Entangled networks of stiff biopolymers exhibit complex dynamic response, emerging from the topological constraints that neighboring filaments impose upon each other. We propose a class of reference models for entanglement dynamics of stiff polymers and provide a quantitative foundation of the tube concept for stiff polymers. For an infinitely thin needle exploring a planar course of point obst...

Motivated by the interest in the role of stiff polymers like actin in cellular processes and as components of biopolymer networks like the cytoskeleton, we present a statistical mechanical study of the twist elasticity of stiff polymers. We obtain simple, approximate analytical forms for the writhe distribution at zero applied force. We also derive simple analytical expressions for the torque-t...

In this paper, we introduce a method to solve linear stiff IVPs. The suggested method, which we call modified homotopy perturbation method, can be considered as an extension of the homotopy perturbation method (HPM) which is very efficient in solving a varety of differential and algebraic equations. In this work, a class of linear stiff initial value problems (IVPs) are solved by the classical ...

Two model problems for stii oscillatory systems are introduced. Both comprise a linear superposition of N 1 harmonic oscillators used as a forcing term for a scalar ODE. In the rst case the initial conditions are chosen so that the forcing term approximates a delta function as N ! 1 and in the second case so that it approximates white noise. In both cases the fastest natural frequency of the os...

Nanoparticles may contain unusual forms of structural disorder that can substantially modify materials properties and thus cannot solely be considered as small pieces of bulk material. We have developed a method to quantify intermediate-range order in 3.4-nanometer-diameter zinc sulfide nanoparticles and show that structural coherence is lost over distances beyond 2 nanometers. The zinc-sulfur ...

Posttraumatic stiff elbow is a frequent and disabling complication and poses serious challenges for its management. In this review forty studies were included to know about the magnitude of the problem, causes, pathology, prevention, and treatment of posttraumatic stiff elbow. These studies show that simple measures such as internal fixation, immobilization in extension, and early motion of elb...

Clinical Presentation: An 11-month-old boy was seen in the emergency department by his pediatrician for evaluation of fever (body temperature, 38.5°C) and a stiff neck. The patient’s illness began 5 days earlier when he developed nasal congestion and fever. His pediatrician prescribed amoxicillin on the third day of illness. The fever persisted, however, and by the fifth day, the patient was ir...

The stiff-person syndrome is a disorder of persistent, painful muscle contractions predominately affecting the axial musculature. We describe a patient with this disorder and review its pathophysiology. Molecular biologic and immunologic techniques have recently added to the understanding of the mechanism of this disorder. Association with diseases such as diabetes, vitiligo and hypothyroidism ...

In two patients, a man aged 54 years and a woman aged 49 years, stiff-person syndrome was diagnosed. This is a rare disorder of the central nervous system, with signs of an autoimmune pathogenesis. Patients present with pain and stiffness of the lower back, a complaint that is regularly seen in general practice. Moreover, the disease causes hypertonia and very painful cramps of the lower back a...

Etiologies of elbow contractures can be classified into intrinsic versus extrinsic causes. Posttraumatic elbow stiffness is the most common intrinsic cause and HO formation is the most common extrinsic cause of elbow contractures. Patients who sustain significant elbow trauma and have one or more risk factors for HO formation should be given prophylaxis against HO formation in the form of eithe...