145,159 research outputs found
Use of open-top chambers to study the effect of climate change in aquatic ecosystems
The aim of this research was to explore the possibility to use inexpensive open-top chambers (OTCs) as passive artificial warming devices in experimental aquatic studies. Our results show that OTCs give a significant temperature increase compared with the control. The measured increase (up to an average of 2.3°C) corresponds with predicted climatic warming. Due to their open top, the light quantity and quality is only minimally reduced. We found that OTCs are especially suited for studying the effect of climate change in small waters as the vertical temperature gradients remain unchanged. They can also easily be transported to remote environments. We discuss other advantages and disadvantages of these devices for aquatic studies and compare them with other warming devices
Life Cycle Assessment across the Food Supply Chain
The environmental impact is one of the major pillars of concerns when addressing the sustainability of food production and sustainable food consumption strategies.
To assess to what extent food production affects the environment, one needs to choose a proper environmental assessment tool. Different types of assessment tools have been developed to establish environmental indicators, which can be used to determine the environmental impact of livestock production systems or agricultural products. The environmen¬tal assessment tools can be divided into the area based or product based (Halberg et al., 2005). Area-based indicators are, for example, nitrate leached per hectare from a pig farm, and product-based indicators are, for example, global warming potential per kg pork (Dalgaard, 2007).
The area-based indicators are useful for evaluating farm emissions of nutrients such as nitrate that has an effect on the local environment. On the other hand, when considering the greenhouse gas emissions from the agricultural production, the product-based indicators are useful for evaluating the impact of food productions on the global environment (e. g., climate change) and have the advantage that in addition to emis-sions from the farms, emissions related to the production of input s (e.g., soybean and artificial fertilizer) and outputs (e.g., slurry exported to other farms) are also included. In that way it is easier to avoid pollution swapping, which means that the solving of one pollution problem creates a new (Dalgaard, 2007)
Recruitment, growth and mortality of an Antarctic hexactinellid sponge, Anoxycalyx joubini.
Polar ecosystems are sensitive to climate forcing, and we often lack baselines to evaluate changes. Here we report a nearly 50-year study in which a sudden shift in the population dynamics of an ecologically important, structure-forming hexactinellid sponge, Anoxycalyx joubini was observed. This is the largest Antarctic sponge, with individuals growing over two meters tall. In order to investigate life history characteristics of Antarctic marine invertebrates, artificial substrata were deployed at a number of sites in the southern portion of the Ross Sea between 1967 and 1975. Over a 22-year period, no growth or settlement was recorded for A. joubini on these substrata; however, in 2004 and 2010, A. joubini was observed to have settled and grown to large sizes on some but not all artificial substrata. This single settlement and growth event correlates with a region-wide shift in phytoplankton productivity driven by the calving of a massive iceberg. We also report almost complete mortality of large sponges followed over 40 years. Given our warming global climate, similar system-wide changes are expected in the future
Geoengineering as an alternative to mitigation: specification and dynamic implications
Geoengineering, i.e. the use of artificial techniques aiming at cooling the planet, is increasingly considered as a realistic alternative to emission mitigation. Several methods are promising for their capacity to quickly halt global warming at a moderate cost. Such cheap technologies might be very beneficial to countries profoundly affected by global warming. In this paper, I propose a dynamic model in which geoengineering is introduced as an alternative to mitigation. Contrary to abatement, geoengineering is fast and cheap, but requires a large initial investment in research and development. Within this framework, I confirm the fear which is common among geoengineering opponents: abatement is reduced if geoengineering is expected to be available in the future. The long-run implications of the model are also alarming as geoengineering will not be undertaken progressively. The sudden implementation of geoengineering, together with the sharp jump in temperature induced, may disturb climate equilibrium and fragile ecosystems. Furthermore, the availability of geoengineering will exacerbate intergenerational issues: while current generations will anticipate the use of geoengineering by increasing their emissions, future generations will have to reduce their emissions, to bear the cost of sustaining geoengineering for centuries and to suffer from its negative side-effects.Geoengineering; Abatement; Climate change; Global warming; R&D; Intergenerational issues
Cryoprotectant-free vitrification of human spermatozoa in new artificial seminal fluid
Vitrification is a new method that has been recently introduced in Assisted Reproduction Technique programs. The aim of this study was to design a new medium similar to normal human seminal fluid (SF), formulation artificial seminal fluid (ASF), and to compare the cryoprotective potency of this medium with SF and human tubal fluid (HTF) medium. Thirty normal ejaculates were processed with the swim-up technique and sperm suspensions were divided into four aliquots: (i) fresh sample (control); (ii) vitrification in HTF medium supplemented with 5 mg/mL human serum albumin and 0.25 mol sucrose (Vit HTF); (iii) vitrification with patients' SF (Vit SF); and (iv) vitrification in ASF (Vit ASF). After warming, sperm parameters of motility, viability, and morphology were analyzed using WHO criteria. Also, sperm pellets were fixed in 2.5% glutaraldehyde and processed for scanning electron microscopy and transmission electron microscopy observations. The results showed that progressive motility (46.09 ± 10.33 vs. 36.80 ± 13.75), grade A motility (36.59 ± 11.40 vs. 16.41 ± 11.24), and normal morphology (18.74 ± 8.35 vs. 11.85 ± 5.84) and viability (68.22 ± 10.83 vs. 60.86 ± 11.72) of spermatozoa were significantly higher in Vit ASF than in Vit HTF. All parameters were better in Vit ASF than in Vit SF, but only viability was significantly different (p = 0.006). After cryopreservation, deep invagination in cytoplasm and mechanically weak point sites and folded tail were commonly observed. But, this phenomenon was more significant in Vit HTF and Vit SF than in ASF (p < 0.05). In transmission electron microscopy evaluation, acrosome damage, plasma membrane loss, chromatin vacuolation, and disruption of mitochondria arrangement and structures were observed in all vitrified groups. Adherence of several tail sections together was also seen in all cryo groups. But this was seen more in Vit HTF and Vit SF than in ASF (p < 0.05). In conclusion, vitrification of human spermatozoa with ASF can effectively preserve the quality of sperm motility in comparison with Vit HTF. © 2016 American Society of Andrology and European Academy of Andrology
The Propagation of the Temperature Wave in Myocardium
The method for estimating the rate of propagation of temperature waves in the myocardium during hypothermia and hyperthermia of the heart based on noninvasive temperature control on the heart surface in conditions of cardiopulmonary bypass is proposed. The solution of the heat conduction equation for temperature waves in the myocardium is presented, which allows determining at each point of the medium the temperature change function, as well as the amplitude and phasing velocity of the temperature wave upon cooling and warming of the heart in conditions of cardiopulmonary bypass. The velocity distribution for the temperature field on the surface of the myocardium and in the depth of tissues during the hypothermia and hyperthermia of the heart is obtained.The thermographic images of the heart during controlled hypothermia and hyperthermia of the heart under cardiopulmonary bypass are obtained. The study of the conditions for spreading the temperature wave in the myocardium is performed, which allows to improve the means of intraoperative protection of vital organs and tools for controlling its effectiveness. The results of introduction of methods of non-invasive temperature control in cardiac surgery and the process of intraoperative cardiac protection in the temperature range from +10°С to +38°С are presented
Cosmotic, Aquatic. Exploring the potential of computational design in the preservation of aquatic ecotones
This paper looks at the possible role of computational design ecologically in the fight against the loss of the aquatic Ecotone. As climate change keeps altering all the natural aspects of our planet, and as our kind continues to sabotage its ecologies, coral reefs come in focus. Aquatically, coral reefs count as a fertile zone for biodiversity. Usually being the Ecotone between land and sea, these barriers host many species and riches. However, due to the excessive abuse caused by human activity be it world-wide pollution or direct human contact, these reefs are constantly bleaching and breaking. In 2016, the Architecture Association gathered a group of international architecture students and professionals in a visiting school in Jordan titled “Hyperbolic Reefs” looking at the possibility of recruiting new computational methods to preserve and possibly regenerate the Ecotone. It was considered that new simulation techniques along with parametric design could contribute into the assessment and prevention of the catastrophic results.
The two-week event was divided into chapters and was initiated by a series of lectures and discussions conducted by worldwide leading architects and experts who presented an important material to build upon. Then, the participants underwent a site visit to the coral reef of Al-Aqaba, collecting data, samples and media and recording insights and local testimonies. The third step of the experience was to assimilate the material and data and discuss openly the ways that computation could lead to a better coral life. Several software and tools were assigned to produce a design that would help attenuate the compromise of the coral reef through computation. An archive of data was produced and exhibited to the public.
The results of this brief exercise was a number of suggestions and future aspirations triggered solely towards revitalizing the Ecotone. Issues such as the abundance of irresponsible snorkeling and diving, many governments’ indifferent policies towards the coral reefs, global warming, climate change, coral bleaching and aquatic architecture were confronted through parametric projects ranging from purely architectural to abstract human capsules. Computational tools allowed the reproduction of the whole system digitally, the precise tracing of the corals’ patterns, dimensions and colors, simulation software predicted the role of light and heat in certain zones, and parametric programs provided an incomparable flexibility in the designing process, going completely in sync with the fragile and intricate aspect of a coral unit. 3D printing was also an integral factor in the presentation and study of the presented models.
This study’s scope was to expand the use of computation in a theoretical way to reach new and creative prospects, and to raise awareness to the situation of the coral reef and the risks facing its degradation
Potential climatic transitions with profound impact on Europe
We discuss potential transitions of six climatic subsystems with large-scale impact on Europe, sometimes denoted as tipping elements. These are the ice sheets on Greenland and West Antarctica, the Atlantic thermohaline circulation, Arctic sea ice, Alpine glaciers and northern hemisphere stratospheric ozone. Each system is represented by co-authors actively publishing in the corresponding field. For each subsystem we summarize the mechanism of a potential transition in a warmer climate along with its impact on Europe and assess the likelihood for such a transition based on published scientific literature. As a summary, the ‘tipping’ potential for each system is provided as a function of global mean temperature increase which required some subjective interpretation of scientific facts by the authors and should be considered as a snapshot of our current understanding. <br/
Turning on the heat: ecological response to simulated warming in the sea
Significant warming has been observed in every ocean, yet our ability to predict the consequences of oceanic warming on marine biodiversity remains poor. Experiments have been severely limited because, until now, it has not been possible to manipulate seawater temperature in a consistent manner across a range of marine habitats. We constructed a "hot-plate'' system to directly examine ecological responses to elevated seawater temperature in a subtidal marine system. The substratum available for colonisation and overlying seawater boundary layer were warmed for 36 days, which resulted in greater biomass of marine organisms and a doubling of space coverage by a dominant colonial ascidian. The "hot-plate'' system will facilitate complex manipulations of temperature and multiple stressors in the field to provide valuable information on the response of individuals, populations and communities to environmental change in any aquatic habitat
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