974 research outputs found
Integer colorings with forbidden rainbow sums
For a set of positive integers , an -coloring of is
rainbow sum-free if it contains no rainbow Schur triple. In this paper we
initiate the study of the rainbow Erd\H{o}s-Rothchild problem in the context of
sum-free sets, which asks for the subsets of with the maximum number of
rainbow sum-free -colorings. We show that for , the interval is
optimal, while for , the set is optimal. We
also prove a stability theorem for . The proofs rely on the hypergraph
container method, and some ad-hoc stability analysis.Comment: 20 page
Transversals via regularity
Given graphs all on the same vertex set and a graph with
, a copy of is transversal or rainbow if it contains at most
one edge from each . When , such a copy contains exactly one edge
from each . We study the case when is spanning and explore how the
regularity blow-up method, that has been so successful in the uncoloured
setting, can be used to find transversals. We provide the analogues of the
tools required to apply this method in the transversal setting. Our main result
is a blow-up lemma for transversals that applies to separable bounded degree
graphs .
Our proofs use weak regularity in the -uniform hypergraph whose edges are
those where is an edge in the graph . We apply our lemma to
give a large class of spanning -uniform linear hypergraphs such that any
sufficiently large uniformly dense -vertex -uniform hypergraph with
minimum vertex degree contains as a subhypergraph. This
extends work of Lenz, Mubayi and Mycroft
Pay It Forward: Unraveling the Role of Cause-related Marketing in the Curvilinear Relationship between Price-oriented Function Usage and Consumer Satisfaction
Price-oriented functions have been prevalently used by sellers for attracting consumers on e-marketplace platforms. However, existing literature has mixed understandings about its influence on improving consumer satisfaction. Besides, few studies have considered how cause-related marketing moderates the impact of price-oriented function usage. Therefore, this paper firstly explores the curvilinear relationship between price-oriented function usage and consumer satisfaction by adopting the repertoire perspective, then further considers the moderating role of cause-related marketing. This study collected data on 29,506 products from one e-marketplace platform in China. By using fixed-effects regression models, it is found that price-oriented function usage (i.e., volume and heterogeneity) have inverted U-shaped relationships with consumer satisfaction. In addition, cause-related marketing weakens the impact of price-oriented function usage heterogeneity on consumer satisfaction. This study contributes to research about platform function usage and guides sellers in terms of using those functions to stimulate consumer satisfaction
Towards Generalizable Deepfake Detection by Primary Region Regularization
The existing deepfake detection methods have reached a bottleneck in
generalizing to unseen forgeries and manipulation approaches. Based on the
observation that the deepfake detectors exhibit a preference for overfitting
the specific primary regions in input, this paper enhances the generalization
capability from a novel regularization perspective. This can be simply achieved
by augmenting the images through primary region removal, thereby preventing the
detector from over-relying on data bias. Our method consists of two stages,
namely the static localization for primary region maps, as well as the dynamic
exploitation of primary region masks. The proposed method can be seamlessly
integrated into different backbones without affecting their inference
efficiency. We conduct extensive experiments over three widely used deepfake
datasets - DFDC, DF-1.0, and Celeb-DF with five backbones. Our method
demonstrates an average performance improvement of 6% across different
backbones and performs competitively with several state-of-the-art baselines.Comment: 12 pages. Code and Dataset: https://github.com/xaCheng1996/PRL
Rainbow Hamilton cycle in hypergraph systems
R\"{o}dl, Ruci\'{n}ski and Szemer\'{e}di proved that every -vertex
-graph , and is sufficiently large, with
contains a tight Hamilton cycle, which can
be seen as a generalization of Dirac's theorem in hypergraphs. In this paper,
we extend this result to the rainbow setting as follows. A -graph system
is a family of not necessarily distinct
-graphs on the same -vertex set , a -graph on is rainbow if
and for
. Then we show that given , sufficiently large
and an -vertex -graph system , if
for , then there exists a rainbow
tight Hamilton cycle.Comment: 20 pages,5 figure
Influence of the Anteromedial Portal and Transtibial Drilling Technique on Femoral Tunnel Lengths in ACL Reconstruction: Results Using an MRI-Based Model
BACKGROUND
In anatomic anterior cruciate ligament (ACL) reconstruction, graft placement through the anteromedial (AM) portal technique requires more horizontal drilling of the femoral tunnel as compared with the transtibial (TT) technique, which may lead to a shorter femoral tunnel and affect graft-to-bone healing. The effect of coronal and sagittal femoral tunnel obliquity angle on femoral tunnel length has not been investigated.
PURPOSE
To compare the length of the femoral tunnels created with the TT technique versus the AM portal technique at different coronal and sagittal obliquity angles using the native femoral ACL center as the starting point of the femoral tunnel. The authors also assessed sex-based differences in tunnel lengths.
STUDY DESIGN
Descriptive laboratory study.
METHODS
Magnetic resonance imaging scans of 95 knees with an ACL rupture (55 men, 40 women; mean age, 26 years [range, 16-45 years]) were used to create 3-dimensional models of the femur. The femoral tunnel was simulated on each model using the TT and AM portal techniques; for the latter, several coronal and sagittal obliquity angles were simulated (coronal, 30°, 45°, and 60°; sagittal, 45° and 60°), representing the 10:00, 10:30, and 11:00 clockface positions for the right knee. The length of the femoral tunnel was compared between the techniques and between male and female patients.
RESULTS
The mean ± SD femoral tunnel length with the TT technique was 40.0 ± 6.8 mm. A significantly shorter tunnel was created with the AM portal technique at 30° coronal/45° sagittal (35.5 ± 3.8 mm), whereas a longer tunnel was created at 60° coronal/60° sagittal (53.3 ± 5.3 mm; P < .05 for both). The femoral tunnel created with the AM portal technique at 45° coronal/45° sagittal (40.7 ± 4.8 mm) created a similar tunnel length as the TT technique. For all techniques, the femoral tunnel was significantly shorter in female patients than male patients.
CONCLUSION
The coronal and sagittal obliquity angles of the femoral tunnel in ACL reconstruction can significantly affect its length. The femoral tunnel created with the AM portal technique at 45° coronal/45° sagittal was similar to that created with the TT technique.
CLINICAL RELEVANCE
Surgeons should be aware of the femoral tunnel shortening with lower coronal obliquity angles, especially in female patients
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