1,476 research outputs found

    Improvement of local Resistance of Safety-Related Structures and Reduction of Dynamic Response due to Missile Impact Loading

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    Evaluation of the load-bearing and shielding capacity of safety-related structures not designed for missile impact loading (e.g. from aircraft crash) led to problem-specific investigations, conducted with the aim of establishing effective shielding, reinforcing and energy dissipation concepts. To ensure protection of structures against missile impact, emphasis was placed in this study not only on upgrading the penetration resistance of the structures in the impacted area, but also in particular on reducing the dynamic response induced by impact loads. Although a number of shielding concepts exist which are useful in a theoretical sense, only a few of these are of any practical significance due to the rather small region affected by impact loading and the rather high magnitude of the loads. Any shielding concept suitable for protecting a building against the impact of a missile (e.g. aircraft) over its entire outer surface must provide the target with homogeneous protection in the form of a jacket of high strength and high energy dissipation capacity. Of the various concepts investigated, the most promising seems to be that providing protection by means of hollow-wall designs or special shielding elements, both made of energy-absorbing high-quality steel-fiberreinforced concrete [1]. This paper covers studies of different local design concepts for the targeted regions and material parameters which have a strong influence on the penetration resistance as well as energy dissipation capabilities of the impacted building. Possibilities for reinforcing the outer shells of typical buildings not originally designed to withstand missile impact are also presented

    Observing Attitudes, Intentions and Expectations (1945-1973)

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    Although involved in projects of influent institutions like the Cowles Commission, the NBER, and the Michigan Survey Research Center (SRC), George Katona, the "pioneer student and chief collector of consumer anticipations data" (Tobin, 1959, p. 1) is virtually absent from accounts of the topics he explored, including the study of the consumption function and the development of behavioral economics. This essay argues that such an absence is partly explained by the theoretical underpinnings of Katona's project, which were incompatible with the economic views of behavior that dominated from the mid-1940s to the mid-1970s. It compares alternative survey programs funded by the Federal Reserve during that period, and analyzes the ensuing controversy on the purposes of the observation of attitudes, intentions and expectations. It claims that understanding Katona's approach "required a real restructuring of thought - a genuine paradigm shift" (Simon, 1979, p. 12), which gives specific interest to this historical episode

    Influence of maltodextrin dextrose equivalent value on rheological and dispersion properties of sunflower oil in water emulsions

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    Effect of dextrose equivalent (DE) of maltodextrin present in continuous phase on flow along with dispersion properties of sunflower oil in water emulsions has been investigated. Both, rheological and disperse characteristics of the emulsions were greatly influenced by continuous phase viscosity and thus by the DE value of maltodextrin.. The smaller DE value the greater high shear viscosity and the smaller the droplet size. Irrespective of the amount and DE value of maltodextrin used was, all the emulsions showed a pseudoplastic behaviour

    Capecitabine-induced lichenoid drug eruption: a case report

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    Capecitabine is a 5-fluorouracil basedchemotherapeutic drug widely used in the treatmentof solid tumors, especially colorectal and breast. Someof the most common side effects of capecitabine arecutaneous in nature, including hand-foot syndrome(palmar-plantar erythrodysesthesia). Several reports inthe literature link capecitabine use with photosensitivelichenoid eruptions. Herein, we present a case ofcapecitabine-induced lichenoid eruption in an elderlyfemale with metastatic breast cancer and discuss ourfindings in relationship to previously reported cases ofthis and other capecitabine-induced skin pathologies

    Nanocomposite-based dual enzyme system for broad-spectrum scavenging of reactive oxygen species

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    A broad-spectrum reactive oxygen species (ROS)-scavenging hybrid material (CASCADE) was developed by sequential adsorption of heparin (HEP) and poly(L-lysine) (PLL) polyelectrolytes together with superoxide dismutase (SOD) and horseradish peroxidase (HRP) antioxidant enzymes on layered double hydroxide (LDH) nanoclay support. The synthetic conditions were optimized so that CASCADE possessed remarkable structural (no enzyme leakage) and colloidal (excellent resistance against salt-induced aggregation) stability. The obtained composite was active in decomposition of both superoxide radical anions and hydrogen peroxide in biochemical assays revealing that the strong electrostatic interaction with the functionalized support led to high enzyme loadings, nevertheless, it did not interfere with the native enzyme conformation. In vitro tests demonstrated that ROS generated in human cervical adenocarcinoma cells were successfully consumed by the hybrid material. The cellular uptake was not accompanied with any toxicity effects, which makes the developed CASCADE a promising candidate for treatment of oxidative stress-related diseases

    Functional and structural deficits at accumbens synapses in a mouse model of Fragile X

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    International audienceFragile X is the most common cause of inherited intellectual disability and a leading cause of autism. The disease is caused by mutation of a single X-linked gene called fmr1 that codes for the Fragile X mental retardation protein (FMRP), a 71 kDa protein, which acts mainly as a translation inhibitor. Fragile X patients suffer from cognitive and emotional deficits that coincide with abnormalities in dendritic spines. Changes in spine morphology are often associated with altered excitatory transmission and long-term plasticity, the most prominent deficit in fmr1-/y mice. The nucleus accumbens, a central part of the mesocortico-limbic reward pathway, is now considered as a core structure in the control of social behaviors. Although the socio-affective impairments observed in Fragile X suggest dysfunctions in the accumbens, the impact of the lack of FMRP on accumbal synapses has scarcely been studied. Here we report for the first time a new spike timing-dependent plasticity paradigm that reliably triggers NMDAR-dependent long-term potentiation (LTP) of excitatory afferent inputs of medium spiny neurons (MSN) in the nucleus accumbens core region. Notably, we discovered that this LTP was completely absent in fmr1-/y mice. In the fmr1-/y accumbens intrinsic membrane properties of MSNs and basal excitatory neurotransmission remained intact in the fmr1-/y accumbens but the deficit in LTP was accompanied by an increase in evoked AMPA/NMDA ratio and a concomitant reduction of spontaneous NMDAR-mediated currents. In agreement with these physiological findings, we found significantly more filopodial spines in fmr1-/y mice by using an ultrastructural electron microscopic analysis of accumbens core medium spiny neuron spines. Surprisingly, spine elongation was specifically due to the longer longitudinal axis and larger area of spine necks, whereas spine head morphology and postsynaptic density size on spine heads remained unaffected in the fmr1-/y accumbens. These findings together reveal new structural and functional synaptic deficits in Fragile X

    Rheological properties of hydroxypropylmethyl cellulose/sodium dodecylsulfate mixtures

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    Rheological properties of mixtures of hydroxypropylmethyl cellulose (HPMC), a nonionic associative cellulose ether, and sodium dodecylsulfate (SDS), an anionic surfactant, were investigated by viscosity measurements performed at different shear rates (0.1-6000 s-1). HPMC/SDS mixtures containing different concentrations of SDS (CSDS=0.00-3.50 % w/w) and HPMC concentrations which corresponded to the overlap parameter c/c*=3, 6, and 12 were prepared. All HPMC/SDS mixtures were found to be shear-thinning when examined in a low-end-to mid-range of the applied shear rates. The degree of shear-thinning, n, and viscosity of the mixtures were influenced by composition of HPMC/SDS mixtures and HPMC-SDS complex formation. The changes in n ranged from values typical for highly shear thinning to almost perfectly Newtonian liquids, and were more pronounced as c/c* was increased from 3 to 6 and 12. A change in flow profile and a buildup of the first normal stress difference (N1) was observed in HPMC/SDS mixtures with c/c*=6 and 12 and CSDS 0.55-1.00 % and 0.55-2.50 %, respectively, when a critical shear rate, crit. was exceeded, suggesting that a shear-induced structure formation in the mixtures took place. [Projekat Ministartsva nauke Republike Srbije, br. Grant III 46010

    Regular dendritic patterns induced by non-local time-periodic forcing

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    The dynamic response of dendritic solidification to spatially homogeneous time-periodic forcing has been studied. Phase-field calculations performed in two dimensions (2D) and experiments on thin (quasi 2D) liquid crystal layers show that the frequency of dendritic side-branching can be tuned by oscillatory pressure or heating. The sensitivity of this phenomenon to the relevant parameters, the frequency and amplitude of the modulation, the initial undercooling and the anisotropies of the interfacial free energy and molecule attachment kinetics, has been explored. It has been demonstrated that besides the side-branching mode synchronous with external forcing as emerging from the linear Wentzel-Kramers-Brillouin analysis, modes that oscillate with higher harmonic frequencies are also present with perceptible amplitudes.Comment: 15 pages, 23 figures, Submitted to Phys. Rev.
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