The soft-tissue restraints of the knee and its balancing capacity in total knee arthroplasty procedures

Total knee arthroplasty is a successful surgical treatment for patients with severe knee joint arthrosis. However, restoring soft-tissue function is a major challenge. Depending on the positioning of the prosthesis, the implantation procedure and the pathology of the patient, it is necessary to adjust the soft-tissue structures of the joint in order to restore the function of the knee. The assessment and adaptation of the soft-tissue envelope is a subjective process that is strongly dependent on the surgeon. This dissertation addresses these challenges and seeks quantitative guidelines for softtissue management based on a meta-analysis of the laxity of the natural knee joint. A further aim of the present study was to clarify in the scope of in-vitro investigations to what extent the loosening and removal of individual structures alters joint laxity and how far the joint can be balanced by targeted resection of soft-tissue structures. In addition, in-silico investigations within the scope of this thesis form the basis for a numerical tool to better understand the function of the ligaments and to better plan soft-tissue balancing preoperatively in the future. The investigations of the natural laxity of the knee jointin different flexion angles and loading directions by utilizing a meta-analysis show a strong dependency of the joint laxity on the flexion angle. Furthermore, the results show a distinct asymmetry of joint laxity when comparing translations in opposite directions within a certain degree of freedom. The data collected provide the surgeon with quantitative target parameters for natural soft-tissue balancing in knee arthroplasty procedures. The in-vitro investigations on 19 human knee specimens show that the restoration of soft-tissue function of the knee after arthroplasty cannot be achieved by kinematic alignment alone. The use of a bicruciate-retaining knee arthroplasty is the only way to keep the anterior and posterior stability of the joint in balance. To correct varus deformities, balancing of the medial collateral ligament appears to be a safe method. Correction of valgus laxity can be achieved by partially or completely resecting the lateral collateral ligament, however this increases the risk of instability in joint flexion. Within the scope of this work, subject-specific multi-body simulation models could be developed with which the laxity of the knee joint can be predicted, especially for low flexion angles. The presented procedure for the approximation of the ligament attachment sites represents a time-saving alternative to the segmentation of the attachments in MRI images.Deutsche Forschungsgemeinschaft/Sachbeihilfe/HU 873/7-1/E

Avaliação da durabilidade das propriedades mecânicas e reação ao fogo dos painéis de derivados de madeira

Mestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do ParanáA madeira e painéis de derivados de madeira tem sido fortemente utilizado na construção civil nos últimos anos, principalmente devido às políticas de sustentabilidade. Devido a isso, houve a necessidade de desenvolver normativas de segurança contra incêndio para produtos utilizados na construção civil fazendo com que as empresas desenvolvessem e aplicassem produtos retardantes de chamas nos seus materiais, com o intuito de diminuir a taxa de libertação de calor e o tempo de ignição da chama. Os produtos de madeira quando expostos às condições climáticas, tais como humidade, temperatura e radiação UV podem perder a sua durabilidade que acabam influenciando nas propriedades mecânicas e de reação ao fogo. Neste trabalho é apresentada uma avaliação do desempenho da durabilidade através de ciclos de envelhecimento artificial dos painéis derivados de madeira com e sem retardante de chama, com o objetivo de avaliar possíveis perdas nas propriedades mecânicas e reação ao fogo. Foram efetuados ciclos de envelhecimento artificial segundo a ETAG 028:2012, [1], com variações de humidade e temperatura durante 10 dias ininterruptos nos painéis de MDF com e sem retardante de chamas, PB com e sem retardante de chamas e OSB sem retardante de chamas. Após o envelhecimento, utilizou-se o teste de flexão em três pontos segundo a EN 310:1993, [2], com o objetivo de avaliar e comparar as propriedades mecânicas dos painéis antes e após o envelhecimento artificial, no que diz respeito à tensão máxima de flexão (MOR) e módulo de elasticidade (MOE). O estudo da reação ao fogo também foi realizado através do calorímetro de perda de massa utilizando a ISO 5660-1, [3], afim de avaliar se as propriedades de reação ao fogo foram mantidas ou alteradas após o envelhecimento dos painéis de acordo com a EN 16775:2017, [4]. Em termos de propriedades mecânicas, todos os painéis apresentaram perdas significativas nos valores de MOR e MOE com exceção do OSB que possuí uma resina de pMDI resistente à humidade. As reduções nas propriedades mecânicas foram menores para os painéis de MDF com retardante de chamas quando comparado ao MDF sem retardante de chama enquanto que o PB sem retardante de chama apresentou perdas menores do que em relação ao PB com retardante de chamas. Os painéis de MDF sem retardante de chama apresentaram perdas nas propriedades de reação ao fogo, libertando mais calor nas amostras após o envelhecimento, enquanto que no PB e OSB sem retardante de chama, as propriedades foram mantidas. Os painéis ignífugos de MDF e PB não perderam a durabilidade e continuaram na classe B de reação ao fogo.The use of wood and wood panels has been heavily used in civil construction in recent years, mainly due to sustainability policies. Due to this, there was a need to develop fire safety regulations for products used in construction, causing companies to develop and apply flame retardant products in their materials in order to reduce the heat release rate, the ignition time and avoiding the flame propagation. Wood products when exposed to weathering conditions, such as humidity, temperature and UV radiation, can lose their durability, influencing the mechanical properties and fire reaction. In this work, a durability evaluation performance through the artificial aging cycles of the wood panels with and without flame retardant is presented, in order to evaluate if there were losses in the mechanical properties and fire reaction. Artificial aging cycles according to ETAG 028: 2012 were performed with humidity and temperature variations for 10 days without interruption in MDF panels with and without flame retardant, PB with and without flame retardant and OSB without flame retardant. After aging, the three-point bending test according to EN 310: 1993 was used to evaluate and compare the mechanical properties of the panels before and after the climatic aging with respect to bending resistance (MOR) and modulus of elasticity (MOE). The study of fire reaction was also carried out through the mass loss calorimeter, in accordance with ISO 5660-1, to evaluate if the fire reaction properties were maintained or altered after exposure of the panels to environmental conditions according to EN 16775: 2017. In terms of mechanical properties, all panels had significant losses in MOR and MOE values except for OSB which had a moisture resistant pMDI resin. Reductions in mechanical properties were lower for MDF panels with flame retardant when compared to MDF without flame retardant whereas PB without flame retardant showed less losses than with PB with flame retardant. The MDF panels without flame retardant presented losses in the fire reaction properties, releasing more heat in the samples after aging, whereas in the PB and OSB without flame retardant properties were maintained. The MDF and PB fire retardant panels did not lose their durability and continued in the fire reaction class B

Portal corporativo Sicredi e estratégias de gestão de pessoas

O objetivo principal deste estudo foi avaliar como o Portal Corporativo SICREDI pode apoiar / sustentar as estratégias de gestão de pessoas do SICREDI. Considerando aspectos apontados por alguns dos principais autores na área de gestão estratégica de pessoas, mudança organizacional e cultura corporativa, bem como tecnologia da informação em recursos humanos, avaliou-se a percepção de gestores de área e colaboradores da área de gestão de pessoas quanto à sustentação das estratégias de gestão de pessoas pelo Portal Corporativo SICREDI. Assim, com a análise qualitativa dos dados obtidos com os entrevistados, verificou- se, entre outras necessidades, que é preciso trabalhar a cultura corporativa, a fim de que os colaboradores do Sistema percebam a relevância do Portal na comunicação organizacional, utilizando-o adequadamente , de modo a trazer ganhos para a organização, já que ao conhecer o seu papel no Sistema, o colaborador tende a melhorar seu desempenho e, conseqüentemente, os resultados da organização

Χαρτογράφηση της ενεργοποίησης της μικρογλοίας στις περιοχές του προμετωπιαίου φλοιού, του ιπποκάμπου και της αμυγδαλής μετά από πρόκληση χρόνιου στρες κοινωνικής ήττας

ΕΙΣΑΓΩΓΗ: Η έκθεση σε πρώιμες στρεσογόνες εμπειρίες επηρεάζει καθοριστικά την ανάπτυξη και τη λειτουργία του κεντρικού νευρικού συστήματος. Όταν αυτή δε ακολουθείται από έκθεση σε χρόνιους στρεσογόνους παράγοντες κατά την ενήλικο ζωή, οι αρνητικές επιπτώσεις τους στρες ενισχύονται. Η μικρογλοία είναι μία κατηγορία κυττάρων του ανοσοποιητικού αλλά και του νευρικού συστήματος που μελετώνται ως πιθανοί διαμεσολαβητές αυτού του φαινομένου ενίσχυσης. ΣΚΟΠΟΣ: Στην παρούσα μελέτη διερευνήσαμε το πρότυπο ενεργοποίησης της μικρογλοίας μετά την έκθεση σε ψυχοκοινωνικό στρες μόνο κατά την νεογνική περίοδο, μόνο κατά την ενήλικο ζωή και κατά τη διαδοχική τους συνύπαρξη. ΥΛΙΚΑ & ΜΕΘΟΔΟI: Για το σκοπό αυτό αξιοποιήθηκαν δύο ζωικά πειραματικά μοντέλα στον επίμυ. Η νεογνική εκπαίδευση σε λαβύρινθο σχήματος Τ υπό συνθήκες άρνησης ή λήψης της ανταμοιβής −νεογνικό μοντέλο ήπιας αντιξοότητας− και το χρόνιο στρες κοινωνικής ήττας στους ενήλικες. Για τον χαρακτηρισμό του προτύπου ενεργοποίησης της μικρογλοίας στον εγκέφαλο, και συγκεκριμένα στις περιοχές του ιπποκάμπου, του προμετωπιαίου φλοιού και της αμυγδαλής, διενεργήθηκε: α) ανοσοϊστοχημικός εντοπισμός της πρωτεΐνης Iba-1 –γενικός κυτταρικός δείκτης της μικρογλοίας– ώστε να αποτιμηθεί αριθμητικά ο πληθυσμός της μικρογλοίας, και β) ποσοτική αλυσιδωτή αντίδραση πολυμεράσης αντίστροφης μεταγραφής των γονιδίων PPARγ, IL-1β και TNFa ώστε να προσδιοριστεί το ανοσολογικό προφίλ της μικρογλοίας. ΑΠΟΤΕΛΕΣΜΑΤΑ: Η έρευνά μας έδειξε ότι η διαδοχή στρεσογόνων γεγονότων στην πρώιμη νεογνική περίοδο και μετέπειτα κατά την ενήλικο ζωή οδηγεί σε αριθμητική αύξηση του πληθυσμού της μικρογλοίας στον ιππόκαμπο και στον προμετωπιαίο φλοιό και σε αύξηση της σχετικής έκφρασης του αντιφλεγμονώδους παράγοντα PPARγ στον ιππόκαμπο. ΣΥΜΠΕΡΑΣΜΑΤΑ: Μια ήπια πρώιμη στρεσογόνος εμπειρία, ενώ από μόνη της δεν επηρεάζει τη μικρογλοία, όταν συνοδεύεται από στρες κατά την ενήλικο ζωή εμφανίζει να έχει σημαντική επίπτωση σε κυτταρικό και μοριακό επίπεδο. Το φαινόμενο αυτό έρχεται σε συμφωνία με την "Υπόθεση των δύο χτυπημάτων", όπου η ευαλωτότητα στο στρες κατά την ενήλικο ζωή καθορίζεται σε μεγάλο βαθμό από την ποιότητα των πρώιμων εμπειριών. Ένα φαινόμενο ιδιαίτερης κοινωνικής αξίας, καθώς επισημαίνει την κρισιμότητα των παιδικών χρόνων στον μακροπρόθεσμο καθορισμό της υγείας και της ποιότητας ζωής.INTRODUCTION: Early life stressful experiences strongly affect both developmental and functional processes of the central nervous system. When followed by chronic stressors in adulthood, the negative effects of stress are enhanced. Microglia is a class of cells belonging both to the immune and the nervous system and is thought to be a potential mediator of this enhancement phenomenon. AIM: In the present study we investigated the pattern of microglial activation as an effect of psychosocial stress during childhood alone, during adulthood alone and at their succession. MATERIALS & METHODS: For this purpose, we used two experimental animal models in the rat. The neonatal training in the T-maze under denial or receipt of reward –a neonatal model of stress of mild adversity– and the model of chronic social defeat at the adults. In order to characterize the microglial activation pattern in the brain, namely in the hippocampus, prefrontal cortex and amygdala, we used: a) immunohistochemistry detection of Iba-1 –a generic cell marker of microglia for all its phenotypes– to estimate the size of microglial population and b) quantitative reverse transcriptase polymerase chain reaction for PPARγ, IL-1β and TNFα genes to determine the immunological profile of microglia. RESULTS: Our results suggest that the succession of stressful events in the early neonatal years and later in adulthood lead to a numerical increase of the microglial population in the hippocampus and the prefrontal cortex and to an increase in the relative expression of the anti-inflammatory marker PPARγ in the hippocampus. CONCLUSIONS: A mild early life stressful experience, while it does not affect microglia per se, when followed by stress during adulthood it appears to have a significant effect on a cellular and molecular level. This phenomenon is in line with the "Two-hit hypothesis", where the vulnerability to stress of an adult is largely determined by the quality of early life experiences. A phenomenon of great value for the society, since it highlights the significance of childhood in the long-term determination of health and wellbeing

The benefits of haptic feedback in robot assisted surgery and their moderators: a metaanalysis

Robot assisted surgery (RAS) provides medical practitioners with valuable tools, decreasing strain during surgery and leading to better patient outcomes. While the loss of haptic sensation is a commonly cited disadvantage of RAS, new systems aim to address this problem by providing artificial haptic feedback. N = 56 papers that compared robotic surgery systems with and without haptic feedback were analyzed to quantify the performance benefits of restoring the haptic modality. Additionally, this study identifies factors moderating the effect of restoring haptic sensation. Overall results showed haptic feedback was effective in reducing average forces (Hedges' g = 0.83) and peak forces (Hedges' g = 0.69) applied during surgery, as well as reducing the completion time (Hedges' g = 0.83). Haptic feedback has also been found to lead to higher accuracy (Hedges' g = 1.50) and success rates (Hedges' g = 0.80) during surgical tasks. Effect sizes on several measures varied between tasks, the type of provided feedback, and the subjects' levels of surgical expertise, with higher levels of expertise generally associated with smaller effect sizes. No significant differences were found between virtual fixtures and rendering contact forces. Implications for future research are discussed

Structure determination of a fluorescent product of the alkaline hydrolysis of pralidoxime

Ispitivanjem raznih svojstava stanica nakon tretmana rafinatom nafte nisu nađene jednoznačne promjene, koje bi upućivale na to da su tretirane stanice poprimile nove elemente malignog ponašanja. Tretirane stanice nisu pokazivale smanjenu kontaktnu lnhlblciju, niti im se signifikantno povećala sposobnost stvaranja tumora nakon injiciranja u ozračene miševe. Brzina rasta i trajanje rasta stanica u jednoslojnim kulturama ostali su također nepromijenjeni. Pozitivni nalazi odnosili su se na uočljive morfološke promjene svih tretiranih stanica, te na stečenu sposobnost C3Hf stanica da nakon tretmana rastu u mekom agaru i stvaraju tumore u miševima. Budući da je radiosenzitivnost stanica znatnim dijelom određena genetski kontroliranim reparacijskim procesima, to su također tražene i promjene u radiosenzitivnosti onih stanica koje su proistekle iz kultura ranije izlaganih navedenom naftnom derivatu. Uočene su promjene oblika krivulja preživljenja stanica tretiranih kultura, što se pripisuje djelovanju rafinata nafte na reparacijske procese.In the examination of various cellular properties after the treatment of cells with a crude oil distillate unambiguous changes which would indicate that the treated cells adopted new elements of malignant behaviour were not found. The treated cells demonstrated neither a decreased contact inhibition nor an increased ability to develop tumours after they had been injected to irradiated mice. The rate and duration of cell growth in mono-layer cultures remained unchanged too. Positive findings related to the morphological changes observed in all treated cells, and to the acquired ability of C3Hf cells after the treatment to grow in soft agar and to develop tumours in mice. Since cellular radiosensitivity is largely determined by genetically reparative processes we also looked for changes in radiosensitivity of the cells which had been earlier exposed to the crude oil distillate. In the treated cultures changes in the shape of the survival curves were observed, what is attributed to the effect of the crude oil distillate on reparative processes

Superfluid to Mott insulator transition in one, two, and three dimensions

We have created one-, two-, and three-dimensional quantum gases and study the superfluid to Mott insulator transition. Measurements of the transition using Bragg spectroscopy show that the excitation spectra of the low-dimensional superfluids differ significantly from the three-dimensional case