Studies on serum somatedin activity and cartilage responsiveness in the regulation of growth

A Thesis Submitted to the Faculty of Science University of the Witwatersrand, Johannesburg for the Degree of Doctor of Philosophy Johannesburg 1976This thesis describes the results of experimental investigation of aspects of the endocrine regulation of growth in the rabbit, rat and man. In particular the role of serum somatomedin and cartilage responsiveness to somatomedin have been examined. Throughout a relationship between the physiological control mechanisms, namely the stimulus and the degree of end- organ responsiveness, and the velocity of growth has been sought.IT201

Optimization and evaluation of the performance of thin-film molecularly imprinted polymers for the analysis of cotinine in fluids from human subjects

Molecularly imprinted polymers (MIPs) are cross-linked synthetic polymers that can selectively take up target analytes from a solution. They are often used in bulk format for solid phase extraction and HPLC. In this work, the main goal was to develop MIPs in a thin-film format for direct analysis of analyte species by desorption electrospray ionization-mass spectrometry (DESI-MS). A cotinine template was used with methacrylic acid (MAA) monomer and ethyleneglycol dimethacrylate (EDGMA) cross-linker to synthesize these MIPs. Cotinine is the primary metabolite of nicotine and was chosen as the template due to its high concentration in biological fluids from smokers and non-smokers. Optimization of the ratios of polymer components (template:monomer:cross-linker) and porogen was completed using a modified Box-Behnken experimental design. Each composition tested was assessed for polymer robustness, imprinting factor and sorption capacity. The optimal molar ratio was 1:2:22.5 (template:monomer:cross-linker), with 239 μL porogen added for each 0.02 mol of template. Template removal from the MIP was studied and reduced from 2 h to 100 min. For optimal analyte uptake, MIPs were placed for 90 min in samples buffered at pH 7.0. Cotinine was quantified in extracts using GC-MS. Myosmine, B-nicotyrine, 1-phenyl-3-pyrazolidinone and nicotine-N-oxide were used as pseudo-templates to overcome template bleed were studied but with little success due to the lack of uptake by these pseudo-templates. Scanning electron microscopy showed that the MIPs were porous and up to approximately 0.05 μm in diameter. Cotinine calibration curves for human urine spiked with cotinine gave results of R²=0.6 with n=2. Testing with saliva samples did not produce any promising results. Proof of principle was demonstrated for detection of cotinine using MIPs with DESI-MS

A numerical adaptation of SAW identities from the honeycomb to other 2D lattices

Recently, Duminil-Copin and Smirnov proved a long-standing conjecture by Nienhuis that the connective constant of self-avoiding walks on the honeycomb lattice is $\sqrt{2+\sqrt{2}}.$ A key identity used in that proof depends on the existence of a parafermionic observable for self-avoiding walks on the honeycomb lattice. Despite the absence of a corresponding observable for SAW on the square and triangular lattices, we show that in the limit of large lattices, some of the consequences observed on the honeycomb lattice persist on other lattices. This permits the accurate estimation, though not an exact evaluation, of certain critical amplitudes, as well as critical points, for these lattices. For the honeycomb lattice an exact amplitude for loops is proved.Comment: 21 pages, 7 figures. Changes in v2: Improved numerical analysis, giving greater precision. Explanation of why we observe what we do. Extra reference

Translational Vestibulo-Ocular Reflex and Motion Perception During Interaural Linear Acceleration: Comparison of Different Motion Paradigms

The neural mechanisms to resolve ambiguous tilt-translation motion have been hypothesized to be different for motion perception and eye movements. Previous studies have demonstrated differences in ocular and perceptual responses using a variety of motion paradigms, including Off-Vertical Axis Rotation (OVAR), Variable Radius Centrifugation (VRC), translation along a linear track, and tilt about an Earth-horizontal axis. While the linear acceleration across these motion paradigms is presumably equivalent, there are important differences in semicircular canal cues. The purpose of this study was to compare translation motion perception and horizontal slow phase velocity to quantify consistencies, or lack thereof, across four different motion paradigms. Twelve healthy subjects were exposed to sinusoidal interaural linear acceleration between 0.01 and 0.6 Hz at 1.7 m/s/s (equivalent to 10 tilt) using OVAR, VRC, roll tilt, and lateral translation. During each trial, subjects verbally reported the amount of perceived peak-to-peak lateral translation and indicated the direction of motion with a joystick. Binocular eye movements were recorded using video-oculography. In general, the gain of translation perception (ratio of reported linear displacement to equivalent linear stimulus displacement) increased with stimulus frequency, while the phase did not significantly vary. However, translation perception was more pronounced during both VRC and lateral translation involving actual translation, whereas perceptions were less consistent and more variable during OVAR and roll tilt which did not involve actual translation. For each motion paradigm, horizontal eye movements were negligible at low frequencies and showed phase lead relative to the linear stimulus. At higher frequencies, the gain of the eye movements increased and became more inphase with the acceleration stimulus. While these results are consistent with the hypothesis that the neural computational strategies for motion perception and eye movements differ, they also indicate that the specific motion platform employed can have a significant effect on both the amplitude and phase of each

Automobile emissions in Mexico City

In order to determine the exhaust characteristics of the Mexico City vehicle fleet, a Fuel Efficiency Automotive Test (FEAT) unit was placed at 5 different sites over a 10 day period from 11 February 1991 through 21 February 1991. Valid data for the percent of carbon Monoxide (CO), hydrocarbons (HC), and carbon dioxide (CO{sub 2}) were obtained on 31 838 vehicles. This represents approximately 1 % of the entire Mexico City fleet

Extinction Maps Toward The Milky Way Bulge: Two-Dimensional And Three-Dimensional Tests With APOGEE

Galactic interstellar extinction maps are powerful and necessary tools for Milky Way structure and stellar population analyses, particularly toward the heavily reddened bulge and in the midplane. However, due to the difficulty of obtaining reliable extinction measures and distances for a large number of stars that are independent of these maps, tests of their accuracy and systematics have been limited. Our goal is to assess a variety of photometric stellar extinction estimates, including both two-dimensional and three-dimensional extinction maps, using independent extinction measures based on a large spectroscopic sample of stars toward the Milky Way bulge. We employ stellar atmospheric parameters derived from high-resolution H-band Apache Point Observatory Galactic Evolution Experiment (APOGEE) spectra, combined with theoretical stellar isochrones, to calculate line-of-sight extinction and distances for a sample of more than 2400 giants toward the Milky Way bulge. We compare these extinction values to those predicted by individual near-IR and near+mid-IR stellar colors, two-dimensional bulge extinction maps, and three-dimensional extinction maps. The long baseline, near+mid-IR stellar colors are, on average, the most accurate predictors of the APOGEE extinction estimates, and the two-dimensional and three-dimensional extinction maps derived from different stellar populations along different sightlines show varying degrees of reliability. We present the results of all of the comparisons and discuss reasons for the observed discrepancies. We also demonstrate how the particular stellar atmospheric models adopted can have a strong impact on this type of analysis, and discuss related caveats.NSF Astronomy & Astrophysics Postdoctoral Fellowship AST-1203017Physics Frontier Center/Joint Institute for Nuclear Astrophysics (JINA) PHY 08-22648U.S. National Science FoundationAlfred P. Sloan FoundationParticipating InstitutionsU.S. Department of Energy Office of Science ANR-12-BS05-0015-01Astronom

The Importance of Hands-on Experience with Telescopes for Students

Proper interpretation and understanding of astronomical data requires good knowledge of the data acquisition process. The increase in remote observing, queue observing, and the availability of large archived data products risk insulating astronomers from the telescope, potentially reducing their familiarity with the observational techniques crucial in understanding the data. Learning fundamental observing techniques can be done in at least three ways: 1) College and university operated observing facilities, 2) Student involvement in national facilities through competitive proposals, 3) Programs at national facilities to increase upper-level undergraduate and graduate student exposure to telescopes. We encourage both national organizations and universities to include programs and funding aimed at supporting hands-on experience with telescopes through the three methods mentioned.Comment: "State of the Profession" white paper for the 2010 Astronomy and Astrophysics Decadal Surve

Measuring Outcome after Wrist Injury: Translation and Validation of the Swedish Version of the Patient-Rated Wrist Evaluation (PRWE-Swe)

<p>Abstract</p> <p>Background</p> <p>There is a need for outcome measurement instruments for evaluation of disability after trauma. The Patient-Rated Wrist Evaluation (PRWE) is a self-administered region-specific outcome measuring instrument developed for use in evaluating disability and pain of the wrist. The aim of this study is to translate and to cross-culturally adapt the PRWE for use in a Swedish patient population. Moreover, we aim at investigating the PRWE in terms of validity, reliability and responsiveness.</p> <p>Methods</p> <p>We performed a translation and cross-cultural adaptation of the PRWE to Swedish (PRWE-Swe), utilising the process recommended by the American Association of Orthopedic Surgeons. A total of 124 patients with an injury to the wrist were included in the study. They filled in the PRWE and the DASH questionnaires at two separate occasions.</p> <p>Results</p> <p>Reliability of the PRWE in terms of internal consistency (Cronbach's alpha 0.97) and test-retest stability (intraclass correlation coefficient 0.93) were excellent. Face validity and content validity were judged as good. Criterion validity assessed as the correlation between the PRWE and the DASH was also good (Spearman's rho = 0.9). Responsiveness measured by the standardized response mean (SRM) was good with an SRM_PRWEof 1.29.</p> <p>Conclusion</p> <p>This Swedish version of the PRWE is a short and easily understood self-administered questionnaire with good validity, reliability, and responsiveness. Our results confirm that the PRWE is a valuable tool in evaluating the results after treatment of a wrist injury.</p