159 research outputs found
Revisiting the original reasons for excluding inorganic fertilizers in organic farming-Why the ban is not consistent with our current scientific understanding
This paper reviews the original reasons of the organic farming movement for excluding mineral (inorganic) fertilizers. In this paper, their theories and decision criteria for excluding use of inorganic fertilizers in crop production were revisited. Original reasons for banning inorganic fertilizers were subjected to scientific scrutiny, which was not possible when they were formulated 50-100 years ago due to limited knowledge of the soil-crop system. The original reasons were as follows: Rudolf Steiner, the founder of biodynamic farming, played down the physical role of plant nutrients and pointed out "flow of forces" as being most important for soils and crops. Eve Balfour and Albert Howard, founders of the Soil Association in England, claimed that inorganic fertilizer increases the breakdown of humus in soil, leading to a decline in soil fertility. Hans-Peter Rusch, the founder of biological organic farming, considered inorganic fertilizers to be imbalanced products not matching crop composition and not in synchrony with crop demand. When testing these historical statements as scientific hypotheses, older and modern scientific literature was used for validation. Steiner's belief about the "flow of forces" has not be verified using current methodologies. The claim by Balfour and Howard that inorganic fertilizers accelerate soil organic matter decomposition is not substantiated by data from long-term field experiments on carbon and nitrogen cycling in soil-plant systems. The statement by Rusch that inorganic fertilizers supply crops inappropriately is difficult to uphold, as the composition, time, and rate of application and the placement of fertilizer in soil or on foliage can be fully adapted to crop requirements. In light of accumulated scientific evidence, the original arguments lack validity. The decision to ban inorganic fertilizers in organic farming is inconsistent with our current scientific understanding. Scientific stringency requires principles found to be erroneous to be abandoned
Changes of Dentario Glanduleosae-Fagetum Forest Stand in Roztocze National Park, South Eastern Poland From 1946 To 2001
Roztocze Nation Park (RNP) is located in the central part of Roztocze, a hilly region in south-eastern Poland. The most important type of forest community in RNP is Dentario glandulosae-Fagetum. Potential and real vegetation, as well as forest stand maps were used to analyze changes of the age and species structure of beechwood stand from 1946 to 2001. Beechwoods were dominated by two species: fir and beech. During the last 50 years their proportion has entirely changed and the share of oldest groups of stand (over 120 years old) has increased significantly
Promoting the use of cycling as an environmentally and socially sustainable form of transport
Solar Cities Congress 2008 “Energising Sustainable Communities – Options for Our Future” THEME 3: Climate Change. Impact on Society and Culture. Sub Theme: planning and implementing holistic strategies for sustainable transport Abstract Promoting the use of cycling as an environmentally and socially sustainable form of transport. We need to reduce carbon emissions. We need to reduce fuel consumption. We need to reduce pollution. We need to reduce traffic congestion. As obesity levels and associated health problems in the developed nations continue to increase we need to adopt a healthier lifestyle. Few if any would argue with these statements. In fact many would consider these problems to be amongst the most urgent that our society faces. What if we had a vehicle that uses no fossil fuel to power it, creates no pollution, takes up far less space on the roads and promotes an active, healthy lifestyle. What if this machine would have energy efficiency levels 50 times greater than the car? This is a solution that is here, now and ready to go and many of us already own one. It is the humble bicycle. Although bicycle sales in Australia now outnumber car sales, bicycle use as a form of transport (as opposed to recreation) only constitutes around 3% to 4% of all trips. So, why are bicycles the forgotten form of transport if they promise to deliver the benefits that I have just outlined? This paper examines the underlying reasons for the relatively low use of bicycles as a means of transport. It identifies the areas of greatest potential for encouraging the use of the world’s most efficient form of transport. Tim Williams - May 200
Object-X: The Brightest Mid-IR Point Source in M33
We discuss the nature of the brightest mid-IR point source (which we dub
Object X) in the nearby galaxy M33. Although multi-wavelength data on this
object have existed in the literature for some time, it has not previously been
recognized as the most luminous mid-IR object in M33 because it is entirely
unremarkable in both optical and near-IR light. In the Local Group Galaxies
Survey, Object X is a faint red source visible in VRI and H-alpha but not U or
B. It was easily seen at JHK_s in the 2MASS survey. It is the brightest point
source in all four Spitzer IRAC bands and is also visible in the MIPS 24-micron
band. Its bolometric luminosity is 5x10^5 L_sun. The source is optically
variable on short time scales (tens of days) and is also slightly variable in
the mid-IR, indicating that it is a star. Archival photographic plates (from
1949 and 1991) show no optical source, so the star has been obscured for at
least half a century. Its properties are similar to those of the Galactic OH/IR
star IRC+10420 which has a complex dusty circumstellar structure resulting from
episodic low velocity mass ejections. We propose that Object X is a M>30 M_sun
evolved star obscured in its own dust ejected during episodic mass loss events
over at least half a century. It may emerge from its current ultra-short
evolutionary phase as a hotter post-RSG star analogous to M33 Var A. The
existence and rarity of such objects can be an important probe of a very brief
yet eventful stellar evolutionary phase.Comment: 20 pages, 10 figures. Accepted for publication by Ap
Mass estimates for visual binaries with incomplete orbits
The problem of estimating the total mass of a visual binary when its orbit is
incomplete is treated with Bayesian methods. The posterior mean of a mass
estimator is approximated by a triple integral over orbital period, time of
periastron and orbital eccentricity. This reduction to 3-D from the 7-D space
defined by the conventional Campbell parameters is achieved by adopting the
Thiele-Innes elements and exploiting the linearity with respect to the four
Thiele-Innes constants. The formalism is tested on synthetic observational data
covering a variable fraction of a model binary's orbit. The posterior mean of
the mass estimator is numerically found to be unbiased when the data cover >
40% of the orbit.Comment: 12 pages, 13 figures. Revised version accepted by Astronomy and
Astrophysic
If Archimedes would have known functions
These are notes and slides from a Pecha-Kucha talk given on March 6, 2013.
The presentation tinkered with the question whether calculus on graphs could
have emerged by the time of Archimedes, if the concept of a function would have
been available 2300 years ago. The text first attempts to boil down discrete
single and multivariable calculus to one page each, then presents the slides
with additional remarks and finally includes 40 "calculus problems" in a
discrete or so-called 'quantum calculus' setting. We also added some sample
Mathematica code, gave a short overview over the emergence of the function
concept in calculus and included comments on the development of calculus
textbooks over time.Comment: 31 pages, 36 figure
The effects of CO2, climate and land-use on terrestrial carbon balance, 1920-1992: An analysis with four process-based ecosystem models
The concurrent effects of increasing atmospheric CO2 concentration, climate variability, and cropland establishment and abandonment on terrestrial carbon storage between 1920 and 1992 were assessed using a standard simulation protocol with four process-based terrestrial biosphere models. Over the long-term(1920–1992), the simulations yielded a time history of terrestrial uptake that is consistent (within the uncertainty) with a long-term analysis based on ice core and atmospheric CO2 data. Up to 1958, three of four analyses indicated a net release of carbon from terrestrial ecosystems to the atmosphere caused by cropland establishment. After 1958, all analyses indicate a net uptake of carbon by terrestrial ecosystems, primarily because of the physiological effects of rapidly rising atmospheric CO2. During the 1980s the simulations indicate that terrestrial ecosystems stored between 0.3 and 1.5 Pg C yr−1, which is within the uncertainty of analysis based on CO2 and O2 budgets. Three of the four models indicated (in accordance with O2 evidence) that the tropics were approximately neutral while a net sink existed in ecosystems north of the tropics. Although all of the models agree that the long-term effect of climate on carbon storage has been small relative to the effects of increasing atmospheric CO2 and land use, the models disagree as to whether climate variability and change in the twentieth century has promoted carbon storage or release. Simulated interannual variability from 1958 generally reproduced the El Niño/Southern Oscillation (ENSO)-scale variability in the atmospheric CO2 increase, but there were substantial differences in the magnitude of interannual variability simulated by the models. The analysis of the ability of the models to simulate the changing amplitude of the seasonal cycle of atmospheric CO2 suggested that the observed trend may be a consequence of CO2 effects, climate variability, land use changes, or a combination of these effects. The next steps for improving the process-based simulation of historical terrestrial carbon include (1) the transfer of insight gained from stand-level process studies to improve the sensitivity of simulated carbon storage responses to changes in CO2 and climate, (2) improvements in the data sets used to drive the models so that they incorporate the timing, extent, and types of major disturbances, (3) the enhancement of the models so that they consider major crop types and management schemes, (4) development of data sets that identify the spatial extent of major crop types and management schemes through time, and (5) the consideration of the effects of anthropogenic nitrogen deposition. The evaluation of the performance of the models in the context of a more complete consideration of the factors influencing historical terrestrial carbon dynamics is important for reducing uncertainties in representing the role of terrestrial ecosystems in future projections of the Earth system
The effectiveness of public health interventions to reduce the health impact of climate change:a systematic review of systematic reviews
Climate change is likely to be one of the most important threats to public health in the coming years. Yet despite the large number of papers considering the health impact of climate change, few have considered what public health interventions may be of most value in reducing the disease burden. We aimed to evaluate the effectiveness of public health interventions to reduce the disease burden of high priority climate sensitive diseases
The Cowl - v.30 - Nov 02, 1977
The Cowl - student newspaper of Providence College. Volume 30 - November 2, 1977. 12 pages. Note: The volume number printed on the banner page of this issue (XXX) duplicates the volume number for the 1967-68 academic year. There is no issue number for this issue
The History of Astrometry
The history of astrometry, the branch of astronomy dealing with the positions
of celestial objects, is a lengthy and complex chronicle, having its origins in
the earliest records of astronomical observations more than two thousand years
ago, and extending to the high accuracy observations being made from space
today. Improved star positions progressively opened up and advanced fundamental
fields of scientific enquiry, including our understanding of the scale of the
solar system, the details of the Earth's motion through space, and the
comprehension and acceptance of Newtonianism. They also proved crucial to the
practical task of maritime navigation. Over the past 400 years, during which
positional accuracy has improved roughly logarithmically with time, the
distances to the nearest stars were triangulated, making use of the extended
measurement baseline given by the Earth's orbit around the Sun. This led to
quantifying the extravagantly vast scale of the Universe, to a determination of
the physical properties of stars, and to the resulting characterisation of the
structure, dynamics and origin of our Galaxy. After a period in the middle
years of the twentieth century in which accuracy improvements were greatly
hampered by the perturbing effects of the Earth's atmosphere, ultra-high
accuracies of star positions from space platforms have led to a renewed advance
in this fundamental science over the past few years.Comment: 52 pages, 14 figures. To appear in The European Physical Journal:
Historical Perspectives on Contemporary Physic
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