Genetic effects on dairy calf growth

Objectives were to establish growth patterns for weight and height in dairy calves from birth to 90 d and to estimate appropriate genetic parameters. Measurements were 7943 body weights and 7005 wither heights of 752 calves. Represented over 12 yr were three breeds, 348 dams, and 115 sires; data resulted from designed calf nutrition experiments. Sources of variation considered in various least squares analyses of variance were breed, sire in breed, calf in sire in breed, sex of calf, treatment-year category, and several interactions. Repeatabilities of weights and heights between birth and 90 d were .64 and .88; heritabilities were .22 and .30; genetic and phenotypic correlations were .53 and .73. A regression equation was estimated for each calf. From these 752 equations, heritabilities of initial weight, initial height, and rates of growth in weight and height were .53, .50, .44, and .19. Genetic correlations were .81; -.07; -.05; .26; .14; .84. Selection schemes for these traits in dairy cattle should consider that although weights and heights at birth and thereafter are highly and positively correlated genetically, as are gains, birth measurements and gains to 90 d may be uncorrelated.     

The Women's Health Curriculum by a problem-based learning method for medical students at the University of California, San Francisco

OBJECTIVES: Our objectives were to (1) expand and strengthen the women's health curriculum at the University of California, San Francisco, and (2) evaluate the responses of both medical students and faculty to this curriculum. STUDY DESIGN: A written evaluation of the curriculum in women's health was completed by both students and faculty. Variables studied included mean scores of cases, the overall course score, and the preferences of medical students for faculty specialty in teaching the small groups. RESULTS: The overall course evaluation score was 7.81 (range 1 to 10). For those students who had both faculty from internal medicine or family medicine and obstetrics and gynecology, there was a strong preference that obstetrician-gynecologists teach the majority of the cases. CONCLUSIONS: The new case-based curriculum in women's health was enthusiastically received by both medical students and faculty.     

Hydroxyapatite bone substitutes developed via replication of natural marine sponges

The application of synthetic cancellous bone has been shown to be highly successful when its architecture mimics that of the naturally interconnected trabeculae bone it aims to replace. The following investigation demonstrates the potential use of marine sponges as precursors in the production of ceramic based tissue engineered bone scaffolds. Three species of natural sponge, Dalmata Fina (Spongia officinalis Linnaeus, Adriatic Sea), Fina Silk (Spongia zimocca, Mediterranean) and Elephant Ear (Spongia agaricina, Caribbean) were selected for replication. A high solid content (80 %wt), low viscosity (126 mPas) hydroxyapatite slurry was developed, infiltrated into each sponge species and subsequently sintered, producing a scaffold structure that replicated pore architecture and interconnectivity of the precursor sponge. The most promising of the ceramic tissue engineered bone scaffolds developed, Spongia agaricina replicas, demonstrated an overall porosity of 56–61% with 83% of the pores ranging between 100 and 500 μm (average pore size 349 μm) and an interconnectivity of 99.92%.     

Forecasting solar radiation – Preliminary evaluation of an approach based upon the national forecast database

Our objective is to develop, and undertake a preliminary evaluation of a simple solar radiation forecast model using sky cover predictions from the National Digital Forecast Database as an input. This report describes the model and presents a limited evaluation of its performance against ground-measured and satellite-derived irradiances in Albany, New York.     

CO2 adsorption on carbon models of organic constituents of gas shale and coal

Imperfections of the organic matrix in coal and gas shales are modeled using defective and defect-free graphene surfaces to represent the structural heterogeneity and related chemical nature of these complex systems. Based upon previous experimental investigations that have validated the stability and existence of defect sites in graphene, plane-wave electronic density functional theory (DFT) calculations have been performed to investigate the mechanisms of CO(2) adsorption. The interactions of CO(2) with different surfaces have been compared, and the physisorption energy of CO(2) on the defective graphene adsorption site with one carbon atom missing (monovacancy) is approximately 4 times as strong as that on a perfect defect-free graphene surface, specifically, with a physisorption energy of ～210 meV on the monovacancy site compared to ～50 meV on a perfect graphene surface. The energy associated with the chemisorption of CO(2) on the monovacancy site is substantially stronger at ～1.72 eV. Bader charge, density of states, and vibrational frequency estimations were also carried out and the results indicate that the CO(2) molecule binds to the surface becoming more stable upon physisorption onto the monovacancy site followed by the original C═O bonds weakening upon CO(2) chemisorption onto the vacancy site.     

An Investigation into Zinc Diffusion and Tin Whisker Growth for Electroplated Tin Deposits on Brass

It is widely documented that whisker growth is more rapid for tin deposits on brass compared with deposits produced on other substrate materials, such as copper. As a result, studies investigating the effect of process variables on tin whisker formation are often conducted on brass substrates to take advantage of the increased whisker growth rates. Although it has been understood since the 1960s that the increased whisker growth results from zinc diffusion, to date there has not been any detailed analysis of the zinc/zinc oxide distribution at the surface of the tin deposit. Using a commercial bright tin electroplating bath, the formation of zinc oxide at the surface of tin deposits on brass has been investigated. Analyses show that zinc oxide is present on the surface of the deposit within 1 day of electroplating. During storage at room temperature, a network of zinc oxide is formed at the surface grain boundaries, the extent of which increases with time. The critical role that zinc surface diffusion plays in whisker growth for tin deposits on brass has been demonstrated by electrochemical oxidation of the tin shortly after electroplating. This develops a tin oxide film that is thicker than the native air-formed oxide and subsequently serves as a diffusion barrier to zinc surface diffusion, thereby mitigating whisker growth.     

A retina with parallel input and pulsed output, extractinghigh-resolution information

Animal eyes resolve images 10-100 times better than either the acceptance angle of a single photoreceptor or the center-to-center distance between neighboring photoreceptors. A new model of the fly's visual system emulates this improved performance, offering a different approach to subpixel resolution. That an animal without a cortex is capable of this performance suggests that high level computation is not involved. The model takes advantage of a photoreceptor cell's internal structure for capturing and transducing light. This organelle is a waveguide. Neurocircuitry exploits the waveguide's optical nonlinearities, namely the shoulder region of its gaussian, angular-sensitivity profile, to extract high resolution information from the visual scene. The receptive fields of optically disparate inputs overlap in space. Photoreceptor input is continuous rather than discretely sampled. The output of the integrating module is a signal proportional to the position of the target within the detector array. Input imbalance at the level of the photodiode modules is detected by circuitry connecting neighboring visual elements. A pulsed network of these connections forms a parallel array that segments edges of an object and continuously reports its position to the underlying layer of feature extractors, offering a new approach to real time processing with high resolution and reduced computational load.     

Quantitative experimental measurements of matrix cracking and delamination using acoustic emission

Quantitative measurements of the amplitude and angular variation of acoustic emission (AE) events due to matrix cracking and delamination in large quasi-isotropic composite plate specimens are reported. A procedure for determining the minimum specimen size necessary to make quantitative measurements is presented. The amplitude of AE events is quoted as the absolute surface displacement of different guided wave modes and can therefore be used as the input to forward models of the AE process. Matrix cracking events are found to be dominated by the S₀ guided wave mode and have a pronounced amplitude variation with angle. Events due to delamination growth are dominated by the A₀ guided wave mode and have no clear angular dependence.     

Preimplantation hormonal differences between the conception and non-conception menstrual cycles of 32 normal women

We compared daily urinary concentrations of oestrogen and progesterone metabolites in paired menstrual cycles (conception and non-conception) from 32 women. Volunteers with no known fertility problems were enrolled in the study at the time they began trying to become pregnant. They collected first-morning urine specimens and kept daily records of menstrual bleeding and sexual intercourse for 6 months or until they became clinically pregnant. Intercourse in non-conception cycles was close to the time of ovulation so that failure to conceive was caused by factors other than poorly timed intercourse. Compared with non-conception cycles, conception cycles had a steeper early luteal rise in progesterone and higher mid-luteal oestrogen and progesterone concentrations. These hormonal characteristics may be markers of better quality cycles, but because all these differences were in the luteal phase, we cannot rule out the possibility that the preimplantation embryo had stimulated early increases in steroid production. We propose an analysis strategy that could help support or refute the importance of preimplantation embryonic signalling, but our small sample size limits our own conclusions about this mechanism.