Photon rockets and gravitational radiation

The absence of gravitational radiation in Kinnersley's ``photon rocket'' solution of Einstein's equations is clarified by studying the mathematically well-defined problem of point-like photon rockets in Minkowski space (i.e. massive particles emitting null fluid anisotro\-pically and accelerating because of the recoil). We explicitly compute the (uniquely defined) {\it linearized} retarded gravitational waves emitted by such objects, which are the coherent superposition of the gravitational waves generated by the motion of the massive point-like rocket and of those generated by the energy-momentum distribution of the photon fluid. In the special case (corresponding to Kinnersley's solution) where the anisotropy of the photon emission is purely dipolar we find that the gravitational wave amplitude generated by the energy-momentum of the photons exactly cancels the usual $1/r$ gravitational wave amplitude generated by the accelerated motion of the rocket. More general photon anisotropies would, however, generate genuine gravitational radiation at infinity. Our explicit calculations show the compatibility between the non-radiative character of Kinnersley's solution and the currently used gravitational wave generation formalisms based on post-Minkowskian perturbation theory.Comment: 21 pages, LATEX, submitted to Class. Quant. Gra

Effects of Training Intensity on Locomotor Performance in Individuals With Chronic Spinal Cord Injury: A Randomized Crossover Study

Background. Many physical interventions can improve locomotor function in individuals with motor incomplete spinal cord injury (iSCI), although the training parameters that maximize recovery are not clear. Previous studies in individuals with other neurologic injuries suggest the intensity of locomotor training (LT) may positively influence walking outcomes. However, the effects of intensity during training of individuals with iSCI have not been tested. Objective. The purpose of this pilot, blinded-assessor randomized trial was to evaluate the effects of LT intensity on walking outcomes in individuals with iSCI. Methods. Using a crossover design, ambulatory participants with iSCI \u3e1 year duration performed either high- or low-intensity LT for ≤20 sessions over 4 to 6 weeks. Four weeks following completion, the training interventions were alternated. Targeted intensities focused on achieving specific ranges of heart rate (HR) or ratings of perceived exertion (RPE), with intensity manipulated by increasing speeds or applying loads. Results. Significantly greater increases in peak treadmill speeds (0.18 vs 0.02 m/s) and secondary measures of metabolic function and overground speed were observed following high- versus low-intensity training, with no effects of intervention order. Moderate to high correlations were observed between differences in walking speed or distances and differences in HRs or RPEs during high- versus low-intensity training. Conclusion. This pilot study provides the first evidence that the intensity of stepping practice may be an important determinant of LT outcomes in individuals with iSCI. Whether such training is feasible in larger patient populations and contributes to improved locomotor outcomes deserves further consideration

Cigarette Smoke Suppresses Type I Interferon-Mediated Antiviral Immunity in Lung Fibroblast and Epithelial Cells

The objective of this study was to investigate the impact of cigarette smoke on innate antiviral defense mechanisms; specifically, we examined the effects of cigarette smoke on the induction of type I interferon (IFN). We observed a dose-dependent decrease in the ability of human lung fibroblast and epithelial cells to elicit an antiviral response against a viral double-strand RNA (dsRNA) mimic, polyI:C, in the presence of cigarette smoke-conditioned medium (SCM). Mechanistically, SCM decreases the expression of IFN-stimulated gene 15 (ISG15) and IFN regulatory factor-7 (IRF-7) transcripts and suppresses the nuclear translocation of key transcription factors, nuclear factor-κB (NF-κB) and IRF-3, after polyI:C stimulation. Furthermore, we provide evidence that the intercellular defense strategy against viral infection is also impaired. We observed a decrease in the ability of fibroblasts to elicit an antiviral state in response to IFN-β stimulation. This was associated with decreased nuclear translocation of phosphorylated Stat1 in response to IFN-β treatment. The effects elicited by SCM are reversible and are almost entirely abrogated in the presence of an antioxidant, such as glutathione. Our findings suggest that cigarette smoke affects the immediate-early, inductive, and amplification phases of the type I IFN response

Observation of Amounts of Movement Practice Provided during Stroke Rehabilitation

Objective To investigate how much movement practice occurred during stroke rehabilitation, and what factors might influence doses of practice provided. Design Observational survey of stroke therapy sessions. Setting Seven inpatient and outpatient rehabilitation sites. Participants We observed a convenience sample of 312 physical and occupational therapy sessions for people with stroke. Interventions Not applicable. Main Outcome Measures We recorded numbers of repetitions in specific movement categories and data on potential modifying factors (patient age, side affected, time since stroke, FIM item scores, years of therapist experience). Descriptive statistics were used to characterize amounts of practice. Correlation and regression analyses were used to determine whether potential factors were related to the amount of practice in the 2 important categories of upper extremity functional movements and gait steps. Results Practice of task-specific, functional upper extremity movements occurred in 51% of the sessions that addressed upper limb rehabilitation, and the average number of repetitions/session was 32 (95% confidence interval [CI]=20–44). Practice of gait occurred in 84% of sessions that addressed lower limb rehabilitation and the average number of gait steps/session was 357 (95% CI=296–418). None of the potential factors listed accounted for significant variance in the amount of practice in either of these 2 categories. Conclusions The amount of practice provided during poststroke rehabilitation is small compared with animal models. It is possible that current doses of task-specific practice during rehabilitation are not adequate to drive the neural reorganization needed to promote function poststroke optimally

Farnesol Concentrations Required To Block Germ Tube Formation in \u3ci\u3eCandida albicans\u3c/i\u3e in the Presence and Absence of Serum

Concentrations of (E,E)-farnesol needed to inhibit germ tube formation were determined for Candida albicans strains A72 and SC5314 by using six different conditions known to trigger germination. For defined media, 1 to 2 μM farnesol was sufficient. However, with serum at 2 to 20%, up to 250 μM farnesol was required. Farnesol blocked germ tube formation but did not block elongation of existing germ tubes

The efficacy of low vision devices for students in specialized schools for students who are blind in Kathmandu Valley, Nepal

In Nepal, children with low vision attend specialized schools for students who are totally blind and are treated as if they were totally blind. This study identified children with low vision and provided low vision devices to them. Of the 22% of the students in the school who had low vision, 78.5% benefited from the devices. Proper devices and counseling improved the quality of life of a significant number of these students. ©2008 AFB, All Rights Reserved

His Dream of Passion: Reflections on the work of Lee Strasberg and his influence on British Actor Training (Part Two)

A previous article for Stanislavski Studies (Vol. 4, No 1, 47-62) explored and examined the impact of Lee Strasberg’s Emotion Memory technique and assessed its influence on contemporary approaches to British actor training. This second ‘companion’ article reflects on a much broader range of Strasbergian training techniques in order, initially, to examine their efficacy and to highlight the extent to which they have been absorbed and adapted by acting teachers working in a British training context. Often viewed as a controversial figure - both in the United Kingdom and in the United States - Strasberg’s approach has frequently been vilified and dismissed. This is particularly true of his interpretation of Stanislavski’s Emotion Memory technique. Whereas the earlier article sought to arrive at an informed and balanced view of his deployment of this technique, what follows is an attempt to review other aspects of Strasberg’s work so as to evaluate the coherence and credibility of the assumptions on which his approach was based and to test whether his work remains appropriate and viable in British training environments today. His work on Relaxation, Concentration and Sense Memory will be examined alongside his development of the Private Moment, Song and Dance and Animal exercises. What, if anything, can we learn from Strasberg’s Method-based approach to actor training and how might we begin to consider the impact and unity of his work as a whole as opposed to focusing almost exclusively on his early work on Emotion Memory

High intensity variable stepping training in persons with motor incomplete spinal cord injury: a case series

Background and Purpose: Previous data suggest that large amounts of high intensity stepping training in variable contexts (tasks and environments) may improve locomotor function, aerobic capacity and treadmill gait kinematics in individuals post-stroke. Whether similar training strategies are tolerated and efficacious for patients with other acute-onset neurological diagnoses, such as motor incomplete spinal cord injury (iSCI) is unknown, particularly with potentially greater, bilateral impairments. This case series evaluated the feasibility and preliminary short and long-term efficacy of high intensity variable stepping practice in ambulatory participants >1 year post-iSCI. Case Series Description: Four participants with iSCI (neurological levels C5-T3) completed up to 40 1-hr sessions over 3–4 months. Stepping training in variable contexts was performed at up to 85% maximum predicted heart rate, with feasibility measures of patient tolerance, total steps/session, and intensity of training. Clinical measures of locomotor function, balance, peak metabolic capacity and gait kinematics during graded treadmill assessments were performed at baseline and post-training, with >1 year follow-up. Outcomes: Participants completed 24–40 sessions over 8–15 weeks, averaging 2222±653 steps/session, with primary adverse events of fatigue and muscle soreness. Modest improvements in locomotor capacity where observed at post-training, with variable changes in lower extremity kinematics during treadmill walking. Discussion: High intensity, variable stepping training was feasible and tolerated by participants with iSCI although only modest gains in gait function or quality were observed. The utility of this intervention in patients with more profound impairments may be limited

Farnesol restores wild-type colony morphology to 96% of \u3ci\u3eCandida albicans\u3c/i\u3e colony morphology variants recovered following treatment with mutagens

Candida albicans is a diploid fungus that undergoes a morphological transition between budding yeast, hyphal, and pseudohyphal forms. The morphological transition is strongly correlated with virulence and is regulated in part by quorum sensing. Candida albicans produces and secretes farnesol that regulates the yeast to mycelia morphological transition. Mutants that fail to synthesize or respond to farnesol could be locked in the filamentous mode. To test this hypothesis, a collection of C. albicans mutants were isolated that have altered colony morphologies indicative of the presence of hyphal cells under environmental conditions where C. albicans normally grows only as yeasts. All mutants were characterized for their ability to respond to farnesol. Of these, 95.9% fully or partially reverted to wildtype morphology on yeast malt (YM) agar plates supplemented with farnesol. All mutants that respond to farnesol regained their hyphal morphology when restreaked on YM plates without farnesol. The observation that farnesol remedial mutants are so common (95.9%) relative to mutants that fail to respond to farnesol (4.1%) suggests that farnesol activates and (or) induces a pathway that can override many of the morphogenesis defects in these mutants. Additionally, 9 mutants chosen at random were screened for farnesol production. Two mutants failed to produce detectable levels of farnesol. Candida albicans est un champignon diploïde qui subit une transition morphologique entre les levures en herbe, les hyphes et les formes pseudohyphales. La transition morphologique est fortement corrélée à la virulence et est régulée en partie par la détection du quorum. Candida albicans produit et sécrète du farnésol qui régule la transition morphologique levure-mycélium. Les mutants qui ne parviennent pas à synthétiser ou à répondre au farnésol pourraient être verrouillés en mode filamenteux. Pour tester cette hypothèse, une collection de mutants de C. albicans a été isolée qui ont modifié les morphologies des colonies, indiquant la présence de cellules hyphales dans des conditions environnementales où C. albicans ne pousse normalement que sous forme de levures. Tous les mutants ont été caractérisés pour leur capacité à répondre au farnésol. Parmi ceux-ci, 95,9% sont entièrement ou partiellement revenus à la morphologie de type sauvage sur des plaques de gélose au levure de malt (YM) complétées par du farnésol. Tous les mutants qui répondent au farnésol ont retrouvé leur morphologie hyphale lorsqu\u27ils ont été recréés sur des plaques YM sans farnésol. L\u27observation selon laquelle les mutants curatifs du farnésol sont si communs (95,9%) par rapport aux mutants qui ne répondent pas au farnésol (4,1%) suggère que le farnésol s\u27active et (ou) induit une voie qui peut supplanter bon nombre des défauts de morphogenèse de ces mutants. De plus, 9 mutants choisis au hasard ont été testés pour la production de farnésol. Deux mutants n\u27ont pas réussi à produire des niveaux détectables de farnésol