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The purpose of this study is to determine whether in-fiber Bragg grating (FBG) sensors detect changes within the periodontal ligament (PDL) of ex-vivo swine tooth-PDL-bone complex (TPBC) when manipulating fluid content. Recording strain will allow for a better understanding of the biomechanics of viscoelastic load transfer from the tooth to the PDL during chewing and/or orthodontic tooth movement, as well as replication of these dynamics in regenerated PDL tissues. FBG sensors placed within the PDL of swine incisor teeth were used to measure strain resulting from an intrusive load. Specimens were mounted in a custom platform within an MTS machine and a compressive load was applied at 0.3 mm/s to a depth of 0.5 mm and held for 10 s. Median peak strain and load and median absolute deviation (MAD) were compared: dry vs. saline (n = 19) with bias-corrected bootstrap 95% CI. Dry vs. saline conditions did not statistically differ (median peaks of 5με, 103–105 N) and recorded strains showed high repeatability (MAD of 0.82με, 0.72με, respectively). FBG sensors did not detect the fluid changes in this study, suggesting that the deformation of tissues in the PDL space collectively determine FBG strain in response to tooth loading. The repeatability of measurements demonstrates the potential for FBG sensors to assess the strain in the PDL space of an in vivo swine model.

In the present study, we examine the relationship between involvement in the criminal justice system and achieved socioeconomic status (SES), as well as the moderating effect of ascribed SES. Using data from the National Longitudinal Study of Adolescent to Adult Health, we find a nonlinear relationship between criminal justice involvement and achieved SES, such that deeper involvement leads to increasingly negative consequences on achieved SES. Furthermore, those coming from the highest socioeconomic backgrounds are not “protected” from the deleterious consequences of system involvement, but instead experience the greatest declines in achieved SES relative to where they started. In contrast, the effect of criminal justice involvement for those from below average ascribed SES is not significant. Our findings reinforce how normal such experiences are for people with the fewest resources, and also how system involvement inevitably destroys human capital, undermines future life chances, and ultimately promotes a “rabble” class.

The consequences of “falling from grace”—or experiencing downward intergenerational mobility—are indeed becoming an abrupt reality for many entering the labor force. Scholars of social mobility speculate that such life course trajectories can result in antisocial behavior, but few have examined whether these trajectories lead to drug use. Thus, with the United States in the midst of a drug epidemic, as well as recovering from an economic recession, the study of social mobility may contribute to a better understanding of what causes individuals to turn to drugs. Using data from The National Longitudinal Study of Adolescent to Adult Health (Add Health) and a series of logistic diagonal reference models, this study examines the association between intergenerational social mobility and drug use. Overall, I find evidence that downward mobility is associated with increases in drug use, with the relationship strongest among those experiencing the greatest loss in status.

In helmet impact testing, parameters including acceleration and velocity are measured using instrumented head-neck models that are meant to be mechanically realistic (i.e. biofidelic) stand-ins, or surrogates, for humans. Currently available models of the human neck are designed primarily for application in automotive crash testing, and their applicability in assessment of helmets is often questioned. The object of the present work is to document the mechanical design, repeatability, and biofidelity in low speed impact of a new neck model that we apply with a Hybrid III head. Focusing on Hybrid III head kinematics measured during impacts at 2 to 6 m/s, the co-efficient of variance of repeated measures of kinematics was generally less than 10%. Differences in kinematics between identical copies of the neck was less than 20% when tested with helmets, and less than 7% when the head was not helmeted. In parallel testing using a Hybrid III head-neck, the co-efficient of variance in repeated measures was less than 4% and the kinematics significantly differed from those measured using the new neck. CORAplus scores for the new neck were approximately 0.70 when compared against data for human subjects with passive neck muscles experiencing impact at 2 m/s.

Due to growing concern on brain injury in sport, and the role that helmets could play in preventing brain injury caused by impact, biomechanics researchers and helmet certification organizations are discussing how helmet assessment methods might change to assess helmets based on impact parameters relevant to brain injury. To understand the relationship between kinematic measures and brain strain, we completed hundreds of impacts using a 50th percentile Hybrid III head-neck wearing an ice hockey helmet and input three-dimensional impact kinematics to a finite element brain model called the Simulated Injury Monitor (SIMon) ( n  = 267). Impacts to the helmet front, back and side included impact speeds from 1.2 to 5.8 ms −1 . Linear regression models, compared through multiple regression techniques, calculating adjusted R 2 and the F -statistic, determined the most efficient set of kinematics capable of predicting SIMon-computed brain strain, including the cumulative strain damage measure (specifically CSDM-15) and maximum principal strain (MPS). Resultant change in angular velocity, Δ ω R , better predicted CSDM-15 and MPS than the current helmet certification metric, peak g , and was the most efficient model for predicting strain, regardless of impact location. In nearly all cases, the best two-variable model included peak resultant angular acceleration, α R , and Δ ω R .

Copper is supplied to plastocyanin for photosynthesis and cytochrome c oxidase for respiration in the thylakoids of Synechocystis PCC 6803 by the membrane-bound P-type ATPases CtaA and PacS, and the metallochaperone Atx1. We have determined the Cu(I) affinities of all of the soluble proteins and domains in this pathway. The Cu(I) affinities of the trafficking proteins range from 5 x 10¹⁶ to 5 x 10¹⁷ M⁻¹ at pH 7.0, consistent with values for homologues. Unusually, Atx1 binds Cu(I) significantly tighter than the metal-binding domains (MBDs) of CtaA and PacS (CtaAN and PacSN), and equilibrium copper exchange constants of approximately 0.2 are obtained for transfer to the MBDs. Dimerization of Atx1 increases the affinity for Cu(I), but the loop 5 His61 residue has little influence. The MBD of the zinc exporter ZiaA (ZiaAN) exhibits an almost identical Cu(I) affinity, and Cu(I) exchange with Atx1, as CtaAN and PacSN, and the relative stabilities of the complexes must enable the metallochaperone to distinguish between the MBDs. The binding of potentially competing zinc to the trafficking proteins has been studied. ZiaAN has the highest Zn(II) affinity and thermodynamics could be important for zinc removal from the cell. Plastocyanin has a Cu(I) affinity of 2.6 x 10¹⁷ M⁻¹, 15-fold tighter than that of the CuA site of cytochrome c oxidase, highlighting the need for specific mechanisms to ensure copper delivery to both of these targets. The narrow range of Cu(I) affinities for the cytoplasmic copper proteins in Synechocystis will facilitate relocation when copper is limiting.

Headforms are widely used in head injury research and headgear assessment. Common headforms are limited to replicating global head kinematics, although intracranial responses are crucial to understanding brain injuries. This study aimed to evaluate the biofidelity of intracranial pressure (ICP) and the repeatability of head kinematics and ICP of an advanced headform subjected to frontal impacts. Pendulum impacts were performed on the headform using various impact velocities (1–5 m/s) and impactor surfaces (vinyl nitrile 600 foam, PCM746 urethane, and steel) to simulate a previous cadaveric experiment. Head linear accelerations and angular rates in three axes, cerebrospinal fluid ICP (CSFP), and intraparenchymal ICP (IPP) at the front, side, and back of the head were measured. The head kinematics, CSFP, and IPP demonstrated acceptable repeatability with coefficients of variation generally being less than 10%. The BIPED front CSFP peaks and back negative peaks were within the range of the scaled cadaver data (between the minimum and maximum values reported by Nahum et al.), while side CSFPs were 30.9–92.1% greater than the cadaver data. CORrelation and Analysis (CORA) ratings evaluating the closeness of two time histories demonstrated good biofidelity of the front CSFP (0.68–0.72), while the ratings for the side (0.44–0.70) and back CSFP (0.27–0.66) showed a large variation. The BIPED CSFP at each side was linearly related to head linear accelerations with coefficients of determination greater than 0.96. The slopes for the BIPED front and back CSFP-acceleration linear trendlines were not significantly different from cadaver data, whereas the slope for the side CSFP was significantly greater than cadaver data. This study informs future applications and improvements of a novel head surrogate.

Abstract Graduation from a four-year college is an important potential means of social mobility for those from lower socioeconomic backgrounds. For “first-generation” students, the path to a degree is often made more difficult by circumstances such as working long hours and living with parents, as well as an unfamiliar college environment. One concerning aspect of college life is the continuing prevalence of substance use, which has hampered graduation rates and led many universities to reconsider the impact that the party subculture has on student well-being. In this paper, we use data from The National Longitudinal Study of Adolescent to Adult Health to examine differences in substance use (binge drinking, marijuana use, other illicit drug use) and four-year college graduation across unique combinations of students defined by college generation, work, and residential statuses. Consistent with previous qualitative studies into the class-specific consequences of the college party subculture, substance use is generally found to be higher among continuing-generation students who are not working nor living with their parents. In addition, substance use appears to have little consequence for the graduation prospects of these most traditional continuing-generation students. In contrast, substance use is negatively associated with graduation for most other groups, particularly first-generation students or those working long hours.