97 research outputs found
Learning of classification models from group-based feedback
Learning of classification models in practice often relies on a nontrivial amount of human annotation effort. The most widely adopted human labeling process assigns class labels to individual data instances. However, such a process is very rigid and may end up being very time-consuming and costly to conduct in practice. Finding more effective ways to reduce human annotation effort has become critical for building machine learning systems that require human feedback.
In this thesis, we propose and investigate a new machine learning approach - Group-Based Active Learning - to learn classification models from limited human feedback. A group is defined by a set of instances represented by conjunctive patterns that are value ranges over the input features. Such conjunctive patterns define hypercubic regions of the input data space. A human annotator assesses the group solely based on its region-based description by providing an estimate of the class proportion for the subpopulation covered by the region. The advantage of this labeling process is that it allows a human to label many instances at the same time, which can, in turn, improve the labeling efficiency.
In general, there are infinitely many regions one can define over a real-valued input space. To identify and label groups/regions important for classification learning, we propose and develop a Hierarchical Active Learning framework that actively builds and labels a hierarchy of input regions. Briefly, our framework starts by identifying general regions covering substantial portions of the input data space. After that, it progressively splits the regions into smaller and smaller sub-regions and also acquires class proportion labels for the new regions. The proportion labels for these regions are used to gradually improve and refine a classification model induced by the regions. We develop three versions of the idea. The first two versions aim to build a single hierarchy of regions. One builds it statically using hierarchical clustering, while the other one builds it dynamically, similarly to the decision tree learning process. The third approach builds multiple hierarchies simultaneously, and it offers additional flexibility for identifying more informative and simpler regions. We have conducted comprehensive empirical studies to evaluate our framework. The results show that the methods based on the region-based active learning can learn very good classifiers from a very few and simple region queries, and hence are promising for reducing human annotation effort needed for building a variety of classification models
Inertial properties in groups
ââLet be a group and be an endomorphism of â. âA subgroup of is called -inert if has finite index in the image â. âThe subgroups that are -inert for all inner automorphisms of are widely known and studied in the literatureâ, âunder the name inert subgroupsâ. âThe related notion of inertial endomorphismâ, ânamely an endomorphism such that all subgroups of are -inertâ, âwas introduced in cite{DR1} and thoroughly studied in cite{DR2,DR4}â. âThe ``dualâ" ânotion of fully inert subgroupâ, ânamely a subgroup that is -inert for all endomorphisms of an abelian group â, âwas introduced in cite{DGSV} and further studied in cite{Ch+â, âDSZ,GSZ}â. âThe goal of this paper is to give an overview of up-to-date known resultsâ, âas well as some new onesâ, âand show how some applications of the concept of inert subgroup fit in the same picture even if they arise in different areas of algebraâ. âWe survey on classical and recent results on groups whose inner automorphisms are inertialâ. âMoreoverâ, âwe show howâ âinert subgroups naturally appear in the realm of locally compact topological groups or locally linearly compact topological vector spacesâ, âand can be helpful for the computation of the algebraic entropy of continuous endomorphismsâ
Clinical and radiographic outcomes of implant-supported zirconia fixed dental prostheses with cantilever extension: AÂ proof-of-principle study with a follow-up of at least 1âyear.
OBJECTIVES
To test the reliability of full zirconia implant-supported fixed dental prostheses with cantilever extension (FDPCs) after at least 1âyear of function.
MATERIALS AND METHODS
Thirty-five patients in need of implant-supported single unit crowns (SUC) and FDPCs in posterior areas were enrolled. After implant placement, patients were rehabilitated with screw-retained full-zirconia FDPCs. Implant survival rate, pocket probing depth (PPD), presence/absence of bleeding on probing (BoP), and presence/absence of mechanical/technical complications were recorded. Mesial and distal radiographic marginal bone levels (mBLs) from baseline (i.e., recall appointment 3-6âmonths after implant loading [T0]) to the follow-up examination (i.e., latest recall appointment after at least 12âmonths after T0 [T1]), were calculated.
RESULTS
Thirty patients with 34 FDPCs (31 SUCs and 3 FDPs) supported by 37 implants were available for analysis after a mean loading time of 2.6âÂąâ1.5âyears (range: 13-87âmonths). No implants were lost. MBLs and mean PPD values did not change statistically significantly from T0 to T1 from 0.92âmmâÂąâ0.42 to 0.96âmmâÂąâ0.38 (95% CI: -0.07/0.17; pâ=â.418) and from 2.99âmmâÂąâ0.70 to 3.27âmmâÂąâ0.71 (95% CI: -0.11/0.68; pâ=â.25) respectively. Peri-implant mucositis was diagnosed in 22 cases. Screw-loosening and zirconia chipping occurred 1Ă in 4 patients.
CONCLUSION
Within the limitations of the present proof-of-principle study, the use of full-zirconia FDPCs in posterior areas seems a valid and safe short-term treatment option
Algebraic Geometry: Moduli Spaces, Birational Geometry and Derived Aspects (hybrid meeting)
The talks at the workshop and the research done during the week focused on aspects of algebraic geometry in the broad sense. Special emphasis was put on hyperkähler manifolds and derived categories
Decision makings in key remanufacturing activities to optimise remanufacturing outcomes : a review
The importance of remanufacturing has been increasing since stricter regulations on protecting the environment were enforced. Remanufacturing is considered as the main means of retaining value from used products and components in order to drive a circular economy. However, it is more complex than traditional manufacturing due to the uncertainties associated with the quality, quantities and return timing of used products and components. Over the past few years, various methods of optimising remanufacturing outcomes have been developed to make decisions such as identifying the best End-Of-Life (EOL) options, acquiring the right amounts of cores, deciding the most suitable disassembly level, applying suitable cleaning techniques, and considering product commonality across different product families. A decision being made at one remanufacturing activity will greatly affect the decisions at subsequent activities, which will affect remanufacturing outcomes, i.e. productivity, economic performance effectiveness, and the proportion of core that can be salvaged. Therefore, a holistic way of integrating different decisions over multiple remanufacturing activities is needed to improve remanufacturing outcomes, which is a major knowledge gap. This paper reviews current remanufacturing practice in order to highlight both the challenges and opportunities, and more importantly, offers useful insights on how such a knowledge gap can be bridged
A multicenter randomized controlled trial using a novel collagen membrane for guided bone regeneration at dehisced single implant sites: Outcome at prosthetic delivery and at 1â year followâ up
ObjectivesTo compare clinical performance of a novel resorbable nonâ crossâ linked collagen membrane (CXP) with a reference membrane (nonâ crossâ linked resorbable membrane; BG) for simultaneous implant placement and guided bone regeneration (GBR) at dehisced single implant sites.Materials and methodsPreliminary data from this randomized controlled trial were reported previously; this is the 12â month report. The primary outcome measure was defected height at 6Ă months postâ GBR. Secondary outcomes included implant cumulative survival rate (CSR) and success rate since placement; bone level changes, pink esthetic score (PES), and patient satisfaction since definitive prosthesis delivery; patient quality of life since pretreatment; and the 1â year bleeding index. Nonâ parametric statistical analyses were performed.ResultsAmong patients, 24 were treated with CXP and 25 with BG. The 1â year implant CSR and success rate were 100% (nĂ =Ă 42). Bone level change between definitive prosthetic delivery and 1Ă year was not significantly different between the CXP and BG groups (BGĂ +Ă 0.42Ă mm, CXPĂ +Ă 0.01Ă mm). The PES increased from 7.55 to 8.10 for the CXP group and from 6.48 to 7.48 for the BG group; 1â year bleeding indices were 0 (16 CXP, 18 BG) and 1 (4 CXP, 2 BG). Patient quality of life changed from an OHIPâ 14 score of 6.5 at pretreatment to 1.9 at 1Ă year. Overall satisfaction (visual analogue score) with function and esthetics was 9.9 and 9.7, respectively. Interâ group differences were not significant for assessed outcomes. No deviceâ related adverse events were reported.ConclusionsThe use of CXP and BG for simultaneous implant placement and GBR at dehisced implant sites similarly reduced defect height and improved secondary measures, indicating nonâ inferiority.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149491/1/clr13426.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149491/2/clr13426_am.pd
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