3,221 research outputs found
1-motivic sheaves and the Albanese functor
We introduce n-generated sheaves and n-motivic sheaves, describing completely
for n = 0, 1 and proposing a conjecture for n > 1. We then obtain functors
L\pi_0 and LAlb on DM_{eff}(k) deriving \pi_0 and Alb. The functor LAlb extends
the one constructed (by the second author jointly with B.Kahn) to
non-necessarily geometric motives. These functors are then used to define
higher N\'eron-Severi groups and higher Albanese sheaves. The latter may be
considered as an algebraic avatar of Deligne (co)homology.Comment: 54 pages, fully revised exposition with a new "structure theorem" for
1-motivic sheaves, see Theorem 1.3.10, including finitely presented (or
constructible) 1-motivic sheave
Nori 1-motives
Let EHM be Nori's category of effective homological mixed motives. In this
paper, we consider the thick abelian subcategory EHM_1 generated by the i-th
relative homology of pairs of varieties for i = 0,1. We show that EHM_1 is
naturally equivalent to the abelian category M_1 of Deligne 1-motives with
torsion; this is our main theorem. Along the way, we obtain several interesting
results. Firstly, we realize M_1 as the universal abelian category obtained,
using Nori's formalism, from the Betti representation of an explicit diagram of
curves. Secondly, we obtain a conceptual proof of a theorem of Vologodsky on
realizations of 1-motives. Thirdly, we verify a conjecture of Deligne on
extensions of 1-motives in the category of mixed realizations for those
extensions that are effective in Nori's sense
A dilogarithmic integral arising in quantum field theory
Recently, an interesting dilogarithmic integral arising in quantum field
theory has been closed-form evaluated in terms of the Clausen function
by Coffey [J. Math. Phys.} 49 (2008), 093508]. It
represents the volume of an ideal tetrahedron in hyperbolic space and is
involved in two intriguing equivalent conjectures of Borwein and Broadhurst. It
is shown here, by simple and direct arguments, that this integral can be
expressed by the triplet of the Clausen function values which are involved in
one of the two above-mentioned conjectures.Comment: 6 page
Assessing the outcome of orthognathic surgery by three-dimensional soft tissue analysis
Studies of orthognathic surgery often focus on pre-surgical versus post-surgical changes in facial shape. In contrast, this study provides an innovative comparison between post-surgical and control shape. Forty orthognathic surgery patients were included, who underwent three different types of surgical correction: Le Fort I maxillary advancement, bilateral sagittal split mandibular advancement, and bimaxillary advancement surgery. Control facial images were captured from volunteers from local communities in Glasgow, with patterns of age, sex, and ethnic background that matched those of the surgical patients. Facial models were fitted and Procrustes registration and principal components analysis used to allow quantitative analysis, including the comparison of group mean shape and mean asymmetry. The primary characteristic of the difference in shape was found to be residual mandibular prognathism in the group of female patients who underwent Le Fort I maxillary advancement. Individual cases were assessed against this type of shape difference, using a quantitative scale to aid clinical audit. Analysis of the combined surgical groups provided strong evidence that surgery reduces asymmetry in some parts of the face such as the upper lip region. No evidence was found that mean asymmetry in post-surgical patients is greater than that in controls
The virtual human face â superimposing the simultaneously captured 3D photorealistic skin surface of the face on the untextured skin image of the CBCT Scan
The aim of this study was to evaluate the impact of simultaneous capture of the three-dimensional (3D) surface of the face and cone beam computed tomography (CBCT) scan of the skull on the accuracy of their registration and superimposition. 3D facial images were acquired in 14 patients using the Di3d (Dimensional Imaging, UK) imaging system and i-CAT CBCT scanner. One stereophotogrammetry image was captured at the same time as the CBCT and another one hour later. The two stereophotographs were then individually superimposed over the CBCT using VRmesh. Seven patches were isolated on the final merged surfaces. For the whole face and each individual patch; maximum and minimum range of deviation between surfaces, absolute average distance between surfaces, and standard deviation for the 90th percentile of the distance errors were calculated. The superimposition errors of the whole face for both captures revealed statistically significant differences (P=0.00081). The absolute average distances in both separate and simultaneous captures were 0.47mm and 0.27mm, respectively. The level of superimposition accuracy in patches from separate captures ranged between 0.3 and 0.9mm, while that of simultaneous captures was 0.4mm. Simultaneous capture of Di3d and CBCT images significantly improved the accuracy of superimposition of these image modalities
A randomized trial of brief intervention strategies in patients with alcohol-related facial trauma as a result of interpersonal violence
Facial trauma is associated with male gender, low socioeconomic status, alcohol misuse, and violence. Brief intervention (BI) for alcohol is effective at reducing consumption in patients presenting with facial trauma. Singlesession control of violence for angry impulsive drinkers(SS-COVAID) is a new intervention that attempts to address alcohol-related violence. This study assessed the effect of SS-COVAID and BI on drinking and aggression in facial trauma patients. Male facial trauma patients who sustained their injuries as a result of interpersonal violence while drinking and who had Alcohol Use Disorders Identification Test (AUDIT) scores of ≥8 were randomized to either BI or SS-COVAID. Patients were followed up at six and 12 months, and drinking and aggression outcomes were analyzed. One hundred ninety-nine patients entered the trial, and 187 were included in the analysis. Of these, 165 (89%) considered themselves to be victims, 92 (51%) had sustained a previous alcohol-related injury, and 28
(15%) had previous convictions for violence. Both interventions resulted in a significant decrease in negative drinking outcomes over 12 months of follow-up (p<0.001). Neither intervention had a significant effect on aggression scores, nor was there a significant difference between interventions in terms of either outcome. Both SS-COVAID and BI had a significant effect on drinking variables in this patient cohort. No effect on aggressionwas seen despite the fact that SS-COVAID specifically addresses the relationship between alcohol and violence. One reason for this may be that the facial trauma patients in this study considered themselves to be victims rather than aggressors. Another possibility is that, while BI may successfully address lifestyle factors such as hazardous or harmful drinking, it may not be effective in modifying personality traits such as aggression
Reshaping Food Systems to improve Nutrition and Health in the Eastern Mediterranean Region
This detailed and comprehensive study examines nutrition and health in the World Health Organization (WHO) Eastern Mediterranean Region, presenting the six game-changing food systems actions proposed by the WHO and the progress of their implementation in the region.
The WHO Eastern Mediterranean Region is a particularly complex place to study: an area of economic contrasts with changing dietary patterns and stark differences between high levels of malnutrition and a prevalence of overweight and obesity. As a result, actions to improve the nutritional situation of the population are urgently sought. The strategies explored in this book offer a unique opportunity to change food systems all over the world, addressing aspects including sustainable food production, the impact of marketing and labelling on behaviour, and the effect of global events such as climate change, war and the COVID-19 pandemic.
Reshaping Food Systems is an essential read at a time when malnutrition in all its forms, including undernourishment, micronutrient deficiencies and overweight and obesity, pose a serious threat to global health, and is of particular interest for policymakers working in nutrition and public health
Influence of salivary conditioning and sucrose concentration on biofilm-mediated enamel demineralization
The acquired pellicle formation is the first step in dental biofilm formation. It distinguishes dental biofilms from other biofilm types. Objective: To explore the influence of salivary pellicle formation before biofilm formation on enamel demineralization. Methodology: Saliva collection was approved by Indiana University IRB. Three donors provided waxâstimulated saliva as the microcosm bacterial inoculum source. Acquired pellicle was formed on bovine enamel samples. Two groups (0.5% and 1% sucroseâsupplemented growth media) with three subgroups (surface conditioning using filtered/pasteurized saliva; filtered saliva; and deionized water (DIW)) were included (n=9/subgroup). Biofilm was then allowed to grow for 48 h using Brain Heart Infusion media supplemented with 5 g/l yeast extract, 1 mM CaCl2.2H2O, 5% vitamin K and hemin (v/v), and sucrose. Enamel samples were analyzed for Vickers surface microhardness change (VHNchange), and transverse microradiography measuring lesion depth (L) and mineral loss (âZ). Data were analyzed using two-way ANOVA. Results: The two-way interaction of sucrose concentration Ă surface conditioning was not significant for VHNchange (p=0.872), âZ (p=0.662) or L (p=0.436). Surface conditioning affected VHNchange (p=0.0079), while sucrose concentration impacted âZ (p<0.0001) and L (p<0.0001). Surface conditioning with filtered/pasteurized saliva resulted in the lowest VHNchange values for both sucrose concentrations. The differences between filtered/pasteurized subgroups and the two other surface conditionings were significant (filtered saliva p=0.006; DIW p=0.0075). Growing the biofilm in 1% sucrose resulted in lesions with higher âZ and L values when compared with 0.5% sucrose. The differences in âZ and L between sucrose concentration subgroups was significant, regardless of surface conditioning (both p<0.0001). Conclusion: Within the study limitations, surface conditioning using human saliva does not influence biofilmâmediated enamel caries lesion formation as measured by transverse microradiography, while differences were observed using surface microhardness, indicating a complex interaction between pellicle proteins and biofilmâmediated demineralization of the enamel surface
Fair inference on error-prone outcomes
Fair inference in supervised learning is an important and active area of
research, yielding a range of useful methods to assess and account for fairness
criteria when predicting ground truth targets. As shown in recent work,
however, when target labels are error-prone, potential prediction unfairness
can arise from measurement error. In this paper, we show that, when an
error-prone proxy target is used, existing methods to assess and calibrate
fairness criteria do not extend to the true target variable of interest. To
remedy this problem, we suggest a framework resulting from the combination of
two existing literatures: fair ML methods, such as those found in the
counterfactual fairness literature on the one hand, and, on the other,
measurement models found in the statistical literature. We discuss these
approaches and their connection resulting in our framework. In a healthcare
decision problem, we find that using a latent variable model to account for
measurement error removes the unfairness detected previously.Comment: Online supplementary code is available at
https://dx.doi.org/10.5281/zenodo.370815
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