14,110 research outputs found
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
Mixed Initiative Systems for Human-Swarm Interaction: Opportunities and Challenges
Human-swarm interaction (HSI) involves a number of human factors impacting
human behaviour throughout the interaction. As the technologies used within HSI
advance, it is more tempting to increase the level of swarm autonomy within the
interaction to reduce the workload on humans. Yet, the prospective negative
effects of high levels of autonomy on human situational awareness can hinder
this process. Flexible autonomy aims at trading-off these effects by changing
the level of autonomy within the interaction when required; with
mixed-initiatives combining human preferences and automation's recommendations
to select an appropriate level of autonomy at a certain point of time. However,
the effective implementation of mixed-initiative systems raises fundamental
questions on how to combine human preferences and automation recommendations,
how to realise the selected level of autonomy, and what the future impacts on
the cognitive states of a human are. We explore open challenges that hamper the
process of developing effective flexible autonomy. We then highlight the
potential benefits of using system modelling techniques in HSI by illustrating
how they provide HSI designers with an opportunity to evaluate different
strategies for assessing the state of the mission and for adapting the level of
autonomy within the interaction to maximise mission success metrics.Comment: Author version, accepted at the 2018 IEEE Annual Systems Modelling
Conference, Canberra, Australi
Bosonization approach for "atomic collapse" in graphene
We study quantum electrodynamics with 2+1 dimensional massless Dirac fermion
around a Coulomb impurity. Around a large charge with atomic number Z > 137,
the QED vacuum is expected to collapse due to the strong Coulombic force. While
the relativistic quantum mechanics fails to make reliable predictions for the
fate of the vacuum, the heavy ion collision experiment also does not give clear
understanding of this system. Recently, the "atomic collapse" resonances were
observed on graphene where an artificial nuclei can be made. In this paper, we
present our nonperturbative study of the vacuum structure of the quasiparticles
in graphene with a charge impurity which contains multi-body effect using
bosonization method.Comment: 18 pages, 7 figure
Effect of cortisol on bovine oocytes maturation and further embryonic development after in vitro fertilization
Dissertação de Mestrado, Engenharia Zootécnica, 07 de dezembro de 2018, Universidade dos Açores.A maturação meiótica dos ovócitos e o posterior desenvolvimento embrionário após a fertilização são importantes requisitos fisiológicos para a sobrevivência das espécies. Desta forma, o objetivo do presente estudo foi avaliar os efeitos da hormona relacionada com o stress, cortisol, na maturação nuclear e desenvolvimento embrionário de oócitos bovinos após fecundação in vitro. Esta hormona (C₂₁H₃₀O₅) é um corticosteroide da família de esteroides, produzido pela parte superior da glândula supra-renal libertada quando um organismo está sob stress. Vários estudos demonstraram que o cortisol desempenha um papel vital inibindo as quinases extracelulares reguladas por sinal, necessárias para a progressão da prófase meiótica, essenciais para o início de eventos iniciais de maturação do ovócito de maturação meiótica (retomada da meiose), ovulação e posterior desenvolvimento embrionário. No presente estudo, para avaliar o efeito do cortisol na maturação dos ovócitos bovinos e desenvolvimento embrionário, foram recolhidos um total de 1439 óculos de vacas e novilhas púberes, abatidas em matadouros e maturados in vitro durante 24 horas com diferentes concentrações de cortisol (0 (controlo); 50 μM; 150 μM; 250 μM). Posteriormente, 412 oócitos foram desnudados, corados com aceto-orceína, sendo avaliado o desenvolvimento meiótico. Os outros 1027 foram submetidos à fecundação in vitro (FIV) e cultivados durante 9 dias, sendo avaliados nos dias 2, 6 e 9, para clivagem, mórula e blastocisto, respetivamente.
No controlo, 85% dos oócitos atingiram a metáfase II, diminuindo para 49, 32 e 15% para a concentração do cortisol (50, 150 e 250 μM, respetivamente). Para os embriões obtidos a partir dos oócitos submetidos à FIV, no grupo controlo, 28,3 ± 4,8% atingiram o estágio do blastocisto, enquanto que para as concentrações de cortisol esse valor diminuiu para 22,1 ± 5,4%, 15,4 ± 6,0% e 6,5 ± 2,1 % para 50, 150 e 250 μM de cortisol, respetivamente). Os resultados do presente estudo demonstraram claramente que o stress do animal e particularmente altas concentrações de cortisol prejudicam a maturação nuclear bovina, bem como o desenvolvimento embrionário posterior após a FIV.ABSTRACT: Oocyte meiotic maturation and further embryonic development after fertilization is the important physiological requirements for species survival. Herein, the aim of the study was to evaluate the effects of the stressful hormone, cortisol, on the nuclear maturation and embryo development of bovine oocytes after in vitro fertilization (IVF). This hormone (C₂₁H₃₀O₅) is a corticosteroid of the steroid family, produced by the upper part of the adrenal gland released when an organism is stressed. Therefore, several studies demonstrated that cortisol plays a vital role inhibiting the extracellular signal-regulated kinases, necessary for meiotic prophase progression, essential for onset of early events of meiotic maturation oocyte maturation (resumption of meiosis), ovulation and further embryo development. In the present study, to evaluate the effect of cortisol on bovine oocyte maturation and further embryonic development, a total of 1439 immature oocytes were collected from slaughtered cows and matured in vitro for 24 hours with different concentrations of cortisol (0 (control); 50 μM; 150 μM; 250 μM). Afterwards, 412 oocytes were denuded, dyed with aceto-orcein and evaluated for meiotic development. The other 1027 were submitted to IVF and cultured for 9 days, being evaluated on day 2, 6 and 9, for cleavage, morula and blastocyst, respectively.
In the control, 85 % of oocytes reached Metaphase II, decreasing to 49, 32 and 15 % for the concentration of the cortisol (50, 150, and 250 μM, respectively). For the embryos, obtained from the oocytes submitted to IVF, in the control group, 28.3 ± 4.8% reached the stage of blastocyst, while for the concentrations of cortisol this value decreased to 22.1 ± 5.4%, 15.4 ± 6.0% and 6.5 ± 2.1% for 50, 150 and 250 μM of cortisol, respectively). Results of the present study clearly demonstrated that animal’s stress and particularly high concentrations of cortisol impair bovine nuclear maturation as well as the further embryonic development after IVF
Intra-cone transition effect to magnetoconductivity in Dirac semimetal
We study the transport of the fermions with a small mass in the presence of
Coulomb impurities, which could be realized in slightly distorted Dirac
semimetals. Using the semiclassical Boltzmann equation, we derive the
relaxation times for two kinds of intra-cone transition process. One is due to
the effect of mass, and the other is due to the excited states in Landau levels
under the weaker magnetic field. Hence we derive the mass dependence and the
magnetic field dependence of the longitudinal magnetoconductivity in the
presence of parallel electric and magnetic fields.Comment: 20 pages, 5 figure
Exact Sampling of Stationary and Time-Reversed Queues
We provide the first algorithm that under minimal assumptions allows to
simulate the stationary waiting-time sequence of a single-server queue
backwards in time, jointly with the input processes of the queue (inter-arrival
and service times). The single-server queue is useful in applications of DCFTP
(Dominated Coupling From The Past), which is a well known protocol for
simulation without bias from steady-state distributions. Our algorithm
terminates in finite time assuming only finite mean of the inter-arrival and
service times. In order to simulate the single-server queue in stationarity
until the first idle period in finite expected termination time we require the
existence of finite variance. This requirement is also necessary for such idle
time (which is a natural coalescence time in DCFTP applications) to have finite
mean. Thus, in this sense, our algorithm is applicable under minimal
assumptions.Comment: 30 pages, 3 figures, Journa
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