scholarly journals $h$-Polynomials via Reduced Forms

10.37236/5172 ◽  
2015 ◽  
Vol 22 (4) ◽  
Author(s):  
Karola Meszaros

The flow polytope $F_{\widetilde{G}}$ is the set of nonnegative unit flows on the graph $\widetilde{G}$. The subdivision algebra of flow polytopes prescribes a way to dissect a flow polytope $F_{\widetilde{G}}$ into simplices. Such a dissection is encoded by the terms of the so called reduced form of the monomial $\prod_{(i,j)\in E(G)}x_{ij}$. We prove that we can use the subdivision algebra of flow polytopes to construct not only dissections, but also regular flag triangulations of flow polytopes. We prove that reduced forms in the subdivision algebra are generalizations of $h$-polynomials of the triangulations of flow polytopes. We deduce several corollaries of the above results, most notably proving certain cases of a conjecture of Kirillov about the nonnegativity of reduced forms in the noncommutative quasi-classical Yang-Baxter algebra.


2020 ◽  
Vol 25 (5) ◽  
pp. 29-35
Author(s):  
M. Yu. Maksimova ◽  
A. V. Ivanov ◽  
K. A. Nikiforova ◽  
F. R. Ochtova ◽  
E. T. Suanova ◽  
...  

Ischemic stroke (IS) and type 2 diabetes mellitus are factors that affect the homeostasis of low-molecularweight aminothiols (cysteine, homocysteine, glutathione etc.). It has already been shown that IS in the acute period led to a decrease a level of reduced forms of aminothiols, but it is not clear whether type 2 diabetes mellitus has a noticeable effect there. Objective: to reveal the features of homeostasis of aminothiols in patients with type 2 diabetes mellitus in acute IS. Material and methods. The study involved 76 patients with primary middle cerebral artery IS in the first 10–24 hours after development of neurological symptoms. Group 1 included 15 patients with IS and type 2 diabetes mellitus, group 2 — 61 patients with IS and stress hyperglycemia. Their total plasma levels of cysteine, homocysteine, and glutathione, their reduced forms, and redox status were determined at admission (in the first 24 hours after IS). Results. There was a decrease in the level of total glutathione level (1.27 vs. 1.65 μM, p = 0.021), as well as its reduced form (0.03 vs. 0.04 μM, p = 0.007) in patients with IS and type 2 diabetes mellitus. Patients with type 2 diabetes mellitus who had a low redox status of homocysteine (0.65–1.2%) and glutathione (0.7–2.0%) were also characterized by a decrease in total glutathione level (p = 0.02; p = 0.03). Conclusion. Thus, type 2 diabetes mellitus is associated with a decrease in the level of total glutathione in acute IS. Probably, type 2 diabetes mellitus is characterized by a particular relationship between the metabolism of homocysteine, glutathione and glucose. Therefore, the search for homocysteine-dependent approaches to correct glutathione metabolism in type 2 diabetes mellitus may be of interest as an adjuvant therapy for IS.



1995 ◽  
Vol 41 (3) ◽  
pp. 361-366 ◽  
Author(s):  
A Andersson ◽  
A Lindgren ◽  
B Hultberg

Abstract Changes in concentration of reduced and oxidized low-M(r) thiols were measured in blood and plasma before and after the separation of blood cells. If centrifugation of blood was postponed, the reduced form of homocysteine in plasma increased with time at 22 degrees C; in contrast, the concentrations of other reduced thiols (cysteine, glutathione, and cysteinylglycine) decreased. In plasma the reduced forms of all thiols disappeared at a rate that followed first-order kinetics. The rates of disappearance ("half-lives") were temperature-dependent; they were about the same for glutathione and homocysteine (11.7 and 14.3 min, respectively, at 22 degrees C) and somewhat higher for cysteinylglycine and cysteine. After establishing proper sampling conditions for reduced thiols, we measured this thiol fraction as well as free (non-protein-bound) and total thiols in 10 reference subjects and 19 patients with cerebral infarction. Mild but significant hyperhomocysteinemia involving total and free homocysteine (but not reduced homocysteine) was found in the patients.



2012 ◽  
Vol 65 (11) ◽  
pp. 2193-2220 ◽  
Author(s):  
Susanne Brouwer ◽  
Holger Mitterer ◽  
Falk Huettig

In listeners' daily communicative exchanges, they most often hear casual speech, in which words are often produced with fewer segments, rather than the careful speech used in most psycholinguistic experiments. Three experiments examined phonological competition during the recognition of reduced forms such as [pjutər] for computer using a target-absent variant of the visual world paradigm. Listeners' eye movements were tracked upon hearing canonical and reduced forms as they looked at displays of four printed words. One of the words was phonologically similar to the canonical pronunciation of the target word, one word was similar to the reduced pronunciation, and two words served as unrelated distractors. When spoken targets were presented in isolation (Experiment 1) and in sentential contexts (Experiment 2), competition was modulated as a function of the target word form. When reduced targets were presented in sentential contexts, listeners were probabilistically more likely to first fixate reduced-form competitors before shifting their eye gaze to canonical-form competitors. Experiment 3, in which the original /p/ from [pjutər] was replaced with a “real” onset /p/, showed an effect of cross-splicing in the late time window. We conjecture that these results fit best with the notion that speech reductions initially activate competitors that are similar to the phonological surface form of the reduction, but that listeners nevertheless can exploit fine phonetic detail to reconstruct strongly reduced forms to their canonical counterparts.



2009 ◽  
Vol DMTCS Proceedings vol. AK,... (Proceedings) ◽  
Author(s):  
Karola Mészáros

International audience The type $A_n$ root polytope $\mathcal{P}(A_n^+)$ is the convex hull in $\mathbb{R}^{n+1}$ of the origin and the points $e_i-e_j$ for $1 \leq i < j \leq n+1$. Given a tree $T$ on vertex set $[n+1]$, the associated root polytope $\mathcal{P}(T)$ is the intersection of $\mathcal{P}(A_n^+)$ with the cone generated by the vectors $e_i-e_j$, where $(i, j) \in E(T)$, $i < j$. The reduced forms of a certain monomial $m[T]$ in commuting variables $x_{ij}$ under the reduction $x_{ij} x_{jk} \to x_{ik} x_{ij} + x_{jk} x_{ik} + \beta x_{ik}$, can be interpreted as triangulations of $\mathcal{P}(T)$. If we allow variables $x_{ij}$ and$x_{kl}$ to commute only when $i, j, k, l$ are distinct, then the reduced form of $m[T]$ is unique and yields a canonical triangulation of $\mathcal{P}(T)$ in which each simplex corresponds to a noncrossing alternating forest. Le polytope des racines $\mathcal{P}(A_n^+)$ de type $A_n$ est l'enveloppe convexe dans $\mathbb{R}^{n+1}$ de l'origine et des points $e_i-e_j$ pour $1 \leq i < j \leq n+1$. Étant donné un arbre $T$ sur l'ensemble des sommets $[n+1]$, le polytope des racines associé, $\mathcal{P}(T)$, est l'intersection de $\mathcal{P}(A_n^+)$ avec le cône engendré par les vecteurs $e_i-e_j$, où $(i, j) \in E(T)$, $i < j$. Les formes réduites d'un certain monôme $m[T]$ en les variables commutatives $x_{ij}$ sous la reduction $x_{ij} x_{jk} \to x_{ik} x_{ij} + x_{jk} x_{ik} + \beta x_{ik}$ peuvent être interprétées comme des triangulations de $\mathcal{P}(T)$. Si on impose la restriction que les variables $x_{ij}$ et $x_{kl}$ commutent seulement lorsque les indices $i, j, k, l$ sont distincts, alors la forme réduite de $m[T]$ est unique et produit une triangulation canonique de $\mathcal{P}(T)$ dans laquelle chaque simplexe correspond à une forêt alternée non croisée.



1997 ◽  
Vol 77 (3) ◽  
pp. 497-502 ◽  
Author(s):  
Y. Mizuno ◽  
E. Kokue ◽  
N. Ohnishi ◽  
Y. Toride

Two experiments were conducted to evaluate the response of plasma folate levels after oral administration of oxidized or reduced forms of folates, using seven Göttingen minipigs. Plasma folate levels, tetrahydrofolate (THF) and 5-methyltetrahydrofolate (5CH3-THF), were determined by high-performance liquid chromatography with electrochemical detection. In exp. 1, the absorption of the oxidized form of folate [(synthetic folic acid(FA)] and the reduced forms of folate (5-formyltetrahydrofolate (5HCO-THF), liver powder and digested bacterial cell powder (DBCP) were evaluated by measuring changes in plasma folate levels after a single oral administration. Liver powder and DBCP contained much reduced forms of folate. The administration of the reduced form of folates increased plasma THF levels while the levels of plasma THF and 5CH3-THF decreased after FA administration. In exp. 2, plasma folate levels were measured after long-term oral administration of FA for 30 d. Immediately after the beginning of the administration, the levels of both THF and 5CH3-THF decreased significantly and remained at a low level during the 30-d administration. Supplementation of sow feed with FA has been recommended in many countries improving reproductive performance. The present study, however, suggests that the oral administration of an oxidized form of folate, FA, may not be as effective as previously thought, and the reduced forms of folate might be preferable for the supplementation of pig feeds. Key words: Folate (reduced), folic acid, pig, oral administration, bacterial cell wall, absorption



2019 ◽  
Vol 71 (6) ◽  
pp. 1495-1521
Author(s):  
Ricky Ini Liu ◽  
Alejandro H. Morales ◽  
Karola Mészáros

AbstractA result of Haglund implies that the$(q,t)$-bigraded Hilbert series of the space of diagonal harmonics is a$(q,t)$-Ehrhart function of the flow polytope of a complete graph with netflow vector$(-n,1,\ldots ,1)$. We study the$(q,t)$-Ehrhart functions of flow polytopes of threshold graphs with arbitrary netflow vectors. Our results generalize previously known specializations of the mentioned bigraded Hilbert series at$t=1$,$0$, and$q^{-1}$. As a corollary to our results, we obtain a proof of a conjecture of Armstrong, Garsia, Haglund, Rhoades, and Sagan about the$(q,q^{-1})$-Ehrhart function of the flow polytope of a complete graph with an arbitrary netflow vector.



1981 ◽  
Vol 199 (3) ◽  
pp. 629-637 ◽  
Author(s):  
J P G Malthouse ◽  
G N George ◽  
D J Lowe ◽  
R C Bray

Different reduced forms of xanthine oxidase, labelled specifically in the cyanide-labile site with 33S, were prepared and examined by electron paramagnetic resonance. Coupling of this isotope to molybdenum(V) was quantified with the help of computer simulations and found to differ markedly from one reduced form to another. The xanthine Very Rapid signal shows strong, highly anisotropic, coupling with A(33S)av. 1.27 mT. For this signal, axes of the g- and A(33S)-tensors are rotated relative to one another. One axis of the A-tensor is in the plane of gxx ang gyy, but rotated by 40 degrees relative to the gxx axis, whereas the direction of weakest coupling to sulphur deviates by 10 degrees from the gzz axis. In contrast with this signal, only rather weaker coupling was observed in different types of Rapid signal [A(33S)av. 0.3--0.4 mT], and in the Inhibited signal coupling was weaker still [A(33S)av. 0.1--0.2 mT]. Clearly, there must be substantial differences in the structures of the molybdenum centre in the different signal-giving species, with the sulphur atom perhaps in an equatorial type of ligand position in the Very Rapid species but in a more axial one in the other species. Structures are discussed in relation to the mechanism of action of the enzyme and the nature of the proton-accepting group that participates in turnover.



1989 ◽  
Vol 257 (3) ◽  
pp. 775-781 ◽  
Author(s):  
P Parham ◽  
F M Brodsky ◽  
K Drickamer

Three forms of clathrin light chain contain two cysteine residues. These are the predominant brain-specific forms of LCa and LCb and the non-brain form of LCb. After purification in the absence of thiols they contain intramolecular disulphide bonds. The reduced and the oxidized forms show differences in electrophoretic mobility, explaining the variable and heterogeneous patterns observed on electrophoresis. Accessibility of the thiol groups in the free light chains is greater than when they are associated with the heavy chain. In contrast the cysteine residues of the clathrin heavy chain are completely inaccessible in the absence of denaturants and are not found in disulphide bonds. The antigenic properties of the oxidized and the reduced forms of the clathrin light chains are similar, as is their capacity to bind to the clathrin heavy chain. After isolation in the presence of 10 mM-iodoacetamide, the light-chain cysteine residues are fully alkylated. The results are consistent with the reduced form being the native state and the light-chain disulphide bonds an artifact of isolation.



2021 ◽  
pp. 174702182110371
Author(s):  
Dominique Knutsen ◽  
Marion Fossard ◽  
Amélie M. Achim

Past research shows that when a discourse referent is mentioned repeatedly, it is usually introduced with a full NP and maintained with a reduced form such as a pronoun. Is this also the case in dialogue, where the same referent may be introduced by one person and maintained by another person? An experiment was conducted in which participants either told entire stories to each other or told stories together, thus enabling us to contrast situations in which characters were introduced and maintained by the same person (control condition) and situations in which the introduction and the maintaining of each character were performed by different people (alternating condition). Story complexity was also manipulated through the introduction of one or two characters in each story. We found that participants were less likely to use reduced forms to maintain referents in the alternating condition. The use of reduced forms also depended on the context in which the referent was maintained (in particular, first or second mention of a character) and on story complexity. These results shed light on how the pressure to signal understanding to one’s conversational partner affects referential choices throughout the interaction.



2010 ◽  
Vol 1 ◽  
pp. 49
Author(s):  
Meghan Clayards

The frequency of a word form influences how efficiently it is processed, but canonical forms often show an advantage over reduced forms even when the reduced form is more frequent. This paper addresses this paradox by considering a model in which representations of lexical items consist of a distribution over forms. Optimal inference given these distributions accounts for item based differences in recognition of phonological variants and canonical form advantage.



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