No abstract

The term 'growing pains' has been used for almost 200 years to refer to the often severe, generally bilateral lower-extremity nocturnal pains experienced by up to one-third of all children at some time during early childhood. No clear mechanism has yet been identified that explains these pains, but there is an increasing body of evidence indicating that several factors, individually or in combination, might be responsible for this phenomenon. These include mechanical factors, such as joint hypermobility and flat feet, decreased pain thresholds, reduced bone strength, and emotional factors involving the patient's family and other social stressors. Correct diagnosis of growing pains requires a thorough patient history and physical examination. The diagnosis can be safely established without unnecessary laboratory investigations or imaging; however, identification of one or more clinical cautionary signs, such as unilateral pain, morning stiffness, joint swelling and systemic symptoms (e.g. fever, weight loss and malaise), should trigger an extended evaluation to exclude other more serious conditions that might also present with limb pain. Once the diagnosis has been established, conservative management, using symptomatic pain medications, massage and other supportive measures, should be employed until the syndrome self-resolves with time.

The deformation behavior of wet lignocellulosic fibers was examined by applying a dilute suspension of dyed pulp fibers to a filter paper and then wet pressing the fibers onto glass slides. The geometry of single fiber crossing was determined using light interference and an image analysis computer program. The effects of pulp type, refining, wet pressing, drying and bleaching on the deformation behavior of pulp fibers were explored. The main effect of refining fibers was to reduce the step height for fiber-fiber crossings for both bleached and unbleached pulps by increasing the tendency of the cell wall to collapse and deform. All the pulps and treatments investigated maintained a relatively constant value for the step height/free span ratio.

Cellulosic fiber interfaces are critical to the material properties of paper. Likewise, the presence of water in a paper sheet is an important property, because paper is a wet-laid structure and the cellulosic fibers that compose it are hygroscopic. This work uses a fluorescence microscopy technique established by the authors to study the development of individual bleached kraft pulp fiber crossings in situ during drying and through a cycle of rewetting and wet pressing. The results indicate that coalescence of the fiber-fiber interface occurs during drying and that the fluorescence resonance energy transfer (FRET) response, which is proportional to the distance between fiber components, increases logarithmically with time. The FRET signal of once-dried fiber crossings increases dramatically after rewetting and wet pressing for a second time. This indicates that fiber bonds are still compliant after a single drying cycle and that the interactions between fiber components are likely reversible at the solids content present in bleached kraft pulp fiber crossings dried at 25°C and 50% relative humidity.