Generalization of Clausius-Mossotti approximation in application to short-time transport properties of suspensions

In 1983 Felderhof, Ford and Cohen gave microscopic explanation of the famous Clausius-Mossotti formula for the dielectric constant of nonpolar dielectric. They based their considerations on the cluster expansion of the dielectric constant, which relates this macroscopic property with the microscopic characteristics of the system. In this article, we analyze the cluster expansion of Felderhof, Ford and Cohen by performing its resummation (renormalization). Our analysis leads to the ring expansion for the macroscopic characteristic of the system, which is an expression alternative to the cluster expansion. Using similarity of structures of the cluster expansion and the ring expansion, we generalize (renormalize) the Clausius-Mossotti approximation. We apply our renormalized Clausius-Mossotti approximation to the case of the short-time transport properties of suspensions, calculating the effective viscosity and the hydrodynamic function with the translational self-diffusion and the collective diffusion coefficient. We perform calculations for monodisperse hard-sphere suspensions in equilibrium with volume fraction up to 45%. To assess the renormalized Clausius-Mossotti approximation, it is compared with numerical simulations and the Beenakker-Mazur method. The results of our renormalized Clausius-Mossotti approximation lead to comparable or much less error (with respect to the numerical simulations), than the Beenakker-Mazur method for the volume fractions below $\phi \approx 30\%$ (apart from a small range of wave vectors in hydrodynamic function). For volume fractions above $\phi \approx 30 \%$, the Beenakker-Mazur method gives in most cases lower error, than the renormalized Clausius-Mossotti approximation

Multipole matrix elements of Green function of Laplace equation

Multipole matrix elements of Green function of Laplace equation are calculated. The multipole matrix elements of Green function in electrostatics describe potential on a sphere which is produced by a charge distributed on the surface of a different (possibly overlapping) sphere of the same radius. The matrix elements are defined by double convolution of two spherical harmonics with the Green function of Laplace equation. The method we use relies on the fact that in the Fourier space the double convolution has simple form. Therefore we calculate the multipole matrix from its Fourier transform. An important part of our considerations is simplification of the three dimensional Fourier transformation of general multipole matrix by its rotational symmetry to the one-dimensional Hankel transformation

Pulmonary embolism during pregnancy: How to avoid computed tomographic pulmonary angiography?

Pregnancy and the postpartum period are well-established risk factors for venous thromboembolism (VTE). Computed tomographic pulmonary angiography (CTPA) remains the gold standard in the diagnosis of pulmonary embolism (PE), but exposure to teratogenic factors should be avoided in pregnant women. A few years ago the YEARS algorithm was developed, primarily to determine the need for CTPA

Look under the sheets – a case report of diabetic foot

     Diabetic foot is a long-term complication of diabetes mellitus that results directly from peripheral arterial disease or sensory neuropathy affecting the feet in diabetes mellitus. Diabetic foot is rare, but potentially lethal complication associated with the diabetes. The management of diabetic foot infections requires assessing the microbial etiology, attentive wound management, good nutrition, antimicrobial therapy and glycemic control. In several clinical circumstances, surgical resection is preferable.     A 65-year-old patient with 2-month necrosis of the second toe of the left foot and recurrent fever is presented. Diabetic foot developed. Citrobacter koseri was isolated from bone cultures. Intravenous treatment with amoxicillin + clavulanic acid and metronidazole was administered for 2 weeks and the wound was poorly recovered. After a surgical consultation, the patient was qualified for the amputation of the second toe of the left foot

Cystic Fibrosis - Related Diabetes

Cystic fibrosis (CF) is life-shortening autosomal recessive disease, caused by mutations in the cystic fibrosis transmembrane conductance regulator protein. The most common of CF complications is cystic fibrosis-related diabetes (CFRD). The pathophysiology of CFRD is complex. The best test for screening and diagnosis of CFRD is the oral glucose tolerance test (OGTT). Insulin therapy is a treatment of choice in CFDR pharmacotherapy. An inseparable element of CFRD therapy is also physical activity and diet

Hyperkalemia - a review article

Introduction: Potassium is critical cation in physiological functions. Hyperkalemia is a common electrolyte disorder, defined as potassium level above 5,5 mmol/L. Knowledge of the basic rules of hyperkalemia management is crucial to every doctor. Purpose: Systemic review of causes, symptoms and treatment of hyperkalemia. Material and methods: Standard criteria were used to review the literature data. The search of articles in the PubMed database was carried out. Description of the state of knowledge: The causes of hyperkalemia are different and mostly result from impaired urinary potassium excretion due to acute or chronic kidney disease. The symptoms of hyperkalemia vary and usually affect skeletal muscles, myocardium and central nervous system. Treatment of hyperkalemia depends on the presence or absence of symptoms, the severity of potassium elevation and the cause of hyperkalemia. Therefore, management with the patient with hyperkalemia includes careful interview, evaluation of clinical symptoms, ECG and searching for possible causes of disorders. Summary: Hyperkalemia requires urgent therapeutic intervention. In each case of elevated potassium concentration ECG should be performed and the obtained laboratory result should be verified. The crucial point in hyperkalemia treatment is the shift of potassium to the cells and simultaneously the removal of potassium from the body

Neuroleptic malignant syndrome – a case report

Neuroleptic malignant syndrome (NMS) is rare, but potentially lethal complication associated with the use of neuroleptic agents. NMS is most often observed after high-potency first-generation neuroleptic agents. NMS is characterised by a distinctive clinical syndrome including: hyperthermia, muscular rigidity, mental status change, autonomic disability. The most common laboratory finding is elevated serum CK. The management of patients with NMS demands aggressive care and discontinuing of the causative agent. A 49-year-old patient with recurrent depressive disorders is presented. NMS developed following the increase in haloperidol dose and concomitant use of olanzapine. The treatment with bromocriptine and lorazepam resulted in a prompt recovery