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Broadband data acquired during the Modal Mapping Experiment (MOMAX) V experiment are used to invert simultaneously for the three-dimensional (3D) water column sound speed profiles and the compressional wave speed and density profiles of the seabed in shallow waters off the coast of New Jersey. Linear Frequency Modulation sweep signals in the band 50-300 Hz are transmitted from a nearly stationary source at several discrete positions to a set of freely drifting receivers. Mode travel times are estimated from the signals acquired by the drifting buoys, and these are then used as input data in an inversion algorithm that estimates the acoustic properties of the water column and sediments. The resulting 3D compressional wave speed profiles in the seabed are generally consistent with the one-dimensional profile obtained during the narrowband component of MOMAX V, as well as the results from other experiments in the same area. The validity of the inversion results has also been assessed by the ability of the inverted model to predict the fields measured during the narrowband experiments.

The football helmet is used to help mitigate the occurrence of impact-related traumatic (TBI) and minor traumatic brain injuries (mTBI) in the game of American football. While the current helmet design methodology may be adequate for reducing linear acceleration of the head and minimizing TBI, it however has had less effect in minimizing mTBI. The objectives of this study are (a) to develop and validate a coupled finite element (FE) model of a football helmet and the human body, and (b) to assess responses of different regions of the brain to two different impact conditions - frontal oblique and crown impact conditions. The FE helmet model was validated using experimental results of drop tests. Subsequently, the integrated helmet-human body FE model was used to assess the responses of different regions of the brain to impact loads. Strain-rate, strain, and stress measures in the corpus callosum, midbrain, and brain stem were assessed. Results show that maximum strain-rates of 27 and 19 s(-1) are observed in the brain-stem and mid-brain, respectively. This could potentially lead to axonal injuries and neuronal cell death during crown impact conditions. The developed experimental-numerical framework can be used in the study of other helmet-related impact conditions.

Importance: Human papillomavirus-related oropharyngeal carcinoma (HPV-OPC) is increasing in incidence in the United States. Although HPV-OPC has favorable prognosis, 10% to 25% of HPV-OPCs recur. Detection of human papillomavirus (HPV) DNA in oral rinses is associated with HPV-OPC, but its potential as a prognostic biomarker is unclear., Objective: To determine whether HPV DNA detection in oral rinses after treatment for HPV-OPC is associated with recurrence and survival., Design, Setting, and Participants: Prospective cohort study of patients with incident HPV-OPC diagnosed from 2009 to 2013 at 4 academic tertiary referral cancer centers in the United States. Oral rinse samples were collected at diagnosis and after treatment (9, 12, 18, and 24 months after diagnosis), and evaluated for HPV DNA. Among an initial cohort of 157 participants with incident HPV-OPC treated with curative intent, 124 had 1 or more posttreatment oral rinses available and were included in this study., Main Outcomes and Measures: Disease-free survival (DFS) and overall survival (OS) were estimated by the Kaplan-Meier method, and the association of HPV DNA detection in oral rinses with survival was evaluated using Cox regression analysis., Results: Oral HPV type 16 (HPV16) DNA was common at diagnosis (67 of 124 participants [54%]). In contrast, oral HPV16 DNA was detected in only 6 participants after treatment (5%), including 5 with HPV16 DNA also detected at diagnosis (persistent oral HPV16 DNA). Two-year DFS and OS were 92% (95% CI, 94%-100%) and 98% (95% CI, 93%-99%). Persistent oral HPV16 DNA was associated with worse DFS (hazard ratio, 29.7 [95% CI, 9.0-98.2]) and OS (hazard ratio, 23.5 [95% CI, 4.7-116.9]). All 5 participants with persistent oral HPV16 DNA developed recurrent disease, 3 with local disease involvement. In contrast, just 9 of 119 participants (8%) without persistent oral HPV16 DNA developed recurrent disease, only 1 (11%) with local disease involvement. Median (range) time from earliest posttreatment oral HPV16 DNA detection to recurrence was 7.0 (3.7-10.9) months., Conclusions and Relevance: Human papillomavirus type 16 DNA in oral rinses is common at diagnosis but rare after treatment for HPV-OPC. Our data suggest that, although infrequent, persistent HPV16 DNA in posttreatment oral rinses is associated with poor prognosis and is a potential tool for long-term tumor surveillance, perhaps more so for local recurrence.

Objective: Brain tissue undergoes dramatic molecular and cellular remodeling at the implant-tissue interface that evolves over a period of weeks after implantation. The biomechanical impact of such remodeling on the interface remains unknown. In this study, we aim to assess the changes in the mechanical properties of the brain-electrode interface after chronic implantation of a microelectrode., Approach: Microelectrodes were implanted in the rodent cortex at a depth of 1 mm for different durations-1 day (n = 4), 10-14 days (n = 4), 4 weeks (n = 4) and 6-8 weeks (n = 7). After the initial duration of implantation, the microelectrodes were moved an additional 1 mm downward at a constant speed of 10 µm s(-1). Forces experienced by the microelectrode were measured during movement and after termination of movement. The biomechanical properties of the interfacial brain tissue were assessed from measured force-displacement curves using two separate models-a two-parameter Mooney-Rivlin hyperelastic model and a viscoelastic model with a second-order Prony series., Main Results: Estimated shear moduli using a second-order viscoelastic model increased from 0.5-2.6 kPa (day 1 of implantation) to 25.7-59.3 kPa (after 4 weeks of implantation) and subsequently decreased to 0.8-7.9 kPa after 6-8 weeks of implantation in 6 of the 7 animals. The estimated elastic modulus increased from 4.1-7.8 kPa on the day of implantation to 24-44.9 kPa after 4 weeks. The elastic modulus was estimated to be 6.8-33.3 kPa in 6 of the 7 animals after 6-8 weeks of implantation. The above estimates suggest that the brain tissue surrounding the microelectrode evolves from a stiff matrix with maximal shear and elastic modulus after 4 weeks of implantation into a composite of two different layers with different mechanical properties-a stiff compact inner layer surrounded by softer brain tissue that is biomechanically similar to brain tissue-during the first week of implantation. Tissue micromotion-induced stresses on the microelectrode constituted 12-55% of the steady-state stresses on the microelectrode on the day of implantation (n = 4), 2-21% of the steady-state stresses after 4 weeks of implantation (n = 4), and 4-10% of the steady-state stresses after 6-8 weeks of implantation (n = 7)., Significance: Understanding biomechanical behavior at the brain-microelectrode interface is necessary for the long-term success of implantable neuroprosthetics and microelectrode arrays. Such quantitative physical characterization of the dynamic changes in the electrode-tissue interface will (a) drive the design and development of more mechanically optimal, chronic brain implants, and (b) lead to new insights into key cellular and molecular events such as neuronal adhesion, migration and function in the immediate vicinity of the brain implant.

Objectives: We investigated attitudes about and acceptance of anal Papanicolaou (Pap) screening among men who have sex with men (MSM)., Methods: Free anal Pap screening (cytology) was offered to 1742 MSM in the Multicenter AIDS Cohort Study, who reported history of, attitudes about, and experience with screening. We explored predictors of declining screening with multivariate logistic regression., Results: A history of anal Pap screening was uncommon among non-HIV-infected MSM, but more common among HIV-infected MSM (10% vs 39%; P < .001). Most participants expressed moderate or strong interest in screening (86%), no anxiety about screening (66%), and a strong belief in the utility of screening (65%). Acceptance of screening during this study was high (85%) across all 4 US sites. Among those screened, most reported it was "not a big deal" or "not as bad as expected," and 3% reported that it was "scary." Declining to have screening was associated with Black race, anxiety about screening, and low interest, but not age or HIV status., Conclusions: This study demonstrated high acceptance of anal Pap screening among both HIV-infected and non-HIV-infected MSM across 4 US sites.

Purpose: To study the effect of varying four parameters on the refractive change induced by the LASIK flap., Methods: Using a variety of patient-specific data such as topography, pachymetry, and axial length, a finite element model is built. The model is used in a non-linear finite element analysis to determine the response and change in optical power of the cornea as a function of a material property of the cornea (corneal elasticity), flap diameter and thickness, and intraocular pressure., Results: The central flattening or hyperopic shift occurred atop the flap in all four of the simulated eyes tested with the creation of the LASIK flap. Of the four parameters tested, modulus of elasticity (Young's modulus) had the most profound effect on the results of hyperopic shift, varying from <0.5 diopters (D) in the least elastic (stiffest) cornea to >2.0 D of hyperopic shift in the most elastic cornea. The depth of the lenticular cut was the second-most significant parameter tested varying from 0.24 D at 100 microns to 1.25 D at 275 microns of depth. Varying intraocular pressure demonstrated less difference, and varying corneal flap diameter demonstrated the least difference in induced refractive change on the model. The hyperopic shift was noted to be greater in hyperopic than in myopic eyes (simulated) tested., Conclusions: Three-dimensional finite element analysis modeling of actual patient data could lead to a better understanding of the biomechanical response of corneal tissue to the lenticular flap creation and potentially for ablation patterns produced by the excimer laser. Understanding these biomechanical responses may lead to greater predictability and improvement of visual outcomes.

Extrapolating information from equations that govern fluid flow, a theoretical formula is developed for a sutureless cataract incision. This theoretical formula defines the resistance of aqueous outflow as a function of three variables: length of cataract incision, the length of the scleral tunnel, the tortuosity of the outflow channel, and one constant friction factor. The nonlinear relationship of corneal incisions to length, depth, and distance from the visual axis is also examined with respect to their effect on central corneal curvature and control of astigmatism. Finite element analysis of differential equations is discussed as the most plausible technique for predicting these incisional effects.