Maximal lengths of exceptional collections of line bundles

In this paper we construct infinitely many examples of toric Fano varieties with Picard number three, which do not admit full exceptional collections of line bundles. In particular, this disproves King's conjecture for toric Fano varieties. More generally, we prove that for any constant $c>\frac34$ there exist infinitely many toric Fano varieties $Y$ with Picard number three, such that the maximal length of exceptional collection of line bundles on $Y$ is strictly less than c\rk K_0(Y). To obtain varieties without exceptional collections of line bundles, it suffices to put $c=1.$ On the other hand, we prove that for any toric nef-Fano DM stack $Y$ with Picard number three, there exists a strong exceptional collection of line bundles on $Y$ of length at least \frac34 \rk K_0(Y). The constant $\frac34$ is thus maximal with this property.Comment: 27 pages, no figures; misprints and typos corrected, an arithmetic mistake in the proof of Theorem 6.2 corrected, consequently Theorem 6.3 slightly modified, new Lemma 4.4 added, description of the constructed varieties extended, references adde

Facial emotion recognition in refugee children with a history of war trauma.

Over 36 million children are currently displaced due to war, yet we know little about how these experiences of war and displacement affect their socioemotional development-notably how they perceive facial expressions. Across three different experiments, we investigated the effects of war trauma exposure on facial emotion recognition in Syrian refugee (n = 130, Mage = 9.3 years, 63 female) and Jordanian nonrefugee children (n = 148, Mage = 9.4 years, 66 female) living in Jordan (data collected 2019-2020). Children in the two groups differed in trauma exposure, but not on any of our measures of mental health. In Experiment 1, we measured children's biases to perceive an emotion using morphed facial expressions and found no evidence that biases differed between refugees and nonrefugees. In Experiment 2, we adapted a novel perceptual scaling task that bypasses semantic knowledge, and again found no differences between the two group's discrimination of facial expressions. Finally, in Experiment 3, we recorded children's eye movements as they identified Middle Eastern actors' facial expressions, and again found no differences between the groups in either their identification accuracies or scanning strategies. Taken together, our results suggest that exposure to war-related trauma and displacement during early development, when reported by the caregiver but not always recollected by the child, does not appear to alter emotion recognition of facial expressions. (PsycInfo Database Record (c) 2023 APA, all rights reserved)

Maternal Trauma and Psychopathology Symptoms Affect Refugee Children's Mental Health But Not Their Emotion Processing.

Refugee children's development may be affected by their parents' war-related trauma exposure and psychopathology symptoms across a range of cognitive and affective domains, but the processes involved in this transmission are poorly understood. Here, we investigated the impact of refugee mothers' trauma exposure and mental health on their children's mental health and attention biases to emotional expressions. In our sample of 324 Syrian refugee mother-child dyads living in Jordan (children's Mage=6.32, SD = 1.18; 50% female), mothers reported on their symptoms of anxiety and depression, and on their children's internalising, externalising, and attention problems. A subset of mothers reported their trauma exposure (n = 133) and PTSD symptoms (n = 124). We examined emotion processing in the dyads using a standard dot-probe task measuring their attention allocation to facial expressions of anger and sadness. Maternal trauma and PTSD symptoms were linked to child internalising and attention problems, while maternal anxiety and depression symptoms were associated with child internalising, externalising, and attention problems. Mothers and children were hypervigilant towards expressions of anger, but surprisingly, mother and child biases were not correlated with each other. The attentional biases to emotional faces were also not linked to psychopathology risk in the dyads. Our findings highlight the importance of refugee mothers' trauma exposure and psychopathology on their children's wellbeing. The results also suggest a dissociation between the mechanisms underlying mental health and those involved in attention to emotional faces, and that intergenerational transmission of mental health problems might involve mechanisms other than attentional processes relating to emotional expressions

Effectiveness of a community-led shared book reading intervention in Syrian refugee children: a randomised controlled trial.

Community-led, shared book reading programs may help improve refugee children's reading abilities and attitudes towards reading. We Love Reading (WLR)-a light-touch, community-led, shared book reading program-was evaluated in a pre-registered, wait-listed, randomised controlled trial (AEARCTR-0006523). 322 Syrian refugee mother-child dyads (children: 4-8-year-olds, 50.0% female) in Jordan were tested at two timepoints, 15 weeks apart. WLR did not significantly affect child literacy or child-reported child attitudes toward reading (ps > 0.05). Mothers did report improved child attitudes toward reading from WLR (p = 0.046, η2 = 0.013). The intervention did not lead to improvements in family relationships (ps > 0.05). WLR may have promise in improving attitudes toward reading in forcibly displaced children but did not affect literacy or child-reported attitudes toward reading; these results provide insight into what changes are needed for effective shared book reading interventions in this population

Predictors of Literacy and Attitudes Toward Reading Among Syrian Refugee Children in Jordan

Refugee children often face disruptions to their education before and during displacement. However, little is known about either levels or predictors of refugee children’s literacy or about their attitudes toward reading in low- or middle-income countries. To address this, we conducted in-home literacy assessments using the Holistic Assessment of Learning and Development Outcomes with 322 Syrian refugee mother–child dyads who lived in Jordan (child age range 4–8 years, M = 6.32 years, 50% female). Overall, the children had quite low levels of literacy, although they indicated a strong enthusiasm for reading. Child age, maternal education, and maternal ability to read all predicted child literacy, although maternal literacy predicted it only among children enrolled in school. Among those enrolled in school (64.9% of the total sample, 88.7% of those aged ≥ 6), students attending hybrid classes had better literacy than those attending either solely in-person or solely online, although the frequency of school attendance did not predict literacy. A less consistent pattern emerged for predicting children’s attitudes toward reading. Our results suggest an urgent need to improve literacy skills among refugee children in Jordan, as well as a need for validated measures of attitudes toward reading for use with Arabic-speaking youth. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13158-022-00334-x

Adenosine-mono-phosphate-activated protein kinase-independent effects of metformin in T cells

The anti-diabetic drug metformin regulates T-cell responses to immune activation and is proposed to function by regulating the energy-stress-sensing adenosine-monophosphate-activated protein kinase (AMPK). However, the molecular details of how metformin controls T cell immune responses have not been studied nor is there any direct evidence that metformin acts on T cells via AMPK. Here, we report that metformin regulates cell growth and proliferation of antigen-activated T cells by modulating the metabolic reprogramming that is required for effector T cell differentiation. Metformin thus inhibits the mammalian target of rapamycin complex I signalling pathway and prevents the expression of the transcription factors c-Myc and hypoxia-inducible factor 1 alpha. However, the inhibitory effects of metformin on T cells did not depend on the expression of AMPK in T cells. Accordingly, experiments with metformin inform about the importance of metabolic reprogramming for T cell immune responses but do not inform about the importance of AMPK