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Search Results: 1 - 10 of 2993 matches for " Rebecca Scheer "
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A Liquid Chromatography Assay for the Simultaneous Quantification of Piperacillin and Ciprofloxacin in Human Plasma and Dialysate in Critically Ill Patients Undergoing Continuous Renal Replacement Therapy  [PDF]
Florian Scheer, Irene Kr?mer
International Journal of Analytical Mass Spectrometry and Chromatography (IJAMSC) , 2014, DOI: 10.4236/ijamsc.2014.22005
Abstract:

Piperacillin/tazobactam and ciprofloxacin are often used in combination as initial empiric anti-biotic therapy in critical ill patients. Especially in patients undergoing continuous renal replacement therapy (CRRT) the pharmacokinetics of antimicrobial agents can be highly variable. In order to avoid under- or overdosage of antibiotics therapeutic drug monitoring (TDM) is highly re-commendable. Based on two known HPLC assays for piperacillin a new method in combination with solid phase extraction (SPE) for the simultaneous determination of piperacillin and ciprofloxacin was developed. Method validation was performed according to the EMA guideline on validation of bioanalytical methods. The HPLC column used was a Perfect Bond ODS-HD C18 analytical column (100 mm × 4.6 mm i.d., particle size 5 μm), equipped with a guard column (10 mm × 4.6 mm, particle size 5 μm) containing the same packing material. Detection wavelength was set at 228 nm for piperacillin and benzylpenicillin was used as internal standard (IS). Ciprofloxacin was determined at two wavelengths (280 nm, 315 nm). This newly developed HPLC method in combination with SPE-extraction allows an accurate, precise, specific and efficient determination of piperacillin and ciprofloxacin in biological matrices. Results allow the calculation of all relevant pharmacokinetic data for critically ill patients undergoing CRRT and the optimization of dosing and TDM.

Analysis of IL-17+ cells in facet joints of patients with spondyloarthritis suggests that the innate immune pathway might be of greater relevance than the Th17-mediated adaptive immune response
Heiner Appel, René Maier, Peihua Wu, Rebecca Scheer, Axel Hempfing, Ralph Kayser, Andreas Thiel, Andreas Radbruch, Christoph Loddenkemper, Joachim Sieper
Arthritis Research & Therapy , 2011, DOI: 10.1186/ar3370
Abstract: Immunohistochemical analysis of IL-17+ cells was performed in facet joints of 33 ankylosing spondylitis (AS) patients and compared with data from 20 osteoarthritis (OA) patients. The frequency of IL-17+CD4+ T cells in PB and SF of SpA patients (PB n = 30, SF n = 11), rheumatoid arthritis (RA) patients (PB n = 14, SF n = 7), OA patients (PB n = 10) and healthy controls (PB n = 12) was analysed after stimulation with Staphylococcus aureus Enterotoxin B and phorbol 12-myristate 13-acetate/ionomycin and quantified by flow cytometry.In AS facet joints, the frequency of IL-17-secreting cells was significantly higher than in samples obtained from OA patients (P < 0.001), with a slight predominance of IL-17+ cells among the mononuclear cells (61.5% ± 14.9%) compared to cells with polysegmental nuclei. Immunofluorescence microscopy revealed that the majority of IL-17+ cells were myeloperoxidase-positive (35.84 ± 13.06/high-power field (HPF) and CD15+ neutrophils (24.25 ± 10.36/HPF), while CD3+ T cells (0.51 ± 0.49/HPF) and AA-1+ mast cells (2.28 ± 1.96/HPF) were less often IL-17-positive. The frequency of IL-17+CD4+ T cells in the PB and SF of SpA patients did not differ significantly compared to RA patients, OA patients or healthy controls.Our data suggest an important role for IL-17 in the inflammatory processes in AS. However, the innate immune pathway might be of greater relevance than the Th17-mediated adaptive immune response.Spondyloarthritis (SpA) comprises ankylosing spondylitis (AS), reactive arthritis, arthritis/spondylitis with inflammatory bowel disease and arthritis/spondylitis with psoriasis. Inflammatory back pain, a similar pattern of peripheral joint involvement with an asymmetrical arthritis predominantly of the lower limbs and the possible occurrence of sacroiliitis, spondylitis, enthesitis and uveitis are typical clinical features in this group of diseases [1]. SpA can be split into two categories, SpA with predominant axial involvement and SpA with pred
A Simple Vector Proof of Feuerbach's Theorem
Michael Scheer
Mathematics , 2011,
Abstract: The celebrated theorem of Feuerbach states that the nine-point circle of a nonequilateral triangle is tangent to both its incircle and its three excircles. In this note, we give a simple proof of Feuerbach's Theorem using straightforward vector computations. All required preliminaries are proven here for the sake of completeness.
Model for the phycobilisome rod with interlocking disks based on domain-weighted linker-polypeptide sequence homologies of Mastigocladus laminosus
Axel Parbel,Hugo Scheer
International Journal of Photoenergy , 2000, DOI: 10.1155/s1110662x00000052
Abstract: The 8 linker-polypeptides from the cyanobacterium Mastigocladus laminosus were examined by comparative amino-acid sequence analysis for the predicted domain structure reported in the literatur (Glauser 1991, Esteban 1993) in detail using split sequences for the rod, rod-core and for the repeats from the core-membrane linker-polypeptide (Lcm127.6). This analysis gives two distinct domains, where domain 1 (∼ 22 kDa, identity between 31 and 70%) is present in the N-terminal two thirds of the class II linkers (∼ 30 kDa) and in the repeats of the Lcm127.6, and domain 2 (∼ 10 kDa, identity between 28 and 41%) in the C-terminal part of the class II rod linkers (Lr31.5 and Lr32.5) and in the two capping linkers (Lc7.7 and Lr8.2). Based on these data, X-ray structure analysis from phycobiliproteins and proteolysis experiments, an interlocking model for the phycobilisome rod organization is proposed, with linkers protruding from one phycobilisome disk into the neighbouring one.
Transport Channels in a Double Junction- coherent coupling changes the picture
Ursula Schroeter,Elke Scheer
Physics , 2009,
Abstract: Transport through a point contact is accurately modelled by assigning to the junction an ensemble of independent transport channels with possibly different transmissions. We here argue that for a series of two contacts, coherently coupled across an island, the transport channels are different from the ensembles that would describe each contact taken as stand-alone device. We further show that instead of two sets of channels with manifold cross-links over the island the double junction can be described by pairs of channels from both sides coherently coupled together, where each pair, however, has no coherent connection to the others. This finding will substantially simplify modelling transport by a Green's functions technique. Additional channels through only one junction may complete the picture. Finally we discuss how partial coherence across the island with an appropriate ansatz can be modelled in the same scheme.
Force-noise spectroscopy by tunnelling current deflection sensing
Markus Herz,Elke Scheer
Physics , 2015,
Abstract: An electro-mechanical setup for the measurement of AC-forces in a low-temperature tunnelling microscope has been developed, which enables extremely high force resolution. The crosstalk of vibrations onto the tunnelling current is used to measure the deflection of a force-sensing cantilever beam. We demonstrate its capability to measure the noise of the force at a tunnelling contact using polycrystalline Iridium. Depending on temperature, spring constant and current, a resolution in the range of $\rm {fN}/\sqrt{\rm Hz}$ is possible. We observe peak levels of the force-noise at the energy of the expected phonon maximal density of states, which suggests that inelastic transport processes contribute to force fluctuations.
Pricing Currency Call Options  [PDF]
Rebecca Abraham
Theoretical Economics Letters (TEL) , 2018, DOI: 10.4236/tel.2018.811148
Abstract: This paper presents a theoretical model to price foreign currency call options. Currency options are employed in international trade to reduce the risk of loss due to the reduction of revenues obtained in depreciating foreign currency for an exporter, or the escalation of expense from appreciating foreign currency for an importer. Other users include banks and hedge funds who engage in currency speculation. Given the fluctuation of option prices over time, the model describes the distribution of foreign currency as a Weiner process for macroeconomically constrained foreign currencies followed by a Laplace distribution for unconstrained currencies. In a departure from existing currency option models, this model expresses foreign currencies as dependent upon the change in macroeconomic variables, such as inflation, interest rates, and government deficits. The distribution of currency calls is described as a Levy process in the context of an option trader’s risk preferences to account for the multiple discontinuities of a jump process. The paper concludes with three models of price functions of the Weiner process for Euro-related currency options, a Weiner process for stable currency options, and a Levy-Khintchine process for volatile currency calls.
The Valuation of Currency Put Options  [PDF]
Rebecca Abraham
Theoretical Economics Letters (TEL) , 2018, DOI: 10.4236/tel.2018.811165
Abstract: Investors who seek to profit from depreciating currencies may invest in put options. Upon option exercise, the currency is sold at a high price, and then purchased at the lower future currency value, resulting in a gain for the put buyer. A series of such transactions yields a stream of income for the put investor. Alternatively, the investor could short sell the currency, reaping gains from the difference between the high short sale price and the low future purchase price. This paper derives the theoretical formulations for combined short sale and puts purchase strategies for the US dollar, the Euro, the Australian dollar and the New Zealand dollar, and the Mexican peso. Utility functions are based upon an assumption of declining risk aversio with negative rescale factors and positive threshold factors in a hyperbolic cosine distribution. This distribution intersects with the cosine distribution of short sale prices on the U. S. dollar, the lognormal distribution of short sale prices on the Euro, the Weiner process for shorts on the Australian dollar and the New Zealand dollar, and the Laplace currency distribution for peso shorts. Similar utility functions intersect with Levy-Khintchine jump processes to provide put option prices for each type of foreign currency.
Hedge Fund Investing or Mutual Fund Investing: An Application of Multi-Attribute Utility Theory  [PDF]
Rebecca Abraham
Theoretical Economics Letters (TEL) , 2019, DOI: 10.4236/tel.2019.94042
Abstract: This paper contrasts high-risk, hedge fund trading, with low-risk, mutual fund trading, in terms of their differing utility functions. We envision hedge funds, led by informed traders who use information to seek out investment opportunities, timing market conditions, with the expectation that prices will move in their favor. Directional hedge funds act to influence prices, while non-directional hedge funds do not act to influence prices. We present utility functions based on steeply-sloping Laplace distributions and hyperbolic cosine distributions, to describe the actions of directional hedge fund traders. Less steeply-sloping lognormal distributions, Coulomb wave functions, quadratic utility functions, and Bessel utility functions are used to describe the investing style of non-directional hedge fund traders. Flatter Legendre utility functions and inverse sine utility functions describe the modest profit-making aspirations of mutual fund traders. The paper’s chief contribution is to develop optimal prices quantitatively, by intersecting utility functions with price distributions. Price distributions for directional hedge fund returns are portrayed as sharp increases and decreases, in the form of jumps, in a discrete arrival Poisson-distributed process. Separate equations are developed for directional hedge fund strategies, including event-driven arbitrage, and global macro strategies. Non-directional strategies include commodity trading, risk-neutral arbitrage, and convertible arbitrage, with primarily lognormal pricing distributions, and some Poisson jumps. Mutual funds are perceived to be Markowitz portfolios, lying on the Capital Market Line, or the International Capital Market Line, tangent to the Efficient Frontier of minimum variance-maximum return portfolios.
Clinical review: Complications and risk factors of peripheral arterial catheters used for haemodynamic monitoring in anaesthesia and intensive care medicine
Bernd Scheer, Azriel Perel, Ulrich J Pfeiffer
Critical Care , 2002, DOI: 10.1186/cc1489
Abstract: Indwelling arterial catheters are used routinely for continuous haemodynamic monitoring in the operating room during major surgery and in critically ill patients. Arterial cannulation provides easy and convenient access, allowing multiple blood samplings and blood gas analysis. Arterial cannulation has generally been found to be a safe procedure, with few serious complications [1,2,3,4,5,6]. Approximately 8 million and 2.5 million arterial catheters are placed yearly in the USA and Europe, respectively [7]. Despite the frequency with which arterial catheters are employed, there is little information on the impact of cannulation site on risk for complications [8]. We reviewed reports concerning arterial cannulation sites such as the radial, femoral, axillary, brachial, ulnar, dorsal pedis, tibial posterior and temporal arteries with regard to thrombotic, infectious and vascular complications.The PubMed, Medline Express and Winspirs databases (publication years 1978-2001) were searched to identify pertinent articles. The keywords 'artery catheter', 'radial artery catheter', 'femoral artery catheter', 'axillary artery catheter', 'catheter complication', 'hemodynamic monitoring' and 'peripheral methods' were used. We reviewed the papers and identified further articles from the references of the papers found in the initial search.We reviewed all studies concerning the use of radial, femoral, axillary, brachial, ulnar, dorsal pedis, tibial posterior and temporal artery catheters for haemodynamic monitoring that dealt with complications and risk factors in adults. We excluded studies conducted in the paediatric patient population.We opted not to perform statistical analyses because the data selection of the published reports do not follow the same criteria, and most of them give no specific information regarding patient population, catheter material, cannulation technique and times. Therefore, comparison between studies and statistical analyses are unlikely to be valid.We
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