Solid Couplings With Flexible Intermediate Shafts For High Speed Turbocompressor Trains.

LecturePg. 101-110The design and application of solid couplings combined with flexible quill shafts for high speed turbocompressors are presented. Solid couplings are rigid in the axial direction. They transmit any residual thrust from one compressor casing to another, and even into the gear. A single thrust bearing then positions the complete rotor train. Elimination of individual thrust bearings results in a smaller lube-oil system and a reduced power loss. Any additional thrust components from a prestressed flexible-disc coupling or a gear-type coupling (gear lock) are completely avoided. The use of a flexible intermediate shaft (quill shaft) gives the solid coupling the same lateral flexibility as for a geartype or flexible-disc coupling. Criteria for allowable misalignment are given in this paper. A solid coupling is neither exposed to any kind of wear nor endangered by corrosion or stress corrosion so that no maintenance is necessary. Couplings have a decisive influence on rotordynamics. The conventional arrangement of a multicasing train with gear-type or flexible-disc couplings incorporates individual thrust bearings located outboard of the journal bearings (long shaft over hangs). Introducing solid couplings leads to a stiffer rotor by eliminating individual thrust bearings. A comparison of critical speeds of a high-speed/high-power compressor train is made alternatively equipped with solid couplings, flexible-disc or gear-type couplings. The response of the different rotors and couplings to specified unbalance weights is calculated and compared throughout the complete speed range. Torsional and lateral critical frequencies can easily be influenced by modification of intermediate shafts, even after installation of a compressor train. Operating experience on nearly 1500 compressors equipped with solid couplings have proven their excellent reliability especially on high speed, high power turbocompressor applications

Neurophysiology of Skin Thermal Sensations

Undoubtedly, adjusting our thermoregulatory behavior represents the most effective mechanism to maintain thermal homeostasis and ensure survival in the diverse thermal environments that we face on this planet. Remarkably, our thermal behavior is entirely dependent on the ability to detect variations in our internal (i.e., body) and external environment, via sensing changes in skin temperature and wetness. In the past 30 years, we have seen a significant expansion of our understanding of the molecular, neuroanatomical, and neurophysiological mechanisms that allow humans to sense temperature and humidity. The discovery of temperature‐activated ion channels which gate the generation of action potentials in thermosensitive neurons, along with the characterization of the spino‐thalamo‐cortical thermosensory pathway, and the development of neural models for the perception of skin wetness, are only some of the recent advances which have provided incredible insights on how biophysical changes in skin temperature and wetness are transduced into those neural signals which constitute the physiological substrate of skin thermal and wetness sensations. Understanding how afferent thermal inputs are integrated and how these contribute to behavioral and autonomic thermoregulatory responses under normal brain function is critical to determine how these mechanisms are disrupted in those neurological conditions, which see the concurrent presence of afferent thermosensory abnormalities and efferent thermoregulatory dysfunctions. Furthermore, advancing the knowledge on skin thermal and wetness sensations is crucial to support the development of neuroprosthetics. In light of the aforementioned text, this review will focus on the peripheral and central neurophysiological mechanisms underpinning skin thermal and wetness sensations in humans. © 2016 American Physiological Society. Compr Physiol 6:1279‐1294, 2016

A single home-based fall prevention intervention reduces falls in seniors

Background. Falls in the elderly are an important public health issue, given the often severe medical consequences and persistent mobility impairments, together with the demographic development. Falls are often due to a combination of internal and external, e.g. environmental, risk factors. The Swiss League Against Rheumatism (SLAR) developed a multidimensional home-based fall prevention programme (FPP), where a trained physiotherapist (PT) or occupational therapist (OT) provides a 60 to 90-minutes visit to the senior at her/his home. The therapist performs a detailed assessment of the senior’s individual risk of falling and subsequently recommends eliminating the identified environmental risk factors and provides tailored exercises. Four weeks later, the PT/OT calls the senior to check if a follow-up visit is required. Purpose. The purpose of this study was to evaluate the effects of the FPP over one year. Primary outcome was the rate of falls; secondary outcomes were fear of falling, as well as PTs’ recommendations and seniors’ satisfaction and adherence. Methods. A prospective observational study was carried out. Participants’ demographic characteristics and fall risk were assessed at baseline, using the ‘Timed Up&Go’ (TUG) with additional motor (TUGmot) and cognitive tasks (TUGcog). Data on falls were assessed at baseline and during one year by fall diaries and bi-monthly telephone calls. The post-intervention fall-rate was compared with the pre-intervention fall-rate; fear of falling was assessed at the same time points using the Fall Efficacy Scale (FESI, 7 items on a 1-4 point scale). A PoissonGEE model for fall counts and a Linear Mixed model for Fall Efficacy Scale were fitted to the data. Additionally the main PTs’ recommendations and seniors’ satisfaction with the intervention and adherence to the exercises after one year were assessed. Results. The analysis was carried out over 335.5 person-years. The participants were mainly female (58%), with a mean age of 82.04 years (SD=5.2, range 57-97 years); 81% and 83% of the participants were able to perform the TUG and the TUGmot respectively, compared to 57% able to perform the TUGcog. The fall rate decreased from 1.34 falls (corresponding to 724 falls) before the intervention to 1.06 falls (corresponding to 577.8 falls) after the intervention, i.e. a relative rate reduction (RRR) of -0.21 (95% CI: -0.37, 0.00). Fear of falling decreased after one year by FESI -1.39 points (95% CI: -1, -1.79). Main recommendations made by PTs/OTs was “fixing down carpets” (69%) and ‘instruction of up to 5 exercises’ (strength, balance, multi-task capability) (83.9%). Almost all seniors (98.2%) were satisfied with the programme, a follow-up visit was provided to 1% of the seniors. After one year, 64% of the participants reported to exercise ‘always’, ‘most of time’ or ‘sometimes’. Conclusions.This low-threshold, multidimensional home-based FPP achieved a 21% fall rate reduction, indicating a potential causal effect of the FPP. The FPP was feasible, and a substantial number of participants was adherent after one year. Implications. Provided that the planned cost-effectiveness study is positive, the FPP developed by the SLAR and provided by PTs and OTs should be established in the national health system and reimbursed to participants. Funding and acknowledgements. This work is funded by the Age Foundation, Zurich, Switzerland and the Foundation for Health Promotion, Lausanne, Switzerland. Ethics approval BASEC 2016-0051

The fall prevention programme 'Sicher durch den Alltag' is effective and cost-effective

Background: Falls in older people are frequent and have often severe health consequences. Reinforced by population ageing, they represent a substantial challenge for health care systems. Falls are often due to a combination of intrinsic and extrinsic risk factors. For these reasons, the Swiss League Against Rheumatism (SLAR) developed the multidimensional, home-based fall prevention programme ‘Sicher durch den Alltag’ (‘Safely Through Everyday Life’). The programme has been implemented nationwide since 2013 and is financed by selected health insurance companies. Trained physiotherapists (PTs) or occupational therapists (OTs) visit the senior at home for a 60-90 minutes session. They perform a detailed assessment of the senior’s individual risk of falling and subsequently eliminate identified environmental risk factors and provide tailored exercises. After 4 weeks, the PT/OT calls the senior to discuss further needs. The cost of the intervention is at 500 Swiss Francs (approximately 460 Euro) per senior. Objectives: Assess the effectiveness and cost-effectiveness of this fall prevention programme. Methods: A prospective, longitudinal observational study was performed. Baseline study data was assessed at the home visit, including the self-reported number of falls during a) the year and b) the month before the visit. The participants of the programme were monitored for one year after the home visit by bi-monthly telephone calls. Participants were asked to report the falls that they continuously documented in a diary. Questionnaires administered orally included the Falls Efficacy Scale-International (FES-I), a Quality of Life Questionnaire (EQ-5D-5L), and the amount of moderately intensive physical activity (PA).To compare the falls during the years before and after the home visit, the mean number of falls before the visit was calculated based on reported falls during a) the year and b) the month (multiplied by 12) before the visit. A 2:1 weighted mean from a) and b) was calculated, considering that retrospective reporting over one year or over one month may underestimate or overestimate, respectively, the number of falls. Statistical analysis fitted a GEE-Poisson-Modell (Generalized Estimating Equations) to the data for number of falls and a Linear Mixed Model (LMM) for fear of falling, quality of life and PA. Falls related health care spending in the years before and after the intervention were compared based on health insurance claims data. Results: Overall, 639 person-years of observation time were available for analysis. Participants were mainly female (59%) and had a mean age of 81.8+/- 5.2 years. On average, rate of falling decreased from 1.35 to 1.02 per person year (-23.9%), fear of falling decreased by -1.27 (95%CI -1.50, -1.05), quality of life improved by -0.88 (95%CI -1.09, -0.68), PA increased by 9.87 minutes per day (95%CI 5.65, 14.09). Health insurance claims data showed a 48.0% reduction (95%CI 30.5%, 61.0%) of medically treated falls. The average cost per prevented medically treated fall was estimated at 1317 Swiss Francs (approximately 1200 Euro) and the probability of the intervention being cost-saving at 47%. Conclusion: This low-threshold fall prevention programme was found to be very effective and cost-effective. Home visits by trained PTs or OTs contribute substantially to reduce falls in the elderly. The high cost-effectiveness is explained by a substantial reduction of severe falls

Structure and dynamics of antigenic peptides in complex with TAP

The transporter associated with antigen processing (TAP) selectively translocates antigenic peptides into the endoplasmic reticulum. Loading onto major histocompatibility complex class I molecules and proofreading of these bound epitopes are orchestrated within the macromolecular peptide-loading complex, which assembles on TAP. This heterodimeric ABC-binding cassette (ABC) transport complex is therefore a major component in the adaptive immune response against virally or malignantly transformed cells. Its pivotal role predestines TAP as a target for infectious diseases and malignant disorders. The development of therapies or drugs therefore requires a detailed comprehension of structure and function of this ABC transporter, but our knowledge about various aspects is still insufficient. This review highlights recent achievements on the structure and dynamics of antigenic peptides in complex with TAP. Understanding the binding mode of antigenic peptides in the TAP complex will crucially impact rational design of inhibitors, drug development, or vaccination strategies