1,299 research outputs found
Molecular perspective of protein-ligand selectivity in host and parasitic plants
No full textSubmission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2024-12-01The student, Jiming Chen, accepted the attached license on 2022-09-26 at 17:06.The student, Jiming Chen, submitted this Dissertation for approval on 2022-09-26 at 17:21.This Dissertation was approved for publication on 2022-10-04 at 13:56.DSpace SAF Submission Ingestion Package generated from Vireo submission #18504 on 2023-04-12 at 08:10:28Witchweed, or Striga hermonthica, is a parasite that destroys $10 billion worth of crops annually. It detects its hosts by detecting strigolactone hormone exuded into the soil by its hosts and using it as a germination stimulant, after which it attaches itself to the root of the host crop and absorbs its nutrients. Despite high sequence, structure, and binding site conservation across different plant species, one strigolactone receptor found in witchweed, ShHTL7 uniquely exhibits picomolar sensitivity to strigolactones, compared to micromolar levels observed in homologs. Previously, the prevailing hypothesis was that this million-fold sensitivity difference is the result of its larger binding pocket volume compared to other receptors, however, this does not account for the dynamics of each of the mechanistic steps of strigolactone signaling. The early steps of strigolactone signaling are binding of the substrate to the receptor, enzymatic hydrolysis of the substrate by the receptor, a conformational change of the receptor to its active state, and association of the active-conformation receptor to its signaling partner. Using a combination of long-timescale molecular dynamics (~3 ms aggregate), QM/MM, and umbrella sampling simulations, we have elucidated mechanistic details of the strigolactone signaling process at atomic resolution in AtD14, a strigolactone receptor found in the non-parasitic plant Arabidopsis thaliana, and ShHTL7. These mechanistic details indicate that while ShHTL7 is more binding with the strigolactone substrate than AtD14, signaling steps that occur after substrate hydrolysis are also key drivers of the selectivity in strigolactone signaling between parasite and host. These mechanistic insights have the potential to aid the design of selective control agents to control witchweed with minimal effect on surrounding host crops
Systematically Challenging Three Prevailing Notions About Entropy and Life
No full textThis article reveals the original, fundamental, and uncontroversial nature of entropy and systematically challenges three
notions prevailing in diverse disciplines: (1) entropy is a measure of disorder; (2) life relies on negative entropy; (3)
many systems tend to become increasingly disordered due to the second law of thermodynamics. The challenge is
supported by numerous compelling facts and the modern explanation of the second law of thermodynamics. The
challenge, if widely accepted, could facilitate the eradication of the entrenched misleading effects of the three
misconceptions in diverse disciplines and facilitate relevant research and education on complexity, entropy, disorder,
order, evolution, life, and thermodynamics
The Promise of Beijing: Evaluating the Impact of the 2008 Olympic Games on Air Quality
No full textTo prepare for the 2008 Olympic Games, China adopted a number of radical measures to improve air quality. Using officially reported air pollution index (API) from 2000 to 2009, we show that these measures improved the API of Beijing during and after the Games, but 60% of the effect faded away by the end of October 2009. Since the credibility of API data has been questioned, an objective and indirect measure of air quality at a high spatial resolution – aerosol optimal depth (AOD), derived using the data from the NASA satellites – was analyzed and compared with the API trend. The analysis confirms that the improvement was real but temporary and most improvement was attributable to plant closure and traffic control. Our results suggest that it is possible to achieve real environmental improvement in an authoritarian regime but the magnitude of the effect and how long it lasts depend on the political motivation behind the policy interventions.
0-1 Semidefinite Programming for Cluster Analysis with Application to Customer Segmentation
No full textTitle: 0-1 Semidefinite Programming for Cluster Analysis with Application to Customer Segmentation, Author: Huarong Chen, Location: ThodeIn general, clustering involves partitioning a give data set into subsets
based on the closeness or similarity among the data. Clustering analysis
has been widely used in many applications arising from different disciplines,
including market analysis, image segmentation, pattern recognition and web
mining. Recently, a new optimization model, the so called 0-1 semidefinite programming(
SDP) has been introduced by Peng and Xia in [2]. It has been
proved that several scenarios of clustering, such as classical K-means clustering,
normalized-cut clustering, balanced clustering and semi-supervised clustering
can be embedded into the 0-1 SDP model. In this thesis, we try to extend the 0-1 SDP model to the scenario of
weighted K-means clustering, where the instances in the data set are associated
with some weights indicating the importance of the instance. We also develop
a hierarchical approach to attack the unified 0-1 SDP model, in which each
binary separation is achieved by the refined weighted K-means method in one
dimensional space. Moreover, we apply the approach developed in this thesis
to a particular industrial application, where the task is to extract a model to
predict the children information of customers based on their buying behaviors.
During the process of the model building, clustering analysis was applied as the first step to group customers with similar children information, and then
the link between the segmentation of customers and their shopping behaviors
was discovered. Numerical results based on our approach are reported in the thesis as
well.ThesisMaster of Science (MS
Bibliographie
No full textLes titres français sont des traductions des titres originaux. Les œuvres correspondantes, cependant, sont inédites en français, et sont signalées par un astérisque à la suite de la date de publication. Cai Yuanpei, 2004 * [1928]. Histoire de l’éthique en Chine, Shanghai, The Commercial Press. Chang Jianhua, 2000 *. « L’histoire sociale en Chine au XXe siècle », in Zhou Jiming et Song Dejin (dir.), Théorie de l’histoire sociale chinoise, Wuhan, Hubei Education Press. Chen Da, 1929 *. La Quest..
Rent - seeking trade policy : a time series approach
No full textUsing a time-series approach, the author analyzes the relationship between the extent of rent-seeking trade policy and both political and economic variables. For rent-seeking trade policy, the indicator he uses is the number of foreign-trade regulations passed each year for the benefit of a single firm or industry. The author uses data from Uruguay for 1925-83. Uruguay, which experienced an impressive economic decline, is an outstanding example of a rent-seeking society. After being a wealthy economy in midcentury, it suffered almost complete stagnation, which led to social and policital disintegration by the end of the 1960s. Three decades of restrictive regulations on foreign trade had created a nearly closed economy by the end of the 1960s. It was worth analyzing whether policymakers'great receptiveness to demands for protection could account for Uruguay's decline. Over the period 1925-83, the author finds almost 4,000 laws, decrees, and administrative resolutions that create, maintain, or modify a foreign-trade regulation for the benefit of a single firm or industry. About half of them explicitly identify the petitioner - usually a firm or guild. Since the size of the Uruguayan economy changed over the period studied, the author scales the annual number of regulations by output or exports to measure the extent of rent-seeking trade policy. The author shows that the extent of rent-seeking trade policy increased with discretionary policies and under dictatorship. (In the period studied, there were two stages of democracy - until 1932 and from 1943-72 - and two stages of dictatorship.) He also shows that rent-seeking trade restrictions increased under import-substitution strategies and, more unexpectedly, under active export promotion. This suggests that discretionary power leads to wasteful distribution, whether it is used to support inward- or outward-oriented policies. Finally, the author analyzes the correlation between innovations in the trade policy indicator and innovations in the growth rates of output and exports, with a lag of up to 20 years. Surprisingly, he finds a positive correlation with output growth rates after two or three years. But the correlation becomes negative some years later, particularly in the case of exports. The short-run positive impact on growth rates, together with the surprisingly long time lag before the negative impact, may account for policymakers'receptiveness to demands for protection.Trade Policy,Achieving Shared Growth,TF054105-DONOR FUNDED OPERATION ADMINISTRATION FEE INCOME AND EXPENSE ACCOUNT,Economic Theory&Research,Environmental Economics&Policies
F.M.: Large scale skill matching through knowledge compilation
No full textAbstract. We present a logic-based framework for automated skill matching, able to return a ranked referral list and the related ranking explanation. Thanks to a Knowledge Compilation approach, a knowledge base in Description Logics is translated into a relational database, without loss of information. Skill matching inference services are then efficiently executed via SQL queries. Experimental results for scalability and turnaround times on large scale data sets are reported, confirming the validity of the approach.
WaaS—Wisdom as a Service
No full textAn emerging hyper-world encompasses all human activities in a social-cyber-physical space. Its power derives from the Wisdom Web of Things (W2T) cycle, namely, “from things to data, information, knowledge, wisdom, services, humans, and then back to things.” The W2T cycle leads to a harmonious symbiosis among humans, computers and things, which can be constructed by large-scale converging of intelligent information technology applications with an open and interoperable architecture. The recent advances in cloud computing, the Internet/Web of Things, big data and other research fields have provided just such an open system architecture with resource sharing/services. The next step is therefore to develop an open and interoperable content architecture with intelligence sharing/services for the organization and transformation in the “data, information, knowledge and wisdom (DIKW)” hierarchy. This chapter introduces Wisdom as a Service (WaaS) as a content architecture based on the “paying only for what you use” IT business trend. The WaaS infrastructure, WaaS economics, and the main challenges in WaaS research and applications are discussed. A case study is described to demonstrate the usefulness and significance of WaaS. Relying on the clouds (cloud computing), things (Internet of Things) and big data, WaaS provides a practical approach to realize the W2T cycle in the hyper-world for the coming age of ubiquitous intelligent IT applications
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