50 research outputs found
The Good, the Bad and the Submodular: Fairly Allocating Mixed Manna Under Order-Neutral Submodular Preferences
We study the problem of fairly allocating indivisible goods (positively
valued items) and chores (negatively valued items) among agents with decreasing
marginal utilities over items. Our focus is on instances where all the agents
have simple preferences; specifically, we assume the marginal value of an item
can be either , or some positive integer . Under this assumption, we
present an efficient algorithm to compute leximin allocations for a broad class
of valuation functions we call order-neutral submodular valuations.
Order-neutral submodular valuations strictly contain the well-studied class of
additive valuations but are a strict subset of the class of submodular
valuations. We show that these leximin allocations are Lorenz dominating and
approximately proportional. We also show that, under further restriction to
additive valuations, these leximin allocations are approximately envy-free and
guarantee each agent their maxmin share. We complement this algorithmic result
with a lower bound showing that the problem of computing leximin allocations is
NP-hard when is a rational number
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Redesigning Beaversource through User Centered Design
Beaversource provides both code-hosting tools and social networking in one place. Students and faculty at Oregon State University have been using Beaversource to host their projects, both for classwork and research. Several usability problems were reported in a survey conducted on Beaversource last year. Some of these issues were severe and eventually led users to leave the site or consider alternative tools. It was clear that the usability of the site needed improvement.
A User Centered Design approach was used to redesign key parts of the website to address some of the usability problems reported by users. A high-fidelity prototype of the new design was developed. A focus group was conducted with Beaversource users to get their opinion and feedback on the new design. Participants gave positive feedback about the design and agreed that the new design would solve many of the usability problems that it had addressed. They also provided suggestions to improve certain aspects of the design
Evaluation of Supply Chain Practices followed by the Rice Industry Operating in India to Serve Market Demand
Purpose: The following dissertation is aimed at investigating the current supply chain management
practices adopted in the Indian rice industry and evaluating their effectiveness in meeting the
market demands. Such understanding is critical in identifying the areas of improvement and
enhancing the efficiency of the current practices. The presented research study aims at such
identification, proposing recommendations for improvement and facilitating the growth and
development of the Indian rice industry.
Methodology: The research adopts a positivist research paradigm, with the study being guided by
the deductive approach and exploratory research design. Both the primary and secondary data is
used to address the research objectives, with the help of interviews and library research. Five supply
chain managers in Indian rice industry, rice farmers in Tamilnadu and key retailers, are contacted to
access the relevant information, which is analyzed using the thematic analysis tool to address the
research questions and reach valid conclusions.
Findings: The analysis and interpretation of the collected data indicate that the predominant supply
chain management practices in the Indian rice industry are inspired by the traditional farming and
supply chain practices, offering both advantages and disadvantages for the industry. Although the
adoption of modern supply chain practices is evident, their effective integration and performance
implications are lacking. The findings also suggest that the SCOR framework can be implemented,
integrating the traditional and modern farming and supply chain management practices, to improve
the performance efficiency of Indian rice supply network and effectively meet the market demands.
Research Implications: The presented research has implications in both the academic and practical
contexts. The research outcomes reveal the key strengths, limitations, and effectiveness of the
Indian rice supply chain, addressing the literature gap identified. On the other hand, the retailers in
the Indian rice industry would be able to use the research outcomes to improve the current supply
chain management practices and adopt the suggested SOR framework to enhance the performance
efficiency of the Indian rice supply network.
Keywords: Supply Chain Management, Indian Rice Industry, SCOR Framewor
Tight Approximations for Graphical House Allocation
The Graphical House Allocation (GHA) problem asks: how can houses (each
with a fixed non-negative value) be assigned to the vertices of an undirected
graph , so as to minimize the sum of absolute differences along the edges of
? This problem generalizes the classical Minimum Linear Arrangement problem,
as well as the well-known House Allocation Problem from Economics. Recent work
has studied the computational aspects of GHA and observed that the problem is
NP-hard and inapproximable even on particularly simple classes of graphs, such
as vertex disjoint unions of paths. However, the dependence of any
approximations on the structural properties of the underlying graph had not
been studied.
In this work, we give a nearly complete characterization of the
approximability of GHA. We present algorithms to approximate the optimal envy
on general graphs, trees, planar graphs, bounded-degree graphs, and
bounded-degree planar graphs. For each of these graph classes, we then prove
matching lower bounds, showing that in each case, no significant improvement
can be attained unless P = NP. We also present general approximation ratios as
a function of structural parameters of the underlying graph, such as treewidth;
these match the tight upper bounds in general, and are significantly better
approximations for many natural subclasses of graphs. Finally, we investigate
the special case of bounded-degree trees in some detail. We first refute a
conjecture by Hosseini et al. [2023] about the structural properties of exact
optimal allocations on binary trees by means of a counterexample on a depth-
complete binary tree. This refutation, together with our hardness results on
trees, might suggest that approximating the optimal envy even on complete
binary trees is infeasible. Nevertheless, we present a linear-time algorithm
that attains a -approximation on complete binary trees
The Role of miRNAs, miRNA Clusters, and isomiRs in Development of Cancer Stem Cell Populations in Colorectal Cancer.
MicroRNAs (miRNAs or miRs) have a critical role in regulating stem cells (SCs) duringdevelopment and altered expression can cause developmental defects and/or disease. Indeed,aberrant miRNA expression leads to wide-spread transcriptional dysregulation which has beenlinked to many cancers. Mounting evidence also indicates a role for miRNAs in the developmentof the cancer SC (CSC) phenotype. Our goal herein is to provide a review of: (i) current researchon miRNAs and their targets in colorectal cancer (CRC), and (ii) miRNAs that are differentiallyexpressed in colon CSCs. MicroRNAs can work in clusters or alone when targeting different SC genesto influence CSC phenotype. Accordingly, we discuss the specific miRNA cluster classifications andisomiRs that are predicted to target theALDH1,CD166,BMI1,LRIG1, andLGR5SC genes.miR-23bandmiR-92Aare of particular interest because our previously reported studies on miRNA expressionin isolated normal versus malignant human colonic SCs showed thatmiR-23bandmiR-92aareregulators of theLGR5andLRIG1SC genes, respectively. We also identify additional miRNAs whoseexpression inversely correlated with mRNA levels of their target genes and associated with CRCpatient survival. Altogether, our deliberation on miRNAs, their clusters, and isomiRs in regulationof SC genes could provide insight into how dysregulation of miRNAs leads to the emergence ofdifferent CSC populations and SC overpopulation in CRC
Towards a Reduced Dependency Framework for Autonomous Unified Inspect-Explore Missions
The task of establishing and maintaining situational awareness in an unknown
environment is a critical step to fulfil in a mission related to the field of
rescue robotics. Predominantly, the problem of visual inspection of urban
structures is dealt with view-planning being addressed by map-based approaches.
In this article, we propose a novel approach towards effective use of Micro
Aerial Vehicles (MAVs) for obtaining a 3-D shape of an unknown structure of
objects utilizing a map-independent planning framework. The problem is
undertaken via a bifurcated approach to address the task of executing a closer
inspection of detected structures with a wider exploration strategy to identify
and locate nearby structures, while being equipped with limited sensing
capability. The proposed framework is evaluated experimentally in a controlled
indoor environment in presence of a mock-up environment validating the efficacy
of the proposed inspect-explore policy
The anti-cancer effect of retinoic acid signaling in CRC occurs via decreased growth of ALDH+ colon cancer stem cells and increased differentiation of stem cells
Background: Tumorigenesis is driven by stem cell (SC) overpopulation. BecauseALDH is both a marker for SCs in many tissues and a key enzyme in retinoid acid (RA)signaling, we studied RA signaling in normal and malignant colonic SCs.Hypothesis: RA signaling regulates growth and differentiation of ALDH+ colonicSCs dysregulation of RA signaling contributes to SC overpopulation and colorectalcancer (CRC) development.Methods: We analyzed normal and malignant colonic tissues and CRC cell linesto see if retinoid receptors (RXR &RAR) are exclusively expressed in ALDH+ SCs,and if RA signaling changes during CRC development. We determined whether RAsignaling regulates cancer SC (CSC) proliferation, differentiation, sphere formation,and population size.Results: RXR &RAR were expressed in ALDH+ colonic SCs, but not in MCM2+proliferative cells. Western blotting/immunostaining of CRCs revealed that RAsignaling components become overexpressed in parallel with ALDH overexpression,which coincides with the known overpopulation of ALDH+ SCs that occurs during,and drives, CRC development. Treatment of SCs with all-trans retinoic acid (ATRA)decreased proliferation, sphere formation and ALDH+ SC population size, and induceddifferentiation along the neuroendocrine cell (NEC) lineage.Conclusions: Retinoid signaling, by regulating ALDH+ colonic CSCs, decreases SCproliferation, sphere formation, and population size, and increases SC differentiation toNECs. Dysregulation of RA signaling in colonic SCs likely contributes to overpopulationof ALDH+ SCs and CRC growth.Implications: That retinoid receptors RXR and RAR are selectively expressed inALDH+ SCs indicates RA signaling mainly occurs via ALDH+ SCs, which provides amechanism to selectively target CSCs. © 2018 Impact Journals LLC. All rights reserved
MicroRNA Expression Profiling of Normal and Malignant Human Colonic Stem Cells Identifies
MicroRNAs (miRNAs) have a critical role in regulating stem cells (SCs) during development, and because aberrant expression of miRNAs occurs in various cancers, our goal was to determine if dysregulation of miRNAs is involved in the SC origin of colorectal cancer (CRC). We previously reported that aldehyde dehydrogenase (ALDH) is a marker for normal and malignant human colonic SCs and tracks SC overpopulation during colon tumorigenesis. MicroRNA expression was studied in ALDH-positive SCs from normal and malignant human colon tissues by Nanostring miRNA profiling. Our findings show that: (1) A unique miRNA signature distinguishes ALDH-positive CRC cells from ALDH-positive normal colonic epithelial cells, (2) Expression of four miRNAs (miRNA200c, miRNA92a, miRNA20a, miRNA93) are significantly altered in CRC SCs compared to normal colonic SCs, (3) miRNA92a expression is also upregulated in ALDH-positive HT29 CRC SCs as compared to ALDH-negative SCs, (4) miRNA92a targets the 3\u27UTR of LRIG1 SC gene, and (5) miRNA92a modulates proliferation of HT29 CRC cells. Thus, our findings indicate that overexpression of miRNA92a contributes to the SC origin of CRC. Strategies designed to modulate miRNA expression, such as miRNA92a, may provide ways to target malignant SCs and to develop more effective therapies against CRC
The v8-10 Variant Isoform of CD44 is Selectively Expressed in the Normal Human Colonic Stem Cell Niche and Frequently is Overexpressed in Colon Carcinomas During Tumor Development
CD44 protein and its variant isoforms are expressed in cancer stem cells (CSCs), and various CD44 isoforms can have different functional roles in cells. Our goal was to investigate how different CD44 isoforms contribute to the emergence of stem cell (SC) overpopulation that drives colorectal cancer (CRC) development. Specific CD44 variant isoforms are selectively expressed in normal colonic SCs and become overexpressed in CRCs during tumor development. We created a unique panel of anti-CD44 rabbit genomic antibodies to 16 specific epitopes that span the entire length of the CD44 molecule. Our panel was used to comprehensively investigate the expression of different CD44 isoforms in matched pairs (n = 10) of malignant colonic tissue and adjacent normal mucosa, using two (IHC & IF) immunostaining approaches. We found that: i) CD44v8-10 is selectively expressed in the normal human colonic SC niche; ii) CD44v8-10 is co-expressed with the SC markers ALDH1 and LGR5 in normal and malignant colon tissues; iii) colon carcinoma tissues frequently (80%) stain for CD44v8-10 while staining for CD44v6 was less frequent (40%). Given that CD44v8-10 expression is restricted to cells in the normal human colonic SC niche and CD44v8-10 expression progressively increases during CRC development, CD44v8-10 expression likely contributes to the SC overpopulation that drives the development and growth of colon cancers. Since the CD44 variant v8-10 epitope is located on CD44\u27s extracellular region, it offers great promise for targeted anti-CSC treatment approaches