24 research outputs found
Verification of an energy-based design procedure for seismic retrofit of a school building
No full textA viable design criterion of supplemental damping strategies for seismic retrofit of frame structures, recently proposed by the first author (Terenzi, 2018), is applied in this paper to a school building in Florence dating back to the early 1980s. The building is composed of two portions, with reinforced concrete and steel frame structure, respectively. Similarly to several other buildings of the same period, the structure is infilled by heavy reinforced concrete panels interacting with the frame elements under horizontal loads. A careful reconstruction of the structural characteristics of the constituting members, based on the original design documentation and on-site testing campaigns, highlighted specific drawbacks in current state, related to a remarkable degration of the materials and a poor performance of several elements. The retrofit solution considered in this study consists in removing the infill panels and replacing them with a set of dissipative braces incorporating fluid viscous dampers as protective devices. The design is carried out by the sizing criterion mentioned above, targeting an elastic structural response up to the maximum considered earthquake normative level
Application of an energy-based procedure to the design of FV devices for seismic retrofit interventions
No full textSupplemental damping techniques are increasingly applied in the field of seismic retrofit of frame buildings. Among these techniques, “mainly dissipative” (MD) ones, i.e. capable of supplying a high damping action without significant stiffening effects of the structural system, are preferred when rather stiff structures are dealt with in current conditions. A typical example in this field, represented by a MD-based retrofit intervention designed for a school gym in Florence, built in 1971, is presented in this paper. The structure is regular, but with dynamic properties significantly different along the two main directions in plan. A careful reconstruction of the characteristics of the constituting members, based on the original design documentation and on-site testing campaigns, helped analyzing in detail the seismic response of the structure in current state, highlighting the most critical elements. The MD-type system adopted as retrofit solution consists in a set of dissipative braces incorporating fluid viscous dampers, sized by an energy-based design procedure recently proposed by the first author. A performance analysis carried out in retrofitted conditions assesses that the targeted performance assumed for the intervention, consisting in an elastic structural response up to the maximum considered earthquake, is reached, along with an optimal level of the damping capacity of the dissipaters
Low-impact seismic retrofit technologies for school buildings
No full textSupplemental damping strategies are increasingly adopted for seismic retrofit of frame structures also in consideration of their low-impact architectural and environmental characteristics. A further spreading of these technologies in the professional community strongly depends on the availability of simple design procedures, especially concerning the preliminary sizing of the dissipaters. A viable design criterion was recently proposed by the author to this aim and applied to the retrofit study of
a reinforced concrete gym buiding. A new case study, namely a school building in Florence dating back to the early 1980s, is examined in this paper, so as to evaluate the feasibility of the criterion for a more complex structure. The building is composed of two portions, with reinforced concrete and steel frame structure, respectively. Similarly to several other buildings of the same period, the structure is infilled by heavy reinforced concrete panels interacting with the frame elements under horizontal loads. A careful reconstruction of the structural characteristics of the constituting members, based on the original design documentation and on-site testing campaigns, highlighted specific drawbacks in current state, related to a remarkable degradation of the materials and a poor performance of several elements. The retrofit solution considered in this study consists in removing the infill panels and replacing them with a set of dissipative braces incorporating fluid viscous dampers as protective devices. The design is carried out by the sizing criterion mentioned above, targeting an elastic structural response up to the maximum considered earthquake normative level. A performance analysis carried out in retrofitted conditions confirms that the proposed sizing criterion helps optimizing the mechanical characteristics of the dampers by carrying out simple procedural design steps
A New Interpretation for Optionality in the English Article Use by Chinese learners of English
No full textThe English article system is well-known for its difficulty in second language learning of English. Since Chinese is a language which does not have functional categories corresponding to English articles, it is not surprising that Chinese learners of English have more difficulty with the English article system. Robertson (2000) shows the variability/non-convergence in the use of the English article system by Chinese learners of English by conducting an experimental study, designed to elicit spontaneous speech filled with referential noun phrases. More specifically, the variability here refers to that an article is used in some cases, but omitted in the exactly same context in other cases. After ruling out the possibility that the optionality is caused by a lack of articles in their interlanguage knowledge representation, the author divides the optionality into two categories: one is of systematic pattern which could be accounted for by several general linguistic principles; the other is unsystematic variation explained by Missing Surface Inflection Hypothesis (MSIH). However, this hypothesis has its disadvantage and is quite old as well. Thus, we intend to replicate his study, and reinterpret the unsystematic variation in light of Interface Hypothesis (IH), which is a more recent framework to account for optionality found in the interlanguage grammar of advanced and near-native L2 learners
Dynamics of cellular responses to radiation.
No full textUnderstanding the consequences of exposure to low dose ionizing radiation is an important public health concern. While the risk of low dose radiation has been estimated by extrapolation from data at higher doses according to the linear non-threshold model, it has become clear that cellular responses can be very different at low compared to high radiation doses. Important phenomena in this respect include radioadaptive responses as well as low-dose hyper-radiosensitivity (HRS) and increased radioresistance (IRR). With radioadaptive responses, low dose exposure can protect against subsequent challenges, and two mechanisms have been suggested: an intracellular mechanism, inducing cellular changes as a result of the priming radiation, and induction of a protected state by inter-cellular communication. We use mathematical models to examine the effect of these mechanisms on cellular responses to low dose radiation. We find that the intracellular mechanism can account for the occurrence of radioadaptive responses. Interestingly, the same mechanism can also explain the existence of the HRS and IRR phenomena, and successfully describe experimentally observed dose-response relationships for a variety of cell types. This indicates that different, seemingly unrelated, low dose phenomena might be connected and driven by common core processes. With respect to the inter-cellular communication mechanism, we find that it can also account for the occurrence of radioadaptive responses, indicating redundancy in this respect. The model, however, also suggests that the communication mechanism can be vital for the long term survival of cell populations that are continuously exposed to relatively low levels of radiation, which cannot be achieved with the intracellular mechanism in our model. Experimental tests to address our model predictions are proposed
Internal and external interfaces in bilingual language development: Beyond structural overlap
No full textThis article deals with the interface between syntax and discourse-pragmatics/semantics in bilingual speakers. Linguistic phenomena at the interface have been shown to be especially vulnerable in both child and adult bilinguals; here we explore four variables that contribute to this vulnerability to different extents depending on the nature of the interface: underspecification, cross-linguistic influence, quantity and quality of the input, and processing limitations. We investigate the role played by the aforementioned variables in two recently completed studies. One compares the performance of English-Italian and Spanish-Italian bilingual children, monolingual English- and Italian-speaking children and adults on forced-choice grammaticality tasks on the distribution of overt and null subject pronouns in Italian and in English. The second explores bilingual and monolingual speakers' sensitivity to the presence of definite articles in specific and generic plural noun phrases in Italian and in English. We show that over and above structural overlap, other factors must be included to account for differences in the behavioural data in the two tasks and in different populations of bilinguals and monolinguals. We argue that processing factors play a non-trivial role in the difficulty encountered by bilinguals in coordinating syntax with contextual discourse-pragmatic information, regardless of the absence or presence of partial structural overlap. In the case of the internal coordination between syntax and semantics, processing factors may be less likely to affect bilinguals' performance, while the extent of structural overlap and the associated internal formal features seem to play a more important role. © 2009 the Author/s
Variability of the parameter estimates across the different experimental setups and cell lines.
No full text<p>Parameters have been estimated by fitting model (2) independently to eight experimental data sets, see <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003513#pcbi-1003513-g002" target="_blank">Figure 2</a> of Supporting <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003513#pcbi.1003513.s001" target="_blank">Text S1</a> and references therein. Box-and-whiskers diagrams for parameters are presented. The dimensionless quantities <i>p<sub>0</sub></i> and <i>p<sub>1</sub></i> parameterize the saturating function , as defined in the caption for <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003513#pcbi-1003513-g004" target="_blank">figure 4(ii)</a>. A box-and-whiskers plot consists of a box that spans the distance between two quantiles surrounding the median, with lines (“whiskers”) that extend to span the full range.</p
In order for the memory model (2) to reproduce the radioadaptive response, the probability for a cell to become permanently altered by radiation exposure, <i>p</i>, must increase sufficiently at the higher radiation dose, <i>α</i>.
No full text<p>In other words, the radioadaptive response is not observed in the model if the increase in the parameter <i>p</i> at the higher value of <i>α</i> lies below a threshold. The graph plots the number of permanently altered cells in the presence of priming divided by the number of altered cells generated in the absence of priming, as a function of <i>n</i>-fold increase in the value of <i>p</i> at high <i>α</i>. If the value of <i>p</i> for high α is not increased sufficiently, more permanently altered cells are generated in the presence of priming. In contrast, if the value of <i>p</i> is increased by a threshold amount at high <i>α</i>, then priming lowers the total number of altered cells relative to the scenario where no low-dose priming is given. The horizontal line represents the ratio of one, where priming makes no difference. Base parameters are given as follows: <i>α = 0.1</i> for priming low dose radiation, and <i>α = 100</i> for higher dose radiation, <i>c = 1</i>, <i>η = 0.01</i>, <i>x<sub>0</sub> = 100</i>, <i>y<sub>0</sub> = 0</i>, <i>z<sub>0</sub> = 0</i>, <i>w<sub>0</sub> = 0</i>. For low-dose priming, <i>p = 0.05</i>. For high dose challenge, the value of <i>p</i> is increased <i>n</i>-fold, the horizontal axis of the graph.</p
Dose-response curve predicted by the memory model (equation 2).
No full text<p>(i) General picture. The fraction of cells surviving after a defined radiation time is plotted against the radiation dose. The model can reproduce experimentally observed patterns, including the phenomena of HRS and IRR at lower doses. Parameters are given by: <i>p = 0.4+0.55α</i>, <i>c = 1</i>, <i>η = 0.01</i>, <i>x<sub>0</sub> = 100</i>, <i>y<sub>0</sub> = 0</i>, <i>z<sub>0</sub> = 0</i>, <i>w<sub>0</sub> = 0</i>. Radiation was applied for a duration of 150 time steps. (ii). Fits of the model to previously published dose-response curves for different cell lines and radiation regimes. The fitting procedures and the estimated parameters are found in the Supporting <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003513#pcbi.1003513.s001" target="_blank">Text S1</a>. A two-parametric saturating function was used for <i>p</i>: where . The data were taken from the following sources: (a) p53 mutant T98G cells from reference <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003513#pcbi.1003513-Krueger1" target="_blank">[41]</a>, <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003513#pcbi-1003513-g001" target="_blank">figure 1</a>; (b) T98G cells from reference <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003513#pcbi.1003513-Short2" target="_blank">[42]</a>, <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003513#pcbi-1003513-g001" target="_blank">figure 1</a>; (c) HGL21 cells from reference <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003513#pcbi.1003513-Short3" target="_blank">[43]</a>, <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003513#pcbi-1003513-g001" target="_blank">figure 1</a>; (d) U138 cells from reference <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003513#pcbi.1003513-Short3" target="_blank">[43]</a>, <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003513#pcbi-1003513-g001" target="_blank">figure 1</a>.</p
