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BackgroundUnderstanding where and how young black men who have sex with men (YBMSM) in the southern United States meet their sexual partners is germane to understanding the underlying factors contributing to the ongoing HIV transmission in this community. Men who have sex with men (MSM) commonly use geosocial networking apps to meet sexual partners. However, there is a lack of literature exploring geosocial networking app use in this particular population. ObjectiveOur aim was to examine the characteristics, preferences, and behaviors of a geographically diverse sample of geosocial networking app-using YBMSM in the southern United States. MethodsData were collected from a sample of 75 YBMSM across three cities (Gulfport, Mississippi; Jackson, Mississippi; and New Orleans, Louisiana). Multiple aspects of geosocial networking app use were assessed, including overall app use, age of participant at first app use, specific apps used, reasons for app use, photos presented on apps, logon times and duration, number of messages sent and received, and characteristics of and behaviors with partners met on apps. Survey measures of app-met partner and sexual behavior characteristics assessed at midpoint (Day 7) and completion visits (Day 14) were compared using McNemar’s test or Wilcoxon signed-rank test. In addition, we assessed activity spaces derived from GPS devices that participants wore for 2 weeks. ResultsOf the 70 participants who responded to the overall app-use item, almost three-quarters (53/70, 76%) had ever used geosocial networking apps. Jack’d was the most commonly used geosocial networking app (37/53, 70%), followed by Adam4Adam (22/53, 42%), and Grindr (19/53, 36%). The mean and median number of apps used were 4.3 (SD 2.7) and 4.0 (range 0-13), respectively. Most app-using participants displayed their face on the profile picture (35/52, 67%), whereas fewer displayed their bare legs (2/52, 4%) or bare buttocks (or ass; 2/52, 4%). The mean age at the initiation of app use was 20.1 years (SD 2.78) ranging from 13-26 years. Two-thirds (35/53, 66%) of the sample reported using the apps to “kill time” when bored. A minority (9/53, 17%) reported using the apps to meet people to have sex/hook up with. The vast majority of participants reported meeting black partners for sex. Over two-thirds (36/53, 68%) reported that the HIV status of their app-met partners was negative, and 26% (14/53) reported that they did not know their partner’s HIV status. There was a significant difference in GPS activity spaces between app using YBMSM compared to nonapp using YBMSM (2719.54 km2 vs 1855.68 km2, P=.011). ConclusionsUse of geosocial networking apps to meet sexual partners among our sample of YBMSM in the southern United States was common, with a diverse range of app use behaviors being reported. Further research should characterize the association between geosocial networking app use and engagement in sexual behaviors that increase risk for HIV acquisition and transmission. In addition, geosocial networking apps present a promising platform for HIV prevention interventions targeting YBMSM who use these apps.

Summary: Phosphate (Pi) availability is a major factor limiting plant growth and development. The key transcription factor controlling Pi‐starvation response (PSR) is PHOSPHATE STARVATION RESPONSE 1 (PHR1) whose transcript levels do not change with changes in Pi levels. However, how PHR1 stability is regulated at the post‐translational level is relatively unexplored in Arabidopsis thaliana.Inositol polyphosphates (InsPn) are important signal molecules that promote the association of stand‐alone SPX domain proteins with PHR1 to regulate PSR. Here, we show that NITROGEN LIMITATION ADAPTATION (NLA) E3 ligase can associate with PHR1 through its conserved SPX domain and polyubiquitinate PHR1 in vitro. The association with PHR1 and its ubiquitination is enhanced by InsP6 but not by InsP5.Analysis of InsPn‐related mutants and an overexpression plant shows PHR1 levels are more stable in itpk4‐1 and vih2‐4/VIH1amiRNA but less stable in ITPK4 overexpression plants. Under Pi‐deficient conditions, nla seedlings contain high PHR1 levels, display long root hair and accumulate anthocyanin in shoots phenocopying PHR1 overexpression plants. By contrast, NLA overexpression plants phenocopy phr1 whose phenotypes are opposite to those of nla.Our results suggest NLA functions as a negative regulator of Pi response by modulating PHR1 stability and the NLA/PHR1 association depends on InsPn levels. [ABSTRACT FROM AUTHOR]

Ships and offshore structures are subjected to impact loads, such as slamming and sloshing. High impact pressures can cause permanent hull deformation by a single impact event. In addition, significant fatigue damage can be accumulated via repeated impact pressures. In this study, the plastic deformation behavior of flat plates under slamming impact is numerically investigated using a coupled Eulerian–Lagrangian method. The dynamic impact pressure of the flat plates by weight and drop height is investigated under the assumption of viscous and compressible fluids. To evaluate the plastic deformation of the plate, contact between water and the plate is removed after a certain duration after dropping, and then the remaining deformation is measured. Optimized finite element models for drop simulations are selected via a mesh sensitivity study, and the simulation results are calibrated and compared with experimental data. Results of the simulation and the experiment show good agreement in general in terms of deflection range. However, because the initial condition of the plate is not reflected in the simulation, some discrepancy is observed in maximum deflections. Finally, a discussion is presented for a more accurate fluid impact analysis model based on the comparison results with the experimental data. [ABSTRACT FROM AUTHOR]