Adsorption of colloidal particles in the presence of external fields

We present a new class of sequential adsorption models in which the adsorbing particles reach the surface following an inclined direction (shadow models). Capillary electrophoresis, adsorption in the presence of a shear, and adsorption on an inclined substrate are physical manifestations of these models. Numerical simulations are carried out to show how the new adsorption mechanisms are responsible for the formation of more ordered adsorbed layers and have important implications in the kinetics, in particular, modifying the jamming limit.

Hydrodynamic fluctuations in fluids under external gradients

Temperature and velocity correlation functions in a fluid subjected to conditions creating both a temperature and a velocity gradient are computed up to second order in the gradients. Temperature and velocity fluctuations are coupled due to convection and viscous heating. When the viscosity goes to infinity one gets the temperature correlation function for a solid under a temperature gradient, which contains a long-ranged contribution, quadratic in the temperature gradient. The velocity correlation function also exhibits long-range behavior. In a particular case its equilibrium term is diagonal whereas the nonequilibrium correction contains nondiagonal terms.

Light scattering from suspensions under external gradients

We analyze the light-scattering spectrum of a suspension in a viscoelastic fluid under density and velocity gradients. When a density gradient is present, the dynamic structure factor exhibits universality in the sense that its expression depends only on the reduced frequency and the reduced density gradient. For a velocity gradient, however, the universality breaks down. In this last case we have found a transition point from one to three characteristic frequencies in the spectrum, which is governed by the value of the external gradient. The presence of the viscoelastic time scales introduces a shift in the ``critical¿¿ point.

Internal and external fluctuations around nonequilibrium steady states in one-dimensional heat-conduction problems

Thermal fluctuations around inhomogeneous nonequilibrium steady states of one-dimensional rigid heat conductors are analyzed in the framework of generalized fluctuating hydrodynamics. The effect of an external source of noise is also considered. External fluctuations come from temperature and position fluctuations of the source. Contributions of each kind of noise to the temperature correlation function are computed and compared through the study of its asymptotic behavior.

Patterns of failure and outcome in patients with carcinoma of the anal margin.

BACKGROUND: To evaluate the outcome of patients with carcinoma of anal margin in terms of recurrence, survival, and radiation toxicity. METHODS: A series of 45 consecutive patients, with anal margin carcinoma treated between 1983 and 2006 with curative intent at two institutions, was retrospectively analyzed. A surgical excision (close or positive surgical margin in 22 out of 29 patients) was realized before radiotherapy (RT). RT consisted of definitive external beam RT (EBRT) in 36 patients, brachytherapy (BT) alone in two patients, and both BT and EBRT in seven patients. The median total radiation dose was 59.4 Gy (range, 30-74 Gy). RESULTS: The 5-year locoregional control (LRC) rate was 78% [95% confidence interval (CI), 64-93%]. The 5-year disease-specific survival (DSS) and overall survival (OS) rates were respectively 86% (95% CI, 72-99%) and 55% (95% CI, 44-66%). The overall anal conservation rate was 80% for the whole series. There was no significant association between local recurrence and patient age, histological grade, tumor size, T stage, overall treatment time, RT dose, or chemotherapy. Long-term side effects were observed in 15 patients (33%). Only three patients developed grade 3-4 late toxicity (CTCAE/NCI v3.0). Significant relationship was found between dose, and complication rate (48% for dose >or=59.4 Gy versus 8% for dose < 59.4 Gy; P = 0.03). CONCLUSIONS: We conclude that definitive RT and/or BT yield a good local control and disease-specific survival comparable with published data. This study suggests that radiation dose over 59.4 Gy seems to increase treatment-related morbidity.

Quantization of AdS3 black holes in external fields: semiclassical results from pure gravity

(2+1)-dimensional anti-de Sitter (AdS) gravity is quantized in the presence of an external scalar field. We find that the coupling between the scalar field and gravity is equivalently described by a perturbed conformal field theory at the boundary of AdS3. This allows us to perform a microscopic computation of the transition rates between black hole states due to absorption and induced emission of the scalar field. Detailed thermodynamic balance then yields Hawking radiation as spontaneous emission, and we find agreement with the semiclassical result, including greybody factors. This result also has application to four and five-dimensional black holes in supergravity.

First-passage-time statistics for diffusion processes with an external random force

We present exact equations and expressions for the first-passage-time statistics of dynamical systems that are a combination of a diffusion process and a random external force modeled as dichotomous Markov noise. We prove that the mean first passage time for this system does not show any resonantlike behavior.

Adsorption kinetics in the presence of external fields

In this article we present a detailed analysis of the kinetics of a class of sequential adsorption models that take into account the effect of externally applied fields (as an electric field, or a shear rate) on the adsorption. The excluded volume interactions related to the finite size of the adsorbing particles are modified by the external fields. As a result, new adsorption mechanisms appear with respect to the ones used to describe the kinetics in a quiescent fluid. In particular, if the adsorbing particles are allowed to roll over preadsorbed ones, adsorption becomes non local even in the simplest geometry. An exact analytic theory cannot be developed, but we introduce a self-consistent theory that turns out to agree with the simulation results over all the range of the parameters.

Adsorption kinetics in the presence of external fields

In this article we present a detailed analysis of the kinetics of a class of sequential adsorption models that take into account the effect of externally applied fields (as an electric field, or a shear rate) on the adsorption. The excluded volume interactions related to the finite size of the adsorbing particles are modified by the external fields. As a result, new adsorption mechanisms appear with respect to the ones used to describe the kinetics in a quiescent fluid. In particular, if the adsorbing particles are allowed to roll over preadsorbed ones, adsorption becomes non local even in the simplest geometry. An exact analytic theory cannot be developed, but we introduce a self-consistent theory that turns out to agree with the simulation results over all the range of the parameters.

Insulin modulation of luteinizing hormone secretion in normal female volunteers and lean polycystic ovary syndrome patients.

BACKGROUND/AIMS: Endocrine features of polycystic ovary syndrome (PCOS) include altered ovarian steroidogenesis, hyperinsulinemia and abnormal luteinizing hormone (LH) secretion. This study was undertaken to further evaluate the role of insulin to modulate LH secretion in lean PCOS patients with normal insulin sensitivity and normal volunteers. METHODS: The study was performed in five nonobese patients diagnosed with PCOS on the basis of amenorrhea and a polycystic morphology at ovarian ultrasound, and 5 normal controls in early to mid-follicular phase and matched for weight and age. All subjects were phenotyped, and then admitted for 12 h of frequent (q 10') blood sampling on two separate occasions, once for a baseline study and the other time for a hyperinsulinemic and euglycemic clamp study. LH was measured in samples obtained throughout each admission in order to perform LH pulse analysis. RESULTS: Baseline LH secretion in PCOS subjects was significantly different from controls: they had higher LH levels, higher LH/FSH ratios as well as a faster LH pulse frequency than normal women. Insulin administration did not affect the pattern of LH secretion of PCOS patients, whereas it significantly increased the LH pulse frequency while decreasing the LH interpulse intervals in the controls. CONCLUSIONS: These data confirm that an abnormal pattern of LH secretion characteristic of PCOS can be observed in lean patients, and appears independent of peripheral insulin levels. Furthermore, our results in lean controls provide the first direct evidence that peripheral insulin can modulate the activity of hypothalamic gonadotropin-releasing hormone (GnRH) neurons in the human.

Female adolescents' views on a youth-friendly clinic

Rapport de synthèse : La satisfaction des patients concernant leur prise en charge fait maintenant partie intégrante de la qualité des soins. Elle a été évaluée à maintes reprises chez des patients adultes ou pédiatriques, mais rarement chez des patients adolescents. Les attentes des adolescents par rapport aux services de soins ont par contre été souvent étudiées et certains facteurs semblent particulièrement importants. Parmi ceux-ci, citons la confidentialité, le respect, l'honnêteté, l'écoute, l'accès aux soins ou le fait d'avoir des informations compréhensibles. L'Organisation Mondiale de la Santé a développé le concept de 'Youth-friendly health services' pour répondre aux besoins et attentes particuliers des adolescents. Il est basé sur sept principes : l'accessibilité, l'équité, l'efficience, l'efficacité, le fait d'être approprié et compréhensible. Notre objectif était d'évaluer la satisfaction des adolescentes consultant dans une clinique multidisciplinaire pour adolescents basée sur le modèle 'Youth-friendly health services' et de déterminer les facteurs qui y sont associés. Nous avons fait une enquête transversale dans une clinique pour adolescents à Lausanne entre mars et mai 2008 moyennant un questionnaire anonyme auto-administré. Tous les patients qui avaient consulté au moins une fois auparavant étaient éligibles. Nous avons ensuite éliminé les garçons, en très petit nombre et donc de faible valeur statistique. Trois cents onze patientes âgées de 12 à 22 ans ont été inclues dans l'étude. Nous avons effectué des analyses bivariées pour comparer les patientes satisfaites et non satisfaites puis avons construit un modèle log- linéaire afin de déterminer les facteurs directement ou indirectement liés à la satisfaction des patientes. Nonante-quatre pourcent des patientes étaient satisfaites. Les facteurs significativement associés à la satisfaction des adolescentes étaient les suivants : Les jeunes filles se sentaient plus écoutées en ce qui concerne leurs plaintes, et avaient plus l'impression que le soignant les comprenait. Elles avaient aussi moins changé de soignant durant le suivi, avaient plus l'impression d'avoir bénéficié du traitement adéquat et pensaient avoir plus suivi les conseils du soignant. Le modèle log-linéaire que nous avons effectué a mis en avant quatre facteurs directement liés à la satisfaction des patientes, qui sont la continuité des soins, le résultat de la prise en charge, l'adhérence au traitement et le sentiment d'être comprise par le soignant. Ces résultats mettent en avant l'importance de la relation interpersonnelle entre le soignant et le patient, mais rendent aussi attentif à des aspects qui pourraient être améliorés, en ce qui concerne par exemple la continuité des soins. En effet, une clinique comme la nôtre fait partie d'un hôpital de formation et le tournus fréquent des soignants est inévitable. Les changements de médecins et autres soignants devraient alors être préparés et expliqués aux patients avec la plus grande attention. L'adhérence au traitement semble être fortement liée à la satisfaction des patients, mais la nature de notre étude ne permet pas de conclure à une relation de cause à effet. Nous pouvons tout de même supposer qu'elle est une conséquence de la satisfaction des patients. Enfin, la confidentialité et l'accès aux soins souvent cités comme essentiels à la satisfaction des patients dans la littérature étaient secondaires dans notre étude. En conclusion, la satisfaction des adolescentes était principalement basée sur une relation de confiance de longue durée avec leurs soignants. Les pédiatres occupent une place privilégiée pour répondre à ces besoins parce qu'ils connaissent leurs patients depuis l'enfance. Ils devraient cependant garder à l'esprit que la relation avec le patient change au moment de l'adolescence et que les jeunes sont très sensibles à la relation de confiance interpersonnelle qu'ils ont avec leur médecin.

Supraclavicular flap in head and neck reconstruction: experience in 50 consecutive patients.

The supraclavicular flap (SCF) is a fasciocutaneous flap used to cover head, oral, and neck region defects after tumor resection. Its main vascular supply is the supraclavicular artery and accompanying veins and it can be harvested as a vascularised pedicled flap. The SCF serves as an excellent outer skin cover as well as a good inner mucosal lining after oral cavity and head-neck tumor resections. The flap has a wide arc of rotation and matches the skin colour and texture of the face and neck. Between March 2006 and March 2011, the pedicled supraclavicular flap was used for reconstruction in 50 consecutive patients after head and neck tumor resections and certain benign conditions in a tertiary university hospital setting. The flaps were tunnelized under the neck skin to cover the external cervicofacial defects or passed medial to the mandible to give an inner epithelial lining after the oral cavity and oropharyngeal tumor excision. Forty-four of the 50 patients had 100% flap survival with excellent wound healing. All the flaps were harvested in less than 1 h. There were four cases of distal tip desquamation and two patients had complete flap necrosis. Distal flap desquamation was observed in SCFs used for resurfacing the external skin defects after oral cavity tumor ablation and needed only conservative treatment measures. Total flap failure was encountered in two patients who had failed in previous chemoradiotherapy for squamous cell cancer of the floor of mouth and tonsil, respectively, and the SCF was used in mucosal defect closure after tumor ablation. The benefits of a pedicled fasciocutaneous supraclavicular flap are clear; it is thin, reliable, easy, and quick to harvest. In head, face and neck reconstructions, it is a good alternative to free fasciocutaneous flaps, regional pedicled myocutaneous flaps, and the deltopectoral flap.

Traumatic recurrent anterior dislocation of the shoulder: two- to four-year follow-up of an anatomic open procedure.

The purpose of this study was to evaluate the results of an anatomic open stabilization procedure. Twenty-three consecutive patients with traumatic, recurrent, anterior glenohumeral instability were managed with a modified open procedure. All had a Bankart lesion. A standardized, true anatomic capsulolabral reconstruction was performed with suture anchors. Two patients were lost to follow-up, and twenty-one were evaluated after 36 months [range, 24-49 months] by an independent observer. Shoulder stability and function were the principal outcome measures. None of the patients had subsequent dislocations. All returned to full working capacity, and 19 reached their previous level of sport activities. The mean loss in active abduction and flexion was 1 degrees, in internal rotation, one vertebral level, and in external rotation, 7 degrees (arm at 90 degrees of abduction). Two patients had a positive anterior apprehension test. No sign of shoulder osteoarthritis was observed. The open anatomic capsulolabral reconstruction provides excellent results and allows the restoration of stability with good function.

Social dysfunctioning after mild to moderate first-ever stroke at vocational age.

BACKGROUND: With improvements in stroke treatments, the number of patients with dramatic recovery is increasing. However, many of them are still complaining of difficulties in returning to work and every day activities. The aim was to assess work and social dysfunctioning in patients with minor to moderate stroke and explore its contributing factors. METHODS: Consecutive patients were prospectively included at a median 7 months after a first-ever stroke. Scores on the Work and Social Adjustment Scale (WSAS), a generic self-reported scale for assessing social functioning, were correlated with scores on the National Institutes of Health Stroke Scale (NIHSS), activities of daily living, Hospital Anxiety and Depression scale (HAD) and MMSE, Iowa Scale of Personality Changes and return to work at 1 year. RESULTS: Among the 84 included patients (mean age 43.5 years), 57 (68%; 95% CI 57 to 78%) complained of significant perturbation of functioning attributed to stroke. WSAS was highly significantly related to modified Rankin scale, daily living activities, Iowa Scale of Personality Changes and return to work at 1 year. Using ordinal logistic regression, the contributors to WSAS were initial neurological severity (NIHSS at admission), HAD and MMSE. CONCLUSIONS: The study showed that up to 68% of our patients complained of significant work and social dysfunction due to stroke, despite a good clinical outcome. This self-estimation was correlated to external validation criteria, stressing the high burden of stroke from the patient's viewpoint. Moreover, when compared across diseases, social dysfunctioning after mild stroke was as important as in other major disabling diseases.