172 research outputs found
LLT polynomials, elementary symmetric functions and melting lollipops
No full textWe conjecture an explicit positive combinatorial formula for the expansion of unicellular LLT polynomials in the elementary symmetric basis. This is an analogue of the Shareshian-Wachs conjecture previously studied by Panova and the author in 2018. We show that the conjecture for unicellular LLT polynomials implies a similar formula for vertical-strip LLT polynomials. We prove positivity in the elementary symmetric basis for the class of graphs called melting lollipops previously considered by Huh, Nam and Yoo. This is done by proving a curious relationship between a generalization of charge and orientations of unit-interval graphs. We also provide short bijective proofs of Lee's three-term recurrences for unicellular LLT polynomials, and we show that these recurrences are enough to generate all unicellular LLT polynomials associated with abelian area sequences.</p
Recommended from our members
A horizontal-strip LLT polynomial is determined by its weighted graph
No full textWe prove that two horizontal-strip LLT polynomials are equal if the associated weighted graphs defined by the author in a previous paper are isomorphic. This provides a sufficient condition for equality of horizontal-strip LLT polynomials and yields a well-defined LLT polynomial indexed by a weighted graph. We use this to prove some new relations between LLT polynomials and we explore a connection with extended chromatic symmetric functions.Mathematics Subject Classifications: 05E05, 05E10, 05C15Keywords: Chromatic symmetric function, LLT polynomial, Hall-Littlewood polynomial, interval graph, Schur function, weighted grap
A combinatorial expansion of vertical-strip LLT polynomials in the basis of elementary symmetric functions
No full textWe give a new characterization of the vertical-strip LLT polynomials GP(x;q) as the unique family of symmetric functions that satisfy certain combinatorial relations. This characterization is then used to prove an explicit combinatorial expansion of vertical-strip LLT polynomials in terms of elementary symmetric functions. Such formulas were conjectured independently by A. Garsia et al. and the first named author, and are governed by the combinatorics of orientations of unit-interval graphs. The obtained expansion is manifestly positive if q is replaced by q+1, thus recovering a recent result of M. D'Adderio. Our results are based on linear relations among LLT polynomials that arise in the work of D'Adderio, and of E. Carlsson and A. Mellit. To some extent these relations are given new bijective proofs using colorings of unit-interval graphs. As a bonus we obtain a new characterization of chromatic quasisymmetric functions of unit-interval graphs.</p
A combinatorial expansion of vertical-strip LLT polynomials in the basis of elementary symmetric functions
No full textWe give a new characterization of the vertical-strip LLT polynomials
as the unique family of symmetric functions that satisfy
certain combinatorial relations. This characterization is then used to prove an
explicit combinatorial expansion of vertical-strip LLT polynomials in terms of
elementary symmetric functions. Such formulas were conjectured independently by
A. Garsia et al. and the first named author, and are governed by the
combinatorics of orientations of unit-interval graphs. The obtained expansion
is manifestly positive if is replaced by , thus recovering a recent
result of M. D'Adderio. Our results are based on linear relations among LLT
polynomials that arise in the work of D'Adderio, and of E. Carlsson and A.
Mellit. To some extent these relations are given new bijective proofs using
colorings of unit-interval graphs. As a bonus we obtain a new characterization
of chromatic quasisymmetric functions of unit-interval graphs.Comment: 49 pages. This version has updated .bib, and some improvements in
section
VOICE IN ACADEMIC WRITING: THE TRANSPOSITIONING OF AUTHOR IDENTITY IN RESPONDING TO MANUSCRIPT BLIND REVIEWERS
No full textVoice as one of vital elements in academic writing can impinge upon the quality of one’s writing. Despite robust controversies over the usefulness of this metaphorical notion, a plethora of studies on voice has contributed to our understanding of its role in determining writing quality. The foci of these studies, however, are constricted on either voice as individual or voice as social, ignoring the perspective of voice as dialogic. This case study investigates the written reviews of a manuscript author by four blind reviewers in different international Scopus-indexed journals. Drawing on the ideas of “voice as dialogic” and of “transpositioning” of identity, this study seeks to identify and to examine the authorial strategies of an author in constructing his own voice in textual realizations as responses to the manuscript blind reviewers. In doing so, it attempts to finds out the author’s writing identity as manifested in the texts constructed. Relativism’s methodology was employed in order to provide the construction of certain phenomena (i.e. dialogical voice) as accurately as possible. Results revealed that the manuscript author employed two key authorial strategies: averring established authority and foregrounding the ecologies of knowledges.
Design of swirl recovery vanes in a slipstream of limited extension
No full textThe angular momentum or swirl in the propeller slipstream is an energy loss. An effective method to recover the swirl and increase the propulsive efficiency is to use Swirl Recovery Vanes (SRVs). Former research showed an over-prediction in SRV thrust by a lifting line theory (LLT) model compared to wind tunnel experiments. The LLT model assumes an unbounded flow field from minus infinity to plus infinity, while in reality the SRV flow field is bounded due to a small axial spacing between the SRVs and the propeller plane. Using a 2D correction method, based on the application of the Kutta–Joukowski theorem in an axially confined domain combined with the thin airfoil approximation, a correction in the angle of attack can be computed for each blade element of the SRV. The LLT model including the correction method could match the SRV thrust of the experiments. Additionally, the original LLT thrust prediction was met with a corrected pitch angle of the SRVS. An SRV in off-design conditions would result in different correction angles. For a smaller thrust setting of the propeller, the thrust of the SRV will also be lower, hence the correction angle will be smaller. To make the correction method also applicable in off-design conditions, a fixed correction angle would be more practical since the whole vane can be rotated with a variable pitch to match the appropriate correction angle for the corresponding thrust setting. The fixed correction angle was determined by taking an average of all correction angles along the blade radius and the thrust prediction showed good agreement, with a negligible thrust loss of the SRV compared to correcting the pitch angle for each blade element separately. Finally, in the airfoil profile optimization, it was found that the profile drag of the profile is of less influence on the SRV thrust, hence more design freedom can be used to select the appropriate airfoil profile for the SRV.Aerospace Engineerin
PROMOTING THE DEVELOPMENT OF LEARNERS’ TRADITIONAL LITERACIES THROUGH DIGITAL STORYTELLING
No full textLearners frequently have problems comprehend the texts and arrange sentences to become good paragraphs. To address this issue, digital storytelling may be utilized as a technique to aid learners' reading and writing skill. The author aimed at finding out whether or not digital storytelling increases the learners’ reading and writing skills. The author employed a quasi-experimental design. The 80 learners of sharia banking study program at IAIN Palopo participated in this research. The instruments of this research were reading tests and writing essays. Reading test consisted of 30 numbers; meanwhile writing test consisted of one number. The test had two parts: an initial test and a final test. To measure the significance difference on the learners’ achievement in the two-class, the average, standard deviation, and t-test was computed. A significant difference was found when the two means were compared (82.50 57.05); the experimental class average improved after the treatment was implemented. Nevertheless, the learners in control class showed no improvement. Prior to the treatment, the learners in both classes exhibited equivalent writing skill. On the other hand, they had different achievement after being treated. Furthermore, whereas the experimental class experienced a change, the control class did not. Then, the author asserted that digital storytelling can increase the learners’ reading and writing skills. The author hopes findings of this research can be valuable resources for the learners, the lecturers, and the future researchers
CORPUS-INFORMED AND CRITICAL APPROACHES TO ADDRESSING SUSTAINABLE DEVELOPMENT GOALS (SDGS)
No full textThis paper showcases how a do-it-yourself (DIY) corpus on the United Nations’ Sustainable Development Goals (SDGs) can be used to increase corpus users’ language awareness (at word, phrase, sentence, and discourse levels) and criticality. To this end, the author justifies the close link between corpus linguistics, various critical approaches, and SDGs in the applied linguistics/ELT literature. Subsequently, the author provides an overview of principles for creating a specialized DIY corpus containing around 700,000 words/tokens based on 882 articles of The Jakarta Post from 2012 to mid-2024. In view of critical discourse analysis in corpus linguistics, SDG-related key word(s) in context (KWIC) were analyzed in four stages to examine their (1) frequencies and collocates, (2) concordance lines, (3) larger contexts within or across texts in the corpus (or beyond), and (4) potential to stimulate questions aiming at social transformation. In the findings, the four-stage analyses explore two of the most frequent SDGs in the corpus – “gender” (SDG 5) and “clean water and sanitation” (SDG 6) – to illustrate poststructuralist and Marxist criticality, respectively. The decolonial criticality is demonstrated through a corpus analysis of the word “indigenous” and its collocates. Possible pedagogical applications of the corpus-informed approach are also discussed
Bibliographic Attributes Extraction with Layer-upon-Layer Tagging
No full textBibliographic attributes extraction is an important research topic for digital libraries. In this paper we propose a rule-based method for bibliographic attributes extraction with Layer-upon-Layer Tagging (LLT). The method analyzes bibliographic attributes' appearances and punctuations to perform format and semantic taggings on two defined parsing layers. The method also resolves to specifically constructed lexicons to achieve high accuracy of semantic tagging. In the experimental evaluation on 1,000 reference strings, the accuracy of author tagging reaches to 96.8% and the accuracy Of whole reference tagging is 82.9%. The experimental results demonstrate that the proposed LLT method can tag bibliographic attributes in reference strings with high degree of accuracy.</p
Adherence to lipid-lowering therapy and risk for cardiovascular disease and death in type 1 diabetes mellitus: A population-based study from the Swedish National Diabetes Register
No full textAims/hypothesis Dyslipidemia is an important modifiable risk factor and lipid-lowering treatment (LLT) is essential to reduce the risk of cardiovascular disease (CVD). Studies in type 2 diabetes indicate that low adherence to statin therapy is a barrier to reach full protective potential, and less is known in type 1 diabetes (T1D). The aim was to assessrisk of CVD by adherence and nonpersistence to LLT in T1D. Method A population-based study with a retrospective longitudinal design was conducted between 2006 and 2010, with follow-up until December 2013. In total, 6192 adult individuals withT1D, initiatingLLTbetween 2006 and 2010, were included.Information on LLT, socioeconomic characteristics, comorbidities and cardiovascular eventswere collected. After 18 months, refill adherence was estimated by calculating medication possession ratio (MPR). Nonpersistence was defined as being without medicines on hand for at least 180 days. Individuals were thereafterfollowed untilCVD, deathorend of follow-up in December 2013. Cox regression analyses were performed to assess adherence level and nonpersistence of LLT as predictor ofCVD. Analyses wereadjusted for cardiovascular risk factors andsocioeconomic status. Results Mean MPRwas 72%, 52% of the participants had an MPR above 80% and 27% discontinued LLT. There were 637nonfataland58 fatal CVDevents, mean follow-up 3.6 and 3.9 years, respectively. MPR above 80% was associated with reduced risk for nonfatal CVD compared with lower MPR, HR 0.78 (95% CI 0.65 to 0.93)). For fatal CVD, results indicated a negative effect of high adherence but the association did not reach statistical significance, HR 1.96 (0.96 to 4.01). Individuals discontinuing LLT had higher risk of nonfatal CVD, HR 1.43 (95% CI 1.18 to 1.73). Conclusions/Interpretation In T1D, the risk for nonfatal CVD was lower among individuals with high adherence and higher among those discontinuing LLT within 18 months. It is important to evaluate andemphasize adherence toprescribedLLTat clinical visits to achieve treatment goals and reduce the risk of CVD. © Author(s) (or their employer(s)) 2020
- …
