Experimental evidence for a continuous variation of effective critical exponents in a microemulsion system

We present light scattering results obtained for a four-component microemulsion system in several distinct positions of a critical line. This line starts at a critical end point The critical points were approached either by raising the temperature at fixed composition (path I) or by increasing the water over surfactant ratio X at constant temperature (path II). For each critical point investigated, the critical exponents ν and γ associated with the X variable (path II) are close to those obtained with the temperature (path I). They vary continuously from the Ising values to largely smaller ones as the critical end point is approached. This complex critical behaviour is discussed in relation with the phase diagram findings.Nous présentons des résultats obtenus par diffusion de la lumière en différents points d'une ligne critique d'un système microémulsion quaternaire. Cette ligne débute par un point critique extreme. Les points critiques ont été approchés, soit en faisant varier la température à composition constante (chemin I), soit en faisant varier le rapport eau sur savon (X) à température constante (chemin II). Pour chaque point critique examiné, les valeurs des exposants critiques ν et γ mesurées le long des deux chemins sont proches. Elles varient continûment des valeurs d'Ising à des valeurs très petites quand le point critique considéré s'approche du point critique extreme. Ce comportement critique complexe est analysé à l'aide des résultats du diagramme de phase

Light scattering study of the critical behaviour in a ternary microemulsion system

The phase diagram composition-temperature of the AOT-water-decane system presents a line of critical points. This line has been approached along two paths which control the interactions between W/O droplets. The two parameters investigated are the temperature and the water over surfactant ratio. The critical behaviour has been followed by using light scattering. The data indicate a liquid-gas type behaviour and are in good agreement with the renormalization group theories for critical phenomena.Le diagramme de phases composition-température du système AOT-eau-décane présente une ligne de points critiques. Nous avons examiné le comportement critique de ce système en fonction de deux paramètres qui contrôlent les interactions entre gouttelettes E/H, à savoir la température et le rapport eau sur savon. Le comportement critique est étudié à l'aide de la diffusion de la lumière. Nos résultats indiquent un comportement de type liquide-gaz. Ils sont en bon accord avec les théories du groupe de renormalisation pour les phénomènes critiques

Pathological work-up of sentinel lymph nodes in breast cancer. Review of current data to be considered for the formulation of guidelines.

Controversies and inconsistencies regarding the pathological work-up of sentinel lymph nodes (SNs) led the European Working Group for Breast Screening Pathology (EWGBSP) to review published data and current evidence that can promote the formulation of European guidelines for the pathological work-up of SNs. After an evaluation of the accuracy of SN biopsy as a staging procedure, the yields of different sectioning methods and the immunohistochemical detection of metastatic cells are reviewed. Currently published data do not allow the significance of micrometastases or isolated tumour cells to be established, but it is suggested that approximately 18% of the cases may be associated with further nodal (non-SN) metastases, i.e. approximately 2% of all patients initially staged by SN biopsy. The methods for the intraoperative and molecular assessment of SNs are also surveyed