Most of the literature of computational geometry concerns geometric properties of sets of static points. M.J. Atallah introduced dynamic computational geometry, concerned with both momentary and long-term geometric properties of sets of moving point-objects. This area of research seems to have been dormant recently. The current paper examines new problems in dynamic computational geometry.
Jue Hua Lau, Anitha Jeyagurunathan, Saleha Shafie
et al.
AbstractBackgroundImpulsivity has been linked to risky behaviours amongst patients with schizophrenia or other psychotic disorders. However, there is a dearth of studies examining impulsivity amongst this population in Singapore. Moreover, to date, scales to measure impulsivity have not been validated in this population. The present study seeks to examine the underlying factor structure of the Barratt Impulsiveness Scale (BIS-11) and explore sociodemographic and clinical correlates of impulsivity within this group.MethodsConfirmatory factor analyses (CFA) were conducted to test factor structures of the BIS-11 proposed in extant literature. However, due to poor fit statistics, the sample (n = 397) was split into two groups, with Exploratory Factor Analyses (EFA) conducted in the first subgroup (n = 200). The final model of the EFA was then tested within the second subgroup (n = 197) with CFA. Multivariable linear regressions were conducted to examine sociodemographic and clinical correlates of each underlying factor.ResultsCFA indicated a three-factor structure amongst 16-items of the BIS-11 with acceptable fit: i) Non-planning impulsivity (5-items; α = 0.94), ii) Motor impulsiveness (6-items α = 0.84), and iii) Lack of self-control (5-items, α = 0.85). Lower education was associated with higher non-planning impulsivity. While age, ethnicity, marital status, and general psychiatric symptom severity were significant correlates of motor impulsiveness, problematic alcohol use and general psychiatric symptom severity were related to a greater lack of self-control.ConclusionFactor structures of the BIS-11 suggested by extant literature were not applicable, and we propose an alternative factor structure for BIS-11. Significant correlates of impulsivity are highlighted, and avenues for future research are suggested.
As countries transition from pandemic mitigation to endemic COVID-19, mass testing may blunt the impact on the healthcare system of the liminal wave. We used GeoDEMOS-R, an agent-based model of Singapore’s population with demographic distributions and vaccination status. A 250-day COVID-19 Delta variant model was run at varying maximal rapid antigen test sensitivities and frequencies. Without testing, the number of infections reached 1,021,000 (899,400–1,147,000) at 250 days. When conducting fortnightly and weekly mass routine rapid antigen testing 30 days into the outbreak at a maximal test sensitivity of 0.6, this was reduced by 12.8% (11.3–14.5%) and 25.2% (22.5–28.5%). An increase in maximal test sensitivity of 0.2 results a corresponding reduction of 17.5% (15.5–20.2%) and 34.4% (30.5–39.1%). Within the maximal test sensitivity range of 0.6–0.8, test frequency has a greater impact than maximal test sensitivity with an average reduction of 2.2% in infections for each day removed between tests in comparison to a 0.43% average reduction per 1% increase in test frequency. Our findings highlight that mass testing using rapid diagnostic tests can be used as an effective intervention for countries transitioning from pandemic mitigation to endemic COVID-19.
We analyze surface patches with a corner that is rounded in the sense that the partial derivatives at that point are antiparallel. Sufficient conditions for $G^1$ smoothness are given, which, up to a certain degenerate case, are also necessary. Further, we investigate curvature integrability and present examples
We consider minimal-perimeter lattice animals, providing a set of conditions which are sufficient for a lattice to have the property that inflating all minimal-perimeter animals of a certain size yields (without repetitions) all minimal-perimeter animals of a new, larger size. We demonstrate this result on the two-dimensional square and hexagonal lattices. In addition, we characterize the sizes of minimal-perimeter animals on these lattices that are not created by inflating members of another set of minimal-perimeter animals.
PurposeThis paper aims to investigate how firms’ relationships with employees define their debt maturity. The authors empirically test the role of employee litigations in influencing firms’ choice of short-term versus long-term debt. The authors study employee relations by analyzing the importance of the workplace environment on capital structure.Design/methodology/approachThe author’s test hypotheses using a sample of US publicly traded firms between 2000 and 2017, including 3,056 unique firms with 4,256 unique chief executive officer, adopting the fixed effect panel model.FindingsThe authors document that employee litigations have a significant negative effect on the use of short-term debt and a significant positive affect on long-term debt. Employee litigations, along with legal fees, outcomes and charging parties, matter the most in explaining debt maturity. In addition, frequently sued firms abandon the short-term debt market and use less shareholders’ equity to finance their operations while relying more on the longer debt market.Originality/valueTo the best of the authors’ knowledge, this is the first study to examine the role of employee mistreatment in debt maturity choice. The study extends the lawsuit and finance literature by examining unique, hand-collected data sets of employee lawsuits, allegations, violations, settlements, charging parties, case outcomes and case durations.
In this paper we study the following problem: Given $k$ disjoint sets of points, $P_1, \ldots, P_k$ on the plane, find a minimum cardinality set $\mathcal{T}$ of arbitrary rectangles such that each rectangle contains points of just one set $P_i$ but not the others. We prove the NP-hardness of this problem.
PurposeThis paper aims to use the passage of the Italian Gender Diversity Law to help isolate the effects of board gender diversity on firm value by investigating conditions under which such diversity provides greater role-enhancing resources to the board.Design/methodology/approachThis paper used a one-day event study to measure when gender diversity matters to investors. Abnormal returns from Italian firms were used to study investors’ anticipated outcomes of the effect of gender diversity on firm value.FindingsBoard gender diversity is financially beneficial especially for firms with a male dual CEO and board chair and with few or no women on board committees and firms that operate in industries with greater levels of competition. Addition of these moderators more than doubles the variance explained. Moreover, the effect of gender is isolated in this study, which examined investor reaction to the expectation of increases in the number of female board members, rather than to specific female appointees.Social implicationsDetermining the conditions when a gender diverse matters to firm value is important for shareholders, policymakers and advocates for gender equality. The findings illustrate precise conditions for stakeholders to make the case for board gender diversity as achieving financial reward, in addition to societal benefit.Originality/valueThe value of a gender diverse board is contingent on the company’s need for diverse resources (e.g. more competition, lack of gender diversity on committees or CEO duality). This paper provides insight as to why prior research linking board gender diversity to firm value finds seemingly contradictory results. Thus, this paper provides useful insights for researchers, boards and legislative bodies.
Let $V$ be a finite set of vertices in the plane and $S$ be a finite set of polygonal obstacles, where the vertices of $S$ are in $V$. We show how to construct a plane $2$-spanner of the visibility graph of $V$ with respect to $S$. As this graph can have unbounded degree, we modify it in three easy-to-follow steps, in order to bound the degree to $7$ at the cost of slightly increasing the spanning ratio to 6.
An abbreviated version of Henikoff/Janssens Cut&RUN protocol. We use in-house prepared pAG-MNase and standard conditions. If library quality is poor, consider using one of the high-salt or low-salt conditions offered in the original protocol.
Clemens Huemer, Alexander Pilz, Rodrigo I. Silveira
We use the concept of production matrices to show that there exist sets of $n$ points in the plane that admit $Ω(42.11^n)$ crossing-free geometric graphs. This improves the previously best known bound of $Ω(41.18^n)$ by Aichholzer et al. (2007).
We consider circle packings in the plane with circles of sizes $1$, $r\simeq 0.834$ and $s\simeq 0.651$. These sizes are algebraic numbers which allow a compact packing, that is, a packing in which each hole is formed by three mutually tangent circles. Compact packings are believed to maximize the density when there are possible. We prove that it is indeed the case for these sizes. The proof should be generalizable to other sizes which allow compact packings and is a first step towards a general result.
Multi-block grids provide the computational efficiency of structured grids and the flexibility for complex geometry. Thus, Multi-block structured grids are widely used for field simulation on complex domains. In this paper we propose a method which adapts multi-block grids according to a monitor function, which specifies cell volume distribution. The method is an extension of the deformation method on a single block to multi-blocks. Key words: multi-block grids, deformation method, adaptive grids
Purpose This study aims to investigate the relationship between corporate governance risk and agency costs across different countries. Design/methodology/approach Corporate governance risk indicators were obtained from the Institutional Shareholder Services Europe (S.A.) for 4,135 firms across 27 countries. Agency costs and other control variables were derived from companies’ annual financial reports using the DataStream database. Ordinary least squares multiple regression analysis model was used to test the study hypothesis. Findings Agency costs have a significant negative impact on corporate governance risk across countries. The extent of corporate governance mechanisms used, however, varies across geographic regions and industry types. The relationship between corporate governance risk and agency costs is more obvious in the non-financial than financial sector. These results were robust after several statistical checks. Practical implications The findings will help stakeholders, including corporate management, regulators and investors to improve corporate governance mechanisms and capital allocation decisions across countries. Originality/value Evidence is provided on the role of agency costs in corporate governance risk across geographic regions for financial and non-financial companies. The paper also overcomes common problems in corporate governance research such as construct validity, limited data and endogeneity.
This study investigates the exact geometry of the configuration space in three-dimensional rotational motion planning. A parameterization of configuration space obstacles is derived for a given triangulated or ball-approximated scene with an object rotating around a given point. The results obtained are an important step towards a complete description of the rich structure of a configuration space in three-dimensional rotational motion planning.
We consider problems involving rich homotheties in a set S of n points in the plane (that is, homotheties that map many points of S to other points of S). By reducing these problems to incidence problems involving points and lines in R^3, we are able to obtain refined and new bounds for the number of rich homotheties, and for the number of distinct equivalence classes, under homotheties, of k-element subsets of S, for any k >= 3. We also discuss the extensions of these problems to three and higher dimensions.
Purpose This paper aims to explore the importance of meaningful participation for Indigenous peoples within the complex and highly political context of mining and mineral extraction. The aim is to consider the multi-dimensional nature of the mining context that takes into account the discursive landscape that frames the often disparate perspectives of corporate, state and Indigenous communities. Design/methodology/approach The paper is a conceptual offering that examines the complex environment within which “meaningful participation” between mining corporates and Indigenous communities operate. Findings This paper highlights the multi-dimensional nature of a proposed relationship between the mining corporates, the state and the Indigenous Māori community within New Zealand. The facilitation of “meaningful participation” requires that any negotiated agreement is undertaken within a framework of meaning that makes sense to the Indigenous community, in addition to the appropriate legislative and corporate initiatives to be in place. Originality/value The paper highlights the complex considerations that must be included in any form of negotiation between mining corporates and Indigenous peoples to achieve meaningful participation in the form that it was intended under international accords. While recognising the different contextual circumstance of Indigenous peoples around the world, this paper illustrates a pathway towards meaningful participation that takes into account economic, socio-cultural and environmental variables.
Renzo Mori Junior, Daniel M. Franks, Saleem H. Ali
Purpose New sustainability certification schemes (SCS) with different scope, governance structure and operating practice are fast emerging. This rapid growth and divergence in metrics has resulted in questions about the effectiveness of such schemes. Although this practice has been growing fast, to date, there are no reviews comprehensively synthesising the literature regarding SCS’ main flaws, challenges and improvement opportunities. This paper aims to identify what are the key components affecting effectiveness of SCS, highlighting their benefits, flaws and improvement opportunities. Design/methodology/approach An integrated literature review was conducted to identify and assess recent studies related to the benefits, flaws, effectiveness and improvement opportunities of SCS worldwide. Findings Key components affecting the effectiveness of SCS were identified (sustainability awareness; market access; management systems and productivity; social, environmental and economic impacts; monitoring outcomes; competition, overlapping and interoperability; stakeholder participation; and accountability and transparency). The authors argue that SCS to succeed have to be effective; provide accountability about their goals and achievements; and manage stakeholders’ expectations. Civil Society’s awareness of the scientific underpinnings of sustainability issues also contributes to the existence and improvement of such schemes. Research limitations/implications The limitations of this study are associated with the secondary material that was publicly available for our literature review. Originality/value This paper fulfils an identified need to explore the key components affecting effectiveness of SCS, their benefits, flaws and improvement opportunities. Such a synthesis also identifies the key areas where interoperability between SCS should be pursued by corporations and governments.