The influence of push-off timing in a robotic ankle-foot prosthesis on the energetics and mechanics of walking

Background: Robotic ankle-foot prostheses that provide net positive push-off work can reduce the metabolic rate of walking for individuals with amputation, but benefits might be sensitive to push-off timing. Simple walking models suggest that preemptive push-off reduces center-of-mass work, possibly reducing metabolic rate. Studies with bilateral exoskeletons have found that push-off beginning before leading leg contact minimizes metabolic rate, but timing was not varied independently from push-off work, and the effects of push-off timing on biomechanics were not measured. Most lower-limb amputations are unilateral, which could also affect optimal timing. The goal of this study was to vary the timing of positive prosthesis push-off work in isolation and measure the effects on energetics, mechanics and muscle activity. Methods: We tested 10 able-bodied participants walking on a treadmill at 1.25 m.s(-1). Participants wore a tethered ankle-foot prosthesis emulator on one leg using a rigid boot adapter. We programmed the prosthesis to apply torque bursts that began between 46% and 56% of stride in different conditions. We iteratively adjusted torque magnitude to maintain constant net positive push-off work. Results: When push-off began at or after leading leg contact, metabolic rate was about 10% lower than in a condition with Spring-like prosthesis behavior. When push-off began before leading leg contact, metabolic rate was not different from the Spring-like condition. Early push-off led to increased prosthesis-side vastus medialis and biceps femoris activity during push-off and increased variability in step length and prosthesis loading during push-off. Prosthesis push-off timing had no influence on intact-side leg center-of-mass collision work. Conclusions: Prosthesis push-off timing, isolated from push-off work, strongly affected metabolic rate, with optimal timing at or after intact-side heel contact. Increased thigh muscle activation and increased human variability appear to have caused the lack of reduction in metabolic rate when push-off was provided too early. Optimal timing with respect to opposite heel contact was not different from normal walking, but the trends in metabolic rate and center-of-mass mechanics were not consistent with simple model predictions. Optimal push-off timing should also be characterized for individuals with amputation, since meaningful benefits might be realized with improved timing

La rappresentazione del rapporto tra utenti e sistema sanitario: I modelli culturali dei medici di medicina generale - The representation of the relationship between users and healthcare system: Cultural models of general practitioners

The present research study explores the emotional and symbolic representation of the Italian healthcare system and specifically of general medical services reported by a group of Italian general practitioners. General medicine is recently affected by a structural change which could be sustained also by a cultural revolution, however this revolution seems to be oriented to expected values without a clear methodology which promotes and accompanies this cultural change. The present study deals with the lack of practices due to these unrealized expected values and assumes that for intervening it is necessary knowing the existing culture before thinking to change it. Interviews to 36 general practitioners were analyzed by Emotional Text Analysis (AET). Results highlight a factorial space characterized by five clusters. According to respondents’ perspective, healthcare problems refer to two large issues characterized by powerlessness of general practitioners to intervene. On the one hand, there is health emergency, dealt with by first aid and emergency medicine. On the other hand, there is chronicity, especially affecting the elderly, which is dealt with by other workers (nurses, private family assistants, social workers) who care patients at home and replace physicians. The general practitioners’ work is difficult because of many different reasons; but the central theme is the lack of absolute power – based on morality and consciousness – which leads to the perception of catastrophic consequences for medical profession and the physician-patient relationship. Often, general practitioners are in their offices and are not able to go to patients’ home, therefore they cannot create care relationships based on trust and dependence which allow useful and trustworthy interventions. In sum, the core theme emerging from data refers to the general practitioners’ perceived lack of personal and trust-based relationships with patients

Experiential Similarity Of Depression And Interpersonal Empathy

The ability to build and maintain supportive, social relationships has been linked to both physical and psychological well-being (e.g., Baumeister & Leary, 1995; Kawachi & Berkman, 2001). Yet, social struggles are a commonly observed symptom among individuals with Major Depressive Disorder (MDD), particularly with regards to interpersonal empathy. Perceptions of interpersonal similarity can influence empathic engagement with others (e.g., Batson et al., 1996; Hodges, Kiel, Kramer, Veach, & Villanueva, 2010); often, interpersonal similarity will lead to greater empathic engagement. The present study asked participants to listen to audio clips of a fictitious therapy client discussing either depression or non-depression-related financial distress and then to indicate the degree to which they felt and expressed empathy for this client via written response letters. I hypothesized that participants with depression would report greater feelings of empathy than non-depressed participants and that depressed participants who specifically listened to the audio clip of a depressed peer would express greater empathy for their peer than depressed participants who listened to the audio clip related to financial distress and non-depressed participants in either recording condition. Although these hypotheses were not supported, a discussion of possible implications for this research is offered

Theoretical models for classical Cepheids. VIII. Effects of helium and heavy elements abundance on the Cepheid distance scale

Previous nonlinear fundamental pulsation models for classical Cepheids with metal content Z <= 0.02 are implemented with new computations at super-solar metallicity (Z=0.03, 0.04) and selected choices of the helium-to-metal enrichment ratio DeltaY/Delta Z. On this basis, we show that the location into the HR diagram of the Cepheid instability strip is dependent on both metal and helium abundance, moving towards higher effective temperatures with decreasing the metal content (at fixed Y) or with increasing the helium content (at fixed Z). The contributions of helium and metals to the predicted Period-Luminosity and Period-Luminosity-Color relations are discussed, as well as the implications on the Cepheid distance scale. Based on these new results, we finally show that the empirical metallicity correction suggested by Cepheid observations in two fields of the galaxy M101 may be accounted for, provided that the adopted helium-to-metal enrichment ratio is reasonably high (Delta Y/Delta Z ~ 3.5).Comment: 23 pages, including 6 postscript figures, accepted for publication on Ap

On Myosin II dynamics in the presence of external loads

We address the controversial hot question concerning the validity of the loose coupling versus the lever-arm theories in the actomyosin dynamics by re-interpreting and extending the phenomenological washboard potential model proposed by some of us in a previous paper. In this new model a Brownian motion harnessing thermal energy is assumed to co-exist with the deterministic swing of the lever-arm, to yield an excellent fit of the set of data obtained by some of us on the sliding of Myosin II heads on immobilized actin filaments under various load conditions. Our theoretical arguments are complemented by accurate numerical simulations, and the robustness of the model is tested via different choices of parameters and potential profiles.Comment: 6 figures, 8 tables, to appear on Biosystem

La relazione che organizza il contesto sanitario: domanda dell’utenza e risposta dei servizi sanitari, nel territorio e nell’ospedale - The relationship which organizes the healthcare context: users’ demand and response of healthcare services, in the territory and the hospital

Our intent is to present citizens’ demand of health care services in Italy through a research structured in three studies. We used the Emotional Text Analysis (ETA) to lead the three s tudies: the first study regarded the citizens’expectations of the healthcare services, the second study regarded the point of view of the hospital personnel (medical doctors and nurses), the third regarded the point of view of the General Practitioners onthe health care services. These three studies are briefly presented. Data and outcome of an Assumed Similarity Test applied to all experimental subjects of the three studies in order to make a comparison among them, are also presented. The findings of the Emotional Text Analysis show that citizens, potential users of health services, center their requests on their individual subjectivity, and seek answers both to their suffering and to the feeling of alienation that characterizes the being sick feeling that makes them go to a medical doctor. For their part, general practitioners and hospital doctors immediately transform this subjective feeling in an objective medical diagnosis. Here a first gap emerges between patient’s demand and medical response, leavingthe possibility of an alliance on the diagnosis in order to jointly fight the disease. It has long been in place though a change that has expelled the patient also from sharing the diagnostic process, increasingly taken from self-centered dynamics within the healthcare system. This widens the gap between the request of the citizens and the response of the health services, that contributes to that conflictual growth to which defensive medicine gives a dysfunctional answer. The Assumed Similarity Test contributes to the interpretation of the health care dynamic identified in the Emotional Text Analysis; particularly in regard to the unfolding conflict, given by the hypothesis emerging from the data analysis, that a feeling of closeness for the hospital personnel goes along with an emotional stance of overpowering the othe

Pili Annulati Coincident with Alopecia Areata, Autoimmune Thyroid Disease, and Primary IgA Deficiency: Case report and Considerations on the Literature

Pili annulati is a rare autosomal dominant hair disorder clinically characterized by a pattern of alternating bright and dark bands of the hair, the bright bands appearing dark if observed by transmitted light. This pattern is due to the periodic occurrence of air-filled cavities along the hair cortex which scatter and reflect the light while precluding its transmission. A susceptibility region, including a possibly responsible Frizzled gene, has been mapped to the telomeric region of chromosome 12q, although a specific mutation has not been identified. The condition has sometimes been observed in concurrence with alopecia areata, and in this paper we report a case in whom the concomitant severe alopecia areata was associated with autoimmune thyroid disease and primary IgA deficiency \u2013 a quadruple complex which, to our knowledge, has never been previously described. The occurrence of multiple immune disorders in the same patient affected by pili annulati could represent a key to understanding the high prevalence of alopecia areata in this condition. Specifically, in individuals predisposed to autoimmune disease, the molecular alterations that cause the anatomical changes of pili annulati could prompt the immune response against the hair root that underlies alopecia areata

Postsurgical Paracicatricial Cutaneous Satellitosis of Giant Cell Tumour of the Tendon Sheath, Localized Type

Tenosynovial giant cell tumour (localized type) is a tumour of tendon sheaths and interphalangeal joints, affecting the digits and arising from the synovium. It is characterized by a proliferation of mononuclear cells and osteoclast-like polykaryocytes. Its propagation to the skin is an exceptional event, which can take place either in localized form in the fingertips (localized type) or in the rare diffuse form called giant cell tumour of the tendon sheath (diffuse type). We report here a case of giant cell tumour with cutaneous satellites, which appeared close to and around the surgical scar following the excision of the primary lesion, in a 9-year-old boy. In the cutaneous satellites, a few signs of transformation could be observed, consisting of the lack of stroma and pronounced cellularity characterized by sheets of rounded synovial-like cells admixed with multinucleated giant cells and xanthoma cells. No relapse was observed 1 year after a plastic surgery procedure (complete replacement of the involved skin). Diffuse lesions usually represent a diagnostic problem in comparison with their localized counterparts. The malignant transformation of an originally typical tenosynovial giant cell tumour is a rare but well-documented event. Our case seems to represent a typical example because the pronounced cellularity might wrongly lead to a diagnosis of malignancy