655 research outputs found
The effect of organic farming systems on aspects of the environment - desk study OF0123
Key Conclusions
1. The crop rotations of organic systems maintain landscape diversity and biodiversity whilst the maintenance of field boundaries on organic units produces benefits to a wide range of organisms.
2. Inorganic nitrogen fertilisation and herbicide treatments of conventionally managed grassland has reduced the floral diversity of permanent pastures and maintained the low diversity of re-seeded pastures, greatly reducing their value as wildlife habitats.
3. Pesticide use is responsible for the removal of food sourcesfor birds and mammals in the form of weeds and invertebrates, as well as removing whole populations of potentially beneficial insects.
4. The majority of water pollution incidents from farms are caused during storage and spreading of cattle and pig slurries. A higher proportion of organic cattle and virtually all organic pigs are kept on solid manure systems and therefore are les of a risk.
5. The nitrogen balance of individual 'conventional' and 'organic' systems will depend greatly on the circumstances and management practices of the individual farms. Consequently it is not possible to generalise that one system is always better than the other in terms of nitrate leaching risk. With this qualification the literature does indicate that generally, organic systems offer less risk of nitrate leaching.
6. Organic systems are less likely to cause loss of phosphate into surface and ground waters. Both leaching and loss in eroded soil are likely to be reduced.
7. Organic management practicess such as rotations, the regular use of manures and non-use of pesticides usually increase soil organic matter contents.
8. Organic practices are likely to increase earthworm numbers compared to conventional systems. The increased numbers are universally acknowledged to benefit soil fertility although such effects are difficult to quantify.
9. Soil erosion is less of a problem on organic units.
10. Accumulations of copper and zinc in soils are much reduced in organic systems because organic pig and poultry producers do not supplement feeds with these metals as growth promoters. Copper fungicides are more widely used on organic farms and their use should be carefully monitored to prevent harmful effects.
11. The practices adopted by organic farmers can reduce emissions of nitrous oxide and methane. Ammonia emissions will not necessarily be less in organic than in conventional farming.
12. Organic farmers adopt practices which benefit the landscape. They maintain and introduce features largely because they are required by the Organic Standards to do so. They introduce such management practices because they are technically necessary for successful organic production
Masses of Neutron Stars in High-Mass X-ray Binaries with Optical Astrometry
Determining the type of matter that is inside a neutron star (NS) has been a
long-standing goal of astrophysics. Despite this, most of the NS equations of
state (EOS) that predict maximum masses in the range 1.4-2.8 solar masses are
still viable. Most of the precise NS mass measurements that have been made to
date show values close to 1.4 solar masses, but a reliable measurement of an
over-massive NS would constrain the EOS possibilities. Here, we investigate how
optical astrometry at the microarcsecond level can be used to map out the
orbits of High-Mass X-ray Binaries (HMXBs), leading to tight constraints on NS
masses. While previous studies by Unwin and co-workers and Tomsick and
co-workers discuss the fact that the future Space Interferometry Mission should
be capable of making such measurements, the current work describes detailed
simulations for 6 HMXB systems, including predicted constraints on all orbital
parameters. We find that the direct NS masses can be measured to an accuracy of
2.5% (1-sigma) in the best case (X Per), to 6.5% for Vela X-1, and to 10% for
two other HMXBs.Comment: 8 pages, Accepted by Ap
Basic and applied renal and gastrointestinal physiology and pathophysiology
In my statement below, the number and scope of the publications chosen are intended to
represent the different elements of my research work and studies over the years; they are
highlighted in yellow by Curriculum Vitae (CV) order number in the following text that
outlines the main topics of investigation and tries to summarise my published work and
place it in a wider context.
To lend further support to my scientific contributions and publication record, I have also
referred, to and referenced, other relevant publications as additional examples, and as they
are listed by order number in my accompanying CV (as CV# in parentheses) for crossreference.
The papers cited and included in the listed (at the end and included in my submission in pdf
format) and representative 27 publications are all conjoint work to which I have made a
significant contribution in deciding the topic for study, in the experimental planning and
execution, in writing up the findings for publication, and in providing financial support.
I have never insisted on any specific author order for myself, considering it a team effort,
and I have always given due recognition to the lead author, a research student, postdoctoral
fellow or senior collaborator, without whom the work could not have been
completed
All-Sky Near Infrared Space Astrometry
Gaia is currently revolutionizing modern astronomy. However, much of the
Galactic plane, center and the spiral arm regions are obscured by interstellar
extinction, rendering them inaccessible because Gaia is an optical instrument.
An all-sky near infrared (NIR) space observatory operating in the optical NIR,
separated in time from the original Gaia would provide microarcsecond NIR
astrometry and millimag photometry to penetrate obscured regions unraveling the
internal dynamics of the Galaxy.Comment: 7 page
Is a gene-centric human proteome project the best way for proteomics to serve biology?
With the recent developments in proteomic technologies, a complete human
proteome project (HPP) appears feasible for the first time. However, there is
still debate as to how it should be designed and what it should encompass. In
"proteomics speak", the debate revolves around the central question as to
whether a gene-centric or a protein-centric proteomics approach is the most
appropriate way forward. In this paper, we try to shed light on what these
definitions mean, how large-scale proteomics such as a HPP can insert into the
larger omics chorus, and what we can reasonably expect from a HPP in the way it
has been proposed so far
Science Impacts of the SPHEREx All-Sky Optical to Near-Infrared Spectral Survey: Report of a Community Workshop Examining Extragalactic, Galactic, Stellar and Planetary Science
SPHEREx is a proposed SMEX mission selected for Phase A. SPHEREx will carry
out the first all-sky spectral survey and provide for every 6.2" pixel a
spectra between 0.75 and 4.18 m [with R41.4] and 4.18 and 5.00
m [with R135]. The SPHEREx team has proposed three specific science
investigations to be carried out with this unique data set: cosmic inflation,
interstellar and circumstellar ices, and the extra-galactic background light.
It is readily apparent, however, that many other questions in astrophysics and
planetary sciences could be addressed with the SPHEREx data. The SPHEREx team
convened a community workshop in February 2016, with the intent of enlisting
the aid of a larger group of scientists in defining these questions. This paper
summarizes the rich and varied menu of investigations that was laid out. It
includes studies of the composition of main belt and Trojan/Greek asteroids;
mapping the zodiacal light with unprecedented spatial and spectral resolution;
identifying and studying very low-metallicity stars; improving stellar
parameters in order to better characterize transiting exoplanets; studying
aliphatic and aromatic carbon-bearing molecules in the interstellar medium;
mapping star formation rates in nearby galaxies; determining the redshift of
clusters of galaxies; identifying high redshift quasars over the full sky; and
providing a NIR spectrum for most eROSITA X-ray sources. All of these
investigations, and others not listed here, can be carried out with the nominal
all-sky spectra to be produced by SPHEREx. In addition, the workshop defined
enhanced data products and user tools which would facilitate some of these
scientific studies. Finally, the workshop noted the high degrees of synergy
between SPHEREx and a number of other current or forthcoming programs,
including JWST, WFIRST, Euclid, GAIA, K2/Kepler, TESS, eROSITA and LSST.Comment: Report of the First SPHEREx Community Workshop,
http://spherex.caltech.edu/Workshop.html , 84 pages, 28 figure
Exo-C: a probe-scale space observatory for direct imaging and spectroscopy of extrasolar planetary systems
"Exo-C" is NASAs first community study of a modest aperture space telescope mission that is optimized for high contrast observations of exoplanetary systems. The mission will be capable of taking optical spectra of nearby exoplanets in reflected light, discovering previously undetected planets, and imaging structure in a large sample of circumstellar disks. It will obtain unique science results on planets down to super-Earth sizes and serve as a technology pathfinder toward an eventual flagship-class mission to find and characterize habitable Earth-like exoplanets. We present the mission/payload design and highlight steps to reduce mission cost/risk relative to previous mission concepts. Key elements are an unobscured telescope aperture, an internal coronagraph with deformable mirrors for precise wavefront control, and an orbit and observatory design chosen for high thermal stability. Exo-C has a similar telescope aperture, orbit, lifetime, and spacecraft bus requirements to the highly successful Kepler mission (which is our cost reference). Much of the needed technology development is being pursued under the WFIRST coronagraph study and would support a mission start in 2017, should NASA decide to proceed. This paper summarizes the study final report completed in March 2015.United States. National Aeronautics and Space Administration. Astrophysics Divisio
A Mossbauer study of gamma-irradiated organotin-stabilised poly(vinylchloride).
Sn Mossbauer spectroscopy has been used to study the nuclear environment of three organotin stabilisers present in PVC, after exposure of the polymer to gamma-irradiation up to a maximum dose of 200 kGy, in order to identify the tin-containing degradation products which could migrate into foodstuffs in contact with the polymer. Chapter One of this thesis covers the aspects of the degradation and stabilisation of organotin-stabilised PVC which may influence the chemical nature of the tin-containing degradation products resulting from gamma-irradiation of the polymer. Chapter Two contains a description of the theory of the Mossbauer effect and the instrumentation and computational methods for recording and processing Mossbauer data. Chapter Three is concerned with the effect of gamma-irradiation, at doses in excess of food irradiation applications, in order to identify the terminal tin-containing degradation products of the stabilisers. In Chapter Four, evidence for the progressive degradation of organotin stabilisers upon increasing irradiation exposure is presented and intermediate degradation products are proposed. A mechanism for the degradation of stabilisers is suggested. In Chapter Five, evidence for dealkylated tin-containing degradation products in irradiated organotin-stabilised PVC is presented. Chapter Six involves the application of the Debye model of solids to variable temperature Mossbauer data for two organotin stabiliser degradation products, dibutyltin dichloride and stannic chloride, in PVC. A significant change in recoilless fraction is shown to occur when these compounds are dispersed in PVC compared with those of the pure compounds. This is attributed to changes in coordination number of the tin atom upon dispersion in PVC, and has a significant effect upon the relative sensitivity of the technique to the degradation products. Chapter Seven contains a comparison of the degradation processes occurring in thermal and gamma-irradiation degradation of organotin-stabilised PVC.It is shown that degradation.of the stabiliser during gamma-irradation is much more severe. In Chapter Eight, an appraisal of the key experimental results and their implications for the gamma-irradiation sterilisation of polymer-packaged foodstuffs is presented
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