In course of preparation of

In course of preparation of MicrOmega IR microscope-spectrometer experiment for ExoMars and Phobos-Grunt missions in 2006–2009 we worked out several technical solutions enhancing the AOTF storage and operation temperature range at the low temperatures. An extreme AOTF operation temperature as low as −175°C was achieved. Some results of these tests are reported in [14,15]. In the following the temperature range requirements were relaxed allowing application of the AO filters manufactured according to the standard technology in both missions.
Even in a “standard” temperature range, the effect of temperature on the AOTF operation is far from being fully characterized. Theoretically the effect of temperature on the operation of an AO deflector is analyzed in [19], also, a theoretical investigation of temperature distribution in operating AO cell was done in [20,21]. Also in [22] the measurements of the AO wide-angular monochromator transfer function spectral shifts were performed for temperature range −40… +60°C; the obtained spectral shift was −0.05nm/°C. A common practical consideration is that following the ultrasound properties of TeO2, the phase matching ultrasound frequency depends on the temperature, and the relative shift amounts to 10−5–10−4K−1. This shift is generally characterized by calibration, and is even compensated for in certain devices intended for real-time operations. However no theoretical analysis of the temperature influence on the AOTF operation was done.
In this p2y receptor paper we analyze the effect of temperature on the AOTF operation, theoretically, and by means of experimental testing. For testing we used two types of a wide-angle paratellurite AO filters, developed for deep-space missions. The first configuration of the AOTFs is employed in SPICAM-IR (SPectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars IR channel), presently in flight onboard Mars Express ESA mission [13]. The second configuration is under development for Lunar Infrared Spectrometer (LIS) and Infrared Spectrometer for ExoMars (ISEM) for the Moon landing missions Luna-Globe (Luna 25) and Luna-Resource (Luna 27), and for ExoMars Rover, respectively [18]. The theoretical background, developed following the approach of [19] is presented in Section 2, the AOTF devices are described in Section 3, and their testing – in Section 4. The results are summarized in Section 5.

Basic relations
The characteristics of AO devices depend on numerous parameters. The AO interaction efficiency, characterized by a ratio of diffracted and incident optical radiation depends not only on the acoustic wave parameters, but also on the crystal properties. The main characteristic of acousto-optic material is the so-called AO figure of merit [23,24]. It is evaluated according to the following equation:where ρ – is the media density, is the matrix of effective elastic coefficients, V – acoustic wave velocity along the chosen direction, , refraction indexes. The more is the figure of merit, the less acoustic power is needed to achieve the diffraction efficiency required. Some physical properties of the crystal, for example the acoustic wave velocity, depend on the temperature. This dependence takes place as the elastic modules matrix elements, [25–28] change with the temperature according to the following equation [24]:where are the elements of thermal coefficients matrix for . The elements can be found in the literature [24–26]. Also, in [27] were experimentally measured for tellurium dioxide for the temperature range of −100°C…+50°C. In [28] were experimentally measured down to the temperature of 10K.
The acoustic wave velocity in crystals is defined by equationwhere ρ is the density, v – acoustic wave phase velocity, – Kronecker delta, and = is the second rank tensor. Using data from [25–28] with the help of (3) it is possible to calculate the dependences of acoustic wave velocities on the propagation direction in the plane for various temperatures. The propagation direction is set by the azimuthal angle θ, measured from the crystallographic axis Z in plane, or in other words by the cut off angle α measured from [110] axis in the same plane α=90°−θ. The schematic drawing of the AO cell on the example of LIS AOTF is presented in Fig. 1.

To investigate the characteristics of different cutting modes in

To investigate the characteristics of different cutting modes in the micro-groove generation process, micro-grooving experiments using stainless steel 0Cr18Ni9 were performed by linear and elliptical vibration cutting. Linear vibrations were applied in the cutting direction. The cutting tools used were commercial tungsten carbide inserts with a nose radius of 200μm. The diameter and length of the workpiecewere19.05mm and 80mm respectively. The workpieces were pre-turned to assure their high concentricity and eliminate any potential runout effects. The machined surfaces were examined using an Alicona infinite focus microscope.
Table 1 presents the experimental conditions used for both the linear and the elliptical vibration cutting experiments, while Table 2 summarizes the physical and mechanical properties of the 0Cr18Ni9stainless steel workpieces. When modifying the excitation frequency and phase angle to the vibration generator, the elliptical vibration cutting and the linear vibration cutting can switch between each other.
The experiment conditions in Table 1 were used to machine two micro-grooves under both linear and elliptical vibration-assisted cutting. In the experimental process, a Kistler 3-component tool dynamometer was used to measure the cutting force components in the tangential, radial and axial directions. Section 4 below will give a comparison of the cutting forces and surface roughness under different experimental conditions for both vibration-assisted cutting cases. The calibrated amplitude of the linear vibrations was 1.25μm and the amplitude of the major axis and minor axis for the elliptical vibrations were respectively 7.8μm and 2μm.

Results and discussion


This work was supported by the National Science & Technology Major Project of China under Grant number 2013ZX04001-021, by China Postdoctoral Science Foundation (No. 2015M570447) and by the Fundamental Research Funds for the Central Universities (No. NS2016048). The first author was also grateful for the financial supports from the Chinese Scholarship Council and Nanjing University of Aeronautics and Astronautics, China.

Aortic stiffness is associated with various cardiovascular (CV) diseases [4,20,22,32,47] and has been extensively studied for risk assessment of CV events. Among various indices of arterial stiffness [21,36], carotid–femoral pulse wave velocity (cfPWV) is considered as the “gold-standard” measurement of the aortic stiffness and a threshold of >10m/s is suggested by the European Society of Hypertension/European Society of Cardiology (ESH/ESC) Guidelines as an conservative estimate of significant alterations of aortic function in hypertensive patients [48,29]. Moreover, aortic PWV is an independent predictor of coronary purchase Nutlin3a disease and stroke in apparently healthy subjects [30] and a strong predictor of future CV events and all-cause mortality [51].
Conventionally, cfPWV is calculated as the distance between the carotid and the femoral arteries divided by the transit time delay of the pulse wave. In practice, the carotid–femoral distance cannot be accurately measured by using a tape meter or a caliper due to the non-uniform geometry of the artery [3,46,53]. The cfPWV quantifies the average stiffness of the arteries along the carotid–femoral pathway. However, the elastic properties of the arteries are non-uniform along the arterial tree, because the ratio of elastin to collagen progressively declines from the central artery toward periphery [36]. In addition, the mechanical properties of arteries are differently affected by aging and diseases, such as atherosclerosis [15,38,49], making the mechanical properties of the arteries site-specific. Being informed of regional or local arterial stiffness is of ultimate importance for it might provide prognostic information [21].
Regional PWV can be measured non-invasively by ultrasound imaging, such as tissue Doppler imaging [10], multiple M-line ultrasound [5,14,13] and pulse wave imaging (PWI). PWI has been proposed for visualization of pulse wave propagation along the arteries as well as quantitative PWV estimation within the ultrasound imaging field of view (FOV) [23,25,27,43,50]. In order to capture the propagation of the pulse wave in a relatively short range (within several centimeters) and improve the estimation performance, high frame rate ultrasound imaging is required [9,19,33,16,10]. Sparse imaging is usually used to achieve high frame rates up to several hundred Hz by reducing the beam density to about 8–32 beams per frame [13,16,23,27]. However, the spatial resolution was correspondingly decreased in visualization of pulse wave propagation and quantification of PWV. For this reason, several techniques have been developed to produce composite high line density imaging without compromising the frame rate, such as electrocardiogram (ECG) gating and motion matching [24,52,18,39]. For the former technique, the full imaging FOV is divided into several sectors which are acquired consecutively at a high frame rate simultaneously with ECG signal, and then a full-view cine-loop is reconstructed via retrospective ECG gating [52]. With the benefit of both high spatial and temporal resolution of this technique, valuable details could be extracted from arterial motions for detection of regional stiffness changes and assessment of arterial diseases [25,34,43,42,1]. However, for cases when ECG signal is irregular or unavailable, such as in patients with arrhythmia or in ex vivo and phantom experiments, an alternative choice would be the motion matching technique. This technique was developed for the reconstruction of high temporal and spatial electromechanical wave imaging by using the periodicity of tissue motion in the overlapping regions to co-register the adjacent two sectors [18,39]. However, as this technique was previously performed on the electromechanical wave imaging of the heart, its feasibility in PWV estimation of the vessels remained to be evaluated.

Historically piezoceramics have been the most

Historically, piezoceramics have been the most commonly used materials in ultrasound transducer arrays but, recently, the improved performance offered by relaxor-based piezocrystals in the Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN-PT) family has been recognized. Piezocrystals are now used widely in biomedical ultrasound imaging and investigation of their possibilities is under way in nondestructive evaluation, particle manipulation and underwater sonar [7–10] based on piezoelectric properties including ≈90% and >1500pC/N [11]. Bulk, monolithic piezocrystal has little advantage over piezoceramic, with the values of being similar, but improved performance can be realized in configurations such as the planks used in biomedical imaging arrays and the pillars used in piezocomposites.
PMN-PT itself, termed a Generation I material, is susceptible to changes in functional properties at elevated temperature and pressure [12], but Generations II and III, respectively exemplified by ternary PIN-PMN-PT and doped ternary Mn:PIN-PMN-PT, are under development to reduce these effects whilst maintaining much of the performance advantage over piezoceramic, e.g. in terms of and that determine piezocomposite performance. Piezocrystal composites thus have potential to improve the effectiveness of focused ultrasound transducers and the work reported here contributes to this by describing the fabrication and testing of a 2D concave phased array made with Generation I piezocrystal.
A widely-reported method to fabricate concave transducer arrays is to place individual single-element transducers in a prefabricated frame at predetermined positions [6,13]. This requires manufacture of each individual array PF-3758309 separately and the presence of the frame can significantly reduce the array fill-factor, i.e. the percentage surface coverage of the active piezoelectric material, and thus the focusing gain and acoustic energy output of the transducer. As an alternative, Raju et al. [14] proposed an array design using a spherically-focused ceramic bowl with printed electrodes defining the elements. However, fabrication of curved sections from piezocrystal boules would be wasteful of material which costs $0.5−3/mm3, and more importantly, performance would be decreased by the lack of alignment between the piezocrystal axes and the surface of the array. Mechanical forming to focus piezocrystal transducers has been achieved successfully using mechanical hard-press [15] and dimpling techniques [16], but reports are limited to single-element transducers. Other possibilities are to thermally form a 1–3 connectivity piezoelectric-polymer composite into the desired shape [17] or to use flexible polymers for flexible composites [18], but these may be difficult at the frequencies of interest here, below 1.0MHz, and the values of volume fraction, e.g. VF>50%, used in focused ultrasound applications.

Geodesic structure
A section of an icosahedron dome structure with dome frequency 6V, referring to a structure with six subdivisions of the original triangles in one icosahedron [19], was chosen for the proposed array. In total, the section requires 24 triangular flat plates positioned as shown in Fig. 1. To match a commercial piezoelectric bowl used as a reference, the target operating frequency of the array was 1.0MHz and its aperture was 62mm across its largest diagonal, with a natural focal distance of 75mm, equal to the dome radius, giving f#≈ 1.2. Table 1 lists the four triangular geometries in this design, with their side lengths and corresponding angles. Each triangle is named for its sides taken in a clockwise direction. Five side lengths in total are needed, denoted D, F, G, H and I. Triangles HGG and HII are isosceles and triangles DFG and DGF are scalene; six of each type are required. These triangles were machined by a precision dicing saw (MicroAce 66, Loadpoint Ltd., Wiltshire, UK) with dicing position accuracy of 0.001mm and theta axis resolution of 0.0005°.

As it can be seen in Fig the values

As it can be seen in Fig. 2, the values of the effective indentation modulus determined for the ULK-350nm and ULK-200nm films differ significantly, despite the same nominal porosity. The lack of a pronounced dependence of M on the applied static load indicates that the results are not influenced by the elastic properties of the substrate. The initial increase in the values of the effective indentation modulus and presence of the hysteresis in the load–unload curve is caused most probably by a small plastic deformation of the film\’s upper layer. Similar behavior was observed for porous organosilicate glasses with a porosity of 30% and a thickness of about 700nm [42]. The mean values of M calculated for the 350nm and 200nm thin films from all the measurement points acquired during the measurements were 6.3GPa±0.2GPa and 7.2GPa±0.2GPa, respectively.
The values of the effective indentation modulus determined for the ULK-46nm sample are presented in Figs. 3 and 4. In the first attempt, we used the rounded tip and relatively large values of the static load ranging from 270nN to 3350nN. The results obtained in this series of measurements are presented in Fig. 3a. The load–unload curve represents the mean values of M calculated as a function of the static load from 20 single point measurements. The error bars represent the corresponding values of the standard deviation. In p2y inhibitor to those presented in Fig. 2, the curve presented in Fig. 3a shows a very strong dependence on the applied static load. The mean values of M increase from 14GPa to 18GPa during load and decrease to about 15GPa during unload. The difference between the load and unload values of M has similar character to that visible in Fig. 2, namely it is smaller than the values of the standard deviation of the corresponding mean value and it decreases with the increasing value of the static load.
The strong increase in the values of the effective indentation modulus suggests a substrate influence. To minimize it, we had to reduce the size of the stress field expanding into the sample. This can be done by applying an AFM tip with a smaller tip radius and/or lower values of the static load. To ensure that radical change in the tip geometry will not influence the results obtained for the indentation modulus of the samples, we performed an additional test. The test sample was also a film of porous organosilicate glass but with a nominal porosity of 40% and thickness of 350nm. Due to the higher porosity content, the modulus of the test sample was lower than that of the ULK-350 sample. Thus, the test sample would deform more under the same load and the influence of the tip geometry would be even more pronounced. The measurement and data evaluation procedures were the same as for the thin-film samples. The mean value of the indentation modulus determined for the test sample with the blunt tip (cantilever #1) in the force range from 650nN to 4750nN was 3.6GPa±0.2GPa. Then we used a cantilever equipped with a standard sensor tip having radius in the range from 30nm to 50nm (cantilever#2). The force ranged from 160nN to 1500nN. The mean value of the indentation modulus obtained with the sharp tip was 3.9±0.1GPa. The result obtained for the indentation modulus with the sharp tip was in a good agreement with that obtained with the blunt tip. The small difference of 0.3GPa could be caused by differences in the actual and the assumed tip geometries, and the corresponding tip–sample contact conditions. We will use this difference in further analysis of the experimental data obtained for ULK-thin film samples sample. Namely, any difference in the data obtained with blunt and sharp tips smaller than 0.3GPa will be treated as negligible.
We repeated the measurements on sample ULK-46nm, but this time we used the cantilever #2 with a smaller tip radius. The applied static load ranged from 200nN to 1400nN. We performed 24 single point measurements. The curve representing the mean values of the M as a function of the applied static load is presented in Fig. 3b. The error bars represent the values of the corresponding standard deviation. As it can be seen in Fig. 3b, the mean values of M obtained for the ULK-46nm sample with standard tip still show dependence on the applied static load. The values of M increase from 8.6GPa to 10.2GPa during load and decrease to 9.2 during unload. The maximal value of M determined during this series of measurements is less than the minimal value of M determined for the same sample with help of the rounded tip.

By good fortune I had

By good fortune, I had hired as my first postdoc Johann Tafto, from the powerful group of Jon Gjonnes in Oslo. Johann arrived full of his Ph.D. work on the theory of membrane transporter channeling, which I\’d been simulating in the hope of reproducing on EELS spectra some of the standing-wave effects on X-ray fluorescence which Batterman had observed using X-rays at Cornell. But the EELS case involved double-channeling, difficult to interpret, and instead Johann conducted a brilliant series of experiments on channeling effects on EDX spectra from polyatomic crystals containing dopants. (Since multiple scattering affects host and dopant atoms equally, the effect cancels). This lead to our Alchemi technique for locating foreign atoms in crystals, used recently in the study of turbine-blade alloys [20] and ceramics [10]. But in a brilliant collaboration with Ondrej and his new spectrometer, they were able to combine the standing-wave effect with the sensitivity of near-edge structure (ELNES) to chemical valence for site-specific valence determination in iron oxide [47]. Johann went on to use the channeling effect to study localization in EELS by a clever experimental arrangement [43], solved the double-channelling problem (through reciprocity and a large beam divergence) and established the usefulness of ELNES with a famous series comparing spectra from octahedral and tetrahedrally coordinated Mg and K in oxides, showing how these could be distinguished [46]. All this provided an important market for future applications of Ondrej\’s wonderful spectrometers.

My own education in energy-loss spectroscopy (EELS) began with my Ph.D. in Melbourne, and was continued by Ray Egerton at Oxford when Ondrej was working in Cambridge on his Ph.D. My Ph.D. was devoted to detection of a second-order \”double-plasmon\” process [40], and, with David Johnson, to developing the logarithmic deconvolution method of removing multiple-scattering effects from EELS spectra [18], now described in detail in Ray Egerton\’s book [9]. Cowley, at that time in the Physics department in Melbourne, had purchased one of the first DEC PDP8 computers in order to automate EELS data collection from our JEOL JEM 7 TEM [3]. These early \”mini\” computers were based mainly on discrete components, with, for example, a complete removable printed circuit board for one binary half-adder, and an associated paperback book for the manual of each board. The retarding-field electrostatic energy filter had a bias voltage applied to it (across the high voltage) using a set of nylon strings running down into the oil tank from relays (driven by the PDP8) which operated binary switches floating at high voltage. Writing instrument-control machine code and constantly rebuilding this system with others, occasionally getting results membrane transporter (mainly plasmon spectra and elastically filtered Bragg scattering for quantification), constituted the four years of my Ph.D., all of us working very long hours against the background of the Vietnam war protests and the music of the Beatles. We were surprised to see the paper [34,35] reporting energy gain in the beam from interaction with previously beam-excited surface plasmons, and immediately reversed the polarity of the bias batteries in the high-voltage tank to seek this effect, without success. Now, 43 years later, the sad recent death of Ahmed Zewail reminds of the energy-gain possibility in his fascinating PINEM observations, discussed elsewhere in this volume. Later at ASU, starting around 1978, with my first student Mark Disko\’s Ph.D. we developed a tight-binding theory of near-edge structure [7] and spent fruitless hours in a search for optical pumping effects from a laser on both high-resolution lattice images and inner-shell EELS spectra during Ondrej\’s time at ASU. In the first case, Naoki Yamamoto and I had built a cathodoluminescence apparatus for STEM [48] for study of luminescence from individual dislocation in diamond at 25K (this part was very successful), and this could be run backwards to illuminate the sample through a spectrometer tuned to the optical absorption edge of strongly absorbing dopants in a crystal. We expected to see the dopant atoms change appearance in the HREM lattice image when they were optically illuminated (because the low-angle electron scattering, well within the resolution of our TEM, is so sensitive to changes in valence due to ionization) but didn\’t. Later calculations showed we\’d have needed to melt the sample to get an effect, and a superlattice of dopants would be needed. Similar attempts to observe optical pumping effects on ELS spectra with this apparatus failed, as did our attempts to detect co-incidence spectra between EDX or CL and EELS (to reduce background in EELS), where it finally dawned on us that we could only expect the statistics of the channel with the poorest counting statistics in such experiments. All this work was done on the superb Philips EM400 TEM/STEM which we shared with Ondrej\’s development of his serial EELS system amid intense discussion at morning teas.

br Gradient based DIC for

Gradient-based DIC for simulation-based HR-EBSD
As commented above, Bragg (kinematic) simulations allow the construction of EBSPs in a computationally efficient way. However, the overall intensities, especially in the neighborhood of a zone axis, are far from the actual intensities of real EBSPs. Dynamical simulations, albeit more accurate, require long computational times (each pattern may take about an hour to be generated on a modern desktop computer [16]).
The algorithm proposed here is similar to the approach of Villert et al. [11]. It is based on the Bragg condition used to determine band locations, together with a modified band profile to emulate excess and deficiency lines. Thus, the intensity of the simulated EBSP is given by the additive contribution of each diffracting plane according to its structure factor, weighted in a very simplistic way by the following criterion: the intensity of the pixel is weighted by 0.8 if it lies within sin  < sin θ < 1.2sin  and by 1.2 if it lies within 0.8sin  < sin θ < sin  (where θ is the angle to the corresponding crystal plane and is the Bragg angle). This modified Bragg model is of course still insufficient to simulate with high accuracy the intensities of an EBSP. In order to improve the fitting quality, a new GB-DIC procedure is proposed, different from the conventional DIC procedure. GB-DIC algorithm is based on the approach suggested by Tzimiropoulos et al. [17]. From an EBSP image, a new image (gradient image) is created based on the intensity gradients in the following form: where I(x, y) is the intensity of the EBSP image (either experimental or simulated) and i is the imaginary unit (see Fig. 1). The cross-correlation image can be obtained from the Fourier transform of the gradient image of a real () and a simulated () EBSP as follows: where is the inverse Fourier transform and is the complex conjugate of . The peak position in corresponds to the image shift between the two images. According to Tzimiropoulos et al., this kind of antimalaria medication brings a more robust and accurate estimation of image translations, rotations and scale changes between images. Moreover, this image transformation leads to a pair of complex images where the Kikuchi lines are visibly highlighted and the overall background intensities are flattened. As a consequence, the quality of the fitting (peak height to background ratio in the FFT correlation image) is largely increased as shown in Fig. 2. A more robust fitting of kinematically simulated EBSPs is then possible.
Image filtering has been shown to be critical for an accurate HR EBSD procedure. Wilkinson et al.[4] studied different filtering parameters and finally applied a Hamming-like window in order to prevent aliasing problems and a low-pass filter in the frequency domain to remove noise. In this case, with the aim of highlighting the benefits of the gradient-based procedure, no windowing was considered and only a low-pass filter was applied (equivalent to the one proposed by Wilkinson et al.[4]) with a double objective: first, remove the residual noise from the EBSP image; and second, to smooth down the edges of the Kikuchi bands in the simulated pattern.

New procedure of calibration of the pattern center
Traditionally, PC location has been calibrated by different methods including feature mirror symmetry methods, screen movement methods or shadow casting methods [18,19]. However, the typical resolution of these methods was of the order of 0.5% of the camera width. With the advent of HR-EBSD this resolution has been shown to be inadequate [15,20] (as it will be demonstrated below) and new PC calibration procedures have been developed. Maurice et al [21], for example, tried to improve the resolution of screen movement methods by cross-correlation techniques but the mechanical insertion/retraction and geometric uncertainties limit its application. Mingard et al. [22] also extended the use of shadow casting techniques with relevant results. Finally, Basinger et al. [23] using an EBSP spherical remapping technique and simulated patterns and reached a resolution of 0.045% in a Ni polycrystal limited by the uncertainty in the exact crystal orientation. In this paper we present a novel method (based on the method proposed by Kacher et al. [13]) with improved resolution that adapts the simulation-based HR-EBSD using GB-DIC procedures to the problem of PC calibration with minimum assumptions on the stress state of the crystal.

A further set of experiments was designed to

A further set of experiments was designed to test the limits of this proportional shift. This was done by varying the size of the test disk in one eye, while presenting the other eye with a large homogeneous test field. The smaller the test field, the closer its area is to its outer contour. Varying the size of the monocular test field from 7 to 5, 3 and 1 degree of visual angle, the contribution of that test field to the binocular brightness impression increased (over 8 observers) from w=.851 to .857 to .887 to .932. In other words, a half-image’s contribution to binocular brightness approaches w=1 when its average distance to a contour approaches zero. This was coined the “contour mechanism”. The perceived brightness remains quite stable for all sizes of the test field, i.e. it is subject to a “constancy rule”. A summary classroom demonstration of all these brightness averaging effects can be experienced by fusing the stereo pair in Fig. 1C.
In additional experiments it was then shown that it takes time for the eye weighting coefficient to settle after bepridil onset. In other words, the contour mechanism shows some degree of inertia. It takes about 100–200ms for an appearing contour to induce w=1 in its immediately adjacent visual field. This delay predicts that a pair of orthogonal gratings, the classic demonstration stimulus for binocular rivalry, should look like a grid (commonly referred to as a plaid) if briefly flashed on and off. That indeed turned out to be the case, indicating that temporarily ==1/2. This settling mechanism is the same as what can be observed and precisely measured in metacontrast (Alpern, 1952; Stigler, 1910) and in “false fusion” (Wolfe, 1983).
Together, these experimental findings led to the following account of the conflict in binocular rivalry. The law of complementary shares and the contour mechanism necessarily come into conflict for any dichoptic bepridil area A where adjacent but non-corresponding contours are presented to the two eyes. The contour mechanism for the left eye induces, with some degree of inertia, →1 in area ; the contour mechanism for the right eye similarly induces →1 in area . This, however, violates the law of complementary shares (+1). The system apparently resolves this conflict by abrogation of the constancy rule, while preserving the law of complementary shares: both →1 and →1, but they do so in turn, steadily alternating. In addition, there was no pressing reason to assume that this process would be different for the normal fused state in binocular vision. The still dominant “permanent rivalry hypothesis” was not challenged, but rather supported by this account for the conflict in binocular rivalry.
The contour mechanism, a contour inducing w=1 for its immediately adjacent visual field, also formed the starting point for the analysis of the alternation process in rivalry. If a contour is presented to one eye only, the resulting percept will be stable, whatever the strength (formally denoted by λ) of that stimulus may be (not considering “Troxler’s fading”, which was shown to be irrelevant for the rivalry mechanism). The only way to make such a stimulus perceptually disappear is by presenting a strong enough stimulus to the other eye. This notion led to the hypothesis that the duration of a monocular contour’s dominance period in rivalry is determined by the strength of a contour in the corresponding area of the other eye. This had never been studied before. Since Breese (1909), there existed a literature on the alternation rate in rivalry that showed that increasing luminance, contrast or amount of contours in one or both eyes increased alternation rate. There also existed an even larger literature on factors affecting the predominance of monocular patterns in rivalry (following Breese, 1909 and Roelofs & Zeeman, 1919), which was affected by the same or similar factors as alternation rate, in particular by the contrast or sharpness of contours. However, at the time no explicit model had been proposed to relate the two, alternation rate and predominance, to each other. Four propositions were intended to fill this gap (Levelt, 1965). In their formal description, they involved a number of symbols: and , denote the mean durations of the left and right eye dominance periods in a two-choice rivalry situation, where the mean duration of the complete cycle is . Predominance () of left-eye stimulus () is calculated as and similarly so for the right eye stimulus (). Stimulus strengths of and are given by and respectively. Operationally, stimulus strength was defined (up to order relations) by two variables: (i) the amount of contour per area, and (ii) the contrast of contour (taking into account the local difference threshold). The above hypothesis can now be stated as and , where f is a monotonic decreasing function of . These two equations together yielded Levelt’s (1965) four propositions in their original form:

br Introduction br Experiment br Experiment br General


Experiment 1

Experiment 2

General discussion
The results obtained in SEM are in line with previous studies showing that the global effect diminishes with time (Coeffe & Oregan, 1987; Findlay, GW5074 Supplier 1982; Ottes, Vangisbergen, & Eggermont, 1985; Van der Stigchel & Theeuwes, 2005). Whereas saccades were aimed at an intermediate location in the immediate-response condition, saccades were aimed at the target in the deferred-response condition. Importantly, the results obtained in the no-delay condition of TEM demonstrate that the decline in the global effect even occurs in the presence of an intermediate saccade. That is, the distributions of landing positions of second eye movements in the no-delay conditions of TEM were, similarly to those obtained in the deferred-response conditions of SEM, bimodal rather than unimodal.
Our results, in particular those obtained in Experiment 2, are difficult to reconcile with the center-of-gravity account (Coren & Hoenig, 1972; Ottes, Vangisbergen, & Eggermont, 1984). This account implies that the global effect is primarily caused by poorly resolved spatial signals. Since the spatial GW5074 Supplier improves over time, the global effect becomes less pronounced and should eventually disappear. Crucially, even in the case that the identity of objects is not yet determined, observers should gradually become more capable of aiming their eyes at single objects. However, in the current study, a global effect was observed in the identity-delay condition of TEM, a condition in which the locations of the objects were given from the start of the trial. Accordingly, the global effect appears to arise from a deficiency of identity information, rather than a deficiency of location information.
The results are consistent with the weighted-average account (Godijn & Theeuwes, 2002; Marino et al., 2012; Meeter, Van der Stigchel, & Theeuwes, 2010; Trappenberg et al., 2001).This account explains that visual stimuli induce peaks of activity in a saccade map, possibly situated in the intermediate layers of the superior colliculus (Schall, 1991). If these signals originate from locations relatively close together, they overlap and conjoin, such that in the absence of target information, eye movements tend to be directed towards the weighted average of the signals. When target information is obtained over time, the peak associated with the target strengthens relative to the peak associated with the distractor. As a result, eye movements become more target-directed and thus the global effect less pronounced. Indeed, the current results confirm that target information is required to prevent the eyes from being directed towards the middle of the object pair. It was only in the no-delay condition of TEM, the condition in which the identity of the target was revealed prior to the first saccade, that the global effect was diminished. Importantly, this finding also suggests that identity information is preserved over eye movements and continuously modulates the activity in the retinotopic saccade map.
The present results are different from those found by Zelinsky et al. (1997). Zelinsky et al. observed sequences of eye movements that were aimed in between objects, even though objects were presented without any delay. Importantly, in contrast to the current stimuli, Zelinsky et al. employed real-world objects. Therefore, whereas the identity information obtained prior to first eye movements sufficed to discriminate the target from the distractor in the present experiments, this was not the case in Zelinsky et al. In this respect, the difference in findings between ours and those obtained by Zelinsky et al. leads to the same conclusion: the global effect primarily arises from uncertainty about a target’s identity rather than insufficiently resolved location information.

This research was partly financed by NWO (ORA grant 464-11-015 to M. Donk).

Despite evidence from a variety of attenuated

Despite evidence from a variety of attenuated alphaherpesviruses suggesting that mutations within ICP4 may be a causative factor driving attenuation of the virus, the two recombinant viruses tested containing high frequency candidate SNVs within ICP4 did not cause any reduction in virulence of MDV, although the Mut ICP4-2 recombinant virus did fail to transmit Lomustine horizontally to contact birds. Recombinant MDV viruses that are virulent and induced MD in challenged Lomustine but failed to transmit horizontally to cause MD in contact birds have been previously reported for mutations in UL44 (gC) and UL13 (protein kinase) (Jarosinski et al., 2007; Jarosinski and Osterrieder, 2010), as well as with a recombinant virus with a point mutation within LORF2 (Hildebrandt et al., 2014). One possible explanation for the failure of Mut ICP4-2 to infect contact birds is due to lower levels of in vivo replication at days 7 and 14, during the times traditionally classified as early cytolytic and latent phases of infection (Baigent and Davison, 2004). The lowest virus load among the three time points was seen during the transition between the early cytolytic phase to latency (7dpi) for Mut ICP4-2. This could affect transmission of the recombinant virus because as chickens mature they develop an age-related resistance towards MD. Therefore, young chicks are most susceptible to MDV infection and due to a decrease or delay in shedding of virulent MDV by Mut ICP4-2, the potential for transmission and infection to older contact birds would decrease (Jarosinski et al., 2007). Alternatively, these mutations within ICP4 may impair replication within the feather follicles, leading to an inability to spread through shed feather dander. Despite the indication that mutations within ICP4 appear to be correlated with attenuation in a multitude of alphaherpesviruses, recombinant viruses containing point mutations within ICP4 show that mutations within ICP4 alone are not sufficient for attenuation in MDV. This conclusion is supported by experiments using the Oka vaccine strain of VZV in which transactivation of downstream promoters regulated by ICP4 was compared between mutated versions of ICP4 from the vaccine strain versus the parental virus. Cohrs et al. (2006) established that regulation and transcription of downstream promoters between the mutated and wild-type ICP4 were comparable, leading to their conclusion that mutations within ICP4 alone are not sufficient to cause attenuation.
Mutations within the VZV Oka vaccine strain did not affect transactivation of viral promoters, but it is known that ICP4 contains different regions with specific functions in addition to transactivation, such as DNA binding, nuclear localization, and regulation of late genes (Wyrwicz and Rychlewski, 2007). Therefore, we sought to computationally determine what function observed mutations within MDV ICP4 may impact, particularly those within amino acids 60–63, which contained mutations in three completely attenuated MDV replicates via sequence comparisons to other alphaherpesviruses. Alignment of the complete amino acid sequence of ICP4 revealed significant variation among alphaherpesviruses, which has previously been described. It is known that certain regions of ICP4, such as regions 2 and 4, are highly conserved among herpesviruses, while other regions are not particularly well conserved among species, such as regions 1, 3 and 5 (Wyrwicz and Rychlewski, 2007; McGeoch et al., 1986). Specifically, comparisons among genera show that Mardiviruses have a significantly longer ICP4 of approximately 2173 amino acids in length compared to the average length of 1500 amino acids for non-Mardiviruses. Furthermore, in our attenuated MDV replicates containing several high frequency mutations around amino acids 60–63, these mutations occur within a region found uniquely in MDV yet absent in other closely related Mardiviruses. Considering that MDV is not only virulent, but is also an oncogenic virus, unlike all other alphaherpesviruses which do not cause tumors, it is difficult to predict what role these unique regions in MDV ICP4 provide during the life cycle of this oncogenic herpesvirus, particularly in light that closely related apathogenic Mardiviruses lack this commonly mutated region of ICP4.

Potential correlations between in vitro findings in apoptosis assays and

Potential correlations between in vitro findings in apoptosis assays and the biological role of apoptosis during in vivo infections must be made cautiously. Nevertheless, it is possible to speculate that the presence of specific Ab at the time of MAP infection could locally promote apoptosis in the macrophages of the intestinal mucosa. Taking into account that intracellular viability of mycobacteria has been demonstrated to decrease in apoptotic cells (Keane et al., 2000) and that apoptosis favors cross-presentation of mycobacterial antigens potentiating T cells response (Winau et al., 2006), the increase in apoptosis induced by Ab might be beneficial in the in vivo response to infection. Indeed, the idea of developing a pro-apoptotic vaccine has been proposed as an alternative for improving tuberculosis control (Behar et al., 2011). In this sense, evidences consistent with a beneficial role of apoptosis in JD infection have been described in deers. BMDM from JD-resistant red deers showed significantly higher apoptosis rates than cells from susceptible animals, when infected ex vivo with MAP (Dobson et al., 2013).
In summary, in this work we provide evidence of a pro-apoptotic effect of buy ambroxol hydrochloride in an in vitro infection model of bovine macrophages with MAP. Collectively, the findings reported herein and in our previous works (Mundo et al., 2008; Jolly et al., 2011) suggest an active role of specific antibodies that might be proposed as beneficial for the host in the MAP–macrophage interaction. Whether the induction of an early potent specific antibody response could serve for JD protection needs to be further elucidated.

Conflict of interest statement

We gratefully thank PhD Daniela Ureta and Vet. Bárbara Fernández for their helpful technical assistance in flow cytometry and serum ELISA assays, respectively. This work was financially supported by Agencia Nacional de Promoción Científica y Técnica (BID PICT 2010-2672) and Universidad de Buenos Aires (UBASeCyT 20020100100912, 20020130100607BA).

Contagious bovine pleuropneumonia (CBPP) is a respiratory disease of cattle caused by Mycoplasma mycoides subsp. mycoides (Mmm) and listed by the World Organization for Animal Health (OIE, 2014) as one of the most economically important livestock diseases in Africa.
Currently, a live attenuated culture of the causative organism strain T1/44 is used as a vaccine of choice. Although it confers some level of immunity, the T1/44 vaccine has certain drawbacks that include low efficacy (Thiaucourt et al., 2000) and a short duration of immunity. Further, the vaccine causes adverse post-vaccinal reactions at the site of inoculation leading to poor acceptance by farmers (Kusiluka and Sudi, 2003; Sori, 2005). Finally, the vaccine has poor stability (short shelf life), hence the requirement for a cold chain during delivery (Rweyemamu et al., 1995) and there is the possibility of reversion to virulence (Mbulu et al., 2004). For this reason, an efficient inactivated vaccine would be a useful addition to the existing prophylactic measures.
Vaccinations using inactivated vaccines have been successful in a number of mycoplasma diseases including contagious agalactia (Buonavoglia et al., 2008) and contagious caprine pleuropneumonia (Rurangirwa et al., 1987). Similar trials for CBPP with a saponin-inactivated vaccine (Nicholas et al., 2003) and with an Immunostimulating Complex (ISCOM) formulation (Hübschle et al., 2003) have not yielded success.
The inactivation method and quantity of mycoplasma administered may play an important role. Inactivation by heat or by sodium hypochlorite can substantially alter the antigens from Mycoplasma agalactiae and hence reduce the immunogenicity (Tola et al., 1999). However, two doses of 20ml at a protein concentration of 14.5mg/ml of heat inactivated mycoplasma formulated with a suitable adjuvant induced immunity against CBPP (Gray et al., 1986). This suggests that mycoplasma may have to be present in large numbers, either alive or dead, to induce a sufficient protective response and confirms that an inactivated vaccine can confer immunity. Protection by the live T1 strain of Mmm has also been shown to be dose dependent, with a low dose of 105 mycoplasma conferring low protection, while there was no significant difference between doses of 107 and 109 (Gilbert and Windsor, 1971; Masiga et al., 1978; Thiaucourt et al., 2000).