Skew Group Research Articles

Improved Risk Prediction Using a Refined European Guidelines Instrument in Pulmonary Arterial Hypertension Related to Congenital Heart Disease

European guidelines advocate a goal-oriented treatment approach in pulmonary arterial hypertension (PAH), based on a comprehensive risk assessment instrument, which has been validated in several PAH subgroups. We investigated its discriminatory ability, and explored tricuspid annular plane systolic excursion (TAPSE) and revised thresholds to improve its predictability within the adult congenital heart disease (CHD) population.In total, 223 adults (42±16 years, 66% female, 68% Eisenmenger) were enrolled from five European PAH-CHD expert centers. Patients were classified as ‘Low’, ‘Intermediate’, or ‘High’ risk at baseline visit and at follow-up within 4-18 months. By the general PAH guidelines instrument, survival did not differ between the risk groups (P=n.s.), mostly due to skewed group distribution. Reclassifying patients using revised thresholds for N-terminal pro-brain natriuretic peptide (NT-proBNP) and 6-minute walk distance (6MWD) (i.e., ‘Low’, ‘Intermediate’, ‘High’ as <500, 500-1400, >1400 ng/l and >400, 165-400 and <165 m, respectively) and use of TAPSE (‘Low’, ‘Intermediate’, ‘High’ as >20, 16-20 and <16mm) significantly improved discrimination between the risk groups both at baseline and follow-up (P=0.001, ROC increase from 0.648 to 0.701), reclassifying 64 (29%) patients. Irrespective of follow-up risk group, survival was better for patients with higher proportions of low-risk variables. Improvement to a ‘Low-risk’ profile at a median of 9 months follow-up provided improved survival comparable to survival of patients who remained in the ‘Low risk’ group.In conclusion, the external validity of general risk instrument for PAH appeared to be of limited discriminatory value in PAH-CHD patients. We propose a refined risk instrument with improved discrimination for PAH-CHD.

Skew group categories, algebras associated to Cartan matrices and folding of root lattices

For an action of a finite group on a finite EI quiver, we construct its ‘orbifold’ quotient EI quiver. The free EI category associated to the quotient EI quiver is equivalent to the skew group category with respect to the given group action. Specializing the result to a finite group action on a finite acyclic quiver, we prove that, under reasonable conditions, the skew group category of the path category is equivalent to a finite EI category of Cartan type. If the ground field is of characteristic $p$ and the acting group is a cyclic $p$ -group, we prove that the skew group algebra of the path algebra is Morita equivalent to the algebra associated to a Cartan matrix, defined in [C. Geiss, B. Leclerc, and J. Schröer, Quivers with relations for symmetrizable Cartan matrices I: Foundations, Invent. Math. 209 (2017), 61–158]. We apply the Morita equivalence to construct a categorification of the folding projection between the root lattices with respect to a graph automorphism. In the Dynkin cases, the restriction of the categorification to indecomposable modules corresponds to the folding of positive roots.

New Binary Quantum Codes from Group Rings and Skew Group Rings

New Binary Quantum Codes from Group Rings and Skew Group Rings

Female directors and firms’ financial performance: an empirical application of Kanter’s theory in the Indian context

Purpose Given the relevance of female directors in the governance of any firm, this paper aims to examine their effect on firms’ financial performance by investigating their general impact and segregating the same into different subgroups based on Kanter’s theory. Design/methodology/approach To achieve the purpose, this study selects a sample of the top 100 listed Indian firms for the period of 2014–2018 and gathers the data pertaining to the variables under consideration from the respective firms’ annual report and corporate database Capitaline Plus. For undertaking the investigation, the authors have segregated the sample into three groups, i.e. firms with boards having less than 10% of female directors are called skewed boards; firms with boards having female directors that range from 10% to 20% are called as tilted board; and firms with boards having sizable representation of female directors of above 20%. To examine the performance impact of overall female directors and their different subgroups, the authors have used a generalized estimating equation model. For the robustness test, the authors have used the fixed-effect model. Findings The authors find a significant positive impact of the overall percentage of female directors on the financial performance of firms. Additionally, the results indicate that boards with a titled group of female directors and boards with a sizable representation of female directors significantly positively impact firms’ performance. However, the authors fail to extricate any significant performance impact of boards with a skewed group of female directors. Practical implications First, the study reveals that despite prevailing nepotism in India, female directors, owing to their core characteristics, can create a favorable perception of firms in the market. Second, it also works as an eye-opener for regulators by revealing the minimum threshold for female directors that a board should have to exploit the benefits of a gender quota rather than mere compliance with the requirements of the Companies Act, 2013. Third, it implies that more gender-diverse boards can improve a firm’s financial performance only if female directors range between the thresholds of 10% to 20%. Finally, the finding is significant for changing the business culture in India, where institutions are traditionally less supportive of women than in other emerging countries. Originality/value Departing from existing studies, which provide evidence on the performance impact of the overall percentage of female directors, the study unveils the differential impact of female directors on firms’ financial performance depending on their level of representation on the board. To the best of the authors’ knowledge, this is the first study in the context of an emerging market to test Kanter’s theory.

On Connected Components of Skew Group Algebras

On Connected Components of Skew Group Algebras

Consuming 30g of Protein at Each of 3 Meals Daily Improves Diet Satisfaction and Promotes Eating Behaviors That Support Weight Loss in Women Consuming an Energy Restricted Diet

ObjectivesThe objective was to test the efficacy of two patterns of daily protein consumption to promote diet satisfaction and eating behaviors that support weight loss when consuming an energy restricted diet in women. MethodsA randomized parallel study consisted of 8 weeks of controlled energy restriction (20% reduction; all foods provided) followed by 8 weeks of self-choice eating during which participants were coached to maintain a similar dietary pattern and energy restriction when choosing, buying, and consuming their own foods. The diets differed only in the daily distribution of dietary protein consumption. For one group (EVEN; n = 18; age = 29 ± 8 years; BMI = 35 ± 3 kg/m2) dietary protein was evenly distributed among breakfast, lunch, and dinner (30 g at each meal). For the other group (SKEWED; n = 19; age = 35 ± 7 years; BMI = 36 ± 4 kg/m2) dietary protein distribution was skewed with 10g at breakfast, 15g at lunch, and 65g at dinner. At each study visit (weeks 0, 8, 16) subjects completed eating behavior questionnaires and the relative reinforcing value (RRV) of energy-dense snack foods was assessed 4 hours after lunch using a computer choice paradigm. Meals provided for each study visit were consistent with the subject’s assigned dietary protein distribution pattern. Diet adherence and satisfaction were reported weekly during the self-choice phase. ResultsCompared to the SKEWED group, RRV in the EVEN group was lower at all time points (p = .019). Both groups reported adhering to their assigned dietary protein distribution pattern on average 6 days each week. However, subjects in the EVEN group were more satisfied with their diet (p = .004), happier with their food choices (p = .008) and tended to be less distracted or bothered by hunger (p = .07) compared to the SKEWED group. During the self-choice phase, intrinsic motivation (p = .0006), body-food choice congruence (p < .0001), and attitude to self-regulation (p < .0001) increased in the EVEN group with no changes in the SKEWED group. ConclusionsIn conclusion, evenly distributing dietary protein throughout the day resulted in women being more satisfied with their dietary choices and improved eating behaviors that support better adherence to a weight loss diet. These preliminary results indicate that eating 30g of protein at each meal is advantageous to women when trying to lose weight. Funding SourcesUSDA ARS and the ND Beef Commission.

Grid nanoindentation on calcium sulfoaluminate (CSA)-Kaolinite pastes

Calcium sulfoaluminate cement (CSA) has garnered attention in the construction industry as a low carbon footprint binder. CSA-kaolinite is a potential building material of the future and holds promise as a sustainable cement-based concrete. While the macroscopic properties of CSA cement have been extensively investigated, the nanomechanical properties of CSA-kaolinite remain largely underexplored. This study investigates the nanomechanical properties (elastic modulus and hardness) of CSA-kaolinite samples by using a grid nanoindentation approach, which enables both spatial mapping and indentation depth studies. A frequency-histogram-derived probability density function (PDF) model was found to fit well to the experimental dataset and revealed that the dominant phase of the system is ettringite irrespective of incorporation of kaolinite. The elastic modulus of ettringite was determined to be 20.8 and 17.5 GPa for samples without and with kaolinite, respectively, which is consistent with results from previous studies. Furthermore, a microstructural investigation confirmed ettringite as the major hydration phase of the system. Descriptive statistics, t-tests, and Kruskal–Wallis analysis of variance (ANOVA) were performed to determine if the measurements belong to a different group of populations. Non-parametric tests were found to be more accurate for these highly heterogeneous and skewed groups of cement-based materials. The mechanical properties from the samples of CSA with kaolinite and from those without kaolinite were found to be significantly statistically different which demonstrates that the nanoindentation test results are from two different sets of samples. The addition of kaolinite, as much as 10 wt%, in the CSA system has a trivial effect on the microscale mechanical properties which broadens the perspective of utilizing the kaolinite as a building constituent prolonging the advantages of infusing sustainability in the construction industry.

On Locally Finite Skew Group Algebras

In this note, we study the problem on the existence of non-cyclic free subgroups of the skew group algebra of a locally finite group over a field.

Consuming 30 Grams of High-Quality Protein at Breakfast, Lunch, and Dinner Does Not Protect Against Loss of Fat-Free Mass During Weight Loss in Women

Abstract Objectives Consuming 30 g of high-quality protein at each meal stimulates skeletal muscle protein synthesis more effectively than the typical intake pattern of consuming the majority of protein at dinner. We tested whether this dietary protein intake pattern protects against loss of skeletal muscle mass during weight loss. Methods Healthy overweight/obese women (age 31.1 ± 7.7 yrs.; BMI 35.6 ± 4.0 kg/m2) were provided with all foods for daily consumption at a level of 20% reduction of energy needs for 8 weeks. The diet provided 90 g of animal source protein daily with at least 30% of weekly protein requirements coming from beef. One group (EVEN; n = 18) received their animal source protein evenly distributed among breakfast, lunch, and dinner (30 g at each meal). The other group (SKEWED; n = 19) received their protein in a skewed distribution pattern with 10 g at breakfast (B), 15 g at lunch (L), and 65 g at dinner (D). Indirect calorimetry and Stanford Brief Activity Survey was used to assess energy intake. Diet History Questionnaire II was used to determine baseline protein intake. Body composition was determined via dual-energy X-ray absorptiometry pre- and post-intervention. Results Protein intake during the intervention was 23.0% ± 1.8% of calories, representing an increase of 7.1% ± 3.0% of calories compared to habitual diet. Weight loss was only marginally different between the groups (P = 0.076), with the EVEN group losing slightly more (5.3 ± 2.2 kg) body weight than the SKEWED group (4.2 ± 1.8 kg). Loss of fat mass did not differ (P = 0.650) between the EVEN (3.8 ± 1.9 kg) and SKEWED (3.7 ± 1.8 kg) groups. However, loss of fat-free mass was greater (P = 0.036) in the EVEN group (1.3 ± 0.8 kg) compared to the SKEWED group (0.8 ± 0.7 kg). Conclusions Contrary to our hypothesis, consuming 30 g of protein at breakfast, lunch, and dinner did not provide better protection against loss of fat-free mass during weight loss than consuming the majority of daily protein intake at a single meal. These preliminary results suggest that a meal protein intake of greater than 30 g is needed to spare metabolically active fat-free mass during energy restriction. Further research is needed to gain a better understanding of women's protein needs during weight loss. Funding Sources The United States Department of Agriculture and the North Dakota Beef Commission.

Queen succession conflict in the paper wasp Polistes dominula is mitigated by age-based convention

AbstractReproduction in cooperative animal groups is often dominated by one or a few individuals, with the remaining group members relegated to nonreproductive helping roles. This reproductive skew can evolve if helpers receive fitness benefits such as potential future inheritance of the breeding position, but the mechanisms by which inheritance is determined are not well resolved. Polistes paper wasps form highly reproductively skewed groups and inheritance of the breeding position is likely to play a key role in the maintenance of this social structure, making them excellent models for the processes by which simple societies are maintained. Reproductive succession is thought to be determined via an age-based convention in some Polistes species, but there is also evidence for contest-based succession systems in which the replacement queen uses physical aggression to overpower and thereby subordinate her nestmates. Here, we provide evidence that queen succession in colonies of the European paper wasp Polistes dominula is determined via convention rather than contest, with little disruption to the colony’s social functioning. We use queen removal experiments and fine-scale behavioral analyses to confirm that age is a strong predictor of succession, and that behavioral responses to queen removal are restricted to the oldest individuals rather than being experienced equally across the group. We provide the most comprehensive and detailed experimental analysis on the dynamics of breeder succession in a cooperatively breeding invertebrate to date, thereby shedding light on the mechanisms by which animal societies are able to maintain cohesion in the face of within-group conflict.

Homological Dimensions of Skew Group Rings

Let R be a ring and let H be a subgroup of a finite group G. We consider the weak global dimension, cotorsion dimension and weak Gorenstein global dimension of the skew group ring RσG and its coefficient ring R. Under the assumption that RσG is a separable extension over RσH, it is shown that RσG and RσH share the same homological dimensions. Several known results are then obtained as corollaries. Moreover, we investigate the relationships between the homological dimensions of RσG and the homological dimensions of a commutative ring R, using the trivial RσG-module.

TiK‐means: Transformation‐infusedK‐means clustering for skewed groups

AbstractTheK‐means algorithm is extended to allow for partitioning of skewed groups. Our algorithm is called TiK‐means and contributes aK‐means‐type algorithm that assigns observations to groups while estimating their skewness‐transformation parameters. The resulting groups and transformation reveal general‐structured clusters that can be explained by inverting the estimated transformation. Further, a modification of the jump statistic chooses the number of groups. Our algorithm is evaluated on simulated and real‐life data sets and then applied to a long‐standing astronomical dispute regarding the distinct kinds of gamma ray bursts.

Skew group algebras of Jacobian algebras

For a quiver with potential (Q,W) with an action of a finite cyclic group G, we study the skew group algebra ΛG of the Jacobian algebra Λ=P(Q,W). By a result of Reiten and Riedtmann, the quiver QG of a basic algebra η(ΛG)η Morita equivalent to ΛG is known. Under some assumptions on the action of G, we explicitly construct a potential WG on QG such that η(ΛG)η≅P(QG,WG). The original quiver with potential can then be recovered by the skew group algebra construction with a natural action of the dual group of G. If Λ is self-injective, then ΛG is as well, and we investigate this case. Motivated by Herschend and Iyama's characterisation of 2-representation finite algebras, we study how cuts on (Q,W) behave with respect to our construction.

Partitioning Ideals of a Semiring R and its Skew Group Semiring R * G

Partitioning Ideals of a Semiring R and its Skew Group Semiring R * G

Skewed Groups, Implicit Sex Bias, and Trainee Evaluations

Skewed Groups, Implicit Sex Bias, and Trainee Evaluations

Critical Mass in the Boardroom of Croatian Banks

AbstractThis paper investigates the influence of gender diversity in the boardroom of Croatian banks on their performance. Specifically, we deal with both management and supervisory boards. Moreover, based on critical mass theory, the authors try to find out what constitutes critical mass. Using a static panel analysis on a sample of all commercial banks that operated in the period 2002-2014, three models were estimated with return on assets (ROA), return on equity (ROE) and net interest margin (NIM) as dependent variables. Board structure variables include gender of the chairperson, size of the board, share of women on the board and four dummy variables constructed on critical mass theory, specifically uniform group, skewed group, tilted group and balanced group. Other controls employed in the model include capital adequacy, the growth rate of assets at the bank level, ownership, age and a crisis dummy. The main finding is that when a critical mass of 20%-40% of women on the management board has been reached, bank performance improves.

Outer Partial Actions and Partial Skew Group Rings

AbstractWe extend the classical notion of an outer action α of a group G on a unital ring A to the case when α is a partial action on ideals, all of which have local units. We show that if α is an outer partial action of an abelian group G, then its associated partial skew group ring A *α G is simple if and only if A is G-simple. This result is applied to partial skew group rings associated with two different types of partial dynamical systems.

High-resolution chromosomal microarray analysis of early-stage human embryonic stem cells reveals an association between X chromosome instability and skewed X inactivation.

X chromosome inactivation (XCI) is a dosage compensation mechanism that silences the majority of genes on one X chromosome in each female cell via a random process. Skewed XCI is relevant to many diseases, but the mechanism leading to it remains unclear. Human embryonic stem cells (hESCs) derived from the inner cell mass (ICM) of blastocyst-stage embryos have provided an excellent model system for understanding XCI initiation and maintenance. Here, we derived hESC lines with random or skewed XCI patterns from poor-quality embryos and investigated the genome-wide copy number variation (CNV) and loss of heterozygosity (LOH) patterns at the early passages of these two groups of hESC lines. It was found that the average size of CNVs on the X chromosomes in the skewed group is twice as much as that in the random group. Moreover, the LOH regions of the skewed group covered the gene locus of either XIST or XACT, which are master long non-coding RNA (lncRNA) effectors of XCI in human pluripotent stem cells. In conclusion, our work has established an experimentally tractable hESC model for study of skewed XCI and revealed an association between X chromosome instability and skewed XCI.Electronic supplementary materialThe online version of this article (doi:10.1186/2045-3701-4-74) contains supplementary material, which is available to authorized users.

Simplicity of Partial Skew Group Rings of Abelian Groups

AbstractLet A be a ring with local units, E a set of local units for A, G an abelian group, and α a partial action of G by ideals of A that contain local units. We show that A*αG is simple if and only if A is G-simple and the center of the corner eδ0(A*αGe)eδ0 is a field for all e ∊ E. We apply the result to characterize simplicity of partial skew group rings in two cases, namely for partial skew group rings arising from partial actions by clopen subsets of a compact set and partial actions on the set level.

PBW Deformations of Skew Group Algebras in Positive Characteristic

We investigate deformations of a skew group algebra that arise from a finite group acting on a polynomial ring. When the characteristic of the underlying field divides the order of the group, a new type of deformation emerges that does not occur in characteristic zero. This analogue of Lusztig’s graded affine Hecke algebra for positive characteristic can not be forged from the template of symplectic reflection and related algebras as originally crafted by Drinfeld. By contrast, we show that in characteristic zero, for arbitrary finite groups, a Lusztig-type deformation is always isomorphic to a Drinfeld-type deformation. We fit all these deformations into a general theory, connecting Poincare-Birkhoff-Witt deformations and Hochschild cohomology when working over fields of arbitrary characteristic. We make this connection by way of a double complex adapted from Guccione, Guccione, and Valqui, formed from the Koszul resolution of a polynomial ring and the bar resolution of a group algebra.