La présente recherche porte sur la relation entre les symptômes dépressifs maternels prénataux et postnataux et la détresse face aux limitations du nourrisson. L'objectif de cette étude est d'examiner comment les symptômes dépressifs pré et postnataux influencent la détresse face aux limitations du nourrisson nés de jeunes mères à risque, tout en contrôlant pour l'anxiété maternelle et le sexe de l'enfant. L'échantillon utilisé aux fins de cette recherche comporte 102 dyades mère-enfant issus d'un projet plus vaste. Une première visite a eu lieu à cinq mois de grossesse et la seconde visite a eu lieu environ huit mois après l'accouchement. En examinant simultanément les contributions de la dépression prénatale et postnatale à la détresse face aux limitations dans une analyse de régression, il est possible de voir que la dépression prénatale a un plus grand effet sur la détresse face aux limitations que la dépression postnatale.

With the advent of digital imagery and its wide spread application in all vistas of life, it has become an important component in the world of communication. Video content ranging from broadcast news, sports, personal videos, surveillance, movies and entertainment and similar domains is increasing exponentially in quantity and it is becoming a challenge to retrieve content of interest from the corpora. This has led to an increased interest amongst the researchers to investigate concepts of video structure analysis, feature extraction, content annotation, tagging, video indexing, querying and retrieval to fulfil the requirements. However, most of the previous work is confined within specific domain and constrained by the quality, processing and storage capabilities. This thesis presents a novel framework agglomerating the established approaches from feature extraction to browsing in one system of content based video retrieval. The proposed framework significantly fills the gap identified while satisfying the imposed constraints of processing, storage, quality and retrieval times. The output entails a framework, methodology and prototype application to allow the user to efficiently and effectively retrieved content of interest such as age, gender and activity by specifying the relevant query. Experiments have shown plausible results with an average precision and recall of 0.91 and 0.92 respectively for face detection using Haar wavelets based approach. Precision of age ranges from 0.82 to 0.91 and recall from 0.78 to 0.84. The recognition of gender gives better precision with males (0.89) compared to females while recall gives a higher value with females (0.92). Activity of the subject has been detected using Hough transform and classified using Hiddell Markov Model. A comprehensive dataset to support similar studies has also been developed as part of the research process. A Graphical User Interface (GUI) providing a friendly and intuitive interface has been integrated into the developed system to facilitate the retrieval process. The comparison results of the intraclass correlation coefficient (ICC) shows that the performance of the system closely resembles with that of the human annotator. The performance has been optimised for time and error rate.

Face recognition is the problem of identifying individuals in images. This thesis evaluates two methods used to determine if pairs of face images belong to the same individual or not. The first method is a combination of principal component analysis and a neural network and the second method is based on state-of-the-art convolutional neural networks. They are trained and evaluated using two different data sets. The first set contains many images with large variations in, for example, illumination and facial expression. The second consists of fewer images with small variations. Principal component analysis allowed the use of smaller networks. The largest network has 1.7 million parameters compared to the 7 million used in the convolutional network. The use of smaller networks lowered the training time and evaluation time significantly. Principal component analysis proved to be well suited for the data set with small variations outperforming the convolutional network which need larger data sets to avoid overfitting. The reduction in data dimensionality, however, led to difficulties classifying the data set with large variations. The generous amount of images in this set allowed the convolutional method to reach higher accuracies than the principal component method.

Thesis (PhD (Surgical Sciences))—University of Stellenbosch, 2007. / Aims: The goal of this study was to identify arterial variations by cadaveric dissection, in the forehead, in order to validate the practicality and implementation of planned forehead flaps and to increase the safety of forehead flaps in plastic and reconstructive surgery. Hypothesis tested: Unique frontal forehead flaps can be safely based on anatomical dissection and on the presence of the central vein and the anastomosing branches of the frontal ramifications of the angular artery (AA). Materials & methods: The study had two strategic components: an anatomical cadaveric study and a clinical study, based on the newly described forehead vasculature. The anatomical study consisted of a) dissection of 30 latex infused cadavers and 20 non-latexed cadavers; b) histological assessment of forehead vasculature of 20 cadavers. The clinical applicability study consisted of a cohort of 12 plastic and reconstructive surgery cases, undergoing nasal rhinoplasty, based on the cadaveric study and anatomical vasculature. The research was conducted within an ethical protocol and all patients gave informed consent. The follow-up period is 2 years. Results: In the cadaveric dissection, the following vessels, relevant to forehead flaps and nasal reconstruction, were consistently identified: DNA, FBSTA, STrA, TFA, AA, CA, CV, PCA, SOA and OV. Side branch analysis of STrA (N = 43) showed: MCB (60%), LCB (23%), SPA (26%), OB (19%), single VB (47%), medial and lateral VB (53%). Side branches of the supra-orbital artery (SOA) were: LRB (91%), OB (91%), VB (100%), MB (44%), BB (5%) and SVB (9%). Side branch profile of the angular artery (AA) was: DNA (96%), CB (67%) and PCA (47%). In 71% of cases the origin of the PCA was from the angular artery (AA). Individual artery side branches of the forehead were as follows: STrA (9), SOA (6), FBSTA (4), DNA (4), AA (3/4), CA (2) and PCA (2). Average diameter of the small arteries at point of entry ranged from 1 – 2mm (CA < 1mm, PCA < 1mm). The central vein was a constant finding in all dissections and an important landmark. Other constant veins detected included the nasofrontal, ophthalmic, angular, supra-trochlear and facial veins. Twelve prospective randomized patients met inclusion criteria for nasal flap reconstruction, based on the cadaveric vascular study. Race profile was white (6), mixed (4) and black (2). There were 8 males and 4 females. Disease demographics included cancer (6; melanoma 2, basal cell cancer 5), trauma (3), infections (1) and congenital (1). Post-operative grading was as follows: defects corrected (12/12), subjective improvement (12/12), objective improvement (12/12), partial flap necrosis (1/12) and secondary interventions (debulking or revision 2/12). Doppler assessment for pedicle vasculature showed identification of the following arteries: TFA (85%), STrA (65%), PCA (20%) and AA (25%). Doppler studies further indicated the following small side branches: TFA (49%), STrA (30%), PCA (9%), AA (12%). The central vein was identified in 9/12 (75%) by macroscopic examination. In one female with a basal cell carcinoma (BCC), modest dermal stock loss was demonstrated by the application of high frequency dermal ultrasound (Dermascan®). The results of the cadaveric anatomy study show the existence of various important subtle arterial variations in the forehead that are not described in the literature. Many arterial side branches not clearly named and others not described before, were highlighted in this anatomical study. Other observations regarding the anatomical relationships of the forehead nerves were of practical surgical value, the most important being to reduce sensory neuropraxia. The histological study endorsed the cadaver dissection observations and showed the importance of the flap vasculature at the proximal level of the pedicle. The clinical study with follow-up period of 24 months, illustrates an evolving refinement in surgical technique based on the findings of the anatomic vasculature study. A new method of planning a “2500-year-old operation” was confidently developed based on the anatomical vasculature observations detected during the cadaver study. The Doppler study suggests that crude arterial variations of the central forehead, in the region of the intended flap pedicle, can not be diagnosed and highlighted accurately pre-operatively. The macroscopic anatomy of the central vein (clinical landmark) is an accurate predictor of underlying arterial variations and may be more valuable clinically than the hand-held Doppler examination. Conclusion: Comprehensive vascular anatomical detail of the forehead was not described accurately or completely by clinical anatomists in the past and does not appear in classic text books of anatomy and morphology. This has led to one-dimensional (arterial) application of the midline forehead flap planning and eventually the introduction of the para-median forehead flap, which has become the modern “work horse” of forehead flaps for nasal reconstruction. Now that in a definitive cadaveric study of the forehead blood supply has been demonstrated, the results show that surgeons will once again be able to embrace the midline forehead flap, only this time there will be possibly no inconsistent descriptions of unnamed blood vessels or ill-defined landmarks for flap planning. New flaps and reconstructive options in or around the forehead will be hopefully planned and executed more effectively and safer based on a more comprehensive understanding of the forehead anatomy and vasculature. The subjective and objective end-point analysis of the clinical study show favourable measured outcomes in the interim follow-up period (24 months) and benefit to the patients, in the presence of a low percentage of flap loss (1/12; 8.3%). The use of pre-operative Doppler assessment helped with flap planning. In one patient, the application of high frequency ultrasound facilitated long term follow-up regarding recurrent tumour formation and enhancement of dermal consistency with anti-aging creams, vitamin A derivations and sunscreens. Recommendations: The classic anatomy text books and clinical plastic surgery works with their inconsistent descriptions of the central forehead blood supply (arterial and venous) need to be updated. The evolution of the midline forehead flap method is far from complete. The refinement of the one-stage midline forehead flap method without an island is in progress and can clinically be implemented, based on a sound anatomical dissection study.

published_or_final_version / Biochemistry / Master / Master of Philosophy

published_or_final_version / abstract / Biochemistry / Master / Master of Philosophy

Sleep deprivation has been studied for over a century, providing knowledge about the benefits of sleep for many physiological, cognitive, and behavioural functions. However, there have only been anecdotal indications about what a tired or sleep-deprived person looks like, despite the fact that appearance influences not only how other people perceive a person but also how they evaluate them and behave towards them. How someone with sleep loss is perceived and evaluated by others is the focus of this thesis. Facial photographs of 48 participants were taken after normal sleep and after either one night of total sleep deprivation or two nights of partial sleep deprivation. The photographs were then evaluated in four different studies by a total of 288 raters recruited from universities and the general public in Stockholm, Sweden. The faces were rated on attractiveness, health, tiredness, sleepiness, sociability, trustworthiness, employability, and leadership ability. These factors were all adversely affected by sleep loss. Furthermore, looking tired was strongly related to being less attractive, looking less healthy and less trustworthy, and being perceived as a poorer employee and leader. One of the studies assessed facial features commonly associated with looking tired, showing that sleep deprivation results in eyes which appear more swollen and red, with dark circles and hanging eyelids, as well as paler skin with more fine lines and wrinkles. When sleep deprived, people were also perceived as more sad. In conclusion, the four studies show that sleep loss and a tired appearance affect how one is perceived by other people. These perceptions may lead to negative evaluations in interpersonal situations, both personal and professional. This thesis thus demonstrates social benefits of prioritizing sleep, adding to the physiological, cognitive, and behavioural research on sleep loss. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.</p>

<p>Women outperform men in face recognition and are especially good at recognizing other females’ faces. This may be caused by a larger female interest in faces. The aims of this study were to investigate if women were more interested in female faces and if depth of friendship was related to face recognition. Forty-one women and 16 men completed two face recognition tasks: one in which the faces shown earlier had been presented one at a time, and one where they had been shown two and two. The Network of Relationships Inventory was used to assess depth of friendships. As hypothesized, but not statistically significant, women tended to recognize more female faces when faces were presented two and two. No relationships were found between depth of friendships and face recognition. The results gave some support for the previously untested hypothesis that interest has importance in women’s recognition of female faces.</p>

Face recognition involves a number of complex cognitive processes, including memory, executive functioning, and perception. A breakdown of one or more of these processes may result in false facial recognition, a memory distortion in which one mistakenly believes that novel faces are familiar. This study examined the cognitive mechanisms underlying false facial recognition in healthy older and younger adults, patients with frontotemporal dementia, and individuals with congenital prosopagnosia. Participants completed face recognition memory tests that included several different types of lures, as well as tests of face perception. Older adults demonstrated a familiarity-based response strategy, reflecting a deficit in source monitoring and impaired recollection of context, as they could not reliably discriminate between study faces and highly familiar lures. In patients with frontotemporal dementia, temporal lobe atrophy alone was associated with a reduction of true facial recognition, while concurrent frontal lobe damage was associated with increased false recognition, a liberal response bias, and an overreliance on "gist" memory when making recognition decisions. Individuals with congenital prosopagnosia demonstrated deficits in configural processing of faces and a reliance on feature-based processing, leading to false recognition of lures that had features in common from study to test. These findings may have important implications for the development of training programs that could serve to help individuals improve their ability to accurately recognize faces.

No description available.