Fragmentation of Random Trees

We study fragmentation of a random recursive tree into a forest by repeated removal of nodes. The initial tree consists of N nodes and it is generated by sequential addition of nodes with each new node attaching to a randomly-selected existing node. As nodes are removed from the tree, one at a time, the tree dissolves into an ensemble of separate trees, namely, a forest. We study statistical properties of trees and nodes in this heterogeneous forest, and find that the fraction of remaining nodes m characterizes the system in the limit N --> infty. We obtain analytically the size density phi_s of trees of size s. The size density has power-law tail phi_s ~ s^(-alpha) with exponent alpha=1+1/m. Therefore, the tail becomes steeper as further nodes are removed, and the fragmentation process is unusual in that exponent alpha increases continuously with time. We also extend our analysis to the case where nodes are added as well as removed, and obtain the asymptotic size density for growing trees.Comment: 9 pages, 5 figure

Extensions of Effective Medium Theory of Transport in Disordered Systems

Effective medium theory of transport in disordered systems, whose basis is the replacement of spatial disorder by temporal memory, is extended in several practical directions. Restricting attention to a 1-dimensional system with bond disorder for specificity, a transformation procedure is developed to deduce, from given distribution functions characterizing the system disorder, explicit expressions for the memory functions. It is shown how to use the memory functions in the Lapace domain forms in which they first appear, and in the time domain forms which are obtained via numerical inversion algorithms, to address time evolution of the system beyond the asymptotic domain of large times normally treated. An analytic but approximate procedure is provided to obtain the memories, in addition to the inversion algorithm. Good agreement of effective medium theory predictions with numerically computed exact results is found for all time ranges for the distributions used except near the percolation limit as expected. The use of ensemble averages is studied for normal as well as correlation observables. The effect of size on effective mediumtheory is explored and it is shown that, even in the asymptotic limit, finite size corrections develop to the well known harmonic mean prescription for finding the effective rate. A percolation threshold is shown to arise even in 1-d for finite (but not infinite) systems at a concentration of broken bonds related to the system size. Spatially long range transfer rates are shown to emerge naturally as a consequence of the replacement of spatial disorder by temporal memories, in spite of the fact that the original rates possess nearest neighbor character. Pausing time distributions in continuous time random walks corresponding to the effective medium memories are calculated.Comment: 15 pages, 11 figure

Statistical mechanics of transport in disordered lattices and reaction-diffusion systems

This thesis is the report of a study of several different problems in statistical physics. The first two are about random walks in a disordered lattice, with applications to a biological system, the third is about reaction-diffusion systems, particularly the phenomena of front propagation and pattern formation, and the last is about a special kind of evolving complex networks, the addition-deletion network. The motivation for the first of the two random walk investigations is provided by the diffusion of molecules in cell membranes. A mathematical model is constructed in order to predict molecular diffusion phenomena relating to the so-called compartmentalized view of the cell membrane. The theoretical results are compared with experimental observations available in the literature. The second random walk part in the thesis contains contributions to the analysis of transport in disordered systems via effective medium theory. Calculation of time-dependent transport quantities are presented along with discussion of effects of finite system size, significance of long-range memory functions, and consequences of correlated disorder. The investigation of reaction-diffusion systems that deals with front propagation is concerned with providing a method of studying transient dynamics in such systems whereas the study of pattern formation focuses on determining necessary conditions for such patterns to arise in situations wherein sub- and super-diffusion are present in addition to simple diffusion. In the network study, results are reported on cluster size distribution in addition-deletion networks, on the basis of both numerical and analytic investigations

Rapid Evolution of cis-Regulatory Architecture and Activity in the Drosophila Yellow Gene.

In the last 10 years, an increasing number of case studies showed that changes in cis-regulatory elements, mainly enhancers, are one of the main causes of altered phenotypes, but the mechanisms underlying enhancer evolution remain to be elucidated. More specifically, what is the relationship between changes in enhancer sequence, transcription factor binding and activity? In this thesis, I used evolution of yellow enhancers among Drosophila species as a model to shed light onto how cis-regulatory architecture and activity change over time. I first identified the enhancer activities lying in the 5’ intergenic and intronic regions of yellow from six Drosophila species spanning the Drosophila evolutionary history, using a reporter gene assay. I found that yellow epidermal-cell and wing-vein, but not bristle enhancers, have different positions, with respect to the coding sequence, in different Drosophila species. This was the first systematic demonstration of altered enhancer position between species and suggested that enhancer position can be labile. Sequence comparisons failed to show any indication of translocation or duplication suggesting gradual compensatory changes in the transcription factor binding profiles of yellow enhancers is the likely mechanism underlying altered enhancer position. Subsequent subdivision of yellow 5’ intergenic and intronic regions showed a complex distribution of enhancer activities among sub-elements, where some drove expression in patterns that were not part of the expression pattern driven by the full region. Existence of such “cryptic” epidermal-cell enhancer activities suggests that yellow cis-regulatory regions were primed for facilitating the rapid evolutionary changes in the position and activities of this enhancer. Lastly, for the first time, I identified a large set of candidate transcription factors binding to yellow enhancers. This thesis shows that position and activity of yellow enhancers diverged rapidly among species, perhaps by taking advantage of the cryptic activities lying in the yellow cis-regulatory sequences. Further in vitro and in vivo tests validating the direct binding of the identified transcription factors on yellow enhancers and characterizing their functional effects on yellow expression among species can elucidate the evolutionary changes underlying altered position and activity of the particular yellow enhancers.Ph.D.Molecular, Cellular, and Developmental BiologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/91435/1/gizemkly_1.pd

Bridging the pragmatic gap between native and non-native English instructors: A comparative analysis of apology patterns

The communicative movement, which emerged in the early 1970s, has been pivotal in shifting the focus of language study towards the contextual use of language. Within this movement, the field of pragmatics has come to the forefront, illuminating the intricate relationship between language and context. Pragmatics presents a unique challenge in language acquisition. It encompasses two critical dimensions: pragmalinguistic and sociopragmatic knowledge. Pragmalinguistic knowledge involves the ability to employ specific linguistic forms to convey intended meanings within a given context. In contrast, sociopragmatic knowledge delves deeper, demanding an understanding of the temporal and societal norms that govern when and where linguistic forms should be employed. The successful execution of speech acts serves as a vivid illustration of this duality, requiring proficiency in both pragmalinguistic forms and adherence to sociocultural norms within a language community. The present study seeks to address this gap (with the research aim) by investigating the pragmatic competence of non-native English teachers in comparison to their native counterparts. We specifically focus on their speech act productions, aiming to shed light on any discernible differences. Our research findings carry broader conclusions and some implications for language pedagogy as they contribute to our understanding of the complex interplay between language acquisition, contextual factors, and pragmatic competence. This study investigates the pragmatic competence of non-native English teachers, comparing it to that of native English teachers, with a specific focus on their speech act productions. By shedding light on these differences, this research contributes to our understanding of the intricate interplay between language acquisition, context, and pragmatic competence. Ultimately, it underscores the importance of incorporating explicit pragmatics training in teacher development programs, equipping educators with the tools needed to foster comprehensive language proficiency

RECEPTIVE VOCABULARY KNOWLEDGE OF UNIVERSITY STUDENTS IN CLIL INSTRUCTION

Content and Language Integrated Learning (CLIL) has recently attracted the attention of practitioners in the language teaching field. As the name suggests, CLIL is an approach built upon teaching content-based area through a language as a medium. For such a language learning process, one of the important language aspects is vocabulary. The number of words language learners know - vocabulary size - and how well they know those words - vocabulary depth - (overall, the receptive dimension of word knowledge) are crucial foci to consider in language learning. Therefore, the primary concern of the present study is to examine the effects of the CLIL approach on the receptive vocabulary knowledge of university students in a state university. Accordingly, Vocabulary Levels Test (VLT) by Schmitt, Schmitt and Clapham (2001) and Word Association Test (WAT) by Read (2000) are administered to the participants before and after CLIL treatment. The findings indicated that the subjects’ size of vocabulary knowledge has significantly differed with CLIL instruction in time, which means that CLIL instruction has been found to be successful for developing both general and academic vocabulary knowledge. Similarly, an increase in the depth of vocabulary knowledge of participants alongside with the CLIL instruction has been observed, indicating that participants’ quality of vocabulary knowledge evaluated through WAT seems to have improved with CLIL treatment. Further research including less frequent words as well as the productive aspect of word knowledge might shed light on the impacts of CLIL treatment on vocabulary development of language learners, especially university students. Article visualizations

UJI EFEK ANTIPIRETIK EKSTRAK ETANOL DAUN PRASMAN (Eupatorium triplinerve Vahl.) PADA TIKUS JANTAN GALUR WISTAR (Rattus Norvegicus L.) YANG DIINDUKSI VAKSIN DTP HB

ABSTRACTPrasman leaves (Eupatorium triplinerve Vahl.) empirically efficacious as treatment of fever.This study aims to prove the antipyretic effects of ethanol extract of leaves Prasman againstwhite male rats Wistar strain vaccines induced DTP HB. This study used 15 male rats weredivided into 5 groups, namely, negative control (CMC), the treatment group (administrationof leaf extracts Prasman 0.03 g/kgBB, 0.06 g/kgBB and 0.12 g/kgBB) and positive control(Paracetamol). Rat fever induced with vaccine DTP HB intramuscularly 0.08 ml/100 KgBB.Rectal temperature of mice was measured every 1 hour for 4 hours after oral administration.The decrease in temperature of mice were analyzed by one-way ANOVA and LSD (α =0.05%). The results showed that the ethanol extract of the leaves prasman with a dose of 0.03g/kgBB, 0.06 g/kgBB and 0.12 g/kgBB has an antipyretic effect on white male rats Wistarstrain induced vaccine DTP HB.Key words : Antipyretics, Eupatorium triplinerve Vahl., vaccine DTP HBABSTRAKDaun Prasman (Eupatorium triplinerve Vahl.) secara empiris berkhasiat sebagai pengobatandemam. Penelitian ini bertujuan untuk membuktikan efek antipiretik ekstrak etanol daunPrasman terhadap tikus putih jantan galur wistar yang diinduksi vaksin DTPHB. Penelitianini menggunakan 15 ekor tikus jantan dan dibagi menjadi 5 kelompok perlakuan yaitu,kontrol negatif (CMC), kelompok perlakuan (pemberian ektrak daun Prasman 0,03 g/kgBB,0,06 g/kgBB dan 0,12 g/kgBB) dan kontrol positif (Parasetamol). Tikus diinduksi demamdengan vaksin DTP HB dosis 0,08 ml/100 gBB secara intramuskular. Suhu rektal tikusdiukur setiap 1 jam selama 4 jam setelah pemberian per oral. Penurunan suhu tikus dianalisisdengan uji ANOVA satu arah dan LSD (α = 0,05%). Hasil penelitian menunjukkan bahwaekstrak etanol daun prasman dengan dosis 0,03 g/kgBB, 0,06 g/kgBB dan 0,12 g/kgBBmempunyai efek antipiretik terhadap tikus putih jantan galur wistar yang diinduksi vaksinDTP HB.Kata kunci : Antipiretik, Eupatorium triplinerve Vahl., Vaksin DTP H