Livin' on the edge: precision yield data shows evidence of ecosystem services from field boundaries.

Field boundaries can provide ecosystem services to crops by creating better abiotic conditions for crop growth, and can also act as habitat for beneficial arthropods. This suggests that crop boundaries may create an intermediate hump-shaped increase in crop yield, where negative edge effects are cancelled out by increased ecosystem services from the field boundary. However, there is little large-scale evidence showing this, largely because plot-scale crop yields are costly and time-consuming to measure. Precision yield data from combine yield monitors has huge potential in this respect, as the equipment is widespread and data is frequently recorded by growers. In this study, we used 252 field-years of yield monitor data from three common crops - wheat (Triticum aestivum), canola (Brassica napus), or peas (Pisum sativum) - recorded across Alberta, Canada, and examined how yield varied with distances from common crop boundary types. Average crop yield tended to increase with distance from crop boundaries before plateauing at about 50 m, and yield variation (SD) tended to decrease with distance. There was evidence of an intermediate increase in yield for wheat away from shelterbelts, and a weak increase in canola, but this was not seen for other crop types or boundary types. This study represents one of the first uses of precision yield data to measure ecosystem service provision at large spatial scales.

Inequalities for Laplacian Eigenvalues of Signed Graphs with Given Frustration Number

Balanced signed graphs appear in the context of social groups with symmetric relations between individuals where a positive edge represents friendship and a negative edge represents enmities between the individuals. The frustration number f of a signed graph is the size of the minimal set F of vertices whose removal results in a balanced signed graph; hence, a connected signed graph G˙ is balanced if and only if f=0. In this paper, we consider the balance of G˙ via the relationships between the frustration number and eigenvalues of the symmetric Laplacian matrix associated with G˙. It is known that a signed graph is balanced if and only if its least Laplacian eigenvalue μn is zero. We consider the inequalities that involve certain Laplacian eigenvalues, the frustration number f and some related invariants such as the cut size of F and its average vertex degree. In particular, we consider the interplay between μn and f.

Order Distances and Split Systems

Given a pairwise distance D on the elements in a finite set X, the order distanceΔ(D) on X is defined by first associating a total preorder ≼x on X to each x ∈X based on D, and then quantifying the pairwise disagreement between these total preorders. The order distance can be useful in relational analyses because using Δ(D) instead of D may make such analyses less sensitive to small variations in D. Relatively little is known about properties of Δ(D) for general distances D. Indeed, nearly all previous work has focused on understanding the order distance of a treelike distance, that is, a distance that arises as the shortest path distances in a tree with non-negative edge weights and X mapped into its vertex set. In this paper we study the order distance Δ(D) for distances D that can be decomposed into sums of simpler distances called split-distances. Such distances D generalize treelike distances, and have applications in areas such as classification theory and phylogenetics.

Parameterized Approximation Algorithms for Bidirected Steiner Network Problems

The D irected S teiner N etwork (DSN) problem takes as input a directed graph G =( V , E ) with non-negative edge-weights and a set D ⊆ V × V of k demand pairs. The aim is to compute the cheapest network N⊆ G for which there is an s\rightarrow t path for each ( s , t )∈ D. It is known that this problem is notoriously hard, as there is no k 1/4− o (1) -approximation algorithm under Gap-ETH, even when parametrizing the runtime by k [Dinur & Manurangsi, ITCS 2018]. In light of this, we systematically study several special cases of DSN and determine their parameterized approximability for the parameter k . For the bi -DSNP lanar problem, the aim is to compute a solution N⊆ G whose cost is at most that of an optimum planar solution in a bidirected graph G , i.e., for every edge uv of G the reverse edge vu exists and has the same weight. This problem is a generalization of several well-studied special cases. Our main result is that this problem admits a parameterized approximation scheme (PAS) for k . We also prove that our result is tight in the sense that (a) the runtime of our PAS cannot be significantly improved, and (b) no PAS exists for any generalization of bi-DSNP lanar , under standard complexity assumptions. The techniques we use also imply a polynomial-sized approximate kernelization scheme (PSAKS). Additionally, we study several generalizations of bi -DSNP lanar and obtain upper and lower bounds on obtainable runtimes parameterized by k . One important special case of DSN is the S trongly C onnected S teiner S ubgraph (SCSS) problem, for which the solution network N⊆ G needs to strongly connect a given set of k terminals. It has been observed before that for SCSS a parameterized 2-approximation exists for parameter k [Chitnis et al., IPEC 2013]. We give a tight inapproximability result by showing that for k no parameterized (2 − ε)-approximation algorithm exists under Gap-ETH. Additionally, we show that when restricting the input of SCSS to bidirected graphs, the problem remains NP-hard but becomes FPT for k .

Network study of responses to unusualness and psychological stress during the COVID-19 outbreak in Korea

The dramatic changes in people’s daily lives caused by the 2019 coronavirus (COVID-19) pandemic have had a huge impact on their emotions and behaviors. This study aimed to examine psychosocial responses to COVID-19 using network analysis. A total of 1,500 urban residents of South Korea, selected from an online public panel, were surveyed using self-rating questionnaires addressing daily life changes, fear of infection, and distress related to COVID-19. Participants also completed a 10-item Perceived Stress Scale survey. We constructed regularized partial correlation networks, estimated global and local network metrics, tested network accuracy and stability, and compared the estimated networks between men and women. The network of the psychosocial responses consisted of 24 nodes that were classified into five groups: ‘fear of infection’, ‘difficulty with outside activities’, ‘economic loss’, ‘altered eating and sleeping’, and ‘adaptive stress’. The node centralities indicated that ‘distress in obtaining daily necessities’ and ‘concern about harming others’ were the most important issues in people’s responses to COVID-19. These nodes were connected by a negative edge, reflecting individual- and community-level issues, respectively. The overall level of perceived stress was linked to the network by the connection node ‘anger toward others or society’, which was associated with economic problems in men, but with distress from changes in daily activities in women. The results suggest that two contrasting feelings—personal insecurity regarding basic needs and a collectivistic orientation—play roles in the response to unusual experiences and distress due to COVID-19. This study also showed that public anger could arise from the psychological stress under the conditions imposed by COVID-19.

Characterization of 2-Path Signed Network

A signed network is a network where each edge receives a sign: positive or negative. In this paper, we report our investigation on 2-path signed network of a given signed network Σ , which is defined as the signed network whose vertex set is that of Σ and two vertices in Σ 2 are adjacent if there exist a path of length two between them in Σ . An edge ab in Σ 2 receives a negative sign if all the paths of length two between them are negative, otherwise it receives a positive sign. A signed network is said to be if clusterable its vertex set can be partitioned into pairwise disjoint subsets, called clusters, such that every negative edge joins vertices in different clusters and every positive edge joins vertices in the same clusters. A signed network is balanced if it is clusterable with exactly two clusters. A signed network is sign-regular if the number of positive (negative) edges incident to each vertex is the same for all the vertices. We characterize the 2-path signed graphs as balanced, clusterable, and sign-regular along with their respective algorithms. The 2-path network along with these characterizations is used to develop a theoretic model for the study and control of interference of frequency in wireless communication networks.

Laryngopharyngeal Reflux Alters Macrophages Polarization in HPV-Negative Squamous Cell Carcinoma of Larynx in Males

Objectives. Among various cells of tumor immune microenvironment (TIME) macrophages have been shown to play a pivotal role in the prognosis of many malignancies including laryngeal squamous cell carcinoma (LSCC). Laryngopharyngeal reflux (LPR) is associated with LSCC and can impact its prognosis. Local factors, particularly pH, can affect cancer growth by altering TIME and tumor associated macrophages phenotype. However, it is still unknown whether and how LPR affects TIME and macrophages polarization in LSCC. In this study we compared macrophage polarization in LSCC of patients with and without coexisting LPR.Methods. A total of 63 patients with T1-2 LSCC without (the 1st group, 30 patients) and with coexisting LPR (the 2nd group, 33 patients) were enrolled in the study. Only HPV-negative cases of males were included in the study. Immunohistochemistry was performed to visualize CD68 and CD163 macrophages. The number of macrophages was counted at the central tumor clusters (TC), peritumor stroma (TS) and at the intact laryngeal mucosa (IM) taken from the tumor-negative edge. Results. Samples of the 2nd group patients with LSCC and LPR demonstrated significantly (P<0.05) higher inflammatory infiltration of all the evaluated compartments (TC, TS and IM). CD68+ cells count was comparable in TC and IM of the 1st and the 2nd group patients. In contrast, CD163+ cells were more numerous in the 2nd group patients in TC, TS and IM (P<0.001). Moreover, the number of M2 macrophages was significantly higher than M1 macrophages in patients with coexisting LPR. As a result, CD163/CD68 ratio was significantly (P<0.001) higher in LSCC with coexisting LPR.Conclusions. LPR is associated with altered macrophages polarization and increase of M2-type macrophages in LSCC. The shift in macrophage polarization towards the M2 type in patients with LPR could facilitate LSCC development and progression.

Housing Profile Design for Improved Apex Seal Lubrication Using a Finite Length Roller Elastohydrodynamic Lubrication Model

Finite-length roller contacts are found in apex seal-housing interfaces in rotary engines, as well as in many other mechanical systems, such as those at the interfaces of meshing gear teeth, cam followers, and roller bearings. Rollers are usually designed with crowns and modified ends to mitigate the negative effects of misalignment, thermal deformation, and edge-induced non-uniform displacement. A crowned-roller elastohydrodynamic lubrication model is enriched and employed to investigate seven housing surface profiles, including a sinusoidal recess, sinusoidal ends, the combination design of a sinusoidal recess and sinusoidal ends, multiple sinusoidal recesses, a concave shape, and a concave shape with sinusoidal ends or round corners, aiming to improve the tribological performance of the interface via increasing the minimum film thickness but reducing the average and maximum film thicknesses, and lowering friction coefficient. The modified discrete convolution and fast Fourier transform method with duplicated padding is utilized to deal with the potential free-end-surface effect. The simulation results suggest that the combinations of a concave shape and sinusoidal ends, or round corners, are the best designs because they can help distribute the lubricant most uniformly without causing a negative edge effect.