Head-to-head addition

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Effect of Head-to-Head Addition in Vinyl Acetate Controlled Radical Polymerization: Why Is Co(acac) 2 -Mediated Polymerization so Much Better?

Effect of Head-to-Head Addition in Vinyl Acetate Controlled Radical Polymerization: Why Is Co(acac) 2 -Mediated Polymerization so Much Better?

The NMR analysis of PVAc made by Co(acac) 2 -mediated radical polymerization confirmed the presence of the expected fraction of inverted monomer units resulting from head-to-head addition in free radical polymerization. Therefore, the reason for the excellent level of control observed in VAc polymerization until high degrees of polymerization when using this controlling agent must be a rapid reactivation of the dormant species of the latent primary radical, with a rate not too much smaller than the reactivation of the latent secondary radical. This situation contrasts with that of the dormant species in ATRP, ITP, TERP and to a certain extent also RAFT. Alkylcobalt(III) complexes that can be taken as models of each type of dormant species are presently unavailable. Therefore, information on any difference in the reactivation rate is not at reach from experimental investigations. Useful information can only be gathered from theoretical calculations.
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Contribution of Different Elements of Inclined Trash Racks to Head Losses Modeling

Contribution of Different Elements of Inclined Trash Racks to Head Losses Modeling

Abstract: Low bar spacing trash racks have been widely investigated in order to guide fish toward bypasses. In addition to this biological function, the formulae to predict head losses, for hydropower plants, are still being discussed. This paper investigates and models the global head losses generated by inclined trash racks with six different bar shapes and two different supports, in an open channel for six angles and two low bar spacings. The girders that supported the trash racks were U-shaped and different profile shapes. In addition to the previously studied rectangular and “hydrodynamic” bars, four new bar shapes, combining different leading and trailing edges, were investigated. Water depths were measured upstream and downstream of the rack for each configuration, and head loss coefficients were characterized and modeled. Three of these new bar shapes generated lower head losses than the hydrodynamic bar shape. The most efficient bar profile reduced the shape coefficient by 40% compared to the hydrodynamic profile and by 67% compared to the conventional rectangular profile. Concerning the supports, the use of a profiled girder to replace a conventional U-shaped girder also significantly reduced the head losses. The addition of the girder effect in a global formula increased its accuracy in predicting head losses of inclined trash racks upstream of hydropower plants.
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Right ventricular diastolic function in aging: a head-to-head comparison between phase-contrast MRI and Doppler echocardiography

Right ventricular diastolic function in aging: a head-to-head comparison between phase-contrast MRI and Doppler echocardiography

resolution which has a major impact on the measurement of peak velocities, or also the fact that PC-MRI measurements are based on velocities perpendicular to a 2D plane while Doppler echocardiographic measurement is based along a unidirectional beam; 2) inherent challenges to image the RV because of the irregular shape including for proper alignment between slice or beam positioning and the flow or myocardial motion direction; 3) physiological differences between the two non-simultaneous exams, including free breathing vs. breath-holding which can have an impact on diastolic function; 4) patient body size which might technically affect echocardiographic more than MRI measures. This might be corroborated by the fact that MRI-to-MRI associations were stronger than echocardiography vs. MRI when comparing RV and LV diastolic function indices, which further demonstrated the reliability of our measurements. Indeed, as expected, parallel changes in RV and LV diastolic function were observed in our healthy population. In addition, differences between MRI and Doppler echocardiography were toned down on the LV with a less complex geometry when compared to the RV. Despite the fair correlation between PC-MRI and echocardiography, associations of RV diastolic function indices as assessed by both imaging modalities with age were in line with previous echocardiographic findings [24–28], and consistent with the knowledge on LV filling and relaxation that has been extensively reported in both MRI and echocardiographic literature [29, 30]. Indeed, we found a decrease in tricuspid early filling wave E and myocardial longitudinal peak velocity E’, as the myocardium might stiffen with aging due to changes in its composition, as well as an increase in A wave, reflecting a compensatory contribution of the right atrium to maintain appropriate RV filling. This resulted in a significant decrease in E/A and a slight increase in E/E’ ratios. Such associations with age were slightly stronger for PC-MRI indices when compared to echocardiography.
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DPP-4 inhibitors in the management of type 2 diabetes: A critical review of head-to-head trials.

DPP-4 inhibitors in the management of type 2 diabetes: A critical review of head-to-head trials.

with HbA1c levels < 7% (53 mmol/mol) by 15-20% when added to pioglitazone, without increasing hypoglycaemic episodes and with minimal weight increases (Table 3). All these studies compared the effect of adding a DPP-4 inhibitor vs a placebo [52-58]. Only one study used an active comparator instead of a placebo to evaluate the DPP-4 inhibitor added to TZD. In this controlled trial, the effects of the addition of sitagliptin (100 mg once a day) or metformin (850 mg twice a day) to pioglitazone monotherapy in poorly controlled T2DM patients showed improvements in HbA1c, fasting plasma glucose and postprandial glucose levels with both interventions. However, metformin also led to a decrease in body weight, and to faster and better improvements in insulin resistance and inflammatory state parameters, even though sitagliptin led to better protection of β-cell function. However, an important limitation of the study was that the dose of piogliazone was different between the two arms (15 mg with metformin and 30 mg with sitagliptin; Table 3) [59]. In another study from the same group, a pioglitazone plus vildagliptin combination was more effective in preserving β-cell function, and reducing insulin resistance and inflammatory state parameters, despite similar improvements in glucose control parameters compared with the glimepiride plus vildagliptin combination [60].
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Radial head arthroplasty: a historical perspective

Radial head arthroplasty: a historical perspective

when compared to RH resection. Similarly, Cherry et al. [21] proposed a second RHP design in 1953, composed of acrylic resin, to prevent proximal translation of the radius and its related consequences; its use was, however, quite limited at that time. Twenty years after Speed’s first caps (1953), Taylor and O ’Connor [ 22] reported that half of patients treated for RH fractures with excision presented with distal radio-ulnar joint (DRUJ) symptoms. Subsequent to this report [22], RHPs became the treatment of choice to avoid distal radio-ulnar joint subluxation related to RH resection. The first long-term results of Vitallium caps were published in 1964 and resulted in sim- ilar clinical outcomes as patients treated with RH resection, in addition to decreased prono-supination among patients receiv- ing caps [23]. As the use of RHPs was becoming more wide- spread, Creyssel and De Morgues [24] changed the material of the ferrule to nylon in order to increase elasticity and lessen stress on the humeral condyle; its use remained however quite rare.
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Effect of head posture on phonation of French vowels

Effect of head posture on phonation of French vowels

In the first works dedicated to articulatory mod- eling carried out with X-ray images, speakers were sitting and adopting a fairly natural position to pro- duce speech. More recent articulatory data are ac- quired with MRI in a supine position, and the head posture is largely dictated by the position of the MRI antenna and foam, which is used to prevent it from moving during acquisitions. Consequently, the position of the head is not natural, and above all it can vary significantly between two acquisi- tions, and a fortiori between two machines. The articulatory models that can be derived from those data implicitly incorporate the head posture. Exper- iments carried out to fit dynamic MRI data of one speaker with an articulatory model built for a ref- erence speaker have shown that the adaptation pro- cedure fails to approximate the whole vocal tract. More precisely, it turned out that the tongue can be fitted fairly well, which is not the case for the pha- ryngeal cavity whose width deviates from what is predicted by the model. In addition, this deviation is likely to change the acoustic properties of speech, and formant frequencies in particular.
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Head tracking and flagellum tracing for sperm motility analysis

Head tracking and flagellum tracing for sperm motility analysis

Index Terms— object detection, object tracking, flagellum trac- ing, sperm motility analysis, confocal microscopy 1. INTRODUCTION Sperm quality assessment plays an important role in human fertility and animal breeding. One of the most important attributes for evalu- ating semen quality is sperm motility, according to the World Health Organization (WHO) report [1]. When performed manually, semen analysis based on sperm motility is labor-intensive and subject to intra- and inter-observer variability. Computer-assisted sperm anal- ysis (CASA) systems, in contrast, provide rapid and objective semen fertility assessment. In addition, they also offer a means of statisti- cal analysis that may not be achieved by visual assessment. Hence, automated sperm motility analysis systems are highly desirable.
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Speech, gaze and head motion in a face-to-face collaborative task

Speech, gaze and head motion in a face-to-face collaborative task

Two subjects are seated on chairs at opposite sides of a table. The table contains two identical designated areas, one on either side of the middle line between the subjects. An area consists of 9 slots in a row: each slot has one of the symbols {A,I,O}, each three slots (A,I,O) have the same color {red, green, or blue}. 9 cubes are placed in the slots of one of the two areas. Each cube shows a label, a letter from {P,T,B,D,G,M,N,F,S}, on that side facing the subject (informant) who is sitting close to the cubes. The informant has access to the labels of the cubes but only the other subject (manipulator) is allowed to modify the environment, i.e. to move cubes. Each move starts with a quasi-random pause of the control script that aims to establish mutual attention. Then the computer informs the manipulator confidentially by earphones about the label of one cube to be moved. Then the manipulator tells the label to the informant in order to request the position of the cube. The informant searches among the cubes and tells the symbol and color of the slot where the requested cube is located. Then the manipulator takes the cube, places it on the opposite field in the area close to herself and completes the move by pressing a mouse button. See Figure 1 for a snapshot of the game during a move. 72 of these moves are completed, arranged in 12 rounds of 6 moves. The role assignment (who is informant and who is manipulator) is changed during the experiment as well as the condition (with or without dark glasses).
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Influence du « head-tracking » sur l’externalisation en écoute binaurale non-individualisée

Influence du « head-tracking » sur l’externalisation en écoute binaurale non-individualisée

-­‐  Baskind,  A.,  Carpen7er,  T.,  Noisternig,  M.,  Warusfel,  O.,  &  Lyzwa,  J.  M.  (2012).  Binaural  and  transaural  spa7aliza7on  techniques  in  mul7channel  5.1  produc7on.  In  27th  Tonmeistertagung,  VDT  Interna7onal  Conven7on.   -­‐  Brimijoin,  W.  O.,  Boyd,  A.  W.,  &  Akeroyd,  M.  A.  (2013).  The  contribu7on  of  head  movement  to  the  externaliza7on  and  internaliza7on  of  sounds.  PloS  one,  8(12),  e83068. References F(1,25) = 5.69; p = 0.025
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Computing Camera Positions from a Multi-Camera Head

Computing Camera Positions from a Multi-Camera Head

/ La version de cette publication peut être l’une des suivantes : la version prépublication de l’auteur, la version acceptée du manuscrit ou la version de l’éditeur. Access and use of [r]

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Modelling and simulation of an harvester head mechanism

Modelling and simulation of an harvester head mechanism

3 Delimbing model 3.1 Analytical formulation Unlike many cutting studies based on the type and the section of a chip for several machining operations, it is not possible in the studied case to define a chip, since the “chip” is the whole branch. The lack of cutting model rep- resentative of delimbing operation in literature confirmed the need to develop an original predictive cutting force model. The geometry of the cutting situation is defined on the basis of McKenzie [ 5 ] approach. In this notation, two angles are used to define cutting process. The first one is formed by the cutting edge with the grain direc- tion, the second one by the cutting speed direction with the grain direction. Delimbing can thus be considered as a 90 ◦ –90 ◦ orthogonal cutting process, sometimes called cross-cutting. In the same way, chipping can follow the same definition. The work from [ 6 ] is adapted to define the cutting situation, as presented in Figure 12 .
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Fusarium Head Blight resistant Canadian wheat through genomics

Fusarium Head Blight resistant Canadian wheat through genomics

Archives des publications du CNRC For the publisher’s version, please access the DOI link below./ Pour consulter la version de l’éditeur, utilisez le lien DOI ci-dessous. Access and use of this website and the material on it are subject to the Terms and Conditions set forth at

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A 3-D display head-set for personalized computing

A 3-D display head-set for personalized computing

and new techniques in computer graphics: small portable video display, transmitter and receiver; write-once optical video disc recorder; a magnetic position sensor, and [r]

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AUTOMATIC PLACEMENT OF THE HUMAN HEAD THANKS TO ERGONOMIC AND VISUAL CONSTRAINTS

AUTOMATIC PLACEMENT OF THE HUMAN HEAD THANKS TO ERGONOMIC AND VISUAL CONSTRAINTS

This article aims to create automatic placement and trajectory generation for the head and the eyes of a virtual mannequin. This feature allows the engineer using off-line programming software of mannequin to quickly verify the usability and accessibility of a visual task. An inverse kinematic model is developed taking into account the joint limits of the neck and the eyes as well as interference between the field of view and the environmental objects. This model uses the kinematic redundancy mechanism: the head and eyes. The resolution algorithm is presented in a planar case for educational reasons and in a spatial case.
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Radial head replacement in adults with recent fractures

Radial head replacement in adults with recent fractures

MRI is effective in detecting capitellar cartilage injuries. 5. Classifications The first widely accepted classification was developed by Mason in 1954 based on 100 radial head fractures treated operatively or non-operatively and re-evaluated after more than 2 years [16] . Three fracture types that require different therapeutic approaches were distinguished: Type I, non-displaced marginal fissure or fracture; Type II, displaced marginal fracture with separation or impaction; and Type III, displaced comminuted fracture involving the entire radial head ( Fig. 9 ). Subsequently, Broberg and Morrey added a type IV defined as a radial head fracture combined with elbow dislocation [17] .
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Pilot’s head tracking as a proxy for gaze tracking

Pilot’s head tracking as a proxy for gaze tracking

1 Peysakhovich, Vsevolod, et al. “The neuroergonomics of aircraft cockpits: the four stages of eye- tracking integration to enhance flight safety.” Safety (2018) [2] LaValle, Steven M., et al. “Head tracking for the Oculus Rift.” 2014 IEEE International Confer- ence on Robotics and Automation. IEEE, 2014.

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Impact of head and neck cancer on partner's sociability

Impact of head and neck cancer on partner's sociability

this, however, do not cover sociability [15]. The present study is the first to show disease impact on partners’ sociability. The environment seemingly least impacted was that of solitary activities, which increased in a quarter of cases. This was counted as impaired sociability, although this is open to debate: it could be seen as necessary “time out”. Moreover, the frequency of telephone calls was not counted as part of this environment, as they seem rather to protect the partner from social isolation. Partners of patients with important disfigurement significantly increased their solitary activity, especially in couples with higher incomes. These findings were in agreement with previous studies [16], [17].
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The minimum follow-up required for radial head arthroplasty

The minimum follow-up required for radial head arthroplasty

We were able to confirm that painful loosening is the main indication for re-operation after RHA 29,30,77 which is in agreement with the findings of van Riet et al, 30 although Neuhaus et al 34 were unable to find a significant link between radiographic loosening and persistent pain. We found that the definition of painful loosening described by O’Driscoll and Herald 77 was clear and reproducible. Accord- ing to biomechanical studies, 78,79 there is an increased risk of painful loosening when using narrow or short stems. The method of anchorage (tight or loose fit, etc.) is also a risk factor. The increased rate of loosening in short-stemmed designs in Group I constituted a confounding bias for the
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Mid-term outcomes of 77 modular radial head prostheses

Mid-term outcomes of 77 modular radial head prostheses

Radiographic analysis. Radiographic results were available for all 77 patients. AP and lateral post-operative radio- graphs were used to assess alignment according to radio- capitellar congruence in both planes, overstuffing (associated or not associated with an asymmetry to the humero-ulnar interval, also called the river delta sign). 19 Assessment included the position of the stem for the stemmed components which was considered to be valgus or varus when the distal extremity apposed the lateral or medial aspect of the radial cortex, respectively, signs of periprosthetic osteolysis (Fig. 2), heterotopic ossification according to the Brooker classification, 35,36 and capitellar wear. These were noted at each post-operative review. Statistical analysis. The primary objective was a descriptive analysis of the mid-term clinical and radiological outcomes. Results were described according to the mean, standard deviation ( SD ), maximum and minimum values. Fisher’s exact test and Kruskal-Wallis tests were used to compare Table I. Characteristics of the components of the radial head arthroplasties
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Identification of scratch mechanisms on a retrieved metallic femoral head

Identification of scratch mechanisms on a retrieved metallic femoral head

In order to verify this new assumption, an algorithm sim- ulating an elementary abrasive wear process was specifically developed and applied on the experimental data file related to the severely damaged area containing large scratches with pile-up material to the sides. The basic idea of this model is that the higher the height of a peak of the profile, the lower its probability of resistance during a wear cycle. This probabil- ity of resistance is assessed assuming an exponential decay of the related probability density function, which is charac- terised by a single parameter defining the magnitude of the wear process. Finally, the probability to remove a peak at a given height is simply obtained by subtracting its probability of resistance from 1. Based on a Monte–Carlo process, the details of this algorithm which simulates the effect of an abra- sive wear process that acts continuously to remove the high- est peaks of the surface topography are reported in Appendix B . Provided an optimisation of the parameters of this ele- mentary wear model by means of a χ 2 calculation, a satisfy- ing goodness-of-fit can be obtained between the bearing area curves related to the processed data file and to the severely damaged area containing large scratches without pile-up ma- terial ( Fig. 10 ). Moreover, while the ADF of original data file is symmetric, the ADF of the processed data file is negatively skewed like the ADF related to severely damaged area con-
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