234 research outputs found

    Common price and volatility jumps in noisy high-frequency data

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    We introduce a statistical test for simultaneous jumps in the price of a financial asset and its volatility process. The proposed test is based on high-frequency data and is robust to market microstructure frictions. For the test, local estimators of volatility jumps at price jump arrival times are designed using a nonparametric spectral estimator of the spot volatility process. A simulation study and an empirical example with NASDAQ order book data demonstrate the practicability of the proposed methods and highlight the important role played by price volatility co-jumps

    Money Illusion Under Test

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    Much progress has been made in recent years in developing and applying a direct measure of utility using survey questions on satisfaction with income and with life in general. In this paper we apply this new type of measurement to the study of money illusion. Using data from the German Socio-Economic Panel for the years 1993 to 2003, we cannot reject the hypothesis of no money illusion.North-South, cost-of-living, subjective well-being, fixed effects

    Wound Healing in a Patient with Psoriasis Vulgaris and Femur Megaprosthesis Implantation

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    Extraskeletal mesenchymal chondrosarcoma is extremely rare and, in combination with psoriasis, it has never been described before. We report a case of wide resection of an extraskeletal chondrosarcoma of the thigh and reconstruction with a femoral megaprosthesis in a patient with psoriasis vulgaris. Special emphasis has been laid to postoperative wound healing in psoriatic skin which did not show any problems

    Osseous hemangioma of the seventh cervical vertebra with osteoid formation mimicking metastasis: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>We report the case of an osseous hemangioma located in the seventh cervical vertebra with reactive osteoid formation and non-typical findings in the radiological and the histopathological examination, mimicking metastasis of a malignant tumor. To our knowledge, this is the first description of such a case in the literature.</p> <p>Case presentation</p> <p>A 44-year-old otherwise healthy Caucasian German woman presented with a discrete sensorimotor loss of both upper limbs. Radiologically, an osteolysis in the seventh cervical vertebra suggestive of metastasis of a malignant neoplasm was diagnosed. After performing corporectomy and cage implantation of C7 on the patient, the histopathological examination was complicated by marked osteoid formation obscuring the true diagnosis of an osseous hemangioma with reactive osteoid formation.</p> <p>Conclusion</p> <p>Though hemangioma of the bone is a rare tumorous lesion in the cervical spine, it has to be taken into consideration as a reason for neck pain and sensomotoric loss of the upper limbs. Atypical radiological and histopathological presentations may hinder determination of the correct diagnosis. The treatment of such lesions must follow clinical guidelines but may be difficult to define in some cases when the correct diagnosis is not known at the time when therapy starts.</p

    Liposarcoma of the forearm in a man with type 1 neurofibromatosis: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>The combination of neurofibromatosis and liposarcoma is very rare. We present a case of a dedifferentiated liposarcoma in the forearm, as a complication in a patient with neurofibromatosis type 1.</p> <p>Case presentation</p> <p>A Caucasian man with neurofibromatosis type 1 presented at our clinic complaining of a slow growing swelling on his left forearm over a period of one and a half years. Clinical examination and history pointed to malignancy. Radiological examination inclusive of magnetic resonance imaging and positron emission tomography confirmed our suspicion. A final diagnosis of dedifferentiated high-grade liposarcoma with axillary lymph node metastases was established after a pathological examination of a tumour biopsy. The consulting tumour board recommended either an elbow exarticulation or an accurate radical local resection including the metastatic axillary lymph nodes. Fortunately, we were able to perform an R-zero resection and the forearm could be saved. The treatment was completed with postoperative radiotherapy of the left forearm's operative bed, the left axillary and the supraclavicular regions. The patient decided against adjuvant chemotherapy.</p> <p>Conclusion</p> <p>Liposarcoma complicating neurofibromatosis type 1 is a very rare combination. Up to now, only five cases have been reported in the literature. We are adding a new case to this short list to stress the importance of early recognition. It is the first known case with this disease combination in an upper extremity. Liposarcoma is usually treated by surgery followed by radiotherapy. The role of chemotherapy is controversial and should be based on a decision made on a case-by-case basis.</p

    Influence of Poly(L-Lactic Acid) Nanofibers and BMP-2–Containing Poly(L-Lactic Acid) Nanofibers on Growth and Osteogenic Differentiation of Human Mesenchymal Stem Cells

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    The aim of this study was to characterize synthetic poly-(L-lactic acid) (PLLA) nanofibers concerning their ability to promote growth and osteogenic differentiation of stem cells in vitro, as well as to test their suitability as a carrier system for growth factors. Fiber matrices composed of PLLA or BMP-2–incorporated PLLA were seeded with human mesenchymal stem cells and cultivated over a period of 22 days under growth and osteoinductive conditions, and analyzed during the course of culture, with respect to gene expression of alkaline phosphatase (ALP), osteocalcin (OC), and collagen I (COL-I). Furthermore, COL-I and OC deposition, as well as cell densities and proliferation, were analyzed using fluorescence microscopy. Although the presence of nanofibers diminished the dexamethasone-induced proliferation, there were no differences in cell densities or deposition of either COL-I or OC after 22 days of culture. The gene expression of ALP, OC, and COL-I decreased in the initial phase of cell cultivation on PLLA nanofibers as compared to cover slip control, but normalized during the course of cultivation. The initial down-regulation was not observed when BMP-2 was directly incorporated into PLLA nanofibers by electrospinning, indicating that growth factors like BMP-2 might survive the spinning process in a bioactive form

    Public Participation in the Development Process of a Mobility Assistance System for Visually Impaired Pedestrians

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    Blind and visually impaired people have to cope with the safe movement through public space and the (lack of) knowledge of spatial issues and walkable routes. These challenges often lead to a fear of accidents and collisions, frequently also of disorientation. This, in turn, can result in a reduced radius of action, restricted mobility, and later on, in social isolation. Against this background, the project TERRAIN aims at developing a technical guidance system for orientation and navigation in urban space. For the development of this assistance system, the project pursues an approach in which reflexive, responsive, and deliberative dimensions have been integrated to address the ethical, legal and social implications (ELSI) in a co-design process. This paper focuses on the participation of citizens independent of vision impairments in the project which provided a variety of relevant indications of impacts and potential technical adaptations from an ‘outer’ point of view. In addition, conclusions can be drawn about the existing desirability and acceptance of the technical solution among the potential users as well as their social environment of potential users. In addition, it turned out that the citizen participation process raised different expectations among the project partners. Therefore, this article evaluates the participation results from the perspective of the technology developers and the technology assessors
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