247 research outputs found
Information Design in Optimal Auctions
We study the information design problem in a single-unit auction setting. The
information designer controls independent private signals according to which
the buyers infer their binary private values. Assuming that the seller adopts
the optimal auction due to Myerson (1981) in response, we characterize both the
buyer-optimal information structure, which maximizes the buyers' surplus, and
the sellerworst information structure, which minimizes the seller's revenue. We
translate both information design problems into finite-dimensional, constrained
optimization problems in which one can explicitly solve for the optimal
information structures. In contrast to the case with one buyer (Roesler and
Szentes, 2017), we show that with two or more buyers, the symmetric
buyer-optimal information structure is different from the symmetric
seller-worst information structure. The good is always sold under the
seller-worst information structure but not under the buyer-optimal information
structure. Nevertheless, as the number of buyers goes to infinity, both
symmetric information structures converge to no disclosure. We also show that
in an ex ante symmetric setting, an asymmetric information structure is never
seller-worst but can generate a strictly higher surplus for the buyers than the
symmetric buyer-optimal information structure
2,2′-(1,3,5,7-TetraÂoxo-1,2,3,5,6,7-hexaÂhydroÂpyrrolo[3,4-f]isoindole-2,6-diÂyl)diacetic acid N,N-dimethylÂformamide disolvate
The asymmetric unit of the title compound, C14H8N2O8·2C3H7NO or L·2DMF (DMF = N,N-dimethylÂformamide), contains one half of the centrosymmetric molÂecule L and one solvent molÂecule, which is disordered between two orientations in a 0.555 (4):0.445 (4) ratio. InterÂmolecular O—H⋯O hydrogen bonds link one L and two DMF molÂecules into a centrosymmetric hydrogen-bonded cluster. The crystal packing is further stabilized by weak interÂmolecular C—H⋯O hydrogen bonds
A gradient-directed Monte Carlo approach to molecular design
The recently developed linear combination of atomic potentials (LCAP)
approach [M.Wang et al., J. Am. Chem. Soc., 128, 3228 (2006)] allows continuous
optimization in discrete chemical space and thus is quite useful in the design
of molecules for targeted properties. To address further challenges arising
from the rugged, continuous property surfaces in the LCAP approach, we develop
a gradient-directed Monte Carlo (GDMC) strategy as an augmentation to the
original LCAP optimization method. The GDMC method retains the power of
exploring molecular space by utilizing local gradient information computed from
the LCAP approach to jump between discrete molecular structures. It also allows
random Monte Carlo moves to overcome barriers between local optima on property
surfaces. The combined GDMC and LCAP approach is demonstrated here for
optimizing nonlinear optical (NLO) properties in a class of donor-acceptor
substituted benzene and porphyrin frameworks. Specifically, one molecule with
four nitrogen atoms in the porphyrin ring was found to have a larger first
hyperpolarizability than structures with the conventional porphyrin motif. 1Comment: 26 pages, 10 figure
Improving band gap prediction in density functional theory from molecules to solids
A novel nonempirical scaling correction method is developed to tackle the challenge of band gap prediction in density functional theory. For finite systems the scaling correction largely restores the straight-line behavior of electronic energy at fractional electron numbers. The scaling correction can be generally applied to a variety of mainstream density functional approximations, leading to significant improvement in the band gap prediction. In particular, the scaled version of a modified local density approximation predicts band gaps with an accuracy consistent for systems of all sizes, ranging from atoms and molecules to solids. The scaled modified local density approximation thus provides a useful tool to quantitatively characterize the size-dependent effect on the energy gaps of nanostructuresFinancial support from the Naval Research Office (N00014-09-0576) (X. Z. and W.Y.), National Science Foundation (CHE-09-11119) (X. H. and W.Y.), Royal Society (A. J. C.), and Ramón y Cajal (P. M.-S.) is gratefully appreciate
High-mobility-group box protein 1 A box reduces development of sodium laurate-induced thromboangiitis obliterans in rats
ObjectiveHigh-mobility-group box protein 1 (HMGB1), as a late mediator of inflammation, plays a key role in inflammatory responses by inducing and extending the production of proinflammatory cytokines. The effect of HGMB1 in the inflammatory disease thromboangiitis obliterans (TAO) is unknown. We aimed to investigate the role of HMGB1 in sodium laurate-induced TAO in rats.MethodsMale Wistar rats were randomly divided into five groups (n = 8 each) for treatment: normal, sham-operated, TAO model, and low-dose (15 mg/kg) or high-dose (30 mg/kg) recombinant A box (rA box) infection (administered intraperitoneally once daily for 15 days). The TAO model was induced by sodium laurate and graded by gross appearance on day 15 after femoral artery injection. Histologic changes were measured by histopathology in rat femoral arteries. Plasma levels of HMGB1, thromboxane B2, 6-keto-prostaglandin F1-α, and blood cell counts and blood coagulation levels were measured. Expression of HMGB1, receptor for advanced glycation end-products (RAGE), interleukin-6, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 was assessed by immunohistochemistry and immunofluorescence, Western blot analysis, and quantitative reverse-transcription polymerase chain reaction.ResultsThe typical signs and symptoms of TAO were observed on day 15 after sodium laurate injection. The expression of HMGB1, RAGE, interleukin-6, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 was markedly increased in rat femoral arteries. Plasma levels of HMGB1 and thromboxane B2 were elevated, but the level of 6-keto-prostaglandin F1-α was decreased. Blood was in a hypercoagulable state, and prothrombin, thrombin, and activated partial thromboplastin times were all significantly shortened, whereas fibrinogen level was increased in TAO rats compared with sham-operated rats. These effects were terminated by the HMGB1 antagonist rA box.ConclusionsHMGB1 is involved in the inflammatory state in a model of TAO induced by sodium laurate in rats, probably via its receptor RAGE. As the antagonist of HMGB1, rA box can attenuate the development of TAO, which may be a potential therapeutic target for the treatment of TAO.Clinical RelevanceThromboangiitis obliterans (TAO), or Buerger disease, is a segmental nonatherosclerotic inflammatory disorder. Patients with Buerger disease have a lower quality of life because of intermittent claudication, rest pain, ulcers, and superficial thrombophlebitis. The specific etiology and pathologic mechanisms remain not elucidated. High-mobility-group box protein 1, as a late mediator of inflammation, plays a key role in inflammatory responses to tissue injury and infection by inducing and extending the production of proinflammatory cytokines. Here, we explored the role of high-mobility-group box protein 1 in rat model of TAO, discovering a new damage marker in TAO. We also investigated the unique role of recombinant A box in the prevention and treatment of TAO
Documentos para a história de Portugal no século XX : a conjuntura do ano de 1946
Successfully predicting the frequency dispersion of electronic hyperpolarizabilities is an unresolved challenge in materials science and electronic structure theory. We show that the generalized Thomas−Kuhn sum rules, combined with linear absorption data and measured hyperpolarizability at one or two frequencies, may be used to predict the entire frequency-dependent electronic hyperpolarizability spectrum. This treatment includes two- and three-level contributions that arise from the lowest two or three excited electronic state manifolds, enabling us to describe the unusual observed frequency dispersion of the dynamic hyperpolarizability in high oscillator strength M-PZn chromophores, where (porphinato)zinc(II) (PZn) and metal(II)polypyridyl (M) units are connected via an ethyne unit that aligns the high oscillator strength transition dipoles of these components in a head-to-tail arrangement. We show that some of these structures can possess very similar linear absorption spectra yet manifest dramatically different frequency-dependent hyperpolarizabilities, because of three-level contributions that result from excited state-to-excited state transition dipoles among charge polarized states. Importantly, this approach provides a quantitative scheme to use linear optical absorption spectra and very limited individual hyperpolarizability measurements to predict the entire frequency-dependent nonlinear optical response
PlantQTL-GE: a database system for identifying candidate genes in rice and Arabidopsis by gene expression and QTL information
We have designed and implemented a web-based database system, called PlantQTL-GE, to facilitate quantitatine traits locus (QTL) based candidate gene identification and gene function analysis. We collected a large number of genes, gene expression information in microarray data and expressed sequence tags (ESTs) and genetic markers from multiple sources of Oryza sativa and Arabidopsis thaliana. The system integrates these diverse data sources and has a uniform web interface for easy access. It supports QTL queries specifying QTL marker intervals or genomic loci, and displays, on rice or Arabidopsis genome, known genes, microarray data, ESTs and candidate genes and similar putative genes in the other plant. Candidate genes in QTL intervals are further annotated based on matching ESTs, microarray gene expression data and cis-elements in regulatory sequences. The system is freely available at
The Pandemic and Higher Education: Learning and Reflection from the Experience of Chinese Higher Education
Twenty months have passed since China's first lockdown of Wuhan city. The Chinese higher education sector has withstood the challenges of the pandemic. This paper discusses the experience of the higher education sector in China, drawing primarily from the early period of the ongoing Covid-19 pandemic. In particular, we present a narrative of Chinese higher education managing some of the multifaceted challenges, which is pivotal to understanding its policies and practices during the early pandemic. In particular, this paper extends and provides further contexts to Ma et al. (2021) in better understanding their Chinese perspective, giving readers a fuller picture of the governance of Chinese higher education and some of its practical insights. It also provides some important lessons and reflections drawing from localised experiences, which provide important insights into the Chinese higher education policies and practices in response to the national crisis. In addition, we suggest further areas of research relating to the content of this paper, and finish this paper with a future picture of hope after the crisis
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