1,519 research outputs found
Rain or shine? Forecasting search process performance in exploratory search tasks
No full textMost information retrieval (IR) systems consider relevance, usefulness, and quality of information objects (documents, queries) for evaluation, prediction, and recommendation, often ignoring the underlying search process of information seeking. This may leave out opportunities for making recommendations that analyze the search process and/or recommend alternative search process instead of objects. To overcome this limitation, we investigated whether by analyzing a searcher’s current processes we could forecast his likelihood of achieving a certain level of success with respect to search performance in the future. We propose a machine-learning-based method to dynamically evaluate and predict search performance several time-steps ahead at each given time point of the search process during an exploratory search task. Our prediction method uses a collection of features extracted from expression of information need and coverage of information. For testing, we used log data collected from 4 user studies that included 216 users (96 individuals and 60 pairs). Our results show 80–90% accuracy in prediction depending on the number of time-steps ahead. In effect, the work reported here provides a framework for evaluating search processes during exploratory search tasks and predicting search performance. Importantly, the proposed approach is based on user processes and is independent of any IR system.This is the peer reviewed version of the following article: Shah, C., Hendahewa, C. and González-Ibáñez, R. (2015), Rain or shine? Forecasting search process performance in exploratory search tasks. Journal of the Association for Information Science and Technology, which has been published in final form at https://dx.doi.org/10.1002/asi.23484. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.Peer reviewe
Capturing collabportunities: A method to evaluate collaboration opportunities in information search using pseudocollaboration
No full textIn explicit collaborative search, two or more individuals coordinate their efforts toward a shared goal. Every day, Internet users with similar information needs have the potential to collaborate. However, online search is typically performed in solitude. Existing search systems do not promote explicit collaborations, and collaboration opportunities (collabportunities) are missed. In this article, we describe a method to evaluate the feasibility of transforming these collabportunities into recommendations for explicit collaboration. We developed a technique called pseudocollaboration to evaluate the benefits and costs of collabportunities through simulations. We evaluate the performance of our method using three data sets: (a) data from single users’ search sessions, (b) data with collaborative search sessions between pairs of searchers, and (c) logs from a largescale search engine with search sessions of thousands of searchers. Our results establish when and how collabportunities would significantly help or hinder the search process versus searches conducted individually. The method that we describe has implications for the design and implementation of recommendation systems for explicit collaboration. It also connects system-mediated and user-mediated collaborative search, whereby the system evaluates the likely benefits of collaborating for a search task and helps searchers make more informed decisions on initiating and executing such a collaboration.This is the peer reviewed version of the following article: González-Ibáñez, R., Shah, C. and White, R. W. (2015), Capturing Collabportunities: A method to evaluate collaboration opportunities in information search using pseudocollaboration. Journal of the Association for Information Science and Technology, 66: 1897–1912, which has been published in final form at https://dx.doi.org/doi:10.1002/asi.23288. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.Peer reviewe
A fiscal needs approach to equalization transfers in a decentralized federation
No full textThe author reviews the conceptual basis for fiscal equalization transfers, analyzes the theoretical implications for optimal design of equalization transfers, and suggests quantitative approaches for assessing the fiscal needs of subnational governments and determining their entitlement to transfers. The author illustrates proposed methods using data for local and provincial Canadian governments. The proposed methods could be useful tools, he says, for undertaking systematic objective reviews of aggregate and sectoral public spending in developing countries. The author argues that in a decentralized federation, fiscal inefficiencies and inequities arise because of subnational governments'differing levels of ability to provide comparable public services at comparable tax rates. Fiscal equalization transfers that reduce or eliminate differentials in net fiscal benefits create a rare instance in economics when considerations of equity and efficiency coincide. These transfers must allow for differences in the spending needs and revenues-raising abilities of the various subnational governments. The author argues for a two-tiered approach to equalization. The first tier would be a federal responsibility to equalize the burden of federal taxes. The second tier would be an interprovincial equalization fund to be administered by the Council of Provincial Finance Ministers. It would entail a comprehensive equalization system that takes into account provincial spending needs. The standard of equalization would be negotiated.Public Sector Economics&Finance,Banks&Banking Reform,Municipal Financial Management,National Governance,Environmental Economics&Policies
Fiscal decentralization in developing and transition economies: progress, problems, and the promise
No full textThe author discusses the revolution in public sector thinking that is transforming the public sectors of developing and transition countries. Countries are reconsidering their fiscal systems and searching for the right balance between central government control and decentralized governance. Political decentralization has advanced in most countries. Subnational expenditures in developing countries as a percentage of total public expenditures have also increased over the past two decades. However, the process is far from complete. In many countries, the central government is still involved in the delivery of local services, local governments have few sources of own-revenues, local governments have limited access to borrowing for capital projects, and the design of intergovernmental transfers does neither address regional fiscal equity nor convey appropriate incentives for fiscal discipline, improved service delivery performance, and accountability to citizens. Decentralized public governance can help realign public sector incentives through greater accountability to citizens, and attenuate the"democracy deficit"caused by globalization and the role of supranational institutions and regimes. However, this requires careful examination of the entire fiscal system. Elements of a comprehensive package of fiscal system reforms would include: (a) Clarifying roles of various levels of government in public service delivery; (b) Reassigning taxing responsibilities to ensure local revenue autonomy, accountability, and efficiency without endangering an internal common market; (c) Designing fiscal transfers to ensure regional fiscal equity and to create an enabling environment for innovative and competitive service delivery; (d) Facilitating responsible credit market access to subnational governments; (e) Designing institutional arrangements for intergovernmental fiscal relations to better coordinate policies; and (f) Aligning operational capacity with the authorizing environment through the"accountability for results"framework of public management.National Governance,Banks&Banking Reform,Environmental Economics&Policies,Public Sector Economics&Finance,Municipal Financial Management,National Governance,Banks&Banking Reform,Public Sector Economics&Finance,Municipal Financial Management,Environmental Economics&Policies
Pioneers of Library Movement in Pakistan
No full textThe paper aims to describe in brief the contribution of seven leaders of Pakistan librarianship, viz. K.B. Khalifa M. Asadullah, Prof. Dr. Abdul Moid, Dr. Abdus Subuh Qasimi, Muhammad Shafi, Fazal Elahi, Khawaja Nur Elahi and S. V. Hussain. The early library developments are given for better understanding of the role of these leaders
Regularizing properties of the Mumford-Shah functional for imaging applications
No full textThe Mumford-Shah functional was originally introduced for image denoising and segmentation problems, and is of interest because it provides a regularization of image edges in addition to images. Recently, this functional has emerged as a regularization technique for several imaging applications, such as x-ray tomography, electric impedance tomography, image deblurring and SPECT. In this context of operator equations it is necessary to understand its regularization properties and to determine its range of applicability. Following the approach of Rondi and Santosa, we exploit an L-infinity-constraint on the images, however in contrast to this approach we achieve convergence results not only for the images but also for the edge sets in the sense of sigma-convergence introduced by Maso et al. The analysis exploits an assumption on the decay properties of the fidelity term. Under the above two conditions, we establish the stability of the Mumford-Shah regularization for perturbations in the data. Moreover we present a parameter choice rule which ensures, that the reconstructed images and edges converge to the true image and its edges as the noise level goes to zero. We demonstrate the applications of the Mumford-Shah regularization to some linear and nonlinear imaging problems, namely image deblurring, x-ray tomography and two-dimensional diffuse optical tomography.Mathematics, AppliedPhysics, MathematicalSCI(E)[email protected]; [email protected]; [email protected]
sj-docx-1-cjk-10.1177_20543581231154183 – Supplemental material for Magnesium and Fracture Risk in the General Population and Patients Receiving Dialysis: A Narrative Review
No full textSupplemental material, sj-docx-1-cjk-10.1177_20543581231154183 for Magnesium and Fracture Risk in the General Population and Patients Receiving Dialysis: A Narrative Review by Andrea C. Cowan, Kristin K. Clemens, Jessica M. Sontrop, Stephanie N. Dixon, Lauren Killin, Sierra Anderson, Rey R. Acedillo, Amit Bagga, Clara Bohm, Pierre Antoine Brown, Brenden Cote, Varun Dev, Claire Harris, Swapnil Hiremath, Mercedeh Kiaii, Eduardo Lacson Jr, Amber O. Molnar, Matthew J. Oliver, Malvinder S. Parmar, Jennifer M. McRae, Bharat Nathoo, Kathleen Quinn, Nikhil Shah, Samuel A. Silver, Daniel J. Tascona, Stephanie Thompson, Robert H. Ting, Marcello Tonelli, Hans Vorster, Davinder B. Wadehra, Ron Wald, Myles Wolf and Amit X. Garg in Canadian Journal of Kidney Health and Disease</p
Partial cluster-tilted algebras via twin cotorsion pairs, quasi-abelian categories and Auslander-Reiten theory
No full textIn this thesis we study partial cluster-tilted algebras. These algebras are opposite endomorphism rings of rigid objects in cluster categories, and they are a generalisation of cluster-tilted algebras. The key motivation for the work we present here is to understand the representation theory of a partial cluster-tilted algebra. In our study of how the Auslander-Reiten theory of a partial cluster-tilted algebra is induced by the Auslander-Reiten theory of the corresponding cluster category, we use twin cotorsion pairs on triangulated categories to extract quasi-abelian categories from cluster categories, and develop Auslander-Reiten theory in quasi-abelian and Krull-Schmidt categories.
We prove that, under a mild assumption, the heart H of a twin cotorsion pair ((S,T),(U,V)) on a triangulated category C is a quasi-abelian category. If C is also Krull-Schmidt and T=U, we show that the heart of the cotorsion pair (S,T) is equivalent to the Gabriel-Zisman localisation of H at the class of its regular morphisms. In particular, suppose C is a cluster category with a rigid object R and let X(R) denote the ideal of morphisms factoring through X(R)=Ker(Hom_(R,-)). Then applications of our results show that C/X(R) is a quasi-abelian category. We also obtain a new proof of an equivalence between the localisation of this category at its class of regular morphisms and a certain subfactor category of C.
We generalise some of the theory developed for abelian categories in papers of Auslander and Reiten to semi-abelian and quasi-abelian categories. In addition, we generalise some Auslander-Reiten theory results of S. Liu for Hom-finite, Krull-Schmidt categories by removing the Hom-finite and indecomposability restrictions. As a main result, we give equivalent characterisations of Auslander-Reiten sequences in a skeletally small, quasi-abelian, Krull-Schmidt category.
Lastly, we construct partial cluster-tilted algebras of arbitrarily large finite global dimension coming from cluster categories associated to Dynkin-type A quivers. In particular, this shows that there is an infinite family of partial cluster-tilted algebras that are not cluster-tilted. Then we consider how the Auslander-Reiten theory of the algebra (End R)^op, where R is a basic rigid object of a Hom-finite, Krull-Schmidt, triangulated k-category C with Serre duality, is induced by the Auslander-Reiten theory of C via the functor Hom(R,-). Let C(R) denote the subcategory of C consisting of objects X for which there is a triangle R_{0} --> R_{1} --> X --> R_{0}[1] with R_{i} in add(R). We show that if f: X-->Y is an irreducible morphism in C with X in C(R), then Hom(R,f) is irreducible if Y also lies in C(R), or Hom(R,f) is split otherwise. If X does not lie in C(R), we provide partial results dependent on properties of the morphism f+X(R)(X,Y) in the quotient C/X(R)
Book review: absolute monarch
No full textAuthor reviews: The Mind of a Monarch, R. K. Karanjia; The Shah, by Margaret Laing; Workers say no to the Shah, by T. Jalil; Workers of Iran: Repression and the Fight for Democratic Trade, by T. Jali
Quasi-abelian hearts of twin cotorsion pairs on triangulated categories
No full textWe prove that, under a mild assumption, the heart H of a twin cotorsion pair ((S,T),(U,V)) on a triangulated category C is a quasi-abelian category. If C is also Krull-Schmidt and T=U, we show that the heart of the cotorsion pair (S,T) is equivalent to the Gabriel-Zisman localisation of H at the class of its regular morphisms.
In particular, suppose C is a cluster category with a rigid object R and [X_R] the ideal of morphisms factoring through X_R=Ker(Hom(R,-)), then applications of our results show that C/[X_R] is a quasi-abelian category. We also obtain a new proof of an equivalence between the localisation of this category at its class of regular morphisms and a certain subfactor category of C.23 pages, to appear in Journal of Algebra (available online: https://doi.org/10.1016/j.jalgebra.2019.06.011
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