2,787 research outputs found

    Competition effects of simultaneous application of flexibility options within an energy community

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    As part of an increased diffusion of decentralized renewable energy technologies, an additional need for flexibility arises. Studies indicate that operating battery storage systems for multiple uses as community electricity storage system (CES) promises superior benefits. This seems decisive, since cheaper flexibility options such as demand response (DR) are more applicable and might further reduce the market size for storage facilities. This research paper aims to analyze the competition effects of CES with simultaneous application of DR. The optimization results of the synthetic case studies provide insights in the profitability level, the service provision and the flexibility potential. While even under requested legal circumstances a CES is only partially profitable, the economic situation improves in terms of an optimal storage utilization. This, however, is reduced through competition effects with DR

    A construction of Frobenius manifolds with logarithmic poles and applications

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    A construction theorem for Frobenius manifolds with logarithmic poles is established. This is a generalization of a theorem of Hertling and Manin. As an application we prove a generalization of the reconstruction theorem of Kontsevich and Manin for projective smooth varieties with convergent Gromov-Witten potential. A second application is a construction of Frobenius manifolds out of a variation of polarized Hodge structures which degenerates along a normal crossing divisor when certain generation conditions are fulfilled.Comment: 46 page

    BMPix and PEAK tools: New methods for automated laminae recognition and counting — Application to glacial varves from Antarctic marine sediment

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    We present tools for rapid and quantitative detection of sediment lamination. The BMPix tool extracts color and gray-scale curves from images at pixel resolution. The PEAK tool uses the gray-scale curve and performs, for the first time, fully automated counting of laminae based on three methods. The maximum count algorithm counts every bright peak of a couplet of two laminae (annual resolution) in a smoothed curve. The zero-crossing algorithm counts every positive and negative halfway-passage of the curve through a wide moving average, separating the record into bright and dark intervals (seasonal resolution). The same is true for the frequency truncation method, which uses Fourier transformation to decompose the curve into its frequency components before counting positive and negative passages. We applied the new methods successfully to tree rings, to well-dated and already manually counted marine varves from Saanich Inlet, and to marine laminae from the Antarctic continental margin. In combination with AMS14C dating, we found convincing evidence that laminations in Weddell Sea sites represent varves, deposited continuously over several millennia during the last glacial maximum. The new tools offer several advantages over previous methods. The counting procedures are based on a moving average generated from gray-scale curves instead of manual counting. Hence, results are highly objective and rely on reproducible mathematical criteria. Also, the PEAK tool measures the thickness of each year or season. Since all information required is displayed graphically, interactive optimization of the counting algorithms can be achieved quickly and conveniently

    Rhizobia contribute to salinity tolerance in common beans (Phaseolus vulgaris L.)

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    Rhizobia are soil bacteria that induce nodule formation on leguminous plants. In the nodules, they reduce dinitrogen to ammonium that can be utilized by plants. Besides nitrogen fixation, rhizobia have other symbiotic functions in plants including phosphorus and iron mobilization and protection of the plants against various abiotic stresses including salinity. Worldwide, about 20% of cultivable and 33% of irrigation land is saline, and it is estimated that around 50% of the arable land will be saline by 2050. Salinity inhibits plant growth and development, results in senescence, and ultimately plant death. The purpose of this study was to investigate how rhizobia, isolated from Kenyan soils, relieve common beans from salinity stress. The yield loss of common bean plants, which were either not inoculated or inoculated with the commercial R. tropici rhizobia CIAT899 was reduced by 73% when the plants were exposed to 300 mM NaCl, while only 60% yield loss was observed after inoculation with a novel indigenous isolate from Kenyan soil, named S3. Expression profiles showed that genes involved in the transport of mineral ions (such as K+, Ca2+, Fe3+, PO43−, and NO3−) to the host plant, and for the synthesis and transport of osmotolerance molecules (soluble carbohydrates, amino acids, and nucleotides) are highly expressed in S3 bacteroids during salt stress than in the controls. Furthermore, genes for the synthesis and transport of glutathione and γ-aminobutyric acid were upregulated in salt-stressed and S3-inocculated common bean plants. We conclude that microbial osmolytes, mineral ions, and antioxidant molecules from rhizobia enhance salt tolerance in common beans

    Optimized culture conditions for tissue explants of uterine leiomyoma

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    Background: Uterine leiomyomas are the most common benign tumours in women, which arise from smooth muscle cells of the uterine myometrium and usually are multicentric. In spite of their frequency pathogenesis is widely unknown, mainly due to the absence of a suitable model system. We describe the systematic optimization of culturing leiomyoma tissue explants in an economical and effective ex vivo system. Methods: Different concentrations of oxygen, different media, sera, hormones, and growth factor supplements were tested. Immunohistochemical stainings with antibodies against hormone receptors as well as specifying proliferation and apoptotic indices and real-time PCR were performed. Results: Main parameters for culturing myoma tissue explants were tested for finding an optimal protocol. Standard medium D-MEM-F12 in combination with the use of horse serum in a reduced concentration of 1% turned out to be optimal for these tissue cultures as well as the addition of estradiol and epidermal growth factor EGF to media. Reduced oxygen content in the incubator air showed no positive effect. Conclusions: For culturing tissue explants of uterine leiomyoma several conditions were optimized. The established tissue culture model allows examining the effects of known and potential therapeutic substances and the influence of immune competent cells in the process of tumour formation to find new targets for medical treatmen

    Frequency of seizures and epilepsy in neurological HIV-infected patients

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    SummaryBackgroundInfection with the human immunodeficiency virus (HIV) is associated both with infections of the central nervous system and with neurological deficits due to direct effects of the neurotropic virus. Seizures and epilepsy are not rare among HIV-infected patients. We investigated the frequency of acute seizures and epilepsy of patients in different stages of HIV infection. In addition, we compared the characteristics of patients who experienced provoked seizures only with those of patients who developed epilepsy.MethodsThe database of the Department of Neurology, University of Münster, was searched for patients with HIV infection admitted between 1992 and 2004. Their charts were reviewed regarding all available sociodemographic, clinical, neurophysiological, imaging and laboratory data, therapy and outcome. Stage of infection according to the CDC classification and the epileptogenic zone were determined.ResultsOf 831 HIV-infected patients treated in our department, 51 (6.1%) had seizures or epilepsy. Three of the 51 patients (6%) were diagnosed with epilepsy before the onset of the HIV infection. Fourteen patients (27%) only had single or few provoked seizures in the setting of acute cerebral disorders (eight patients), drug withdrawal or sleep withdrawal (two patients), or of unknown cause (four patients). Thirty-four patients (67%) developed epilepsy in the course of their HIV infection. Toxoplasmosis (seven patients), progressive multifocal leukencephalopathy (seven patients) and other acute or subacute cerebral infections (five patients) were the most frequent causes of seizures. EEG data of 38 patients were available. EEG showed generalized and diffuse slowing only in 9 patients, regional slowing in 14 patients and regional slowing and epileptiform discharges in 1 patient. Only 14 of the patients had normal EEG. At the last contact, the majority of the patients (46 patients=90%) were on highly active antiretroviral therapy (HAART). Twenty-seven patients (53%) were on anticonvulsant therapy (gabapentin: 14 patients, carbamazepine: 9 patients, valproate: 2 patients, phenytoin: 1 patient, lamotrigine: 1 patient). Patients with only provoked seizures had no epilepsy risk factors except HIV infection, and were less likely to be infected via intravenous drug abuse.ConclusionsSeizures are a relevant neurological symptom during the course of HIV infection. Although in some patients seizures only occur provoked by acute disease processes, the majority of patients with new onset seizures eventually develops epilepsy and require anticonvulsant therapy. Intravenous drug abuse and the presence of non-HIV-associated risk factors for epilepsy seem to be associated with the development of chronic seizures in this patient group

    Transactivation of the epidermal growth factor receptor in responses to myocardial stress and cardioprotection

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    The epidermal growth factor receptor (EGFR) family comprises the ErbB1 (EGFR) and ErbB4 receptors as well as the ‘co-receptors’ ErbB2 (which does not bind EGF ligands) and ErbB3 (which lack tyrosine kinase activity). This family of receptors is essential for cardiac development, myocardial, renal and vascular function, and cardiac responses to physiological and pathological perturbations. The EGFR appears critical in protecting cardiac cells from injury, while considerable attention has focussed on neuregulin/ErbB4 signalling in potentially ameliorating cardiomyopathy/heart failure. Indeed, the EGFRs provide a signalling nexus, upon which multiple cardioprotective stimuli appear to converge, including ischaemic preconditioning and various G protein-coupled receptors (opioid, muscarinic, adenosine, adrenergic, bradykinin, sphingosine 1-phosphate). These stimuli engage the EGFR axis (in a process referred to as transactivation) in differing ways, involving both G protein-dependent and -independent mechanisms, to promote myocardial cell survival during and following ischaemia/infarction. Elucidating the molecular processes that underpin EGFR transactivation and mediate cardiac protection will advance our understanding of the intrinsic capacity of the heart to withstand pathological insult. It should also reveal new approaches to facilitate cardioprotective therapy to limit damage during and following myocardial ischaemia/infarction, which despite intense investigation remains an unrealised, yet highly desirable, clinical goal. This review focuses on the cardiovascular functions of the EGFR, its role in cardioprotection, and the potential influences of common disease states on this signalling
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