Problems in the Lifshitz Theory of Atom-Wall Interaction

Problems in the Lifshitz theory of atom-wall interaction arise when the dc conductivity of dielectric wall is included into the model of the dielectric response. We review the low-temperature behavior of the free energy and entropy of dispersion interaction for both dielectric and metallic walls. Consistency of the obtained results with thermodynamics and experimental data is analyzed. Recent attempts to include the screening effects and diffusion currents into the Lifshitz theory are considered. It is shown that this leads to the violation of the Nernst heat theorem for wide classes of wall materials. The physical reasons for the emergence of thermodynamic and experimental inconsistencies are elucidated.Comment: 12 pages, 2 figures, style file ws-ijmpa.cls is use

Results of the method of transanal Haemorrhoid dearterialization for treatment

Purpose: Hemorrhoidal disease is a polyetiologic disorder at active age. Recently, the methods of hemorrhoidal artery ligation (HAL) and transanal hemorrhoid dearterialization (THD) were introduced. The aim of the present study was to analyze the initial results from THD treatment of hemorrhoidal disease.Material and methods: The study covered 26 patients, 14 males and 12 females, at a mean age of 46 years, with hemorrhoidal disease. Physical examinations, rectal examination and colonoscopy were preoperatively performed. THD was done of 6 arteries along with mucoplication of the distal rectalmucosa.Results: There were no early postoperative complications requiring surgery. Patients` complaints were dominated by low to medium pain not requiring any narcotic analgesics. One patient reported bleeding and pain necessitating re-hospitalization on the 11th day and conservative treatment without blood transfusion. Five patients reported mild pain complaints and 7 ones complained of discomfort in the anal area until the end of the second week. In two patients a residual mucous prolapse up to the 6th month without other symptoms was found out.Conclusion: THD is an effective and minimally invasive method after which application mild to moderate pain and good patient`s comfort are reported. The relative share of the intra- and postoperative complications is low

Tactics of treatment of acute left colon cancer obstruction

Back ground: Advanced colorectal cancer is commonly associated with colon obstruction/between 15-20% of patients with colonic cancer/ or/and tumor infiltration to adjacent organs. We set out to study in-hospital morbidity and mortality after operations of acute left colon cancer obstruction.Methods: From 2000 to 2010 the medical records of 204 cases /15.1%/ of acute left colon cancer obstruction were reviewed from total of 1351 patients who were operated from colorectal cancer. Results: The types of operations were a Hartmann procedure in 78 patients /38.2%/, colostomy in 58 patients /29.4%%, a type of colectomy with ileo-coloanastomosis in 54 patients /26.5%/ and a standard resection in 14 patients /6.8%/. The following early complications were occurred: anastomotic leakage in 4 patients, wound infections in 5 patients, dehiscence of operative wound in 2 patients. The in-hospital mortality rate was 11.3%.Conclusions: The emergency management of acute left-sided colonic obstruction remains controversial. The one-stage resection anastomosis which could be subtotal colectomy or segmental resection is useful and the preferred choice for low risk patients. Simple colostomy or Hartmann procedure should be re served for high risk patients. Colonic stenting is the best option either for palliation or as a bridge to surgery

Proximal protective stoma by low anterior resection of the rectum - When? How? How long?

There is an evolution in the diagnostic algorithm of rectal cancer. In this condition preoperative investigations assist in deciding the optimal treatment. The relation of the tumor edge to the circumferential margin (CRM) is an important factor in deciding the need for neoadjuvant treatment and determines the prognosis. Those with threatened or involved margins are offered long course chemoradiation to enable R0 surgical resection. Endoanal ultrasound (EUS) is useful for tumor (T) staging; hence EUS is a useful imaging modality for early rectal cancer. Magnetic resonance imaging (MRI) is useful for assessing the mesorectum and the mesorectalfascia which has useful prognostic significance and for early identification of local recurrence. Computerized tomography (CT) of the chest, abdomen and pelvis is used to rule out distant metastasis. Identification of the malignant nodes using EUS, CT and MRI is based on the size, morphology and internal characteristics but has drawbacks. Most of the common imaging techniques are suboptimal for imaging following chemoradiation as they struggle to differentiate fibrotic changes and tumor. In this situation, EUS and MRI may provide complementary information to decide further treatment. Functional imaging using positron emission tomography (PET) is useful, particularly PET/CT fusion scans to identify areas of the functionally hotspots. In the current state, imaging has enabled the multidisciplinary team of surgeons, oncologists, radiologists and pathologists to decide on the patient centered management of rectal cancer. Functional imaging may play an active role in identifying patients with lymph node metastasis and those with residual and recurrent disease following neoadjuvant chemoradiotherapy in near future

Van der Waals interaction between microparticle and uniaxial crystal with application to hydrogen atoms and multiwall carbon nanotubes

The Lifshitz theory of the van der Waals force is extended for the case of an atom (molecule) interacting with a plane surface of an uniaxial crystal or with a long solid cylinder or cylindrical shell made of isotropic material or uniaxial crystal. For a microparticle near a semispace or flat plate made of an uniaxial crystal the exact expressions for the free energy of the van der Waals and Casimir-Polder interaction are presented. An approximate expression for the free energy of microparticle- cylinder interaction is obtained which becomes precise for microparticle-cylinder separations much smaller than cylinder radius. The obtained expressions are used to investigate the van der Waals interaction between hydrogen atoms (molecules) and graphite plates or multiwall carbon nanotubes. To accomplish this the behavior of graphite dielectric permittivities along the imaginary frequency axis is found using the optical data for the complex refractive index of graphite for the ordinary and extraordinary rays. It is shown that the position of hydrogen atoms inside multiwall carbon nanotubes is energetically preferable compared with outside.Comment: 23 pages, 8 figures, 2 tables. Minor corrections are made and new references added. Accepted for publication in Phys. Rev.

Visualization and Cluster Analysis of So-cial Networks

Abstract. The article is devoted to the analysis of social networks, which are presented by graphs. The paper presents approaches to the modeling of distributions of social networks as well as the algorithms used for finding communities, as well as accounts that have the greater impact on the community