Weak non-linear surface charging effects in electrolytic films

A simple model of soap films with nonionic surfactants stabilized by added electrolyte is studied. The model exhibits charge regularization due to the incorporation of a physical mechanism responsible for the formation of a surface charge. We use a Gaussian field theory in the film but the full non-linear surface terms which are then treated at a one-loop level by calculating the mean-field Poisson-Boltzmann solution and then the fluctuations about this solution. We carefully analyze the renormalization of the theory and apply it to a triple layer model for a thin film with Stern layer of thickness $h$. For this model we give expressions for the surface charge $\sigma(L)$ and the disjoining pressure $P_d(L)$ and show their dependence on the parameters. The influence of image charges naturally arise in the formalism and we show that predictions depend strongly on $h$ because of their effects. In particular, we show that the surface charge vanishes as the film thickness $L \to 0$. The fluctuation terms about this class of theories exhibit a Casimir-like attraction across the film and although this attraction is well known to be negligible compared with the mean-field component for thick films in the presence of electrolyte, in the model studied here these fluctuations also affect the surface charge regulation leading to a fluctuation component in the disjoining pressure which has the same behavior as the mean-field component even for large film thickness.Comment: 17 pages, 12 figures, latex sourc

Boundary Effects in the One Dimensional Coulomb Gas

We use the functional integral technique of Edwards and Lenard to solve the statistical mechanics of a one dimensional Coulomb gas with boundary interactions leading to surface charging. The theory examined is a one dimensional model for a soap film. Finite size effects and the phenomenon of charge regulation are studied. We also discuss the pressure of disjunction for such a film. Even in the absence of boundary potentials we find that the presence of a surface affects the physics in finite systems. In general we find that in the presence of a boundary potential the long distance disjoining pressure is positive but may become negative at closer interplane separations. This is in accordance with the attractive forces seen at close separations in colloidal and soap film experiments and with three dimensional calculations beyond mean field. Finally our exact results are compared with the predictions of the corresponding Poisson-Boltzmann theory which is often used in the context of colloidal and thin liquid film systems.Comment: 28 pages, LATEX2e, 11 figures, uses styles[12pt] resubmission because of minor corrections to tex

Electrostatic Fluctuations in Soap Films

A field theory to describe electrostatic interactions in soap films, described by electric multi-layers with a generalized thermodynamic surface-charging mechanism, is studied. In the limit where the electrostatic interactions are weak this theory is exactly soluble. The theory incorporates in a consistent way, the surface-charging mechanism and the fluctuations in the electrostatic field which correspond to the zero frequency component of the van der Waals force. It is shown that these terms lead to a Casimir like attraction which can be sufficiently large to explain the transition between the Common Black Film to a Newton Black Film.Comment: RevTeX4 17 pages 4 figures.ep

Attitudes of surgeons to the use of postoperative markers of the systemic inflammatory response following elective surgery

Background: Cancer is responsible for 7.6 million deaths worldwide and surgery is the primary modality of a curative outcome. Postoperative care is of considerable importance and it is against this backdrop that a questionnaire based study assessing the attitudes of surgeons to monitoring postoperative systemic inflammation was carried out. Method: A Web based survey including 10 questions on the “attitudes of surgeons to the use of postoperative markers of the systemic inflammatory response following elective surgery” was distributed via email. Two cohorts were approached to participate in the survey. Cohort 1 consisted of 1092 surgeons on the “Association of Coloproctology of Great Britain and Ireland (ACPGBI)” membership list. Cohort 2 consisted of 270 surgeons who had published in this field in the past as identified by two recent reviews. A reminder email was sent out 21 days after the initial email in both cases and the survey was closed after 42 days in both cases. Result: In total 29 surgeons (2.7%) from cohort 1 and 40 surgeons (14.8%) from cohort 2 responded to the survey. The majority of responders were from Europe (77%), were colorectal specialists (64%) and were consultants (84%) and worked in teaching hospitals (54%) and used minimally invasive techniques (87%). The majority of responders measured CRP routinely in the post-operative period (85%) and used CRP to guide their decision making (91%) and believed that CRP monitoring should be incorporated into postoperative guidelines (81%). Conclusion: Although there was a limited response the majority of surgeons surveyed measure the systemic inflammatory response following elective surgery and use CRP measurements together with clinical findings to guide postoperative care. The present results provide a baseline against which future surveys can be compared

Some observations on the renormalization of membrane rigidity by long-range interactions

We consider the renormalization of the bending and Gaussian rigidity of model membranes induced by long-range interactions between the components making up the membrane. In particular we analyze the effect of a finite membrane thickness on the renormalization of the bending and Gaussian rigidity by long-range interactions. Particular attention is paid to the case where the interactions are of a van der Waals type.Comment: 11 pages RexTex, no figure

Comparison of the prognostic value of measures of the tumor inflammatory cell infiltrate and tumor-associated stroma in patients with primary operable colorectal cancer

The aim of the present study was to compare the clinical utility of two measures of the inflammatory cell infiltrate - a H&E-based assessment of the generalised inflammatory cell infiltrate (the Klintrup-Mäkinen (KM) grade), and an immunohistochemistry-based assessment of combined CD3+ and CD8+ T-cell density (the “Immunoscore”), in conjunction with assessment of the tumor stroma percentage (TSP) in patients undergoing resection of stage I-III colorectal cancer (CRC). 246 patients were identified from a prospectively maintained database of CRC resections in a single surgical unit. Assessment of KM grade and TSP was performed using full H&E sections. CD3+ and CD8+ T-cell density was assessed on full sections and the Immunoscore calculated. KM grade and Immunoscore were strongly associated (P<0.001). KM grade stratified cancer-specific survival (CSS) from 88% to 66% (P=0.002) and Immunoscore from 93% to 61% (P<0.001). Immunoscore further stratified survival of patients independent of KM grade from 94% (high KM, Im4) to 60% (low KM, Im0/1). Furthermore, TSP stratified survival of patients with a weak inflammatory cell infiltrate (low KM: from 75% to 47%; Im0/1: from 71% to 38%, both P<0.001) but not those with a strong inflammatory infiltrate. On multivariate analysis, only Immunoscore (HR 0.44, P<0.001) and TSP (HR 2.04, P<0.001) were independently associated with CSS. These results suggest that the prognostic value of an immunohistochemistry-based assessment of the inflammatory cell infiltrate is superior to H&E-based assessment in patients undergoing resection of stage I-III CRC. Furthermore, assessment of the tumor-associated stroma, using TSP, further improves prediction of outcome

How and why systemic inflammation worsens quality of life in patients with advanced cancer

Introduction: The presence of an innate host systemic inflammatory response has been reported to be a negative prognostic factor in a wide group of solid tumour types in both the operable and advanced setting, both local and distant. In addition, this host systemic inflammatory response is associated with both clinician reported patient performance status and self-reported measures of quality of life in patients with cancer. Areas covered: A variety of mechanisms are thought to underlie this, including the influence of the host immune response on physical symptoms such as pain and fatigue, its effect on organ systems associated with physical ability and well being such as skeletal muscle, and bone marrow. Furthermore, this innate inflammatory response is thought to have a direct negative impact on mood through its action on the central nervous system. Expert commentary: It is clear that the host systemic inflammatory response represents a target for intervention in terms of both improving quality of life and prognosis in patients with advanced cancer. Based on this paradigm, future research should focus both on pathways which might be targeted by novel agents, but also on whether existing anti-inflammatory drugs might be of benefit

The thermal Casimir effect in lipid bilayer tubules

We calculate the thermal Casimir effect for a dielectric tube of radius $R$ and thickness delta formed from a membrane in water. The method uses a field-theoretic approach in the grand canonical ensemble. The leading contribution to the Casimir free energy behaves as -k_BTL kappa_C/R giving rise to an attractive force which tends to contract the tube. We find that kappa_C ~ 0.3 for the case of typical lipid membrane t-tubules. We conclude that except in the case of a very soft membrane this force is insufficient to stabilize such tubes against the bending stress which tends to increase the radius.Comment: 4 pages no figures RevTe

S_3 and the L=1 Baryons in the Quark Model and the Chiral Quark Model

The S_3 symmetry corresponding to permuting the positions of the quarks within a baryon allows us to study the 70-plet of L=1 baryons without an explicit choice for the spatial part of the quark wave functions: given a set of operators with definite transformation properties under the spin-flavor group SU(3) x SU(2) and under this S_3, the masses of the baryons can be expressed in terms of a small number of unknown parameters which are fit to the observed L=1 baryon mass spectrum. This approach is applied to study both the quark model and chiral constituent quark model. The latter theory leads to a set of mass perturbations which more satisfactorily fits the observed L=1 baryon mass spectrum (though we can say nothing, within our approach, about the physical reasonableness of the parameters in the fit). Predictions for the mixing angles and the unobserved baryon masses are given for both models as well as a discussion of specific baryons.Comment: 24 pages, requires picte

Path integrals for stiff polymers applied to membrane physics

Path integrals similar to those describing stiff polymers arise in the Helfrich model for membranes. We show how these types of path integrals can be evaluated and apply our results to study the thermodynamics of a minority stripe phase in a bulk membrane. The fluctuation induced contribution to the line tension between the stripe and the bulk phase is computed, as well as the effective interaction between the two phases in the tensionless case where the two phases have differing bending rigidities.Comment: 11 pages RevTex, 4 figure