37495 research outputs found
Sort by
Does Green Stem Photosynthesis Affect Plant Drought Tolerance and Recovery in Avocado?
No full textWoody plants with green stems may have advantages over non-green-stemmed plants in that extra photosynthetic carbon gain has the potential to improve plant drought tolerance and aid drought recovery. However, most studies relating to green stem photosynthesis and drought tolerance have been conducted on non-horticultural plants under natural growing conditions. We investigated whether avocado green stem photosynthesis enhances drought tolerance and recovery. We applied light exclusion and drought treatments to 3-year-old potted trees of cultivars ‘Hass’ and ‘Fuerte’. Measurements of soil moisture, midday stem water potential, stem photosynthesis, bark chlorophyll concentration, concentration of sugars + starch and stem hydraulic conductivity were conducted before, during, and 3 weeks after rewatering. Green stems of avocado re-assimilate CO2, but values did not significantly differ between cultivars. We also found that light exclusion reduced stem photosynthesis by 65% in ‘Fuerte’ and 30% in ‘Hass’ although bark chlorophyll concentration was unchanged. Drought reduced stem photosynthesis by 60%. Following drought recovery, there were neither treatment nor cultivar effects on stem photosynthesis. We also observed no effect of light treatment on hydraulic conductivity, such that there is no clear effect of stem photosynthesis on drought tolerance of these avocado trees. However, we observed an increase in hydraulic conductivity during the drought period with an increase in the concentration of sugars in the sapwood and a decrease in the concentration of starch, suggesting osmotic adjustment. Nonetheless, the contribution of carbon gain through stem photosynthesis may not play a significant role in hydraulic functioning of avocado under these conditions
Air Pollution and Diseases: Signaling, G Protein-Coupled and Toll Like Receptors
No full textAir pollution is a significant public health issue that impacts lung health, particularly in vulnerable populations such as children, the elderly, and individuals with pre-existing respiratory conditions. Both natural and anthropogenic sources of air pollution give rise to a variety of toxic compounds, including particulate matter (PM), ozone (O₃), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO), and polycyclic aromatic hydrocarbons (PAHs). Exposure to these pollutants is strongly associated with the development and exacerbation of respiratory diseases, including asthma, chronic obstructive pulmonary disease (COPD), lung cancer, and idiopathic pulmonary fibrosis (IPF). Notably, early life exposure to pollutants such as PM, NO₂, and O₃ is linked to an increased risk of childhood asthma. Air pollution can mediate adverse effects through effects on receptor signaling pathways, particularly those involving G-protein coupled receptors (GPCRs) and Toll-like receptors (TLRs). Both of these receptor families play key roles in regulating pulmonary function and immune responses. GPCRs are involved in mediating cellular responses via cyclic AMP (cAMP), calcium and other second messengers, while TLRs initiate immune responses. Understanding how air pollutants and cigarette smoke alter GPCR and TLR function to contribute to lung disease is a critical area of study, as these receptors play central roles in regulating inflammation, immune responses, oxidative stress, airway remodeling and airway tone. Disruption of their signaling by pollutants can exacerbate respiratory conditions such as asthma and COPD. This review explores what is known about how air pollution impacts GPCR and TLR signaling, offers insights into the mechanisms underlying respiratory disease development and highlights potential therapeutic strategies aimed at mitigating the impact of air pollution on lung health
Warming Induces Unexpectedly High Soil Respiration in a Wet Tropical Forest
No full textTropical forests are a dominant regulator of the global carbon cycle, exchanging more carbon dioxide with the atmosphere than any other terrestrial biome. Climate models predict unprecedented climatic warming in tropical regions in the coming decades; however, in situ field warming studies are severely lacking in tropical forests. Here we present results from an in situ warming experiment in Puerto Rico, where soil respiration responses to +4 oC warming were assessed half-hourly for a year. Soil respiration rates were 42-204% higher in warmed relative to ambient plots, representing some of the highest soil respiration rates reported for any terrestrial ecosystem. While respiration rates were significantly higher in the warmed plots, the temperature sensitivity (Q10) was 71.7% lower, pointing to a mechanistic shift. Even with reduced Q10, if observed soil respiration rates persist in a warmer world, the feedback to future climate could be considerably greater than previously predicted or observed
Tokenization and Interconnectedness: A Numerical Exploration
No full textTokenization of assets has multiple implications for the operation of financial markets, among which are mitigating trade frictions and improving the interconnectedness of financial firms. This feature—if not properly managed—can propagate shocks more widely as compared to a traditional system. We study this double-edged aspect of tokenization using a matching model that makes explicit how firms are exposed to counterparty risk. We propose a way to manage this increased risk, through Financial Transactions Limiters, which exploit the technical advantages of tokenization in monitoring financial transactions of individual firms. We numerically analyze the possible social welfare consequences of tokenization, in both the short and long run, based on the economy’s fundamentals
Effective Control of Tomato Leaf Miner, \u3cem\u3eTuta absoluta\u3c/em\u3e (Meyrick) (Lepidoptera: Gelechiidae) Using the Entomopathogenic Fungus, \u3cem\u3eBeauveria pseudobassiana\u3c/em\u3e Rehner & Humber in Commercial High-Arched Plastic Tunnels
No full textBackground
The tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is a highly invasive pest that causes significant damages to tomato crops globally. Its resistance to commonly used chemical insecticides has made management increasingly difficult, prompting the need for sustainable, effective alternatives. This study investigated the efficacy of a Lebanese isolate of Beauveria pseudobassiana as a biological control agent against T. absoluta, compared its performance to Bacillus thuringiensis and conventional pesticide mixtures under both controlled, commercial production conditions Results
Three preliminary cage experiments were conducted under controlled infestation conditions using larvae reared from field-collected adults. Conidial suspensions of B. pseudobassiana were applied following standard protocols. The fungal treatment achieved a 90.7% mortality rate at 20 °C, closely matching B. thuringiensis (85.4%), and reached 100% mortality at 14 °C. Subsequently, two field trials were carried out in commercial high-arched plastic tunnels under natural infestation. In these trials, B. pseudobassiana and B. thuringiensis significantly reduced leaf mine incidence, with control levels comparable to or exceeding those achieved by calendar-based chemical sprays. In fall production, B. pseudobassiana reduced leaf mines to 1.9 mines/leaf by week 11, outperforming chemical pesticides (3.6 mines/leaf) and performing similarly to B. thuringiensis (2.6 mines/leaf). In summer production, B. pseudobassiana maintained strong efficacy, resulting in 2.3 and 2.1 mines/leaf at weeks 3 and 4, respectively, compared to 3.1 and 5.8 mines/leaf for B. thuringiensis. Conclusion
This is the first study to demonstrate the high efficacy of B. pseudobassiana in commercial tomato production, offering broader control than B. thuringiensis. These findings conclude that B. pseudobassiana is a viable alternative or complementary agent to B. thuringiensis in integrated pest management programs, supporting more sustainable tomato production, reduced insecticide use, and improved worker safety
Phi Beta Kappa, Psi of California Chapter, Induction Ceremony 2025
No full texthttps://digitalcommons.chapman.edu/pbk_induction_ceremony_2025/1026/thumbnail.jp
Phi Beta Kappa, Psi of California Chapter, Induction Ceremony 2025
No full texthttps://digitalcommons.chapman.edu/pbk_induction_ceremony_2025/1037/thumbnail.jp
Phi Beta Kappa, Psi of California Chapter, Induction Ceremony 2025
No full texthttps://digitalcommons.chapman.edu/pbk_induction_ceremony_2025/1040/thumbnail.jp
Moderators of Peer Influence Effects for Adolescents’ Smoking and Vaping Norms and Outcomes in High and Middle-Income Settings
No full textBackground: Peer influence is central to adolescent smoking initiation, yet its impact varies depending on individual and contextual factors. Understanding which moderators (personality, contextual, cultural, and environmental traits) shape these processes can inform more effective prevention strategies. We investigated hypothesized moderators of peer influence for adolescent smoking/vaping norms and other smoking-related outcomes in high and low-middle-income countries (LMICs): Northern Ireland and Bogotá.
Methods: Across 12 schools (n = 1,344, age 12–13 years), participants completed novel behavioral economics experiments measuring social norms, and self-report surveys, before and after school-based prevention interventions (ASSIST and Dead Cool). We examined how peer influence effects were moderated by setting, intervention type, gender, school socio-economic status (SES), personality traits, social network positions, and self-efficacy. Moderation was examined using regressions with interactions between peer-group means (friends, school classes, school year groups) of the outcome variables and moderators (p ≤ 0.01).
Results: Peer influence was moderated by study setting, intervention, gender, school SES, personality characteristics (pro-sociality, fear of negative evaluation, extraversion), and social network structure. Effects were stronger among girls and in schools with lower SES. ASSIST schools showed greater peer influence effects than Dead Cool, reflecting the programs’ distinct mechanisms, as ASSIST operates primarily through network diffusion and Dead Cool through teacher-led instruction and skills-building. Network measures highlighted that peer influence was stronger amongst more central individuals and more homogenous networks.
Conclusion: Susceptibility to peer influence depends on contextual, individual, and network factors. Future social norms interventions should provide information on both injunctive and descriptive norms and highlight the social consequences of smoking, particularly in LMICs. Gender-tailored approaches are needed to address heightened susceptibility among girls. Future intervention research should combine peer-led diffusion approaches with teacher-led instruction to maximize reach and sustainability in different contexts. Social influence-based interventions may be particularly beneficial for schools with lower SES or in LMICs without tobacco control legislation, where smoking remains largely normalized. Network-based interventions like ASSIST could benefit from careful consideration of which network metrics are used to select peer leaders (e.g., eigenvector or closeness centralities) and exploring alternative approaches for more heterogeneous networks (e.g., ‘segmentation’, which targets clusters of individuals within social networks)
Systematic Reexamination of Early Verb Dominance: Verbal and Nonverbal Characteristics of Caregiver Input and Their Contribution to Long-Term Language Outcomes
No full textEarly language input to infants varies in lexical composition across languages and contexts. For instance, American-English input emphasizes nouns more than verbs, while Mandarin Chinese and Korean inputs provide more verbs than nouns, the difference of which is considered an influential factor in the child’s early vocabulary acquisition. Furthermore, a possibility was raised that nonverbal input accompanying child-directed language provides additional support for verb meanings in verb-dominant caregiver input. However, these early verb dominance and support patterns have been derived from a handful of studies that examined very small samples. Thus, we aimed to systematically reexamine the verb dominance pattern in Korean caregiver input, considering both verbal and nonverbal aspects and their relative contributions to long-term vocabulary outcomes using a larger longitudinal sample. From 70 caregiver inputs to their 14- to 20-month-olds (41,349 utterances; 2,186 min, 30 s total), we found that the Korean language supports verb learning through lexical distribution and nonverbal extralinguistic input quality. Both the noun representation ratio and verb proportion positively predicted 54-month vocabulary outcomes, indicating that overall frequency is crucial for long-term vocabulary growth. Differences in caregiver nonverbal input quality between nouns and verbs explained 36-month vocabulary outcomes but did not predict long-term growth. These findings suggest that verbal and nonverbal inputs play different roles in long-term language development and that these might explain why Korean infants demonstrate better comprehension for verbs than nouns early on