Driving style indicator using UDRIVE NDS data.

OBJECTIVE: In order to analyze specific events while driving (such as a safety critical event [SCE] or secondary task), we were interested in studying whether driving behavior was unusual around the event. An indicator characterizing driving style (driving style indicator [DSI]) was estimated for each driver by using naturalistic data. The analysis of the gap in driving style could be calculated for a specific trip or even a time window and could help characterize events: a more risky situation when DSI was above average, increase in safety margins when under average. METHODS: Lateral acceleration and longitudinal acceleration were used for DSI calculation. The first step consisted in filtering the signal acquired by the inertial measurement unit (60 Hz). The noise was filtered out with an eighth order, phase-compensated digital low-pass Butterworth filter with a cut-out frequency of 5 Hz and offsets were compensated for. The second step consisted in calculating the jerk of the acceleration in lateral and longitudinal directions for each trip. The third step summarized the distribution of these jerks for all trips of each driver. Finally, the DSI was defined as the standard deviation of this distribution. A driver was represented by lateral DSI and longitudinal DSI. RESULTS: The indicator was used on French pilot data (10 drivers) and on UK data (30 drivers) from the UDRIVE project. To assess this indicator, tests on track were conducted by professional drivers simulating two opposite driving style. The first results were promising and discriminated a smooth from a rough driving style. Indeed, in the pilot data, the classification was in accordance with our expectations and confirmed by videos. The same kind of distribution was observed in the UK data and needs to be confirmed when the UDRIVE database is complete. CONCLUSION: DSI is a new parameter that will be used to define clusters of drivers and study variation of driving parameters in each class during selected events (SCE, secondary task, etc.) in the UDRIVE project.

Corrigendum: Perceptual factors contribute more than acoustical factors to sound localization abilities with virtual sources.

[This corrects the article on p. 451 in vol. 8, PMID: 25688182.].

Benefits of cord blood collection in the prevention of post-partum hemorrhage: a cohort study.

OBJECTIVE: The aim of this study was to assess the benefit of umbilical cord drainage through cord blood collection (CBC) for the prevention of post-partum hemorrhage (PPH). METHODS: This is a retrospective cohort study based on data collected prospectively including all vaginal delivery of singletons pregnancies after 37 weeks of gestation between July 2011 and May 2013 at the Strasbourg Teaching Hospital. We performed a univariate comparison of PPH risk factors with χ(2) tests and then we built multivariate logistic regressions to predict PPH, severe PPH (>1000 cc), retained placenta over 30 min and manual removal of the placenta. RESULTS: A total of 7810 vaginal deliveries were analyzed, among which 1957 benefited from CBC (25%). In the CBC group, 71 PPH (3.6%) were observed versus 260 (4.4%) in the control group (p = 0.12). In multivariate analysis, after adjustment on PPH risk factors, CBC revealed to be a protective factor of PPH: OR = 0.69 (95% CI 0.50-0.97; p = 0.03). CBC is neither a significant predictive factor of severe PPH, time to placental delivery nor rate of manual removal of the placenta. CONCLUSIONS: In our study, CBC and thus umbilical cord drainage was a protective factor against PPH but it did reduce neither retained placenta nor the need for artificial placental delivery.

Perceptual factors contribute more than acoustical factors to sound localization abilities with virtual sources.

Human sound localization abilities rely on binaural and spectral cues. Spectral cues arise from interactions between the sound wave and the listener's body (head-related transfer function, HRTF). Large individual differences were reported in localization abilities, even in young normal-hearing adults. Several studies have attempted to determine whether localization abilities depend mostly on acoustical cues or on perceptual processes involved in the analysis of these cues. These studies have yielded inconsistent findings, which could result from methodological issues. In this study, we measured sound localization performance with normal and modified acoustical cues (i.e., with individual and non-individual HRTFs, respectively) in 20 naïve listeners. Test conditions were chosen to address most methodological issues from past studies. Procedural training was provided prior to sound localization tests. The results showed no direct relationship between behavioral results and an acoustical metrics (spectral-shape prominence of individual HRTFs). Despite uncertainties due to technical issues with the normalization of the HRTFs, large acoustical differences between individual and non-individual HRTFs appeared to be needed to produce behavioral effects. A subset of 15 listeners then trained in the sound localization task with individual HRTFs. Training included either visual correct-answer feedback (for the test group) or no feedback (for the control group), and was assumed to elicit perceptual learning for the test group only. Few listeners from the control group, but most listeners from the test group, showed significant training-induced learning. For the test group, learning was related to pre-training performance (i.e., the poorer the pre-training performance, the greater the learning amount) and was retained after 1 month. The results are interpreted as being in favor of a larger contribution of perceptual factors than of acoustical factors to sound localization abilities with virtual sources.

Amniotic fluid embolism: 10-year retrospective study in a level III maternity hospital.

OBJECTIVE: To provide updated data on amniotic fluid embolism (AFE) based on our population over a 10 year period, and to propose steps for improving current practice. STUDY DESIGN: Retrospective study carried out in the Department of Gynaecology and Obstetrics at the Strasbourg University Teaching Hospital between 1 January 2000 and 31 December 2010. Dossiers of patients with AFE were identified using medical information system programme (MISP) coding and cross-checked with the pathology reports (hysterectomy, post-mortem examination). RESULTS: Eleven dossiers were found (0.28/1000). Eight cases (73%) of AFE occurred during labour, two (18%) in the post-partum period and one (9%) outside of parturition. Induction was initiated in four patients (45%) and labour sustained with oxytocin in 9 patients (90%). Acute circulatory collapse with cardio-respiratory arrest (CRA) was the herald symptom of AFE in 2 patients, and secondary cardio-respiratory arrest occurred rapidly in 6 patients (55%) following a relatively non-indicative prodromal phase. Disseminated intravascular coagulopathy (DIC) was observed in 10 cases (91%) and massive transfusion was necessary in all patients. Seven haemostatic hysterectomies (63%) were performed, with secondary arterial embolisation in 2 cases (22%). Although all patients presented a clinical picture of AFE, confirmation through histology or laboratory test results was forthcoming in only 7 cases (63%). Three patients died (27%). When AFE occurred during labour, 8 fetuses (75%) received intensive care support. In all, 11 newborns survived (85%). Their pH was less than 7.00 in 3 cases (27%) and 4 fetuses (36%) had an Apgar score of less than 5 at 5 minutes of life. CONCLUSION: AFE is a rare but extremely serious disease. Some risk factors for AFE have been identified but they do not allow its occurrence to be predicted. The diagnosis may be supported by specific laboratory test results but only a post-mortem examination provides a pathognomonic diagnosis: unfortunately it is always retrospective. Obstetrical and intensive care management is complex and must be adapted to the situation bearing in mind the significant risk of haemorrhage and DIC. Hysterectomy must be performed if there is the least doubt.

Auditory efferents facilitate sound localization in noise in humans.

The mammalian auditory system contains descending neural pathways, some of which project onto the cochlea via the medial olivocochlear (MOC) system. The function of this efferent auditory system is not entirely clear. Behavioral studies in animals with olivocochlear (OC) lesions suggest that the MOC serves to facilitate sound localization in noise. In the current work, noise-induced OC activity (the OC reflex) and sound-localization performance in noise were measured in normal-hearing humans. Consistent with earlier studies, both measures were found to vary substantially across individuals. Importantly, significant correlations were observed between OC-reflex strength and the effect of noise on sound-localization performance; the stronger the OC reflex, the less marked the effect of noise. These results suggest that MOC activation by noise helps to counteract the detrimental effects of background noise on neural representations of direction-dependent spectral features, which are especially important for accurate localization in the up/down and front/back dimensions.

Dynamics of homemade aortic endografts: in vivo study in humans with computed tomography scanner modeling.

BACKGROUND: Several cases of aortic endograft rupture have been described. In most cases, they stem from component wear and perforation of the graft, leading to leakage. Friction of the stents on the graft can cause abrasion and perforate the textile. This friction results from movements inside the endograft implanted in the aorta exposed to blood flow, arterial pressure, and the movements of the aorta itself. METHODS: To study in vivo the movements of homemade stent grafts (HMSGs) designed and constructed by the surgeons at La Pitié Salpêtrière Hospital (Paris), the displacements of the metallic skeleton of the HMSG after implantation were measured using a dynamic CT scanner connected to the patient's ECG. The geometric structure of the HMSG was modeled using MATLAB software to specify the different displacements in the HMSG: angular displacements (A) (in degrees) at the sutures between two eyelets, radial displacements (R) (in millimeters for absolute values and percentile diameter for relative values) describing HMSG pulsation, and longitudinal displacements (L) (in millimeters) reflecting compression movements. These movements differ from the global movements of the aorta in the Windkessel wave: they are movements between the different levels of eyelets in the metallic structure. RESULTS: The results obtained were A = 4.5 + or - 1.5 degrees , R = 0.6 + or - 0.4 mm, R% = 4.2 + or - 2.4, and L = 0.4 + or - 0.2 mm. These values are the maximum displacements measured. They are located close to the junctions between the HMSG necks and body. These transition areas between the neck anchored in the aorta and the body, which not fixed in the aneurysm pouch, seem to be the areas of the maximum displacements, mainly angular and radial. On the other parts of the HMSG, displacements were less pronounced, approaching the CT scan's detection limit (0.1 to 0.2 mm). CONCLUSION: We made videos while modeling the amplitude of the displacements in the HMSG with a color code. This sequence could be a very good way to monitor the progression of HMSG displacements.

Neck strength and EMG activity in fighter pilots with episodic neck pain.

INTRODUCTION: Neck pain is common in fighter pilots due to repeated exposure to high +Gz loads, but studies comparing neck function in symptomatic and healthy fighter pilots are lacking. This study compared neck strength and EMG activity during maximal isometric contractions in a sitting position in the sagittal and coronal planes in neck pain (SP), asymptomatic fighter pilots (AP), and healthy, male, non-pilot subjects (NPS). METHODS: There were 9 SP, 10 AP, and 8 NPS, all males, who performed maximal isometric neck contractions on a specific dynamometer. Surface EMG activity was recorded bilaterally over the sternocleidomastoid and paraspinal muscles. EMG amplitude during side bending was normalized to that measured in the sagittal plane. RESULTS: SP exhibited lower side-bending strength than AP (17-19%, P < 0.05). In addition, SP and NPS exhibited lower left side-bending-to-extension torque ratios (20% and 14%, respectively, P < 0.05) than AP. Similar activation level of neck flexors and extensors during side bending was found in SP and AP, whereas EMG activity of the extensors was higher than the flexors in NPS (+48%, P < 0.05). In addition, antagonistic EMG activity was higher in AP compared to NPS (26% vs. 41%, respectively, P < 0.05). CONCLUSION: Our results suggest altered muscle function in SP compared with AP in the coronal but not in the sagittal plane. Further, AP appeared to be more efficient in the coronal plane with reference to neck extension than NPS, suggesting that some adaptations occurred due to flight exposure. These findings may have clinical implications for the management and the follow-up of neck pain in fighter pilots.

Selecting one of two regular sound sequences: perceptual and motor effects of tempo.

This study assessed the influence of tempo on selecting a sound sequence. In Exp. 1, synchronization with one of the two regular subsequences in a complex sequence was measured. 30 participants indicated a preference for the fastest subsequence when subsequences were in a slow tempo range (> or = 500 msec. IOI), and with the slower subsequence when they were in the fast tempo range (< or = 300 msec. IOI). These results were replicated using a perceptual task (Exp. 2 and 3) in which the 30 listeners had to detect a temporal irregularity in one of the two subsequences. Detection was better when the temporal irregularity was in the fastest subsequence than in the slowest one when the complex sequence was in a slow tempo range (> or = 500 msec. IOI) and the reverse was obtained when the complex sequence was in a fast tempo range (< or = 180 msec. IOI). These results have implications for design of auditory alarms.

Unattended speech processing: effect of vocal-tract length.

Rivenez et al. [J. Acoust. Soc. Am. 119 (6), 4027-4040 (2006)] recently demonstrated that an unattended message is able to prime by 28 ms a simultaneously presented attended message when the two messages have a different F0 range. This study asks whether a difference in vocal-tract length between the two messages rather than a difference in F0 can also produce such priming. A priming effect of 13 ms was found when messages were in the same F0 range but had different (15%-30%) vocal-tract length, suggesting that the processing of unattended speech strongly relies on the presence of perceptual grouping cues.

Processing unattended speech.

Three experiments examine the effect of a difference in fundamental frequency (F0) range between two simultaneous voices on the processing of unattended speech. Previous experiments have only found evidence for the processing of nominally unattended speech when it has consisted of isolated words which could have attracted the listener's attention. A paradigm recently used by Dupoux et al. [J. Exp. Psychol.: Human Percept. Perform. 29(1), 172-184 (2003)] was modified so that participants had to detect a target word belonging to a specific category presented in a rapid list of words in the attended ear. In the unattended ear, concatenated sentences were presented, some containing a repetition prime presented just before a target word. Primes speeded category detection by 25 ms when the two messages were in a difference F0 range. This priming effect was unaffected by whether the target was led to the left or the right ear, but disappeared when there was no F0 range difference between the messages. Finally, it was replicated when participants were compelled to focus on the attended message in order to perform a second task. The results demonstrate that repetition priming can be produced by words in unattended continuous speech provided that there is a difference in F0 range between the voices.

Chronology of the push pull effect on nonhuman primates-shift of the arterial pressure threshold.

Fighter pilots are frequently exposed to high Gz acceleration which may induce in-flight loss of consciousness (G-LOC). One factor reducing tolerance to accelerations is a previous exposure to negative accelerations. This phenomenon, which happens during the first few seconds after the onset of the positive plateau, is called the push pull effect. Our goal was to validate a non human primate model in order to study push pull physiological mechanisms and possible changes in arterial pressure, which may occur after the first ten seconds of the positive acceleration plateau. Eight rhesus monkeys were centrifuged in profile runs, including positive Gz accelerations (+1.4, +2 and +3 Gz) with or without previous negative Gz acceleration (-2 and -3 Gz vs. +1.4 Gz). Heart rate, blood pressure and esophageal pressure were recorded during the entire centrifugation run. Results showed that the push pull effect was observed in the non human primate model. Moreover, the reduced tolerance to acceleration lingered longer than that during the first ten seconds after exposure to +Gz acceleration. It was found that, after the fourteenth second, mean blood arterial pressure stabilizes at a lower value, when the positive acceleration is preceded by a negative acceleration (15.8 kPa for -1 Gz and 15.5 for -2 Gz vs. 16.9 for 1.4 Gz). The chronology of the push pull effect seems to involve two periods. One has a short time span. The other one has a longer time span and could be induced by shift of pressure threshold, coming from exposure to previous negative acceleration.

Judging the urgency of nonvocal auditory warning signals: perceptual and cognitive processes.

Previous research has identified acoustic properties modulating the perceived urgency of alarms. The authors conducted 3 experiments using a multidimensional approach in which participants made acoustic dissimilarity judgments and urgency dissimilarity judgments for pairs of sequences. Experiment 1 confirmed the validity of acoustic parameters in urgency perception of experimental alarms. Experiment 2 confirmed the role of these acoustic parameters with real alarms but suggested the importance of additional factors. Experiment 3 compared the relative degrees of urgency of alarms from Experiments 1 and 2, highlighting the role of both sequence structure and associated mental representation. The authors conclude that the design of alarms should not be based exclusively on acoustic factors but should also take into consideration the acquisition of an appropriate mental representation.

Physiological implications of mechanical effects of +Gz accelerations on brain structures.

BACKGROUND: In certain flight configurations, fighter pilots are exposed to high Gz acceleration (G) which may induce inflight loss of consciousness (G-LOC). When acceleration is of high amplitude, and the onset rate very rapid, G-LOC can occur extremely suddenly. HYPOTHESIS: Mechanisms other than brain hypoxia could be involved, enhancing its effects. In order to study the mechanical effects induced by such accelerations on cerebral structures, we estimated the stresses imposed on cerebral tissue when the brain is exposed to +Gz acceleration forces. METHODS: An "in vitro" experiment was performed to measure brain deformations during centrifugation. A finite element model of the brain was formulated. RESULTS: Computations indicate that traction and shear stresses are enhanced around the tentorial notch, and that compression stresses increase at the base of the cerebral hemispheres. CONCLUSION: The amplitude of these stresses is not sufficient to directly disturb proper nerve cell functioning. However, they could interfere with brain vessels as external surface forces, thus enhancing vessel collapse and brain ischemia.