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  • Springer  (50)
  • Oxford University Press  (8)
  • Sage Publications
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  • 1
    ISSN: 1432-1351
    Schlagwort(e): Cobalt staining ; Gas chromatography-mass spectrometry ; Immunohistochemistry ; Insect ; Neuromodulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The two Protocerebral-Medulla 4 neurons (PM4a and b) in the locust brain have adjacent cell bodies in the medial deutocerebrum. They project through the posterior protocerebrum, forming limited arborisations en route, and enter the lobula and medulla of the ipsilateral optic lobe, where they form extensive, overlapping arborisations. The PM4a and b neurons are octopamine immunoreactive. Their octopamine content (approximately 25 pg per cell) is confirmed by gas chromatography-mass spectrometry; each cell contains approximately 25 pg p-octopamine. Simultaneous intracellular recording from exposed PM4a and b cell bodies reveals that the two cells are physiologically indistinguishable. They receive multimodal sensory inputs. Tactile/mechanosensory stimuli to much of the animal's body and head, acoustic stimuli, and simple visual stimuli all give rise to e.p.s.p.s and action potentials in the PM4 cell body. Simultaneous recording from the cell body in the deutocerebrum and the axon in the lobula demonstrates that action potentials are predominantly initiated in the deutocerebrum and propagate centrifugally, towards the optic lobe. Occasionally, bright light flashes will initiate an action potential in the axon in the optic stalk, which probably propagates bidirectionally: centripetally to the cell body, and centrifugally into the optic lobe. The extensive arborisations in the lobula and medulla are therefore likely to be sites of octopamine release. Because PM4 neurons are octopaminergic, project to the optic lobe, and receive modalities of sensory input known to dishabituate the Descending Contralateral Movement Detector (DCMD) visual interneuron, it is proposed that PM4 neurons are neuromodulatory — mediating dishabituation or arousal of the visual system.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    ISSN: 1432-2099
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Physik
    Notizen: Abstract The effect was studied of a low dose ofγ-ray preexposure on the frequency and molecular spectrum of radiation-induced mutations at the hprt locus in a human T-cell leukemia line. When the cells were preexposed to 0.01 Gy ofγ-rays, the yield of mutations induced by a subsequent 2-Gy challenge dose was reduced by 60%, compared with the 2 Gy of irradiation alone. The data of Southern blot analysis showed that 47% of the mutants induced by 2 Gy in the cells without low-dose preexposure were of the deletion or rearranged mutations type. In contrast, in the low-dose radioadapted cells the proportion of this type of 2-Gy-induced mutations decreased to 28%. This is close to the control level (22%) of spontaneous mutations. Our results confirm that a low dose ofγ-ray preexposure leads to a decreased susceptibility to gene deletions and rearrangements after high-dose irradiation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    The journal of membrane biology 172 (1999), S. 113-120 
    ISSN: 1432-1424
    Schlagwort(e): Key words: Apoptosis — 4-Aminopyridine — High K+ concentration — Gene expression — Membrane potential
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract. Mcl-1, a member of the Bcl-2 family, has been identified as an inhibitor of apoptosis induced by anticancer agents and radiation in myeloblastic leukemia cells. The molecular mechanism underlying this phenomenon, however, is not yet understood. In the present study, we report that hyperpolarization of the membrane potential is required for prevention of mcl-1 mediated cell death in murine myeloblastic FDC-P1 cells. In cells transfected with mcl-1, the membrane potential, measured by the whole-cell patch clamp, was hyperpolarized more than −30 mV compared with control cells. The membrane potential was repolarized by increased extracellular K+ concentration (56 mV per 10-fold change in K+ concentration). Using the cell-attached patch-clamp technique, K+ channel activity was 1.7 times higher in mcl-1 transfected cells (NP o = 22.7 ± 3.3%) than control cells (NP o = 13.2 ± 1.9%). Viabilities of control and mcl-1 transfected cells after treatment with the cytotoxin etoposide (20 μg/ml), were 37.9 ± 3.9% and 78.2 ± 2.0%, respectively. Suppression of K+ channel activity by 4-aminopyridine (4-AP) before etoposide treatment significantly reduced the viability of mcl-1 transfected cells to 49.0 ± 4.6%. These results indicate that as part of the prevention of cell death, mcl-1 causes a hyperpolarization of membrane potential through activation of K+ channel activity.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Neural computing & applications 7 (1998), S. 334-342 
    ISSN: 1433-3058
    Schlagwort(e): Benchmarks ; Learning criteria ; Multilayer perceptron networks ; Pattern classification ; Radial basis function networks ; Training methods
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract This paper presents a study of two learning criteria and two approaches to using them for training neural network classifiers, specifically a Multi-Layer Perceptron (MLP) and Radial Basis Function (RBF) networks. The first approach, which is a traditional one, relies on the use of two popular learning criteria, i.e. learning via minimising a Mean Squared Error (MSE) function or a Cross Entropy (CE) function. It is shown that the two criteria have different charcteristics in learning speed and outlier effects, and that this approach does not necessarily result in a minimal classification error. To be suitable for classification tasks, in our second approach an empirical classification criterion is introduced for the testing process while using the MSE or CE function for the training. Experimental results on several benchmarks indicate that the second approach, compared with the first, leads to an improved generalisation performance, and that the use of the CE function, compared with the MSE function, gives a faster training speed and improved or equal generalisation performance.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 79 (1990), S. 177-179 
    ISSN: 1434-6036
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract An experimental method is proposed for measuring the refractive indices of anisotropic crystals. The results of the first measurements are in good agreement with those of other methods.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Environmental monitoring and assessment 38 (1995), S. 253-269 
    ISSN: 1573-2959
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract The energy balances of most African countries suggest that biofuels (woodfuel, crop and wood residues, and dung) constitute the largest share of total energy consumption (up to 97% in some sub-Saharan Africa countries). There is, however, an increasing scarcity of woodfuel (fuelwood and charcoal), the major biofuel, and a feared increase in greenhouse gas (GHG) emissions associated with biofuel combustion. The extent of GHG emissions is estimated from biofuel consumption levels that are in turn based on methodologies that might be inaccurate. A questionnaire, supplemented by informal interviews, are used to collect data, yielding information regarding end-uses, technologies used, scale of consumption, determinants of fuel consumption, and interfuel substitution (among other parameters). The survey revealed that cooking is the major end-use, with other common uses, such as space and water heating. Improved stoves that provide better combustion efficiency and, thus, reduce woodfuel consumption have not been widely disseminated and are associated with higher methane emissions than open fires. More than 90% of the households in Africa use open fires. Consumption is presented as per capita for households and as products and quantity of fuel in the small scale industries, commercial, and public sectors. Among the determinants for biofuel consumption are affordability, availability of the fuel, and interfuel substitutions. Flaws in estimating biofuel consumption yield large uncertainties in GHG emissions, with implications for the development of policies on energy planning and environmental protection. However, the application of scenarios can guide policy formulation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Journal of materials science 35 (2000), S. 4337-4341 
    ISSN: 1573-4803
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract Small angle neutron scattering and X-ray diffraction were used to study the effect of oxidation treatment on the structure and Li capacity of disordered carbons. The oxidation treatment increase the pore density and reduce the degree of parallel arrangement of graphene layers, all with no detectable change in pore size. Scattering from Li-doped samples indicates that the Lithium is most likely coating the pore surfaces rather than creating clusters inside the pores. The results are analyzed in terms of the newly proposed “potato-chips” (edge-connected graphene fragments, or “cards”) model of amorphous carbons, from which we infer translation, or “surfing”, of connected fragments during heat treatment.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 15 (2001), S. 267-277 
    ISSN: 1434-6079
    Schlagwort(e): PACS. 42.50.Hz Strong-field excitation of optical transitions in quantum systems; multi-photon processes; dynamic Stark shift – 42.50.Lc Quantum fluctuations, quantum noise, and quantum jumps
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract: The dressed-state populations and the resonance fluorescence spectrum of a V-type three-level atom driven by a strong coherent field and a weak stochastic one simultaneously are investigated. There can be significant population inversion due to the effect of the stochastic field. The atomic resonance fluorescence spectrum can be controlled by adjusting the frequency difference between the coherent field and the stochastic one and the coherent Rabi frequency. Peak suppression and line narrowing occur under appropriate conditions.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Publikationsdatum: 2019-07-01
    Print ISSN: 0038-0741
    Digitale ISSN: 1573-9279
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geologie und Paläontologie
    Publiziert von Springer
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    facet.materialart.
    Unbekannt
    Oxford University Press
    Publikationsdatum: 2016-03-29
    Beschreibung: File download vulnerability, which exposes web servers' local filesystem to the public, is among the most serious security threats in the web. Exploiting this vulnerability will cause disastrous consequences such as, but not limited to, system intrusion, database intrusion and even the leakage of massive confidential documents. Although the file download vulnerability has been known in the literature for a long time, a comprehensive study of its exploitability in the wild is still lacked. In this paper, we survey the landscape of file download vulnerabilities across different countries and domains, and more importantly, examines their exploitability from a hacker's perspective. We have successfully revealed the weak protection of this vulnerability in today's web, as well as confirmed its wide exploitability. To demonstrate the serious consequences, we present two real-world intrusion case studies. One is a system intrusion against a Chinese government website, and the other is a database intrusion targeted to a Chinese industrial service. Our intrusion cases have been confirmed as severe security events by CNCERT (an official security agency in China). At the end, we explore the root cause of this weak protection by analyzing the perils and pitfalls of existing defending solutions, and thereby propose a new enhancement. The basic idea is to deploy a mandatory access control mechanism in the server-side script engine kernel, so as to isolate the files managed by the web server from the local filesystem. We have implemented security-enhanced PHP (i.e. SEPHP), a prototype of our new solution by modifying the source code of PHP5 script engine, and also evaluated the performance overhead induced by SEPHP in a real-world web setting.
    Print ISSN: 0010-4620
    Digitale ISSN: 1460-2067
    Thema: Informatik
    Publiziert von Oxford University Press
    Standort Signatur Erwartet Verfügbarkeit
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