Performance-Based Optimization for Strut-Tie Modeling of Structural Concrete

Conventional trial-and-error methods are not efficient in developing appropriate strut-and-tie models in complex structural concrete members. This paper describes a performance-based optimization (PBO) technique for automatically producing optimal strut-and-tie models for the design and detailing of structural concrete. The PBO algorithm utilizes the finite element method as a modeling and analytical tool. Developing strut-and-tie models in structural concrete is treated as an optimal topology design problem of continuum structures. The optimal strut-and-tie model that idealizes the load transfer mechanism in cracked structural concrete is generated by gradually removing regions that are ineffective in carrying loads from a structural concrete member based on overall stiffness performance criteria. A performance index is derived for evaluating the performance of strut-and-tie systems in an optimization process. Fundamental concepts underlying the development of strut-and-tie models are introduced. Design examples of a low-rise concrete shearwall with openings and a bridge pier are presented to demonstrate the validity and effectiveness of the PBO technique as a rational and reliable design tool for structural concrete

Difference in Plumage Color Used in Species Recognition between Incipient Species Is Linked to a Single Amino Acid Substitution in the Melanocortin‐1 Receptor

This is the publisher's version, also available electronically from http://www.jstor.org/stable/10.1086/600084Many studies demonstrate that differences in mating signals are used by incipient species in recognizing potential mates or sexual competitors (i.e., species recognition). Little is known, however, about the genetic changes responsible for these differences in mating signals. Populations of the Monarcha castaneiventris flycatcher vary in plumage color across the Solomon Islands, with a subspecies on Makira Island having chestnut bellies and blue‐black upper parts (Monarcha castaneiventris megarhynchus) and a subspecies on neighboring satellite islands being entirely blue‐black (melanic; Monarcha castaneiventris ugiensis). Here we show that a single nonsynonymous point mutation in the melanocortin‐1 receptor (MC1R) gene is present in all melanic birds from one island (Santa Ana) but absent in all chestnut‐bellied birds from Makira Island, implicating this mutation in causing melanism. Birds from a second satellite island (Ugi) do not show the same perfect association between this MC1R variant and plumage color, suggesting an alternative mechanism for melanism on this island. Finally, taxidermic mount presentation experiments in Makira (chestnut) and Santa Ana (melanic) suggest that the plumage difference mediates species recognition. Assuming that the signals used in species recognition are also used in mutual mate choice, our results indicate that a single amino acid substitution contributes to speciation

Enantiomer‐selective pharmacokinetics and metabolism of ketorolac in children

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110020/1/cptclpt1999381.pd

Debt Sustainability and the Terms of Official Support

We study theoretically and quantitatively how official lending regimes affect a government's decision to raise saving as opposed to defaulting, and its implication for sovereign bond pricing by investors. We reconsider debt sustainability in the face of both output and rollover risk under two types of institutional bailouts: one based on long-maturity, low-spread loans similar to the ones offered by the euro area official lenders; the other, on shorter maturity and high-spread loans, close to the International Monetary Fund standards. We show that official lending regimes raise the stock of safe debt and facilitate consumption smoothing through debt reduction. However, to the extent that bailouts translates into higher future debt stocks and countercyclical deficits in persistent recessions, they also have countervailing effects on sustainability. Quantitatively, the model is able to replicate Portuguese debt and spread dynamics in the years of the bailout after 2011. We show that, depending on the composition of debt by maturity and official lending, sustainable debt levels can vary between 50% of GDP and 180% of GDP depending on the state of the economy and the conditions for market access. Longer maturities have a stronger effect on sustainability than lower spreads

Official Sector Lending Strategies During the Euro Area Crisis

In response to the euro area crisis, European policymakers took a gradual, incremental approach to official lending, at first relying on the approach followed by the International Monetary Fund, then developing their own crisis resolution framework. We review this development, marked by a substantial divergence in the terms of official loans offered to the crisis countries by the IMF and the euro area official lenders. Based on a unique dataset, we use event analysis to assess the impact of changing maturity and spreads of official loans on bond yields, liquidity and market access. In light of the euro area experience, we discuss arguments for rebalancing Debt Sustainability Analysis and programme design towards cash-flow management. While the official assistance granted to crisis countries in the euro area may not be replicable elsewhere, key lessons from it that could foster a reconsideration of the modalities by which official lending institutions handle crises

Learning Strategies and Innovations among Medical Students in the Philippines during the COVID-19 Pandemic

This paper highlights the experience of graduating medical students or clinical clerks in the Philippines during the COVID-19 pandemic. For instance, clinical clerks are supposed to be having their actual face-to-face patient encounters in the hospital setting. It is during the clinical clerkship, the final year of a four-year medical degree program, that a medical student applies his or her theoretical knowledge in practice. However, due to the pandemic, changes needed to be done in order to ensure continuous learning despite having to have little to no contact with actual patients. Hence, in this paper, various learning strategies and innovations have been presented to give examples of how Filipino medical students or clinical clerks tried to cope and adapt with the changes in the mode of learning in the medical field

Leukemia Inhibitory Factor Augments Neurotrophin Expression and Corticospinal Axon Growth after Adult CNS Injury

The cytokine leukemia inhibitory factor (LIF) modulates glial and neuronal function in development and after peripheral nerve injury, but little is known regarding its role in the injured adult CNS. To further understand the biological role of LIF and its potential mechanisms of action after CNS injury, effects of cellularly delivered LIF on axonal growth, glial activation, and expression of trophic factors were examined after adult mammalian spinal cord injury. Fibroblasts genetically modified to produce high amounts of LIF were grafted to the injured spinal cords of adult Fischer 344 rats. Two weeks after injury, animals with LIF-secreting cells showed a specific and significant increase in corticospinal axon growth compared with control animals. Furthermore, expression of neurotrophin-3, but not nerve growth factor, brain-derived neurotrophic factor, glia cell line-derived neurotrophic factor, or ciliary neurotrophic factor, was increased at the lesion site in LIF-grafted but not in control subjects. No differences in astroglial and microglial/macrophage activation were observed. Thus, LIF can directly or indirectly modulate molecular and cellular responses of the adult CNS to injury. These findings also demonstrate that neurotrophic molecules can augment expression of other trophic factors in vivo after traumatic injury in the adult CNS

Radiative Corrections to Double Dalitz Decays: Effects on Invariant Mass Distributions and Angular Correlations

We review the theory of meson decays to two lepton pairs, including the cases of identical as well as non-identical leptons, as well as CP-conserving and CP-violating couplings. A complete lowest-order calculation of QED radiative corrections to these decays is discussed, and comparisons of predicted rates and kinematic distributions between tree-level and one-loop-corrected calculations are presented for both pi-zero and K-zero decays.Comment: 25 pages, 18 figures, added figures and commentar