directions. We use an improved morphology function introduced with multi‐directional structure elements, to extract the blood vessels from retinal images. Connected component analysis and an adaptive filter are used to refine appeared frills with the size of smaller than arterioles in images. The proposed algorithm is evaluated on available images of the DRIVE database and accuracy rate of 94.58% for the blood vessel extraction is obtained. The obtained results show efficiency of the proposed algorithm in comparison with the presented approaches in the literature.
Angle consistency for registration between catadioptric omni‐images and orthorectified aerial images
Authors: Xu Wei , Chen Wang , Zhang Jianguo , Zhang Maojun
Published: July 2013

Registration between catadioptric omni‐images and orthorectified aerial images is the key step to integrate them to achieve three‐dimensional urban construction. This problem becomes very challenging because of the non‐linearity of the imaging model of catadioptric omni‐cameras. In this study, the authors attempt to address this problem. The authors first study the properties of horizontal line structure under catadioptric omni‐cameras to prove and extend the theorem of catadioptric distance, and then present angle consistency of horizontal lines between a catadioptric omni‐image and an orthorectified aerial image. The authors further employ them to achieve registration between catadioptric omni‐images and orthorectified aerial images. To the best of authors’ knowledge, this study has not been done before. Experimental results on both simulated data and real scene images confirm the effectiveness of this approach.
Colour fringe detection and correction in YCbCr colour space
Authors: Ju Hae Jin , Park Rae‐Hong
Published: July 2013

Colour fringe is an artefact that mainly appears at the boundary of an object in an image, where colours change abruptly and luminance value is large. Thus, colour fringe should be corrected in a colour digital image. This study proposes a method for detection and correction of colour fringe in YCbCr colour space. The luminance value as well as gradient magnitudes/directions of YCbCr are used to detect colour fringed region. Then, chrominance values in colour fringed regions are corrected using those of pixels in the neighbouring regions along the colour fringe direction. The experimental results show the effectiveness of the proposed colour fringe detection and correction method.
Fusion framework for multi‐focus images based on compressed sensing
Authors: Kang Bin , Zhu Wei‐ Ping , Yan Jun
Published: July 2013

In this study, an efficient image fusion framework for multi‐focus images is proposed based on compressed sensing. The new fusion framework consists of three parts: image sampling, measurement fusion and image reconstruction. First, the dual‐channel pulse coupled neural network model is used in the image sampling part as an important weighting factor in the fusion scheme. Second, the result from the measurement fusion part is reconstructed through a new reconstruction algorithm called self‐adaptively modified Landwebber filter. Finally, computer simulation‐based experiment is conducted, showing that the novel fusion framework is capable of saving computational resource and enhancing the fusion result and is easy to implement.
Identification of small-molecule binding pockets in the soluble monomeric form of the Aβ42 peptide
Authors: Zhu Maximillian , De Simone Alfonso , Schenk Dale , Toth Gergely , Dobson Christopher M. , Vendruscolo Michele
Published: July 2013

The aggregation of intrinsically disordered peptides and proteins is associated with a wide range of highly debilitating neurological and systemic disorders. In this work we explored the potential of a structure-based drug discovery procedure to target one such system, the soluble monomeric form of the Aβ42 peptide. We utilised for this purpose a set of structures of the Aβ42 peptide selected from clusters of conformations within an ensemble generated by molecular dynamics simulations. Using these structures we carried out fragment mapping calculations to identify binding “hot spots” on the monomeric form of the Aβ42 peptide. This procedure provided a set of hot spots with ligand efficiencies comparable to those observed for structured proteins, and clustered into binding pockets. Such binding pockets exhibited a propensity to bind small molecules known to interact with the Aβ42 peptide. Taken together these results provide an initial indication that fragment-based drug discovery may represent a potential therapeutic strategy for diseases associated with the aggregation of intrinsically disordered proteins.
Tunneling transport through multi-quantum-dot with Majorana bound states
Authors: Li Yu-Xian , Bai Zhi-Ming
Published: July 2013

We have studied tunneling transport properties through multi-quantum-dot coupled to Majorana bound states (MBSs), in which only one quantum dot is connected with two normal leads. When the MBSs are sandwiched between two quantum dots (dot-MBSs-dot), the signature of Majorana fermions; namely, that the conductance is e2/h at zero fermion energy, is robust against the coupling (ϵM) between the two Majorana bound states as well as the coupling between the MBSs and the quantum dots which, in the dot-MBSs structure, will change even with a very small value of ϵM. The model that the Majorana bound states are coupled with one of a series of connected quantum dots (three connected quantum dots coupled with MBSs, e.g., dot-dot-dot-MBSs) is also investigated. Unlike the resonant condition for quantum dots structure with zero MBSs, if the MBSs couple with an even number of quantum dots, the conductance at zero Fermion energy is 2e2/h. On the other hand, in case of an odd number of quantum dots, it is e2/h.
Dependence of the Mg-related acceptor ionization energy with the acceptor concentration in p-type GaN layers grown by molecular beam epitaxy
Authors: Brochen Stéphane , Brault Julien , Chenot Sébastien , Dussaigne Amélie , Leroux Mathieu , Damilano Benjamin
Published: July 2013

Hall effect and capacitance-voltage C(V) measurements were performed on p-type GaN:Mg layers grown on GaN templates by molecular beam epitaxy with a high range of Mg-doping concentrations. The free hole density and the effective dopant concentration NA−ND as a function of magnesium incorporation measured by secondary ion mass spectroscopy clearly reveal both a magnesium doping efficiency up to 90% and a strong dependence of the acceptor ionization energy Ea with the acceptor concentration NA. These experimental observations highlight an isolated acceptor binding energy of 245±25 meV compatible, at high acceptor concentration, with the achievement of p-type GaN:Mg layers with a hole concentration at room temperature close to 1019 cm−3.
Microwave diode switchable metamaterial reflector/absorber
Authors: Xu Wangren , Sonkusale Sameer
Published: July 2013

We embed diodes as active circuit elements within a metamaterial to implement a switchable metamaterial reflector/absorber at microwave frequencies. Diodes are placed in series with the unit cells of the metamaterial array. This results in just a pair of control lines to actively tune all the diodes in a metamaterial. Diodes can be tuned on and off to switch the function of the metamaterial between a perfect absorber and a reflector. The design, simulation, and experimental results of a switchable reflector/absorber in 2–6 GHz range are presented.
Transparent organic thin film transistors with WO3/Ag/WO3 source-drain electrodes fabricated by thermal evaporation
Authors: Zhang Nan , Hu Yongsheng , Liu Xingyuan
Published: July 2013

High-performance transparent organic thin film transistors using a WO3/Ag/WO3 (WAW) multilayer as the source and drain electrodes have been developed without breaking the vacuum. The WAW electrodes were deposited by thermal evaporation at room temperature, leading to little damage to organic film. The optimized WAW electrode shows high transmittance (86.57%), low sheet resistance (11 Ω/sq), and a high work function (5.0 eV). Consequently, we obtained high performance devices with mobility of 8.44 × 10−2 cm2/V · s, an on/off ratio of approximately 1.2 × 106, and an average visible range transmittance of 81.5%.
CTIP2 is a negative regulator of P-TEFb
Authors: Cherrier Thomas , Le Douce Valentin , Eilebrecht Sebastian , Riclet Raphael , Marban Céline , Dequiedt Franck , Goumon Yannick , Paillart Jean-Christophe , Mericskay Mathias , Parlakian Ara , Bausero Pedro , Abbas Wasim , Herbein Georges , Kurdistani Siavash K. , Grana Xavier , Van Driessche Benoit , Schwartz Christian , Candolfi Ermanno , Benecke Arndt G. , Van Lint Carine , Rohr Olivier
Published: July 2013

The positive transcription elongation factor b (P-TEFb) is involved in physiological and pathological events including inflammation, cancer, AIDS, and cardiac hypertrophy. The balance between its active and inactive form is tightly controlled to ensure cellular integrity. We report that the transcriptional repressor CTIP2 is a major modulator of P-TEFb activity. CTIP2 copurifies and interacts with an inactive P-TEFb complex containing the 7SK snRNA and HEXIM1. CTIP2 associates directly with HEXIM1 and, via the loop 2 of the 7SK snRNA, with P-TEFb. In this nucleoprotein complex, CTIP2 significantly represses the Cdk9 kinase activity of P-TEFb. Accordingly, we show that CTIP2 inhibits large sets of P-TEFb- and 7SK snRNA-sensitive genes. In hearts of hypertrophic cardiomyopathic mice, CTIP2 controls P-TEFb-sensitive pathways involved in the establishment of this pathology. Overexpression of the β-myosin heavy chain protein contributes to the pathological cardiac wall thickening. The inactive P-TEFb complex associates with CTIP2 at the MYH7 gene promoter to repress its activity. Taken together, our results strongly suggest that CTIP2 controls P-TEFb function in physiological and pathological conditions.