759 research outputs found
Fertility and fertility management in thirteen well-established organic dairy herds in the UK
This report was presented at the UK Organic Research 2002 Conference of the Colloquium of Organic Researchers (COR).
Milk production and breeding records from thirteen organic dairy herds were collected between January 1997 and December 1999. Mean lactation yields in the herds ranged from 5127 kg to 7031 kg. Whilst seasonality of calving varied widely between herds, a majority of them (6/13) were autumn calving. Mean calving to first service interval was 80 days (range 68 to 97), and mean calving interval was 385 days (range 370 to 413). The mean number of services per conception was 2.3 (range 1.6 to 3.1). Overall culling rates and culling rates for fertility related problems were at 15.8% and 5.4%, respectively. A preliminary study of selected breeding periods of cows that had a subsequent calving revealed no significant differences in calving interval between high or low yielding cows or between cows with different calving month or parit
The productivity of organic dairy herds
This report was presented at the UK Organic Research 2002 Conference. Organically managed ruminant systems place particular emphasis on maximising production from forage. Therefore, it is important that efficiency measures take full account of forage inputs. The Livestock Production Efficiency Calculator (LPEC) calculates the total metabolisable energy (ME) required by livestock and estimates forage inputs as the difference between total requirement and that supplied by other measured feeds. Productivity is expressed in terms of output (£) minus other valued inputs (£) per unit of forage ME. Estimates of production parameters were used to produce productivity indices for thirteen organic dairy herds. The productivity of herds was compared, and sensitivity analyses were conducted to examine the potential impact of a number of economic and production scenario. The relationships between yield, fertility, culling and herd productivity were examined. The advantages of this productivity analysis of organic production systems is that full account is taken of the most important input i.e. grazed and conserved forage and that all of the determinants of productivity and their interactions are considered
DNA sequence of the mouse H-2Dd transplantation antigen gene
The inbred BALB/c mouse has three transplantation antigens, H2-Kd, H2-Ld, and H2-Dd. We present the complete nucleotide sequence of the H2-Dd gene as well as 777 residues of previously unpublished H-2Dd protein sequence. These data complete the sequences of all the BALB/c transplantation antigen genes and permit detailed comparison with each other and with their counterparts from the inbred C57BL/10 mouse. Transplantation antigens may differ from one another by as much as 5%-15% of their amino acid sequence for the external domains. These extensive differences may arise by gene conversion. The H-2D region of the BALB/c mouse encodes the H2-Dd and the H2-Ld genes. Serologic data suggest that at least two additional transplantation antigen molecules, H2-Rd and H2-Md, are encoded in the H-2D region of the major compatibility complex. Paradoxically, gene cloning studies have only identified the H2-Dd and the H2-Ld genes in the H-2D region. A complete DNA sequence of the H2-Dd gene shows that a variety of alternative splice sites exist throughout the gene, which may lead to additional gene products and may explain the multiplicity of H-2D-encoded polypeptides
Preliminary measurements of the edge magnetic field pitch from 2-D Doppler backscattering in MAST and NSTX-U
The Synthetic Aperture Microwave Imaging (SAMI) system is a novel diagnostic consisting of an array of 8 independently-phased antennas. At any one time, SAMI operates at one of 16 frequencies in the range 10-34.5GHz. The imaging beam is steered in software post-shot to create a picture of the entire emission surface. In SAMI’s active probing mode of operation, the plasma edge is illuminated with a monochromatic source and SAMI reconstructs an image of the Doppler back-scattered (DBS) signal. By assuming that density fluctuations are extended along magnetic field lines, and knowing that the strongest back-scattered signals are directed perpendicular to the density fluctuations, SAMI’s 2-D DBS imaging capability can be used to measure the pitch of the edge magnetic field. In this paper we present preliminary pitch angle measurements obtained by SAMI on the Mega-Amp Spherical Tokamak (MAST) at Culham Centre for Fusion Energy and on the National Spherical Torus Experiment Upgrade at Princeton Plasma Physics Laboratory. The results demonstrate encouraging agreement between SAMI and other independent measurements
Stage-specific sensitivity to p53 restoration during lung cancer progression
2011 May 25Tumorigenesis is a multistep process that results from the sequential accumulation of mutations in key oncogene and tumour suppressor pathways. Personalized cancer therapy that is based on targeting these underlying genetic abnormalities presupposes that sustained inactivation of tumour suppressors and activation of oncogenes is essential in advanced cancers. Mutations in the p53 tumour-suppressor pathway are common in human cancer and significant efforts towards pharmaceutical reactivation of defective p53 pathways are underway1, 2, 3. Here we show that restoration of p53 in established murine lung tumours leads to significant but incomplete tumour cell loss specifically in malignant adenocarcinomas, but not in adenomas. We define amplification of MAPK signalling as a critical determinant of malignant progression and also a stimulator of Arf tumour-suppressor expression. The response to p53 restoration in this context is critically dependent on the expression of Arf. We propose that p53 not only limits malignant progression by suppressing the acquisition of alterations that lead to tumour progression, but also, in the context of p53 restoration, responds to increased oncogenic signalling to mediate tumour regression. Our observations also underscore that the p53 pathway is not engaged by low levels of oncogene activity that are sufficient for early stages of lung tumour development. These data suggest that restoration of pathways important in tumour progression, as opposed to initiation, may lead to incomplete tumour regression due to the stage-heterogeneity of tumour cell populations.National Cancer Institute (U.S.) (Cancer Center Support Grant P30-CA14051)American Cancer Society (New England Area Fellow)Leukemia & Lymphoma Society of America (Fellow)Massachusetts Institute of Technology. Undergraduate Research Program (John Reed Fund)Damon Runyon Cancer Research Foundation (Merck Fellow)Genentech, Inc. (Postdoctoral Fellow)Howard Hughes Medical Institut
Induced Anisotropy in Liquids
The spectra of depolarized light scattered from Isotropic
and anisotropic liquids were Investigated In order to obtain information
on both the reorientational and collisional motions of the liquid molecules. The liquid spectra taken at 22°C on a Coderg spectrometer (1 cm. ^-1 slits) were decomposed into relaxational and collisional components using least squares fitting techniques. Integrated Intensities and depolarization ratios in the zero em -1 (1 cm ^-1= 3 x 10^10 hz.) frequency sjift region as well as in the less than 5 cm^-1 region are reported. The Isotropic liquid spectra from 5 cm ^-1 consisted of a narrow Lorentz and a broader coliisional component which was exponential at shifts > 10 cm^-1. The anisotropic spectra also consisted of relaxational and collisional components; however, the Integrated Intensity of the relaxational and the collisional components Increased by a factor of 20 and 10 respectively from the isotropic liquids. A simple model based on frame distortion Induced anisotropy was constructed to predict the relative Intensity ratios of the collisional component for both Isotropic and anisotropic liquids. The relaxation time of the Lorentz component was Interpreted for both isotropic and anisotropic liquids as being the average time between collisions. It was, found to vary as μ^((3/4)/p), where μ is the reduced mass of two colliding molecules and p the liquid density. The line width parameter 1/vo for all the collisional components was interpreted as being a measure of the duration
of a collision and was found to vary as μ^1/2 independent of the density P. ThesisMaster of Science (MSc
AN EXPERIMENTAL STUDY OF USER SATISFACTION WITH MULTIPLE DIALOG MODES
This paper investigated a normative theory that says computer users have different dialog needs depending on their level of experience in using a computer. It hypothesizes that the answer to satisfy the needs of a mixed population is to have multiple dialog modes that the user is free to choose from and switch between as required. The hypotheses that experts and novices would be more satisfied with multiple dialog modes than with just one mode were tested empirically in a controlled laboratory setting. Both novice and expert computer users used one of three types of user-system interfaces (menu, command language, or both modes) to solve the same database problem. Results showed that those with both types of dialog modes were more satisfied and performed better than the command language group. However, they were statistically equal to the menu group, while the menu group\u27s satisfaction rating and performance scores were slightly better. It was concluded that the subject\u27s choice of dialog mode, when both modes were available, and their satisfaction with a dialog mode have more to do with past experience and preference than with the difference in expert and novice problem solving strategies
A process-based model of conifer forest structure and function with special emphasis on leaf lifespan
We describe the University of Sheffield Conifer Model (USCM), a process-based approach for simulating conifer forest carbon, nitrogen, and water fluxes by up-scaling widely applicable relationships between leaf lifespan and function. The USCM is designed to predict and analyze the biogeochemistry and biophysics of conifer forests that dominated the ice-free high-latitude regions under the high pCO2 “greenhouse” world 290–50 Myr ago. It will be of use in future research investigating controls on the contrasting distribution of ancient evergreen and deciduous forests between hemispheres, and their differential feedbacks on polar climate through the exchange of energy and materials with the atmosphere. Emphasis is placed on leaf lifespan because this trait can be determined from the anatomical characteristics of fossil conifer woods and influences a range of ecosystem processes. Extensive testing of simulated net primary production and partitioning, leaf area index, evapotranspiration, nitrogen uptake, and land surface energy partitioning showed close agreement with observations from sites across a wide climatic gradient. This indicates the generic utility of our model, and adequate representation of the key processes involved in forest function using only information on leaf lifespan, climate, and soils
Panentheism and the undoing of disenchantment
In this article I draw on historical and conceptual arguments to show, first, that disenchantment and the influential view of the relationship between science and religion to which disenchantment gives rise are rooted in the metaphysics of theism. I then introduce the alternative metaphysical position of panentheism and identify Jungian psychology as an important, if implicit, mid-twentieth-century instance of panentheistic thought. Using the example of Jungian psychology, I demonstrate how the viewpoint of panentheism undoes the implications of disenchantment for the relationship between science and religion, promoting greater opportunities for dialogue and reconciliation between science and religion. I note, however, that these closer relations may depend on understanding science and religion differently from how they are understood under disenchantment. While the original tension between science and religion is eased, another tension – between panentheistic and disenchanted understandings of science and religion – is exposed. I conclude by reflecting on some implications of this discussion for sociology
Trials and tribulations of recruiting 2,000 older women onto a clinical trial investigating falls and fractures : vital D study
Background Randomised, placebo-controlled trials are needed to provide evidence demonstrating safe, effective interventions that reduce falls and fractures in the elderly. The quality of a clinical trial is dependent on successful recruitment of the target participant group. This paper documents the successes and failures of recruiting over 2,000 women aged at least 70 years and at higher risk of falls or fractures onto a placebo-controlled trial of six years duration. The characteristics of study participants at baseline are also described for this study.Methods The Vital D Study recruited older women identified at high risk of fracture through the use of an eligibility algorithm, adapted from identified risk factors for hip fracture. Participants were randomised to orally receive either 500,000 IU vitamin D3 (cholecalciferol) or placebo every autumn for five consecutive years. A variety of recruitment strategies were employed to attract potential participants.Results Of the 2,317 participants randomised onto the study, 74% (n = 1716/2317) were consented onto the study in the last five months of recruiting. This was largely due to the success of a targeted mail-out. Prior to this only 541 women were consented in the 18 months of recruiting. A total of 70% of all participants were recruited as a result of targeted mail-out. The response rate from the letters increased from 2 to 7% following revision of the material by a public relations company. Participant demographic or risk factor profile did not differ between those recruited by targeted mail-outs compared with other methods.Conclusion The most successful recruitment strategy was the targeted mail-out and the response rate was no higher in the local region where the study had extensive exposure through other recruiting strategies. The strategies that were labour-intensive and did not result in successful recruitment include the activities directed towards the GP medical centres. Comprehensive recruitment programs employ overlapping strategies simultaneously with ongoing assessment of recruitment rates. In our experience, and others direct mail-outs work best although rights to privacy must be respected. <br /
- …
