Aerogravity-assist maneuvering of a tethered satellite system

Two new implementations of a tethered satellite system to provide aeroassist during a planetary flyby are investigated. In each mission scenario the interaction of the Martian atmosphere with an aerodynamic lifting surface, which is tethered to an orbiter, is used to perturb the flight path of the system. The aerodynamic forces generated by interacting with the atmosphere augment the gravity assist provided by the planet. In the first aerogravity-assist maneuver the tethered satellite system has congruent post- and preflyby configurations. The second scenario, which is referred to as a dual-destination mission, involves the system mass being separated during the flyby. Both of these aerogravity-assist maneuvers are shown to facilitate significant, propellant-free velocity changes.

A case study of the resolution of paediatric dysphagia following brainstern injury: clinical and instrumental assessment

The coexistance of a swallowing impairment can severely impact upon the medical condition and recovery of a child with traumatic brain injury [ref.(1): Journal of Head Trauma Rehabilitation 9 (1) (1994) 43]. Limited data exist on the progression or outcome of dysphagia in the paediatric population with brainstem injury. The present prospective study documents the resolution of dysphagia in a 14-year-old female post-brainstem injury using clinical, radiological and endoscopic evaluations of swallowing. The subject presented with a pattern of severe oral-motor and oropharyngeal swallowing impairment post-injury that resolved rapidly for the initial 12 weeks, slowed to gradual progress for weeks 12-20, and then plateaued at 20 weeks post-injury. Whilst a clinically functional swallow was present at 10 months post-injury, radiological examination revealed a number of residual physiological impairments, reduced swallowing efficiency, and reduced independence for feeding, indicating a potential increased risk for aspiration. The data highlight the need for early and continued evaluation and intensive treatment programs, to focus on the underlying physiological swallowing impairment post-brainstem injury, and to help offset any potential deleterious effects of aspiration that may affect patient recovery, such as pneumonia. (C) 2003 Elsevier Ltd. All rights reserved.

Clinical progression and outcome of dysphagia following paediatric traumatic brain injury: a prospective study

Objectives : To provide a preliminary clinical profile of the resolution and outcomes of oral-motor impairment and swallowing function in a group of paediatric dysphagia patients post-traumatic brain injury (TBI). To document the level of cognitive impairment parallel to the return to oral intake, and to investigate the correlation between the resolution of impaired swallow function versus the resolution of oral-motor impairment and cognitive impairment. Participants : Thirteen children admitted to an acute care setting for TBI. Main outcome measures : A series of oral-motor (Verbal Motor Production Assessment for Children, Frenchay Dysarthria Assessment, Schedule for Oral Motor Assessment) and swallowing (Paramatta Hospital's Assessment for Dysphagia) assessments, an outcome measure for swallowing (Royal Brisbane Hospital's Outcome Measure for Swallowing), and a cognitive rating scale (Rancho Level of Cognitive Functioning Scale). Results : Across the patient group, oral-motor deficits resolved to normal status between 3 and 11 weeks post-referral (and at an average of 12 weeks post-injury) and swallowing function and resolution to normal diet status were achieved by 3-11 weeks post-referral (and at an average of 12 weeks post-injury). The resolution of dysphagia and the resolution of oral-motor impairment and cognitive impairment were all highly correlated. Conclusion : The provision of a preliminary profile of oral-motor functioning and dysphagia resolution, and data on the linear relationship between swallowing impairment and cognition, will provide baseline information on the course of rehabilitation of dysphagia in the paediatric population post-TBI. Such data will contribute to more informed service provision and rehabilitation planning for paediatric patients post-TBI.

The antlepileptic Materia Medica of Pedoacus Dioscorides

Since it was written about the middle of the 1st Century AD, and up to comparatively recent times, the great Herbal, or Materia Medica, of Dioscorides provided medicine with its chief source of information about what were then considered therapeutic substances. The work contained data on various materials of botanical, biological and mineral origin which were claimed to provide benefit to sufferers from epilepsy, though often with no clear underlying rationale for their use. Some of these materials continued to be used as antiepileptic remedies over many centuries till they were finally recognised to be without useful effect in the disorder. The longest survivor amongst the Dioscoridean antiepileptic remedies was a rather esoteric one, viz. two stones taken from the belly of a young swallow during the rising phase of the moon and also whilst the swallow's parent birds were absent from the nest. The stones, or one of them, were worn against the skin of the seizure sufferer. The use of the swallow stones for epilepsy was recommended as late as in the writings of Thomas Willis (1675). (C) 2004 Elsevier Ltd. All rights reserved.

Abdominal muscle recruitment during a range of voluntary exercises

Various exercises are used to retrain the abdominal muscles in the management of low back pain and other musculoskeletal disorders. However. few studies have directly investigated the activity of all the abdominal muscles or the recruitment of regions of the abdominal muscles during these manoeuvres. This study examined the activity of different regions of transversus abdominis (TrA), obliquus internus (OI) and externus abdominis (OE), and rectus abdominis (RA), and movement of lumbar spine, pelvis and abdomen during inward movement of the lower abdominal wall, abdominal bracing, pelvic tilting, and inward movement of the lower and upper abdominal wall. Inward movement of the lower abdominal wall in supine produced greater activity of TrA compared to OI. OE and RA. During posterior pelvic tilting. middle OI was most active and with abdominal bracing. OE was predominately recruited. Regions of TrA were recruited differentially and in inverse relationship between lumbopelvic motion and TrA electromyography (EMG) was found. This study indicates that inward movement of the abdominal wall in supine produces the most independent activity of TrA relative to the other abdominal muscle, recruitment varies between regions of TrA, and observation of abdominal and lumbopelvic motion may assist in evalation of exercise performance. (c) 2004 Elsevier Ltd. All rights reserved.

Differential activity of regions of transversus abdominis during trunk rotation

The role of the abdominal muscles in trunk rotation is not comprehensively understood. This study investigated the electromyographic (EMG) activity of anatomically distinct regions of the abdominal muscles during trunk rotation in six subjects with no history of spinal pain. Fine-wire electrodes were inserted into the right abdominal wall; upper region of transversus abdominis (TrA), middle region of TrA, obliquus internus abdominis (OI) and obliquus externus abdominis (OE), and lower region of TrA and OI. Surface electrodes were placed over right rectus abdominis (RA). Subjects performed trunk rotation to the left and right in sitting by rotating their pelvis relative to a fixed thorax. EMG activity was recorded in relaxed supine and sitting, and during an isometric hold at end range. TrA was consistently active during trunk rotation, with the recruitment patterns of the upper fascicles opposite to that of the middle and lower fascicles. During left rotation, there was greater activity of the lower and middle regions of contralateral TrA and the lower region of contralateral OI. The upper region of ipsilateral TrA and OE were predominately active during right rotation. In contrast, there was no difference in activity of RA and middle OI between directions (although middle OI was different between directions for all but one subject). This study indicates that TrA is active during trunk rotation, but this activity varies between muscle regions. These normative data will assist in understanding the role of TrA in lumbopelvic control and movement, and the effect of spinal pain on abdominal muscle recruitment.

Regional morphology of the transversus abdominis and obliquus internus and externus abdominis muscles

Background. The mechanisms by which the abdominal muscles move and control the lumbosacral spine are not clearly understood. Descriptions of abdominal morphology are also conflicting and the regional anatomy of these muscles has not been comprehensively examined. The aim of this study was to investigate the morphology of regions of transversus abdominis and obliquus internus and externus abdominis. Methods. Anterior and posterolateral abdominal walls were dissected bilaterally in 26 embalmed human cadavers. The orientation, thickness and length of the upper, middle and lower fascicles of transversus abdominis and obliquus internus abdominis, and the upper and middle fascicles of obliquus externus abdominis were measured. Findings. Differences in fascicle orientation, thickness and length were documented between the abdominal muscles and between regions of each muscle. The fascicles of transversus abdominis were horizontal in the upper region, with increasing inferomedial orientation in the middle and lower regions. The upper and middle fascicles of obliquus internus abdominis were oriented superomedially and the lower fascicles inferomedially. The mean vertical dimension of transversus abdominis that attaches to the lumbar spine via the thoracolumbar fascia was 5.2 (SD 2.1) cm. Intramuscular septa were observed between regions of transversus abdominis, and obliquus internus abdominis could be separated into two distinct layers in the lower and middle regions. Interpretation. This study provides quantitative data of morphological differences between regions of the abdominal muscles, which suggest variation in function between muscle regions. Precise understanding of abdominal muscle anatomy is required for incorporation of these muscles into biomechanical models. Furthermore, regional variation in their morphology may reflect differences in function. (C) 2004 Elsevier Ltd. All rights reserved.

Estimating state-contingent production frontiers

Chambers and Quiggin (2000) use state-contingent representations of risky production technologies to establish important theoretical results concerning producer behavior under uncertainty. Unfortunately, perceived problems in the estimation of state-contingent models have limited the usefulness of the approach in policy formulation. We show that fixed and random effects state-contingent production frontiers can be conveniently estimated in a finite mixtures framework. An empirical example is provided. Compared to conventional estimation approaches, we find that estimating production frontiers in a state-contingent framework produces significantly different estimates of elasticities, firm technical efficiencies, and other quantities of economic interest.

Output price subsidies in a stochastic world

This article studies the comparative statics of output subsidies for firms, with monotonic preferences over costs and returns, that face price and production uncertainty. The modeling of deficiency payments, support-price schemes, and stochastic supply shifts in a state-space framework is discussed. It is shown how these notions can be used, via a simple application of Shephard's lemma, to analyze input-demand shifts once comparative-static results for supply are available. A range of comparative-static results for supply are then developed and discussed.

Effects of care pathways on stroke care practices at regional hospitals

Background: Our previous work identified deficiencies in stroke care practices at regional hospitals in comparison to standards suggested by published stroke care guidelines. These deficiencies might be improved by the implementation of clinical pathways. The aim of this study was to assess changes in acute stroke care practices following the implementation of stroke care pathways at four regional Queensland hospitals. Methods: The medical records of two cohorts of 120 patients with a discharge diagnosis of stroke or transient ischaemic attack were retrospectively audited before and after implementation of stroke care pathways to identify differences in the use of acute interventions, investigations and secondary prevention strategies. Results: Following pathway implementation there were clinically important, but not statistically significant, increases in the rates of swallow assessment, allied health assessment (significant for occupational therapy, P = 0.04) and use of deep vein thrombosis prevention strategies (also significant, P = 0.006). Fewer patients were discharged on no anti-thrombotic therapy (statistically significant in the subgroup of patients with atrial fibrillation, P = 0.02). Only 37% of the patients audited were actually enrolled on the pathway. Among this subgroup there were significant increases in the rates of swallow assessment (first 24 h, P = 0.01; any time during admission, P = 0.0001), allied health assessments (all P < 0.05), estimation of blood glucose level (P = 0.0015) and the use of deep vein thrombosis prevention strategies (P = 0.0003). Conclusion: Stroke care pathways appear to improve the process of care. Whether this influences outcomes such as mortality, functional and neurological recovery, the incidence of complications, length of stay or the cost of care was beyond the scope of this study and will require further examination.