Numeric reconstruction of cytoskeleton with finite element method and topology optimization method

The importance of mechanical aspects related to cell activity and its environment is becoming more evident due to their influence in stem cell differentiation and in the development of diseases such as atherosclerosis. The mechanical tension homeostasis is related to normal tissue behavior and its lack may be related to the formation of cancer, which shows a higher mechanical tension. Due to the complexity of cellular activity, the application of simplified models may elucidate which factors are really essential and which have a marginal effect. The development of a systematic method to reconstruct the elements involved in the perception of mechanical aspects by the cell may accelerate substantially the validation of these models. This work proposes the development of a routine capable of reconstructing the topology of focal adhesions and the actomyosin portion of the cytoskeleton from the displacement field generated by the cell on a flexible substrate. Another way to think of this problem is to develop an algorithm to reconstruct the forces applied by the cell from the measurements of the substrate displacement, which would be characterized as an inverse problem. For these kind of problems, the Topology Optimization Method (TOM) is suitable to find a solution. TOM is consisted of an iterative application of an optimization method and an analysis method to obtain an optimal distribution of material in a fixed domain. One way to experimentally obtain the substrate displacement is through Traction Force Microscopy (TFM), which also provides the forces applied by the cell. Along with systematically generating the distributions of focal adhesion and actin-myosin for the validation of simplified models, the algorithm also represents a complementary and more phenomenological approach to TFM. As a first approximation, actin fibers and flexible substrate are represented through two-dimensional linear Finite Element Method. Actin contraction is modeled as an initial stress of the FEM elements. Focal adhesions connecting actin and substrate are represented by springs. The algorithm was applied to data obtained from experiments regarding cytoskeletal prestress and micropatterning, comparing the numerical results to the experimental ones

Design of alternative energy storage systems for hybrid vehicles based on statistical processing of driving cycles information

Hybrid vehicles represent the future for automakers, since they allow to improve the fuel economy and to reduce the pollutant emissions. A key component of the hybrid powertrain is the Energy Storage System, that determines the ability of the vehicle to store and reuse energy. Though electrified Energy Storage Systems (ESS), based on batteries and ultracapacitors, are a proven technology, Alternative Energy Storage Systems (AESS), based on mechanical, hydraulic and pneumatic devices, are gaining interest because they give the possibility of realizing low-cost mild-hybrid vehicles. Currently, most literature of design methodologies focuses on electric ESS, which are not suitable for AESS design. In this contest, The Ohio State University has developed an Alternative Energy Storage System design methodology. This work focuses on the development of driving cycle analysis methodology that is a key component of Alternative Energy Storage System design procedure. The proposed methodology is based on a statistical approach to analyzing driving schedules that represent the vehicle typical use. Driving data are broken up into power events sequence, namely traction and braking events, and for each of them, energy-related and dynamic metrics are calculated. By means of a clustering process and statistical synthesis methods, statistically-relevant metrics are determined. These metrics define cycle representative braking events. By using these events as inputs for the Alternative Energy Storage System design methodology, different system designs are obtained. Each of them is characterized by attributes, namely system volume and weight. In the last part the work, the designs are evaluated in simulation by introducing and calculating a metric related to the energy conversion efficiency. Finally, the designs are compared accounting for attributes and efficiency values. In order to automate the driving data extraction and synthesis process, a specific script Matlab based has been developed. Results show that the driving cycle analysis methodology, based on the statistical approach, allows to extract and synthesize cycle representative data. The designs based on cycle statistically-relevant metrics are properly sized and have satisfying efficiency values with respect to the expectations. An exception is the design based on the cycle worst-case scenario, corresponding to same approach adopted by the conventional electric ESS design methodologies. In this case, a heavy system with poor efficiency is produced. The proposed new methodology seems to be a valid and consistent support for Alternative Energy Storage System design.

Ortsaufgelöste Speziation von Schwermetallen in geogenen Proben mit Röntgenabsorptionsspektrometrie (my-XAS)

Die Vergesellschaftung und Bindungsform von Arsen in Düngekalk wurde durch chemische und mineralogische Analysen sowie XANES/EXAFS-Messungen untersucht. Die durch-schnittliche As-Konzentration im Düngekalk (70 mg/kg) überschreitet den Grenzwert der DüMV (40 mg/kg). Arsen ist in Mn- (Romanechit) und Fe-Dendriten (Goethit, Ferrihydrit) angereichert. Seine Oxidationsstufe ist jeweils 5+. µ-EXAFS-Untersuchungen ergaben Hin-weise auf zweizähnige und einzähnige mononukleare Durchdringungskomplexe mit Eisen-oxid. Das Mobilisierungsverhalten von Arsen wurde durch sequentielle Extraktion des Dün-gekalks und Mobilisierungsversuche mit wassergesättigtem Boden untersucht. Die Lösung erfolgte vorwiegend im dritten Extraktionsschritt gemeinsam mit kristallinen Eisenoxiden. Unter moderat anoxischen Bedingungen war im Boden keine zusätzliche Mobilisierung von Arsen aus dem Düngekalk nachweisbar. Erhöhte As-Konzentrationen und As3+-Anteile im Porenwasser traten bei niedrigem Eh unabhängig von Kalkzugabe auf. Eine Kopplung des Arsen-Grenzwerts an den Eisenoxidgehalt erscheint sinnvoll. Ein Messaufbau für Mikro-XAS Imaging wurde in Betrieb genommen. Er ermöglicht die si-multane Erfassung einer Probenfläche von 26,6×6,6 mm² wahlweise im Transmissions- oder Fluoreszenzmodus mit der räumlichen Auflösung 52×52 µm² durch eine CCD-Kamera. Zur Datenverarbeitung wurden IDL-Programme sowie die Fernerkundungssoftware ENVI ver-wendet. Die Messergebnisse zeigen weniger Störungen und Rauschen als die Ergebnisse frü-herer Messungen mit einem Prototyp. Die Ergebnisse und Erfahrungen der Messungen liefern Hinweise für die weitere erfolgreiche Nutzung des Messaufbaus.

Kinematics and statics of cable-driven parallel robots by interval-analysis-based methods

In the past two decades the work of a growing portion of researchers in robotics focused on a particular group of machines, belonging to the family of parallel manipulators: the cable robots. Although these robots share several theoretical elements with the better known parallel robots, they still present completely (or partly) unsolved issues. In particular, the study of their kinematic, already a difficult subject for conventional parallel manipulators, is further complicated by the non-linear nature of cables, which can exert only efforts of pure traction. The work presented in this thesis therefore focuses on the study of the kinematics of these robots and on the development of numerical techniques able to address some of the problems related to it. Most of the work is focused on the development of an interval-analysis based procedure for the solution of the direct geometric problem of a generic cable manipulator. This technique, as well as allowing for a rapid solution of the problem, also guarantees the results obtained against rounding and elimination errors and can take into account any uncertainties in the model of the problem. The developed code has been tested with the help of a small manipulator whose realization is described in this dissertation together with the auxiliary work done during its design and simulation phases.

Surgical treatment of upper, middle and lower cervical injuries and non-unions by anterior procedures

The goals of any treatment of cervical spine injuries are: return to maximum functional ability, minimum of residual pain, decrease of any neurological deficit, minimum of residual deformity and prevention of further disability. The advantages of surgical treatment are the ability to reach optimal reduction, immediate stability, direct decompression of the cord and the exiting roots, the need for only minimum external fixation, the possibility for early mobilisation and clearly decreased nursing problems. There are some reasons why those goals can be reached better by anterior surgery. Usually the bony compression of the cord and roots comes from the front therefore anterior decompression is usually the procedure of choice. Also, the anterior stabilisation with a plate is usually simpler than a posterior instrumentation. It needs to be stressed that closed reduction by traction can align the fractured spine and indirectly decompress the neural structures in about 70%. The necessary weight is 2.5 kg per level of injury. In the upper cervical spine, the odontoid fracture type 2 is an indication for anterior surgery by direct screw fixation. Joint C1/C2 dislocations or fractures or certain odontoid fractures can be treated with a fusion of the C1/C2 joint by anterior transarticular screw fixation. In the lower and middle cervical spine, anterior plating combined with iliac crest or fibular strut graft is the procedure of choice, however, a solid graft can also be replaced by filled solid or expandable vertebral cages. The complication of this surgery is low, when properly executed and anterior surgery may only be contra-indicated in case of a significant lesion or locked joints.

Spectral-domain optical coherence tomography use in macular diseases: a review

The introduction of spectral-domain optical coherence tomography (SD-OCT) has improved the clinical value for assessment of the eyes with macular disease. This article reviews the advances of SD-OCT for the diagnostic of various macular diseases. These include vitreomacular traction syndrome, cystoid macular edema/diabetic macular edema, epiretinal membranes, full-thickness macular holes, lamellar holes, pseudoholes, microholes, and schisis from myopia. Besides offering new insights into the pathogenesis of macular abnormalities, SD-OCT is a valuable tool for monitoring macular disease.

Macular edema: Miscellaneous

Abstract. This article provides the reader with practical information to be applied to the various remaining causes of macular edema. Some macular edemas linked to ocular diseases like radiotherapy after ocular melanomas remained of poor functional prognosis due to the primary disease. On the contrary, macular edemas occurring after retinal detachment or after some systemic or local treatment use are often temporary. Macular edema associated with epiretinal membranes or vitreomacular traction is the main cause of poor functional recovery. However, the delay to observe a significant improvement of vision after surgery should be long, as usually observed in tractional myopic vitreoschisis. Finally, some circumstances of macular edemas such as hemangiomas or macroaneurysms should be treated, if symptomatic, with the treatments currently used in diabetic macular edema or exudative macular degeneration.

Macular edema. Miscellaneous

This chapter provides the reader with practical information to be applied to the various remaining causes of macular edema. Some clinical cases of macular edema linked to ocular diseases like postradiotherapy for ocular melanomas remained of poor functional prognosis due to the primary disease. On the contrary, macular edema occurring after retinal detachment or after diverse systemic or local treatment use is often temporary. Macular edema associated with epiretinal membranes or vitreomacular traction is the main cause of poor functional recovery. In other cases, as in tractional myopic vitreoschisis, the delay to observe a significant improvement of the vision after surgery should be long. Finally, macular edema associated with hemangiomas or macroaneurysms should be treated, if symptomatic, using the same current treatment as in diabetic macular edema or exudative macular degeneration.

Oral misoprostol for third stage of labor: a randomized placebo-controlled trial

OBJECTIVE: To investigate whether orally administered misoprostol during the third stage of labor is efficient in reducing postpartum blood loss. METHODS: In a double-masked trial, during vaginal delivery women were randomly assigned to receive a single oral dose of misoprostol (600 microg) or placebo in third stage of labor, immediately after cord clamping. The third stage of labor was managed routinely by early cord clamping and controlled cord traction; oxytocin was administered only if blood loss seemed more than usual. Blood loss was estimated by the delivering physician and differences in hematocrit were measured before and after delivery. RESULTS: Mean (+/- standard error of the mean) estimated blood loss (345 +/- 19.5 mL versus 417 +/- 25.9 mL, P = .031) and hematocrit difference (4.5 +/- 0.9% versus 7.9 +/- 1.2%, P = .014) were significantly lower in women who received misoprostol than those who received placebo. Fewer women in the misoprostol group had postpartum hemorrhage (blood loss of at least 500 mL), but that difference was not statistically significant (7% versus 15%, P = .43). Additional oxytocin before or after placental separation was used less often in the misoprostol group (16% versus 38%, P = .047). There were no differences in the length of third stage of labor (8 +/- 0.9 minutes versus 9 +/- 1 minutes, P = .947). There were no differences in pain during third stage of labor, postpartum fever, or diarrhea, but shivering was more frequent in the misoprostol group. CONCLUSION: Oral misoprostol administered in the third stage of labor reduced postpartum blood loss and might be effective in reducing incidence of postpartum hemorrhage.

Adipogenic and myogenic gene expression in rotator cuff muscle of the sheep after tendon tear

Chronic rotator cuff tendon tears lead to fatty infiltration and muscle atrophy with impaired physiological functions of the affected muscles. However, the cellular and molecular mechanisms of corresponding pathophysiological processes remain unknown. The purpose of this study was to characterize the expression pattern of adipogenic (PPARgamma, C/EBPbeta) and myogenic (myostatin, myogenin, Myf-5) transcription factors in infraspinatus muscle of sheep after tenotomy, implantation of a tension device, refixation of the tendon, and rehabilitation, reflecting a model of chronic rotator cuff tears. In contrast to human patients, the presented sheep model allows a temporal evaluation of the expression of a given marker in the same individual over time. Semiquantitative RT/PCR analysis of PPARgammaã, myostatin, myogenin, Myf-5, and C/EBPbeta transcript levels was carried out with sheep muscle biopsy-derived total RNA. We found a significantly increased expression of Myf-5 and PPARgamma after tenotomy and a significant change for Myf-5 and C/EBPbeta after continuous traction and refixation. This experimental sheep model allows the molecular analysis of pathomechanisms of muscular changes after rotator cuff tear. The results point to a crucial role of the transcription factors PPARgamma, C/EBPbeta, and Myf-5 in impairment and regeneration of rotator cuff muscles after tendon tears in sheep.

Reibschlüssige Greifsysteme für die automatische Handhabung im Materialfluss

Die personalintensive manuelle Durchführung notwendiger Handhabungsaufgaben im Materialfluss ist bedingt durch die oftmals vielfältig auftretenden charakteristischen Eigenschaften der zu behandelnden Stückgutobjekte. Typische Beispiele hierfür sind die Tätigkeiten des Kommissionierens und Sortierens, geprägt durch einen hohen Anteil manueller Tätigkeiten zur Handhabung wie: Vereinzeln, Greifen, Bewegen, Auf- und Abstapeln, Ordnen, Beladen und Ähnliche. Innovative Greifersysteme zur Stückguthandhabung eröffnen neue Möglichkeiten zur weiteren Automatisierung auch in diesem Bereich. Ein Lösungsansatz zur Entwicklung neuer Greifsysteme ist es, gezielt Friktionskräfte in Oberflächenbereiche des zu greifenden Objektes einzubringen und diese für den Handhabungsvorgang z.B. als Haltekräfte zu nutzen. Bei guten Reibwerten und entsprechender Anordnung der Wirkelemente können Objekte auch dann rein reibschlüssig gegriffen werden, wenn deren Oberfläche nur seitlich und von oben zugänglich ist, wie etwa Kartons im Packmusterverbund auf der Palette.

Entwicklung textiler Maschinenelemente für den Einsatz in Windkraftanlagen und Seilwinden

Es sollen hochfeste, gewichtreduzierte Zug- und Tragmittel aus hochmodularen (HM) und hochfesten (HT) Fasern validiert und dabei sowohl runde als auch flache, riemenartige Strukturen untersucht werden. Dadurch sind effizientere Fördersysteme und die Überwindung technischer Grenzen möglich. Darüber hinaus soll das Hauptkriterium für ein breites Anwendungsspektrum geschaffen werden: ein anerkanntes, zerstörungsfreies Prüfverfahren, mit dem der Austausch- bzw. Wartungszeitpunkt des textilen Tragmittels bestimmt werden kann. Können die o. g. Punkte erfolgreich bearbeitet werden, erfolgt eine Ausdehnung der textilen Strukturen in den Bereich kraftübertragender Maschinenelemente. Anhand von Feldversuchen in fördertechnischen Anlagen im Bergbau/ Intralogistik soll erstmals der vollständige Nachweis geführt werden, dass derartige textile Strukturen in technischen Anwendungen eingesetzt werden können. Der Nachweis umfasst die Validierung einer Vielzahl von Einzelschwerpunkten wie die Entwicklung einer Endlos-Herstellungstechnologie bzw. Endverbindung, die Tragmitteldimensionierung, die Erbringung von Festigkeitsnachweisen, die Erarbeitung von Vorschriften und die Erprobung der Verfahren zur Zustandsüberwachung.

Neue Generation von Aufzügen mit Faserseil

Energieeffiziente und leistungsfähige Zug- und Tragmittel aus hochmoduligen (HM) und hochfesten (HT) Fasern rücken seit einigen Jahren in den Fokus von Aufzugherstellern und Betreibern. Hauptgrund dafür ist, das die bisher eingesetzten Stahldrahtseile auf Grund ihrer vergleichsweise hohen Eigenmasse an technische Grenzen stoßen. Seile aus hochfesten Polymerfasern haben gegenüber Stahldrahtseilen eine vergleichbare oder sogar höhere Zugfestigkeit und ein vier- bis sechsfach geringeres Gewicht. Um das Potential dieser Fasern optimal auszunutzen, sind sowohl die Anordnung der Fasern als auch die Schmierstoffeinbringung zu untersuchen. Diesbezüglich wurden verschiedenen Seilkonstruktions- und Schmierstoffvarianten entwickelt und im Dauerbiegeversuch validiert.

Operative treatment of congenital hip osteoarthritis with high hip luxation (Crowe type IV)

OBJECTIVE The aim of the therapy is mechanical and functional stabilization of high dislocated hips with dysplasia coxarthrosis using total hip arthroplasty (THA). INDICATIONS Developmental dysplasia of the hip (DDH) in adults, symptomatic dysplasia coxarthrosis, high hip dislocation according to Crowe type III/IV, and symptomatic leg length inequality. CONTRAINDICATIONS Cerebrospinal dysfunction, muscular dystrophy, apparent disturbance of bone metabolism, acute or chronic infections, and immunocompromised patients. SURGICAL TECHNIQUE With the patient in a lateral decubitus position an incision is made between the anterior border of the gluteus maximus muscle and the posterior border of the gluteus medius muscle (Gibson interval). Identification of the sciatic nerve to protect the nerve from traction disorders by visual control. After performing trochanter flip osteotomy, preparation of the true actetabulum if possible. Implantation of the reinforcement ring, preparation of the femur and if necessary for mobilization, resection until the trochanter minor. Test repositioning under control of the sciatic nerve. Finally, refixation of the trochanteric crest. POSTOPERATIVE MANAGEMENT During hospital stay, intensive mobilization of the hip joint using a continuous passive motion machine with maximum flexion of 70°. No active abduction and passive adduction over the body midline. Maximum weight bearing 10-15 kg for 8 weeks, subsequently, first clinical and radiographic follow-up and deep venous thrombosis prophylaxis until full weight bearing. RESULTS From 1995 to 2012, 28 THAs of a Crow type IV high hip-dislocation were performed in our institute. Until now 14 patients have been analyzed during a follow-up of 8 years in 2012. Mid-term results showed an improvement of the postoperative clinical score (Merle d'Aubigné score) in 86 % of patients. Good to excellent results were obtained in 79 % of cases. Long-term results are not yet available. In one case an iatrogenic neuropraxia of the sciatic nerve was observed and after trauma a redislocation of the arthroplasty appeared in another case. In 2 cases an infection of the THA appeared 8 and 15 months after index surgery. No pseudoarthrosis of the trochanter or aseptic loosening was noticed.

Vitreoretinal Interface Changes in Geographic Atrophy.

PURPOSE Geographic atrophy (GA) is the end-stage manifestation of atrophic age-related macular degeneration (AMD). The disease progresses slowly over time, eventually causing loss of central vision. Its cause and pathomechanism are not fully known. Previous studies have suggested that vitreoretinal traction (VRT) may contribute to the progression of neovascular AMD. The aim of this study was to examine whether an association between changes at the vitreoretinal interface (VRI), in particular traction (VRT), and the characteristics and progression of GA in eyes with dry AMD can be established. DESIGN Clinic-based prospective cohort study. PARTICIPANTS A total of 97 patients (age range, 61-90 years; mean, 78.4 years) with GA secondary to dry AMD were enrolled. Patients exhibiting neovascular signs on fluorescein angiography in either eye were excluded. METHODS The VRI changes were examined using spectral-domain optical coherence tomography (SD-OCT). Characteristics of GA were examined using fundus autofluorescence (FAF) imaging. All imaging was performed using a Spectralis SLO+OCT device (Heidelberg Engineering, Heidelberg, Germany); GA area was measured using the Region Finder (Heidelberg Engineering) software native to the Spectralis platform. MAIN OUTCOME MEASURES Area and increase in area of GA. RESULTS A total of 97 eyes were examined. Vitreoretinal traction was found in 39 eyes (40%). The GA area at baseline was 6.65±5.64 mm(2) in eyes with VRT and 5.73±4.72 mm(2) in eyes with no VRT. The annual rate of progression of GA area progression was 2.99±0.66 mm(2) in eyes with VRT and 1.45±0.67mm(2) in eyes without VRT. Differences between groups in both parameters were statistically significant (n = 97 total number of eyes; P<0.001). Multiple regression analysis confirmed this finding (B = 0.714, P<0.001; F3,93 = 72.542, P<0.001; adjusted R(2) = 0.691) CONCLUSIONS: Our results indicate an association between VRT and an increased rate of progression of GA area in dry AMD. Monitoring VRT may contribute to an improved estimate of the prospective time of visual loss and to a better timing of emerging therapies in dry AMD.