The effect of added head mass during pilot ejection from an aircraft is currently being studied at the Wright Patterson Air Force Base in Ohio. The Articulated Total Body model, a FORTRAN computer program capable of simulating three-dimensional human body motion using rigid body dynamics, has been chosen to simulate the response of the head and neck to an ejection-like acceleration. The present Viscoelastic configuration of the head/neck model, which is capable of head rotation and axial neck deformation, was validated with experimental head acceleration data from live human volunteers subjected to a 10G_Z deceleration in the Vertical Deceleration Tower at Wright Patterson Air Force Base. Experimental head z-direction acceleration data from a first subject, L7, was reproduced accurately using the ATB model. However, Simulated head z-direction acceleration profiles for a second subject, B9, could not match experimental data for this subject, even after numerous variations of parameters controlling the head/neck response of the ATB model. Two of these parameters were determined to be time-varying for subject B9, and regression equations were developed describing the parameters as functions of time. Because the current ATB program does not allow time-varying parameters, the program code was modified to include two new subroutines in which the values of the parameters are calculated with each time increment. Modifications to the ATB model resulted in an improved simulated head z-direction acceleration profile for subject B9 when compared with previous simulations using constant value parameters. / Master of Science

Les réacteurs de 4ème génération ont pour objectif l’avènement d’un nucléaire durable susceptible de soutenir la transition énergétique. Anticipant un possible retard, dû à des difficultés techniques et économiques, des solutions innovantes inspirées des technologies actuelles (REP) sont à l’étude. Ces réacteurs à haute conversion nécessitent le développement d’outils académiques simples et robustes adaptés aux phases de la conception et capables :- D’évaluer les performances du combustible (burnup). Cet aspect est géré par l’environnement C++ SMURE (Serpent/MCNP Utility for Reactor Evolution), ici adapté et complété pour modéliser l’évolution du combustible à l’échelle de l’assemblage comme à l’échelle du cœur.- D’évaluer les performances de sûreté, ce qui nécessite le couplage entre la neutronique, ici approximée par la théorie de la diffusion et résolue par la NDM (Nodal Drift Method), et la thermohydraulique dont le traitement est simplifié dans le code BATH (Basic Approach to ThermalHydraulics). Le couplage NDM/BATH a fait l’objet d’une validation sur un benchmark d’éjection de grappe.Nos outils et méthodes de conception sont appliqués au dimensionnement de SMR sous-modérés à eau légère fonctionnant soit au Th/U soit au Th/Pu. Outre les critères usuels de conception (i.e. facteur de forme), il s’est avéré nécessaire, pour la crédibilité du concept, de spécifier la gestion de la réactivité, ce qui a mené au développement d’une méthodologie d’optimisation des poisons consommables. L’analyse de sûreté a permis de poser de nouveaux critères de conception, notamment sur le niveau maximal de sous-modération permettant d’éviter la crise d’ébullition nucléée. Cela a également mis en lumière les implications sur la sûreté de certains choix de conception comme le fonctionnement avec un inventaire réduit en bore soluble. / The Generation IV of nuclear reactors aims at making the nuclear energy a sustainable power source, able to contribute efficiently to the energetic transition. To anticipate the delay of this Gen. IV, innovative retro-fitted nuclear reactors with high level of conversion are studied. The conception of such reactors needs the development of a flexible and robust academical tool box in order to:- Evaluate fuel performance. This is done by means of SMURE (Serpent/MCNP Utility for Reactor Evolution), the dedicated CNRS C++ framework, which is adapted to perform burnup calculation both at assembly scale and at core scale.- Evaluate safety performance. This implies coupled transient simulation between neutronics and thermohydraulics. Neutronics is handled by the Nodal Drift Method (NDM) which solves the diffusion equations while thermohydraulics is simplified and computed by the code Basic Approach to ThermalHydraulics (BATH). This coupling between NDM/BATH has been validated on a Rod Ejection Accident (REA) benchmark.Ours tools and methods are applied on the design of sub-moderated water-cooled SMR cores using either Th/U or Th/Pu fuel. In addition to basic conception criteria such as the form factor, the reactivity management has been investigated in details, which has led to the development of a new methodology for optimal used of burnable poisons. The safety analysis against REA highlights new conceptions limits, in particular on the maximal sub-moderating ratio in order to avoid nucleate boiling. It also reveals the consequences on the reactor safety of some design choices such as low soluble boron inventory.

<p>  </p> <p><strong>Background: </strong></p> <p>Torsades de pointes (TdP) is a polymorphic ventricular tachycardia (VT) associated with heart rate-corrected QT interval (QTc) prolongation on the electrocardiogram (ECG). TdP can cause sudden cardiac arrest (SCA), a catastrophic outcome. The antiarrhythmic drugs dofetilide and sotalol can cause QTc prolongation and arrhythmias, as can more than 200 other medications available on global markets. Heart failure (HF) with reduced ejection fraction (HFrEF) is a risk factor for drug-induced TdP, and HFrEF heightens sensitivity to drug-induced QTc lengthening. However, ~55% of patients with HF have preserved, rather than reduced, ejection fraction. It remains unknown whether patients with HF with preserved ejection fraction (HFpEF) are at increased risk for drug-induced VT/SCA. Assessment of the risk of drug-induced VT/SCA in HFpEF patients is important, so that recommendations can be made regarding the safety of QTc-prolonging drugs and need for enhanced ECG monitoring in this population. </p> <p><strong>Objective:</strong></p> <p>In aim 1, we sought to determine the risk of VT and SCA associated with dofetilide and sotalol in patients with HFpEF. In aim 2, we were able to use QTc interval to determine the odds of dofetilide/sotalol-associated QT interval prolongation in patients with HFpEF. In Aim 3, we investigated the influence of HFpEF on VT and SCA associated with a broader group of drugs known to cause TdP (“known “TdP drugs”), as designated by the QT drugs list at www.crediblemeds.org. </p> <p><strong>Methods:</strong></p> <p>In aim 1, we used Medicare claims (2014-2016) and ICD-9/10 codes to identify patients taking the QT interval-prolonging drugs dofetilide or sotalol, which are used commonly in patients with HF and atrial fibrillation, as well as non-dofetilide or sotalol users among 3 groups: HFpEF, HFrEF, and no HF. Multinomial propensity score-matching was performed. Cochran–Mantel–Haenszel statistics and standardized differences were used to compare baseline characteristics. A generalized Cox proportional hazards model was used to estimate hazard ratios (HRs) and test the association of VT and SCA among dofetilide/sotalol users, HFpEF, HFrEF, and no HF.</p> <p>In Aim 2, the data source was electronic health records from the Indiana Network for Patient Care (February 2010 to May 2021). After removing patients with overlapping diagnoses of HFpEF and HFrEF, no diagnosis code, absence of QT interval records, and no validated record of using dofetilide or sotalol, we identified patients taking dofetilide or sotalol among three groups: HFrEF, HFpEF, and no HF. Cochran–Mantel–Haenszel statistics were used to compare baseline characteristics. QT interval prolongation was defined as heart rate-corrected QT (QTc) > 500 ms during dofetilide/sotalol therapy. Unadjusted odds ratios (OR) of QT interval prolongation were determined by univariate analysis, and adjusted ORs were determined by generalized estimating equations (GEE) with logit link to account for an individual cluster with different times of hospitalization and covariates.</p> <p>In aim 3, we used Medicare enrollment in fee-for-service medical and pharmacy benefits (2014 to 2016) and ICD-9/10 codes, we identified patients taking drugs known to cause torsades de pointes (TdP drugs; www.crediblemeds.org) and non-TdP drug users among three groups: HFrEF, HFpEF, and no HF. Multinomial propensity score-matching was performed to minimize baseline differences in covariates (patient demographics, comorbidities, health care utilization and drug history). Cochran–Mantel–Haenszel statistics and standardized differences were used to compare baseline characteristics. A generalized Cox proportional hazards model was used to estimate HRs and test the association of VT and SCA among TdP drug users with HFpEF, HFrEF, and no HF.</p> <p><strong>Results:</strong></p> <p>In Aim 1, VT and SCA occurred in 166 (10.68%) and 16 (1.03%), respectively, of 1,554 dofetilide/sotalol users with HFpEF, 543 (38.76%) and 40 (2.86%) of 1,401 dofetilide/sotalol users with HFrEF, and 245 (5.06%) and 13 (0.27%) of 4,839 dofetilide/sotalol users with no HF. The adjusted HR for VT in patients with HFrEF was 7.00 (95% CI 6.12-8.02) and in patients with HFpEF was 1.99 (1.71-2.32). The risk of VT associated with dofetilide/sotalol was increased across the overall study population (HR: 2.47 [1.89-3.23]). Use of dofetilide/sotalol increased the risk of VT in patients with HFrEF (HR: 1.53 [1.07-2.20]) and in those with HFpEF (HR: 2.34 [1.11-4.95]). However, while the overall risk of SCA was increased in patients with HFrEF (HR: 5.19 [4.10-6.57]) and HFpEF (HR: 2.53 [1.98-3.23]) compared to patients with no HF, dofetilide/sotalol use was not significantly associated with an increased risk of SCA.</p> <p>In Aim 2, QTc prolongation associated with dofetilide/sotalol occurred in 51.2% of patients with HFpEF, 70.1% of patients with HFrEF, and 29.4% of patients with no HF. After adjusting for age, sex, race, serum potassium and magnesium concentrations, kidney function, concomitant drug therapy, and comorbid conditions, the adjusted odds of having QTc interval larger than 500ms during the hospital stay were 5.23 [3.15-8.67] for HFrEF and 1.98 [1.17-3.33] for HFpEF with no HF as the reference group. </p> <p>In Aim 3, of 23,910 known TdP drug users with HFrEF, VT and SCA occurred in 4,263 (17.8%) and 493 (2.1%) patients, respectively. In comparison, among 31,359 known TdP drug users with HFpEF, VT and SCA occurred in 1,570 (5.0%) and 340 (1.1%) patients. VT and SCA occurred in 3,154 (0.8%) and 528 (0.1%) of 384,824 known TdP drug users without HF. The overall HR of both VT and SCA was increased in patients with HFrEF (HR: 7.18 [6.13-8.40])  and in those with HFpEF (HR: 2.09 [1.80-2.42]). The risk of VT associated with known TdP drugs was increased across the overall population (HR: 1.34 [1.20-1.51]). Use of known TdP drugs significantly increased the risk of VT and SCA in patients with HFrEF (HR: 1.34 [1.07-1.67]), but not in patients with HFpEF.</p> <p><strong>Conclusion:</strong></p> <p>HFpEF may exhibit an enhanced response to drug-associated VT, and is associated with a higher risk of drug-associated QTc interval prolongation. Further study is needed to identify methods to minimize this risk for patients with HFpEF requiring therapy with dofetilide, sotalol, or drugs known to cause TdP. </p>

Esse projeto de pesquisa teve como objetivo estudar simultaneamente as concentrações da ocitocina no líquido cefalorraquidiano (LCR) e no plasma de ovelhas multíparas durante a ordenha, estabelecendo suas possíveis correlações entre os dois compartimentos corporais, bem como em relação à produção e ejeção do leite. Para tanto, foram utilizadas 10 ovelhas multíparas (Ovis aries) da raça Santa Inês apresentado peso médio de 40 Kg. Os animais foram divididos em quatro grupos, sendo eles: ordenha mecânica exclusiva (OME; cordeiros apartados 3 dias após o parto), manejo misto com ordenha mecânica (MMom; cordeiros permanecem com as mães durante o período diurno, após a ordenha mecânica, sendo apartados durante a noite), manejo misto com ordenha manual (MMoma) e amamentação exclusiva (AE; cordeiros apartados durante o período noturno). Para a obtenção de LCR foram realizadas a punção do espaço subaracnóideo e implantação de um cateter epidural, enquanto que o plasma foi colhido com o auxílio de um scalp. As amostras de LCR e sangue foram coletadas simultaneamente antes (-0,5 min), durante (0,5; 1 e 4 min) e após (10; 15 min) a amamentação ou ordenha para posterior quantificação das concentrações de ocitocina por ensaio imunoenzimático. Foi obtido um total de 503 amostras, sendo 241 de LCR e 262 de plasma. As estimativas de média, desvio padrão, coeficiente de variação, mínimo e máximo para as concentrações de ocitocina no LCR e plasmáticas foram 257,880 ± 265,90 pg/ml; 103,11%; 11,70 pg/ml e 1000,00 pg/ml, respectivamente. A análise estatística não revelou correlação significante entre LCR e plasma para os quatros grupos experimentais avaliados. O coeficiente de correlação para os grupos OME, AE, MMom e MMoma foram, respectivamente: -0,26, -0,19, 0,05 e 0,04. Com relação ao LCR, não ocorreu diferença significante entre os 4 grupos experimentais em relação às concentrações de ocitocina. Já para o plasma, os animais do grupo MMom (679,80 ± 25,63) e MMoma (591,82 ± 30,56) apresentaram maiores concentrações plasmáticas médias de ocitocina em relação a OME e AE. Assim também, o grupo OME (381,04 ± 22,09) apresentou maior concentração média de ocitocina em relação ao grupo AE (218,82 ± 27,04). Conclui-se que, não existe correlação positiva entre as concentrações de ocitocina central e na circulação periférica durante a ordenha ou amamentação. Os padrões de liberação de ocitocina plasmática diferem de acordo com o tipo de manejo ao qual o animal é submetido, o que pode ter conseqüências para a ejeção do leite e conseqüentemente, para a produção. Finalmente, as concentrações de ocitocina presentes no LCR não sofrem influência do tipo de manejo de ordenha ao qual o animal foi submetido, ao contrário daquilo que foi observado para o plasma. / The aim of the present work was to study a possible relationship between central and peripheral oxytocin release and its consequences to milk production during milking in experimental ewes. Ten multiparous Santa Ines ewes (Ovis aries) were divided in 4 groups according to milk ejection stimuli: exclusive machine milking (OME), mixedmanagement of milking and suckling (MMom: lambs separated during night and reunited to their mother after morning milking; MMoma: mixed-management with manual milking) and exclusive suckling (AE: lambs separated also during night). Cerebrospinal fluid (CSF) was collected through a implanted sub-arachnoid catheter and plasma was collected from the jugular vein. imultaneous sampling was performed at -0.5, 0.5, 1, 4, 10 and 15 min (0 min was teat attachment to either machine or manual milking system or lamb suckling). A total of 241 samples of CSF and 262 plasma samples were processed and oxytocin concentrations were quantified by immunoenzimatic assays. Estimated means, standard deviation, variation coefficient and minimum and maximun values of CSF and plasma oxytocin concentrations were, respectively: 257.880 ± 265.90 pg/ml; 103.11%; 11.70 pg/ml e 1000.00 pg/ml. No statistical strong positive correlations (OME= -0.26, AE= -0.19, MMom= 0.05 and MMoma= 0.04) were found between CSF and plasma samples. Also, CSF was not influenced by milk ejection stimuli, although plasmatic oxytocin was higher in MMom (679.80 ± 25.63) and MMoma (591.82 ± 30.56) compared to OME and AE. In addition, OME (381.04 ± 22.09) plasmatic oxytocin concentration was higher when compared to AE (218.82 ± 27.04). In conclusion, no positive correlations between central and peripheral oxytocin concentrations were observed during milking or suckling. Plasma oxytocin oncentrations differ as a function of management and have consequences to milk ejection as well as to milk production Also, plasma, but not CSF oxytocin, was influenced by different milk ejection stimuli.

Esse projeto de pesquisa teve como objetivo estudar simultaneamente as concentrações da ocitocina no líquido cefalorraquidiano (LCR) e no plasma de ovelhas multíparas durante a ordenha, estabelecendo suas possíveis correlações entre os dois compartimentos corporais, bem como em relação à produção e ejeção do leite. Para tanto, foram utilizadas 10 ovelhas multíparas (Ovis aries) da raça Santa Inês apresentado peso médio de 40 Kg. Os animais foram divididos em quatro grupos, sendo eles: ordenha mecânica exclusiva (OME; cordeiros apartados 3 dias após o parto), manejo misto com ordenha mecânica (MMom; cordeiros permanecem com as mães durante o período diurno, após a ordenha mecânica, sendo apartados durante a noite), manejo misto com ordenha manual (MMoma) e amamentação exclusiva (AE; cordeiros apartados durante o período noturno). Para a obtenção de LCR foram realizadas a punção do espaço subaracnóideo e implantação de um cateter epidural, enquanto que o plasma foi colhido com o auxílio de um scalp. As amostras de LCR e sangue foram coletadas simultaneamente antes (-0,5 min), durante (0,5; 1 e 4 min) e após (10; 15 min) a amamentação ou ordenha para posterior quantificação das concentrações de ocitocina por ensaio imunoenzimático. Foi obtido um total de 503 amostras, sendo 241 de LCR e 262 de plasma. As estimativas de média, desvio padrão, coeficiente de variação, mínimo e máximo para as concentrações de ocitocina no LCR e plasmáticas foram 257,880 ± 265,90 pg/ml; 103,11%; 11,70 pg/ml e 1000,00 pg/ml, respectivamente. A análise estatística não revelou correlação significante entre LCR e plasma para os quatros grupos experimentais avaliados. O coeficiente de correlação para os grupos OME, AE, MMom e MMoma foram, respectivamente: -0,26, -0,19, 0,05 e 0,04. Com relação ao LCR, não ocorreu diferença significante entre os 4 grupos experimentais em relação às concentrações de ocitocina. Já para o plasma, os animais do grupo MMom (679,80 ± 25,63) e MMoma (591,82 ± 30,56) apresentaram maiores concentrações plasmáticas médias de ocitocina em relação a OME e AE. Assim também, o grupo OME (381,04 ± 22,09) apresentou maior concentração média de ocitocina em relação ao grupo AE (218,82 ± 27,04). Conclui-se que, não existe correlação positiva entre as concentrações de ocitocina central e na circulação periférica durante a ordenha ou amamentação. Os padrões de liberação de ocitocina plasmática diferem de acordo com o tipo de manejo ao qual o animal é submetido, o que pode ter conseqüências para a ejeção do leite e conseqüentemente, para a produção. Finalmente, as concentrações de ocitocina presentes no LCR não sofrem influência do tipo de manejo de ordenha ao qual o animal foi submetido, ao contrário daquilo que foi observado para o plasma. / The aim of the present work was to study a possible relationship between central and peripheral oxytocin release and its consequences to milk production during milking in experimental ewes. Ten multiparous Santa Ines ewes (Ovis aries) were divided in 4 groups according to milk ejection stimuli: exclusive machine milking (OME), mixedmanagement of milking and suckling (MMom: lambs separated during night and reunited to their mother after morning milking; MMoma: mixed-management with manual milking) and exclusive suckling (AE: lambs separated also during night). Cerebrospinal fluid (CSF) was collected through a implanted sub-arachnoid catheter and plasma was collected from the jugular vein. imultaneous sampling was performed at -0.5, 0.5, 1, 4, 10 and 15 min (0 min was teat attachment to either machine or manual milking system or lamb suckling). A total of 241 samples of CSF and 262 plasma samples were processed and oxytocin concentrations were quantified by immunoenzimatic assays. Estimated means, standard deviation, variation coefficient and minimum and maximun values of CSF and plasma oxytocin concentrations were, respectively: 257.880 ± 265.90 pg/ml; 103.11%; 11.70 pg/ml e 1000.00 pg/ml. No statistical strong positive correlations (OME= -0.26, AE= -0.19, MMom= 0.05 and MMoma= 0.04) were found between CSF and plasma samples. Also, CSF was not influenced by milk ejection stimuli, although plasmatic oxytocin was higher in MMom (679.80 ± 25.63) and MMoma (591.82 ± 30.56) compared to OME and AE. In addition, OME (381.04 ± 22.09) plasmatic oxytocin concentration was higher when compared to AE (218.82 ± 27.04). In conclusion, no positive correlations between central and peripheral oxytocin concentrations were observed during milking or suckling. Plasma oxytocin oncentrations differ as a function of management and have consequences to milk ejection as well as to milk production Also, plasma, but not CSF oxytocin, was influenced by different milk ejection stimuli.

Assessment of left ventricular (LV) function is one of the most common requests made to cardiac imaging services. This demand stems from a large body of evidence that shows abnormal LV systolic and, more recently, diastolic function has important prognostic and treatment related implications for patients with a wide range of cardiovascular diseases. The vast majority of information supporting the use of conventional measures of LV function, such as ejection fraction, originates from population studies and large clinical trials. However, the application of these measurements to individual patients is far less defined, especially when used for serial evaluation. Central to these concerns is the relative paucity of data surrounding the test-retest reliability of conventional measures in clinical settings. Newer measures of LV function have been developed over recent years, with several techniques becoming widely used in clinical practice (i.e. tissue Doppler imaging) and others remaining largely research tools (i.e. 3D echocardiography, tissue strain/strain rate). Possible benefits of new technologies include improved identification and early detection of myocardial disease, improved reliability for monitoring progression of disease, and the development of novel methods to assess response to therapy. Despite this potential, the application and clinical utility of these techniques above and beyond more conventional measures remains in many cases to be adequately characterized. This thesis addresses several of these issues: from variability of novel and conventional measures of LV function in clinical practice, to new applications of novel functional measures in clinical settings.

The focus of this Ph.D. thesis is the theoretical, computational, and experimental analysis of electrohydrodynamics and ionization in the Array of Micromachined UltraSonic Electrospray (AMUSE) ion source. The AMUSE ion source, for mass spectrometry (MS), is a mechanically-driven, droplet-based ion source that can independently control charge separation and droplet formation, thereby conceptually differing from electrospray ionization (ESI). This aspect allows for low voltage soft ionization of a variety of analytes and flexibility in the choice of solvents, providing a multifunctional interface between liquid chromatography and mass spectrometry for bioanalysis. AMUSE is a versatile device that operates in an array format, enabling a wide range of configurations, including high-throughput and multiplexed modes of operation. This thesis establishes an in-depth understanding of the fundamental physics of analyte charging and electrokinetic charge separation in order to enhance droplet charging and ionization efficiency. A detailed electrohydrodynamic (EHD) computational model of charge transport during the droplet formation cycle in the AMUSE ion source is developed, coupling fluid dynamics, pressure and electric fields, and charge transport in multiphase flow. The developed EHD model presents a powerful tool for optimal design and operation of the AMUSE ion source, providing insight into the microscopic details of physicochemical phenomena, on the microsecond time scale. Analyte charging and electrohydrodynamics in AMUSE are characterized using dynamic charge generation measurements and high-spatial-resolution stroboscopic visualization of ejection phenomena. Specific regimes of charge transport, which control the final droplet charging, have been identified through experimental characterization and simulations. A scale analysis of the ejection phenomena provides a parametric regime map for AMUSE ejection modes in the presence of an external electric field. This analysis identifies the transition between inertia-dominated (mechanical) and electrically-dominated (electrospraying) ejection, where inertial and electric forces are comparable, producing coupled electromechanical atomization. The understanding of analyte charging and charge separation developed through complimentary theoretical and experimental investigations is utilized to improve signal abundance, sensitivity, and stability of the AMUSE-MS response. Finally, these tools and fundamental understanding provide a sound groundwork for the optimization of the AMUSE ion source and future MS investigations.

Human Systems Integration Capstone / Approved for public release; distribution is unlimited / Current ejection seat certified aircrew weight ranges (136 to 213 lbs.), such as for the F/A-18, prohibited over one third (38%) of women and (8%) of men from accessing the naval aviation strike pipeline (carrierbased aviation) between 2008 and 2013. This is deleterious to the Naval Aviation Enterprise to restrict access of otherwise qualified and talented applicants to the strike aviation pipeline due to an outdated anthropometric survey based specification. The acceptable level of risk that was utilized by the Naval Aviation Systems Command was overly conservative and needs to be updated to align with current operational risk management principles, actual ejection seat performance mishap data and the naval aviation anthropometric population. This research is a deep exploration of all aspects of this issue and makes recommendations that can be used by Commander of Naval Air Forces in establishing an operational weight limit for all ejection seat aircraft.

[Truncated abstract] In women, as in other mammals, the ability to successfully lactate depends on both complete functional development of the mammary gland and the stimulation of the milk ejection reflex to enable the suckling young to remove stored milk. Prior to my studies, Sir Astley Cooper’s carried out the most comprehensive investigation of the gross anatomy of the lactating human breast in 1840. I have used ultrasound to image the anatomy of the breasts of fully breastfeeding women (1-6 months, n=22) with particular emphasis on the distribution of the main milk ducts, glandular and adipose tissue. Scanning of the milk duct system demonstrated that the anatomy in the region of the areola and nipple is different to that depicted in standard anatomical textbooks. The main milk ducts were small (diameter, left: 1.9 ± 0.6 mm; right: 2.1 ± 0.7 mm), superficial (depth, left: 4.50 ± 1.98 mm; right: 4.74 ± 1.59 mm) and branched close to the nipple (within 8.20 ± 6.27 mm, left; 7.00 ± 3.98 mm, right) (mean ± SD). The lactiferous sinuses (described in current textbooks) were not observed and the number of main ducts detected at the base of the nipple was less than the quoted 15-20 (9.4, range 4-18). Quantitative descriptions of the morphology of either the lactating or, indeed, the non-lactating breasts have not been attempted using ultrasound. I developed a systematic approach to ultrasound imaging of the breast that provided a semi-quantitative description of the distribution of glandular and adipose tissues within the lactating breast. Approximately two thirds of the breast was comprised of glandular tissue. Intraglandular fat was identified as hypoechoic transects within the hyperechoic glandular tissue. Over 65% of the glandular tissue together with 50% of the intraglandular fat and 25% of the subcutaneous fat was located within a 30 mm radius of the base of the nipple. The absence of lactiferous sinuses and the arrangement of tissue within a 30 mm radius of the nipple suggested that the current conceptualisation of sucking dynamics of the infant requires revision. Successful milk removal depends on the stimulation of the milk ejection reflex and currently subjective assessments of milk ejection such as the mother’s sensations and an alteration in the infants sucking and swallowing are used clinically to confirm milk ejection whereas in research two stressful invasive procedures; changes blood oxytocin and intra-ductal pressure have been used. I have developed a non-invasive ultrasound technique to detect milk ejection in women

Cette thèse est dédiée aux processus de transport de moment cinétique et de flux magnétique dans les disques faiblement magnétisés et faiblement ionisés ; l’influence des effets microphysiques sur la dynamique du disque à grande échelle y est centrale. Dans un premier temps, j’exclue les effets de stratification et j’examine l’impact des effets MHD non-idéaux sur la turbulence dans le plan du disque. Je montre que l’écoulement peut spontanément s’organiser si la fraction d’ionisation est assez faible ; dans ce cas, l’accrétion est stoppée, et le disque exhibe des anneaux axisymétriques susceptibles d’affecter la formation planétaire. Dans un second temps, je caractérise l’interaction du disque avec un vent magnétisé via un modèle global de disque stratifié. Ce modèle est le premier à décrire globalement les effets MHD non-idéaux d’après un réseau chimique simplifié. Il révèle que le disque est essentiellement non-turbulent, et que le champ magnétique peut adopter différentes configurations globales, affectant drastiquement les processus de transport. Un nouveau processus d’auto-organisation est identifié, produisant aussi des structures axisymétriques, tandis que le précédent est invalidé par l’action du vent. Les propriétés des vents magnéto-thermiques sont examinées pour différentes magnétisations, permettant de discriminer les vents magnétisés des vents photo-évaporés par leur efficacité d’éjection. / This thesis is devoted to the transport of angular momentum and magnetic flux through weakly ionized and weakly magnetized accretion disks ; the role of microphysical effects on the large- scale dynamics of the disk is of primary importance. As a first step, I exclude stratification effects and examine the impact of non-ideal MHD effects on the turbulent properties near the disk midplane. I show that the flow can spontaneously organize itself if the ionization fraction is low enough ; in this case, accretion is halted and the disk exhibits axisymmetric structures, with possible consequences on planetary formation. As a second step, I study the disk-wind interaction via a global model of stratified disk. This model is the first to compute non-ideal MHD effects from a simplified chemical network in a global geometry. It reveals that the flow is essentially laminar, and that the magnetic field can adopt different global configurations, drastically affecting the transport processes. A new self-organization process is identified, also leading to the formation of axisymmetric structures, whereas the previous mechanism is discarded by the action of the wind. The properties of magneto-thermal winds are examined for various magnetizations, allowing discrimination between magnetized and photo-evaporative winds based upon their ejection efficiency.