The Development of a Multi-Directional Wear Apparatus and the Characterization and Correlation of Biomechanical and Biotribological Properties of Bovine Articular Cartilage

A multi-directional wear apparatus was developed to simulate the kinematic motion of diarthrodial joints. A comprehensive evaluation including biotribological and biomechanical characterization of articular surfaces was performed with concomitant translational and oscillating rotational motion similar to that experienced in vivo. Various system parameters were evaluated in the designed experiments including normal load magnitude (high/low), surface quality (defect/no defect), and wear pattern (with/without rotation). Biomechanical characterization was achieved through stress relaxation and dynamic cyclical testing. Quasi-linear viscoelastic theory was used to curve-fit the stress relaxation data, while the dynamic data was used to determine the dynamic properties through Fast Fourier Transform analysis and verify the assumptions posed with the QLV theory.Overall tissue compression was significantly dependent on load magnitude (pstatic was significantly dependent on surface quality (pinitial was significantly dependent on both surface quality (pComparisons of the curve-fit parameters showed a significant decrease in pre- vs post-wear elastic response, A, and viscous response, c. In addition, the short term relaxation response, τ1, showed a significant decrease between no defect (0.801 ± 0.13 sec) and a defect (0.679 ± 0.16 sec). lGlpost-wear/lGlpre-wear tan δ , was generally greater while lGl was less for those specimens experiencing rotation Qualitatively, SEM photographs revealed the mechanical degradation of the tissue surface due to wear. Surfaces with a defect had increased wear debris, which ultimately contributes to third body wear. Surfaces without a defect had preferentially aligned abrasions, while those surfaces outside the wear path showed no signs of wear.Significant correlation was detected between the μstatic and μinitial for both the nonliner viscous response, B (p2 (p\u3c0.013 and p\u3c0.062). Thus, the comprehensive evaluation of biomechanical and biotribological characteristics suggests the new wear regime and standardization of analysis techniques will aid in the development of functional articular repair and clinical repair techniques

Postmenopausal Women With Greater Paracardial Fat Have More Coronary Artery Calcification Than Premenopausal Women: The Study of Women's Health Across the Nation (SWAN) Cardiovascular Fat Ancillary Study.

BackgroundVolumes of paracardial adipose tissue (PAT) and epicardial adipose tissue (EAT) are greater after menopause. Interestingly, PAT but not EAT is associated with estradiol decline, suggesting a potential role of menopause in PAT accumulation. We assessed whether volumes of heart fat depot (EAT and PAT) were associated with coronary artery calcification (CAC) in women at midlife and whether these associations were modified by menopausal status and estradiol levels.Methods and resultsEAT and PAT volumes and CAC were measured using electron beam computed tomography scans. CAC was evaluated as (1) the presence of CAC (CAC Agatston score ≥10) and (2) the extent of any CAC (log CAC Agatston score >0). The study included 478 women aged 50.9 years (58% pre- or early perimenopausal, 10% late perimenopausal, and 32% postmenopausal). EAT was significantly associated with CAC measures, and these associations were not modified by menopausal status or estradiol. In contrast, associations between PAT and CAC measures were modified by menopausal status (interaction-P≤0.01). Independent of study covariates including other adiposity measures, each 1-SD unit increase in log PAT was associated with 102% higher risk of CAC presence (P=0.04) and an 80% increase in CAC extent (P=0.008) in postmenopausal women compared with pre- or early perimenopausal women. Additional adjustment for estradiol and hormone therapy attenuated these differences. Moreover, the association between PAT and CAC extent was stronger in women with lower estradiol levels (interaction P=0.004).ConclusionsThe findings suggest that PAT is a potential menopause-specific coronary artery disease risk marker, supporting the need to monitor and target this fat depot for intervention in women at midlife

Desirable Difficulties: Toward a Critical Postmodern Arts-Based Practice

Prior scholarship on collaborative writing projects by women in the academy acknowledges sustained attempts of intraracial and interracial collaboration/divides. Interracial collaborative scholarship, while noble in effort, may result in unacknowledged tensions surrounding racial identity politics. In these collaborative environments the problematics of race cannot be denied, with Black women often drawing upon their racialized identities, while White women emphasize their gendered identities. An unawareness and/or invisibility of Whiteness as a racial construct of privilege further problematizes feminist postmodern discourse. This polyvocal text focuses on responding to and working within the tensions of identity politics encountered in interracial scholarship among four women academics. What follows is an attempt at describing an arts-based project, emerging from concentrated efforts to develop an approach to collaborative scholarship aimed at identifying and inhabiting the divides rather than only navigating around, over or under them

AGN's UV and X-ray luminosities in clumpy accretion flows

We consider the fuelling of the central massive black hole in Active Galactic Nuclei, through an inhomogeneous accretion flow. Performing simple analytical treatments, we show that shocks between elements (clumps) forming the accretion flow may account for the UV and X-ray emission in AGNs. In this picture, a cascade of shocks is expected, where optically thick shocks give rise to optical/UV emission, while optically thin shocks give rise to X-ray emission. The resulting blue bump temperature is found to be quite similar in different AGNs. We obtain that the ratio of X-ray luminosity to UV luminosity is smaller than unity, and that this ratio is smaller in massive objects compared to less massive sources. This is in agreement with the observed $L_{X}/L_{UV}$ ratio and suggests a possible interpretation of the $\alpha_{OX}-l_{UV}$ anticorrelation.Comment: 8 pages, 1 figure, accepted for publication in A&

Sexuality talk during adolescent health maintenance visits

IMPORTANCE: Physicians may be important sources of sexuality information and preventive services, and one-on-one confidential time during health maintenance visits is recommended to allow discussions of sexual development, behavior, and risk reduction. However, little is known about the occurrence and characteristics of physician-adolescent discussions about sexuality. OBJECTIVE: To examine predictors of time spent discussing sexuality, level of adolescent participation, and physician and patient characteristics associated with sexuality discussions during health maintenance visits by early and middle adolescents. DESIGN, SETTING, AND PARTICIPANTS: Observational study of audio-recorded conversations between 253 adolescents (mean age, 14.3 years; 53% female; 40% white; 47% African American) and 49 physicians (82% pediatricians; 84% white; 65% female; mean age, 40.9 years; mean [SD] duration in practice, 11.8 [8.7] years) coded for sexuality content at 11 clinics (3 academic and 8 community-based practices) located throughout the Raleigh/Durham, North Carolina, area. MAIN OUTCOMES AND MEASURES: Total time per visit during which sexuality issues were discussed. RESULTS One hundred sixty-five (65%) of all visits had some sexual content within it. The average time of sexuality talk was 36 seconds (35% 0 seconds; 30% 1-35 seconds; and 35% ≥ 36 seconds). Ordinal logistic regression (outcome of duration: 0, 1-35, or ≥ 36 seconds), adjusted for clustering of patients within physicians, found that female patients (odds ratio [OR] = 2.58; 95% CI, 1.53-4.36), older patients (OR = 1.37; 95% CI, 1.13-1.65), conversations with explicit confidentiality discussions (OR = 4.33; 95% CI, 2.58-7.28), African American adolescents (OR = 1.58; 95% CI, 1.01-2.48), and longer overall visit (OR = 1.07; 95% CI, 1.03-1.11) were associated with more sexuality talk, and Asian physicians were associated with less sexuality talk (OR = 0.13; 95% CI, 0.08-0.20). In addition, the same significant associations between adolescent, physician, and visit characteristics were significantly associated with greater adolescent participation. CONCLUSIONS AND RELEVANCE: Our study may be the first to directly observe sexuality talk between physicians and adolescents. We found that one-third of all adolescents had annual visits without any mention of sexuality issues; when sexuality talk occurred, it was brief. Research is needed to identify successful strategies physicians can use to engage adolescents in discussions about sexuality to help promote healthy sexual development and decision making. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01040975

Resolving the dynamical mass of a z~1.3 QSO host galaxy using SINFONI and Laser Guide Star assisted Adaptive Optics

Recent studies of the tight scaling relations between the masses of supermassive black holes and their host galaxies have suggested that in the past black holes constituted a larger fraction of their host galaxies' mass. However, these arguments are limited by selection effects and difficulties in determining robust host galaxy masses at high redshifts. Here we report the first results of a new, complementary diagnostic route: we directly determine a dynamical host galaxy mass for the z=1.3 luminous quasar J090543.56+043347.3 through high-spatial-resolution (0.47", 4kpc FWHM) observations of the host galaxy gas kinematics over 30x40 kpc using ESO/VLT/SINFONI with LGS/AO. Combining our result of M_dyn = 2.05+1.68_0.74 x 10^11 M_sun (within a radius 5.25 +- 1.05 kpc) with M_BH,MgII = 9.02 \pm 1.43 x 10^8 M_sun, M_BH,Halpha = 2.83 +1.93-1.13 x 10^8 M_sun, we find that the ratio of black hole mass to host galaxy dynamical mass for J090543.56+043347.3 matches the present-day relation for M_BH vs. M_Bulge,Dyn, well within the IR scatter, deviating at most a factor of two from the mean. J090543.56+043347.3 displays clear signs of an ongoing tidal interaction and of spatially extended star formation at a rate of 50-100 M_sun/yr, above the cosmic average for a galaxy of this mass and redshift. We argue that its subsequent evolution may move J090543.56+043347.3 even closer to the z=0 relation for M_BH vs. M_Bulge,Dyn. Our results support the picture where any substantive evolution in these relations must occur prior to z~1.3. Having demonstrated the power of this modelling approach we are currently analyzing similar data on seven further objects to better constrain such evolution.Comment: Accepted for publication in ApJ, 14 pages, 10 Figure

The Berkeley Sample of Stripped-Envelope Supernovae

We present the complete sample of stripped-envelope supernova (SN) spectra observed by the Lick Observatory Supernova Search (LOSS) collaboration over the last three decades: 888 spectra of 302 SNe, 652 published here for the first time, with 384 spectra (of 92 SNe) having photometrically-determined phases. After correcting for redshift and Milky Way dust reddening and reevaluating the spectroscopic classifications for each SN, we construct mean spectra of the three major spectral subtypes (Types IIb, Ib, and Ic) binned by phase. We compare measures of line strengths and widths made from this sample to the results of previous efforts, confirming that O I {\lambda}7774 absorption is stronger and found at higher velocity in Type Ic SNe than in Types Ib or IIb SNe in the first 30 days after peak brightness, though the widths of nebular emission lines are consistent across subtypes. We also highlight newly available observations for a few rare subpopulations of interest.Comment: 13 pages; 14 figures; 3 tables. Accepted for publication in MNRA

Complement protein C3 and coronary artery calcium in middle-aged women with polycystic ovary syndrome and controls

Circulating complement protein C3 (C3) levels have been associated with coronary artery calcification (CAC) in women with systemic lupus erythematosus, but have yet to be evaluated in women with polycystic ovary syndrome (PCOS). We aimed to determine whether C3 levels were elevated in women with PCOS compared to controls, and to quantify the association of C3 with cardiovascular disease (CVD) risk factors and CAC, and if PCOS modified this association. This cross-sectional analysis included 132 women with PCOS and 155 controls 35-62 years old from the third visit of a case-control study. CAC was measured during the study visit and circulating C3 was measured in stored sera. The presence of CAC and CAC categories (Agatston score 0, 1-9.9, and ≥10) were used for logistic and ordinal regression analysis, respectively. C3 levels were not significantly different between women with PCOS and controls. Among all women, C3 was associated with the presence of CAC and increasing CAC groups after adjusting for age, PCOS status, and insulin or BMI, all p<0.05. In addition, C3 was associated with the presence of CAC after adjusting for age, PCOS status, BMI, insulin and African American race, p=0.049. PCOS status did not modify these associations. In conclusion, circulating C3 levels may prove beneficial in identifying women at risk of CVD in women with PCOS and the general population

Advanced localization of massive black hole coalescences with LISA

The coalescence of massive black holes is one of the primary sources of gravitational waves (GWs) for LISA. Measurements of the GWs can localize the source on the sky to an ellipse with a major axis of a few tens of arcminutes to a few degrees, depending on source redshift, and a minor axis which is 2--4 times smaller. The distance (and thus an approximate redshift) can be determined to better than a per cent for the closest sources we consider, although weak lensing degrades this performance. It will be of great interest to search this three-dimensional `pixel' for an electromagnetic counterpart to the GW event. The presence of a counterpart allows unique studies which combine electromagnetic and GW information, especially if the counterpart is found prior to final merger of the holes. To understand the feasibility of early counterpart detection, we calculate the evolution of the GW pixel with time. We find that the greatest improvement in pixel size occurs in the final day before merger, when spin precession effects are maximal. The source can be localized to within 10 square degrees as early as a month before merger at $z = 1$; for higher redshifts, this accuracy is only possible in the last few days.Comment: 11 pages, 4 figures, version published in Classical and Quantum Gravity (special issue for proceedings of 7th International LISA Symposium