2,933 research outputs found
Implementation Challenges and Opportunities in the Outcome-Based Education (OBE) for Teaching Engineering Courses: A Case Study
No full textAbstract: Outcome-based education is a closed-loop control system accepted globally for enhancing the teaching-learning processes. However, the success of the system is not prominently visible in fresh graduates. Hence detailed research and optimal process to implement OBE is necessary. This paper aims to investigate the challenges in implementing Outcome-based education and explores opportunities for improvement. Further, pedagogic planning for the analytical subjects has been proposed and the performance of the proposed method is analyzed using a case study. Performance improvement in Course Outcome attainments of the course Antennas and Wave Propagation, offered for undergraduate engineering (ECE) students have been investigated and evaluated in this paper. The investigation shows that dynamically adapting the teaching-learning and assessment methods during the course based on the assessments of the student’s capabilities results in improved performance. The following changes in the system have been suggested for the optimal implementation of OBE. The CO targets for the current semester course should be fixed based on the CO attainment of the previous semester courses of the same batch instead of the traditional way of fixing CO attainment targets. The microanalysis of the end-semester marks and students’ feedback at the ratio of 5:1 may be considered for overall CO attainment computation at the end of the course.Published By: Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP)
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Popular Roommates in Simply Exponential Time
Get PDFWe consider the popular matching problem in a graph G = (V,E) on n vertices with strict preferences. A matching M is popular if there is no matching N in G such that vertices that prefer N to M outnumber those that prefer M to N. It is known that it is NP-hard to decide if G has a popular matching or not. There is no faster algorithm known for this problem than the brute force algorithm that could take n! time. Here we show a simply exponential time algorithm for this problem, i.e., one that runs in O^*(k^n) time, where k is a constant.
We use the recent breakthrough result on the maximum number of stable matchings possible in such instances to analyze our algorithm for the popular matching problem. We identify a natural (also, hard) subclass of popular matchings called truly popular matchings and show an O^*(2^n) time algorithm for the truly popular matching problem
Stable Matchings with One-Sided Ties and Approximate Popularity
Get PDFWe consider a matching problem in a bipartite graph G = (A ∪ B, E) where vertices in A rank their neighbors in a strict order of preference while vertices in B are allowed to have weak rankings, i.e., ties are allowed in their preferences. Stable matchings always exist in G and are easy to find, however popular matchings need not exist and it is NP-complete to decide if one exists. This motivates the "approximately popular" matching problem.
A well-known measure of approximate popularity is low unpopularity factor. We show that when each tie in G has length at most k, there always exists a stable matching whose unpopularity factor is at most k. Our proof is algorithmic and we compute such a stable matching in polynomial time. Our result can be considered to be a generalization of Gärdenfors' result (1975) which showed that when rankings are strict, every stable matching is popular.
There are several applications where the size of the matching is its most important attribute. What one seeks here is a maximum matching M such that there is no maximum matching more popular than M. When rankings are weak, it is NP-hard to decide if G admits such a matching. When ties are one-sided and of length at most k, we show a polynomial time algorithm to find a maximum matching whose unpopularity factor within the set of maximum matchings is at most 2k
Fairly Popular Matchings and Optimality
Get PDFWe consider a matching problem in a bipartite graph G = (A ∪ B, E) where vertices have strict preferences over their neighbors. A matching M is popular if for any matching N, the number of vertices that prefer M is at least the number that prefer N; thus M does not lose a head-to-head election against any matching where vertices are voters. It is easy to find popular matchings; however when there are edge costs, it is NP-hard to find (or even approximate) a min-cost popular matching. This hardness motivates relaxations of popularity.
Here we introduce fairly popular matchings. A fairly popular matching may lose elections but there is no good matching (wrt popularity) that defeats a fairly popular matching. In particular, any matching that defeats a fairly popular matching does not occur in the support of any popular mixed matching. We show that a min-cost fairly popular matching can be computed in polynomial time and the fairly popular matching polytope has a compact extended formulation.
We also show the following hardness result: given a matching M, it is NP-complete to decide if there exists a popular matching that defeats M. Interestingly, there exists a set K of at most m popular matchings in G (where |E| = m) such that if a matching is defeated by some popular matching in G then it has to be defeated by one of the matchings in K
Popular matchings: structure and algorithms
Get PDFAn instance of the popular matching problem (POP-M) consists of a set of applicants and a set of posts. Each applicant has a preference list that strictly ranks a subset of the posts. A matching M of applicants to posts is popular if there is no other matching M' such that more applicants prefer M' to M than prefer M to M'. This paper provides a characterization of the set of popular matchings for an arbitrary POP-M instance in terms of a structure called the switching graph, a directed graph computable in linear time from the preference lists. We show that the switching graph can be exploited to yield efficient algorithms for a range of associated problems, including
the counting and enumeration of the set of popular matchings and computing popular matchings that satisfy various additional optimality criteria. Our algorithms for computing such optimal popular matchings improve those described in a recent paper by Kavitha and Nasre
Supplemental Material - Prevalence and correlates of human immunodeficiency virus infection among spouses of married men who have sex with men in India
No full textSupplemental Material for Prevalence and correlates of human immunodeficiency virus infection among spouses of married men who have sex with men in India by Aylur K Srikrishnan, Kavitha Ganesan, Shruti H Mehta, Cecilia Tomori, Canjeevaram K Vasudevan, David D Celentano and Sunil S Solomon in International Journal of STD & AIDS</p
Cycle bases in graphs characterization, algorithms, complexity, and applications.
No full textCycles in graphs play an important role in many applications, e.g., analysis of electrical networks, analysis of chemical and biological pathways, periodic scheduling, and graph drawing. From a mathematical point of view, cycles in graphs have a rich structure. Cycle bases are a compact description of the set of all cycles of a graph. In this paper, we survey the state of knowledge on cycle bases and also derive some new results. We introduce different kinds of cycle bases, characterize them in terms of their cycle matrix, and prove structural results and apriori length bounds. We provide polynomial algorithms for the minimum cycle basis problem for some of the classes and prove APX -hardness for others.
We also discuss three applications and show that they require different kinds of cycle bases
STUDIO DEI MECCANISMI DI PRODUZIONE DI ESOPOLISACCARIDI NEI BATTERI ACETICI UTILIZZANDO COME MODELLO LA BIOSINTESI DI CELLULOSA BATTERICA E LEVANI
No full textI batteri acetici sono batteri strettamente aerobi, gram-negativi che fanno parte della famiglia delle Acetobacteraceae. Attualmente, il raggruppamento dei batteri acetici include 19 generi e 110 specie, le fonti di isolamento maggiormente descritte sono fiori, frutti e bevande fermentate. I batteri acetici sono conosciuti per il loro metabolismo ossidativo e produzione di acidi organici grazie alla presenza di deidrogenasi di membrana. Oltre al metabolismo ossidativo, i batteri acetici stanno ricevendo una grande attenzione da parte della comunità scientifica e industriale, grazie alla loro capacità di produrre biopolimeri come cellulosa e levani. I biopolimeri sono ampiamente studiati per la formulazione di composti a basso impatto ambientale. La cellulosa batterica e i levani sono tra i biopolimeri più studiati grazie alle loro proprietà meccaniche e fisiche, oltre alle caratteristiche di biocompatibilità e non tossicità. La biosintesi di polimeri da parte dei batteri acetici avviene ad opera di complessi enzimatici in grado di polimerizzare monomeri di zucchero in catene polisaccaridiche ben strutturate. La regolazione delle vie biosintetiche e dei meccanismi molecolari non sono tuttavia ben conosciuti. La riprogrammazione del metabolismo in base a fattori ambientali, tra cui la disponibilità di fonti di carbonio è una strategia che è stata applicata su altri generi batterici con lo scopo di aumentare la resa di produzione di composti target. In base a queste considerazioni, lo scopo principale di questa tesi di dottorato è stato quello di studiare i meccanismi molecolari che stanno alla base della sintesi di levani e cellulosa batterica.
Per quanto riguarda i levani, questi polimeri sono utilizzati ampiamente in ambito alimentare come prebiotici. L’applicazione industriale dei batteri acetici per la sintesi di levani è limitata da una carenza di conoscenze nel loro metabolismo. Per colmare questa carenza, ceppi appartenenti ai generi Gluconobacter, Acetobacter, Komagataeibacter, Neoasaia and Kozakia sono stati utilizzati per caratterizzare la sintesi di levani. La cinetica di produzione di questi composti è stata studiata in questi ceppi con lo scopo di analizzare la variabilità fenotipica a livello inter- e intra-specie. Questo studio ha permesso di identificare i migliori produttori di levani e di stabilire le condizioni migliori, identificando i fattori che ne limitano la produzione.
La cellulosa batterica è stata studiata approfonditamente negli ultimi decenni, ponendo particolare attenzione all’utilizzo delle fonti di carbonio da parte dei batteri, definendo strategie di modifica del polimero e applicando l’ingegneria genetica con lo scopo di migliorare la resa o disegnare nuovi polimeri. Metodi naturali alternativi come lo sfruttamento delle abilità dei batteri ad adattarsi alle condizioni ambientali, come ad esempio la disponibilità di una fonte di carbonio diversa, risultano poco studiati. Per colmare queste lacune, in questo lavoro di tesi è stato applicato un approccio di evoluzione in laboratorio che consente di studiare l’adattamento a una nuova fonte di carbonio. Il ceppo K. xylinus K2G30 è stato ripetutamente coltivato utilizzando mannitolo come fonte di carbonio per un totale di 350 giorni. Dal punto di vista fenotipico, è stato osservato un incremento della resa di cellulosa del 100%. L’analisi del trascrittoma è stata applicata per monitorare l’espressione di geni che regolano il metabolismo in condizioni diverse e consentono di capire le strategie adottate da ceppi in studio. I risultati ottenuti possono essere sfruttati per incrementare l’applicabilità di questi batteri in ambito industriale, disegnando nuovi processi, e valorizzando scarti agroalimentari contenenti fonti di carbonio idonee.Acetic acid bacteria are strictly aerobic, gram-negative bacteria belonging to Acetobacteraceae family. So far, 19 genera with 110 species of acetic acid bacteria have been reported, which are isolated from variety of sources such as flowers, fruits, and fermented beverages. Acetic acid bacteria are well known for their oxidative metabolism, producing a wide range of organic acids, thanks to membrane-bound dehydrogenases. Besides the oxidative metabolism, acetic acid bacteria are receiving great attention for their ability to produce biopolymers, such as cellulose and fructans, including levan. Biopolymer synthesis has received great attention in the recent years by the scientific community and industries, paving the way towards environmentally friendly green composites. Bacterial cellulose and levan, have widely been used for food, medical and industrial applications due to their mechanical and physical properties, bio-compatibility, and non-toxicity. The biosynthesis of polymers in acetic acid bacteria occurs through enzymatic complexes, able to polymerize sugars and sugar alcohols into well-structured polysaccharide chains. The biochemical pathways involved in the production of bacterial cellulose and levan have been extensively studied, with the main aim to improve the yield and to design scalable- processes. The regulation of the biochemical pathways and the molecular mechanisms that tune the entire metabolism to the environmental availability of carbon source are not completely known. The reprogramming of the metabolism is a strategy that was already applied to bacteria with the aim of optimize the production of the target compounds. Based on these considerations, the main aim of this PhD thesis was to study these aspects for both levan and bacterial cellulose production. Regarding levan, they are mainly used as a prebiotic and are highly exploited in food industries. The industrial application of acetic acid bacteria for levan production is constrained by a lack of understanding their metabolism. To address this gap, in this study, strains of Gluconobacter, Acetobacter, Komagataeibacter, Neoasaia and Kozakia genera were used to characterize the levan synthesis. Phenotypic behavior of the individual strains in terms of inter- and intra-specific variability was analyzed by the production kinetics of levan, related to biochemical changes. This study allowed to identify the best levan producers in the tested conditions and impacting factors that are limiting the production of levan.
Bacterial cellulose was deeply studied in the last decades, with a particular emphasis on the carbon source utilization, cellulose modification, and genetic engineering, obtaining interesting results. Alternative methods, such as, the study of regulating mechanisms of the carbohydrate metabolism and the adaptation to the availability of a certain carbon source, were not elucidated, constraining the applicability of bacterial cellulose. With this aim, adaptation strategies to a new carbon source were studied in this thesis by applying the adaptive laboratory evolution approach and new sequencing techniques. The strain K. xylinus K2G30 from UMCC was continuously cultivated in mannitol as a sole-carbon source for different cycles (350 days). From phenotypic point of view, the bacterial cellulose yield was increased by two/fold by using mannitol. The transcriptome analysis was applied to understand the expression of key genes that regulates the metabolism in a different condition and the strategies adopted by these bacteria. Data obtained can be exploited to set new strategies for scale up, increasing the applicability at industrial level and testing different bio-wastes that are rich in mannitol for bacterial cellulose production
Delayed fathering and risk of mental disorders in adult offspring
No full textSaroja Krishnaswamy, Kavitha Subramaniam, Padma Ramachandran, Tishya Indran, Jemain Abdul Azi
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