Co-founder selection is a pivotal decision in new venture formation, yet how lead founders evaluate potential partners remains underexplored. Drawing on insights from marriage market theory, we conceptualize co-founder selection as an act of individuated judgment guided by cooperative logic and associated joint utility projection, wherein lead founders assess co-founder candidates based on social-emotional, instrumental, and distributive considerations reflected in interpersonal attraction, resource contributions, and equity demand. We further propose that lead founders' dark triad shifts this judgmental process from joint utility logic to personal utility maximization. Using a conjoint experiment with 206 entrepreneurs making 3296 co-founder selection decisions, we find that interpersonal attraction and resource contributions positively influence willingness to select a co-founder candidate, whereas higher equity demand reduces candidate attractiveness. Critically, lead founders higher in the dark triad display distinct patterns: they discount interpersonal attraction and display heightened sensitivity to equity dilution—assessments that indicate their prioritization of personal over joint value creation. Taken together, these findings reveal how dispositional tendencies influence the judgments underlying co-founder selection, indicating a shift away from the cooperative logic assumed in marriage market theory and co-founder selection toward greater emphasis on personal utility considerations. We discuss theoretical implications of these findings and offer practical guidance for navigating the complexities of co-founder selection.
BACKGROUND:Tetrahydrobiopterin (BH4) deficiency is reported to uncouple the enzymatic activity of endothelial nitric oxide synthase in diabetes mellitus. The mechanism by which diabetes actually leads to BH4 deficiency remains elusive. Here, we demonstrate that diabetes reduced BH4 by increasing 26S proteasome-dependent degradation of guanosine 5'-triphosphate cyclohydrolase I (GTPCH), a rate-limiting enzyme in the synthesis of BH4, in parallel with increased formation of both superoxide and peroxynitrite (ONOO-). METHODS AND RESULTS:Exposure of human umbilical vein endothelial cells to high glucose concentrations (30 mmol/L D-glucose) but not to high osmotic conditions (25 mmol/L L-glucose plus 5 mmol/L D-glucose) significantly lowered the levels of both GTPCH protein and BH4. In addition, high glucose increased both the 26S proteasome activity and the ubiquitination of GTPCH. Inhibition of the 26S proteasome with either MG132 or PR-11 prevented the high glucose-triggered reduction of GTPCH and BH4. Exposure of human umbilical vein endothelial cells to exogenous ONOO- increased proteasome activity and 3-nitrotyrosine in 26S proteasome. Furthermore, adenoviral overexpression of superoxide dismutase and inhibition of endothelial nitric oxide synthase with N(G)-nitro-L-arginine methyl ester significantly attenuated the high glucose-induced activation of 26S proteasome and the reduction of GTPCH. Finally, administration of MG132 or a superoxide dismutase mimetic, tempol, reversed the diabetes mellitus-induced reduction of GTPCH and BH4 and endothelial dysfunction in streptozotocin-induced diabetes mellitus. CONCLUSIONS:We conclude that diabetes mellitus triggers BH4 deficiency by increasing proteasome-dependent degradation of GTPCH.
Africa is increasingly being exposed to the negative impacts of climate and environmental change, while having less capacity to respond compared to other continents. The vulnerability partially results from unprecedented demographic growth, urbanization, and industrialization. However, the continent has still largely been underserved by the broader Earth system science (ESS) community, as evidenced by the limited amount of ESS data and research that cover Africa compared to other areas of the world. Here, we present the recent University Corporation for Atmospheric Research (UCAR) Africa Initiative that aims to enhance environmental sustainability in Africa by fostering international collaborative research partnerships coled by African scientists. Specifically, we outline urgent challenges and opportunities identified through an international workshop in six areas of ESS, namely, 1) air quality and health, 2) weather, 3) climate, 4) land and water, 5) social science perspectives, and 6) developing equitable collaboration and sustainable infrastructure. We highlight examples of successful partnerships and conclude with recommendations to advance collaborative, actionable ESS research that addresses Africa's critical environmental challenges.
Accurately forecasting mesovortex tornado potential within quasi-linear convective systems (QLCSs) remains a major challenge. One technique used to support QLCS tornado warning operations is the three ingredients method (3IM), which is based on system balance modulated by line-normal vertical wind shear. However, observational studies examining prolific mesovortex-and tornado-producing QLCSs have identified a substantial line-parallel component of the low-level environmental shear field, which is unaccounted for in the 3IM. Recent numerical studies suggest that line-parallel shear promotes the development of strong, cyclonic mesovortices, thereby increasing the overall likelihood of QLCS tornadoes. Motivated by these recent findings, this proof-of-concept study represents the first attempt to quantify the physical factors comprising the 3IM using a prototype composite forecast parameter QTor. QTor integrates near-storm environmental vertical wind shear components with leading-line geometry to generate system-relative probabilistic forecasts for mesovortex tornado potential. QTor is evaluated using three tornadic QLCS cases and one null case within the Warn-on-Forecast System (WoFS), leveraging object-based methods to identify QLCS structures and isolate their leading lines. Results indicate that QTor forecasts show promise in effectively identifying areas conducive to mesovortex tornado development, providing qualitatively accurate probabilistic forecasts of tornadic portions of the QLCSs with up to 3 h of lead time. SIGNIFICANCE STATEMENT: Squall-line tornadoes are difficult to forecast due to their small size and transient nature, leading to lower predictability and shorter warning lead times compared to supercell tornadoes. This study introduces QTor, a new forecasting parameter designed to predict tornado potential within squall lines. Results indicate that QTor may effectively identify areas of increased tornado likelihood, predicting tornadic portions of a squall line over 3 h in advance. While still in early development, QTor shows great promise and has the potential to enhance squall-line tornado prediction in the future.
Most operational radar systems to date produce data with volumetric update times that are insufficient for capturing some of the rapidly evolving processes of hailstorms. Recent advances in rapid scan radar technology and innovative approaches to obtain faster scans have paved the way for a better analysis of hailstorms. This study utilizes the National Severe Storms Laboratory (NSSL)'s research Weather Surveillance Radar-1988 Doppler (WSR-88D) S-band radar, KOUN, located in Norman, Oklahoma, to examine rapidly evolving polarimetric features in hailstorms. Quantities such as rate of hail descent and changes in the updraft can be calculated through the analysis of these rapidly evolving polarimetric features, which can increase forecaster confidence in hailstorm evolution and hail sizing. Multi-Radar Multi-Sensor (MRMS) system products were generated using KOUN data, which captured the full life cycle of a hailstorm, including the cyclic evolution of hail production and its relation to tornado production. These data were compared to KTLX, located in Oklahoma City, Oklahoma, to explore what features would not be resolved without a rapid-scanning radar system. Rapid-scanning radar observations provided more details on storm-scale processes related to hail, which can aid in operational forecasting and give insight into future operational phased array radar benefits.
