1,695 research outputs found
Vascularization of the trachea in the bottlenose dolphin: Comparison with bovine and evidence for evolutionary adaptations to diving
The rigid structure of the mammalian trachea is functional to maintain constant patency and airflow during breathing, but no gas exchange takes place through its walls. The structure of the organ in dolphins shows increased rigidity of the tracheal cartilaginous rings and the presence of vascular lacunae in the submucosa. However, no actual comparison was ever made between the size and capacity of the vascular lacunae of the dolphin trachea and the potentially homologous structures of terrestrial mammals. In the present study, the extension of the lacunae has been compared between the bottlenose dolphin and the bovine, a closely related terrestrial Cetartiodactyla. Our results indicate that the extension of the blood spaces in the submucosa of dolphins is over 12 times larger than in the corresponding structure of the bovines. Furthermore, a microscopic analysis revealed the presence of valve-like structures in the walls of the cetacean lacunae. The huge difference in size suggests that the lacunae are not merely a product of individual physiological plasticity, but may constitute a true adaptive evolutionary character, functional to life in the aquatic environment. The presence of valve-like structures may be related to the regulation of blood flow, and curtail excessive compression under baric stress at depth
Reconstruction of Markovian Master Equation parameters through symplectic tomography
In open quantum systems, phenomenological master equations with unknown
parameters are often introduced. Here we propose a time-independent procedure
based on quantum tomography to reconstruct the potentially unknown parameters
of a wide class of Markovian master equations. According to our scheme, the
system under investigation is initially prepared in a Gaussian state. At an
arbitrary time t, in order to retrieve the unknown coefficients one needs to
measure only a finite number (ten at maximum) of points along three
time-independent tomograms. Due to the limited amount of measurements required,
we expect our proposal to be especially suitable for experimental
implementations.Comment: 7 pages, 3 figure
A tomographic approach to non-Markovian master equations
We propose a procedure based on symplectic tomography for reconstructing the
unknown parameters of a convolutionless non-Markovian Gaussian noisy evolution.
Whenever the time-dependent master equation coefficients are given as a
function of some unknown time-independent parameters, we show that these
parameters can be reconstructed by means of a finite number of tomograms. Two
different approaches towards reconstruction, integral and differential, are
presented and applied to a benchmark model made of a harmonic oscillator
coupled to a bosonic bath. For this model the number of tomograms needed to
retrieve the unknown parameters is explicitly computed.Comment: 15 pages, 2 figure
Multi-criteria analysis applied to multi-objective optimal pump scheduling in water systems
This work presents a multi-criteria-based approach to automatically select specific non-dominated solutions from a Pareto front previously obtained using multi-objective optimization to find optimal solutions for pump control in a water supply system. Optimal operation of pumps in these utilities is paramount to enable water companies to achieve energy efficiency in their systems. The Fuzzy Technique for Order of Preference by Similarity to Ideal Solution (FTOPSIS) is used to rank the Pareto solutions found by the Non-Dominated Sorting Genetic Algorithm (NSGA-II) employed to solve the multi-objective problem. Various scenarios are evaluated under leakage uncertainty conditions, resulting in fuzzy solutions for the Pareto front. This paper shows the suitability of the approach for quasi real-world problems. In our case-study, the obtained solutions for scenarios including leakage represent the best trade-off among the optimal solutions, under some considered criteria, namely, operational cost, operational lack of service, pressure uniformity and network resilience. Potential future developments could include the use of clustering alternatives to evaluate the goodness of each solution under the considered evaluation criteria
Arianna: towards a new paradigm for assistive technology at home
Providing elderly and people with special needs to retain their independence
as long as possible is one of the biggest challenges of the society of
tomorrow. Teseo, a startup company spinoff from the University of Genoa, aims
at accelerating the transition towards a sustainable healthcare system. Teseo's
first concept and product, Arianna, allows for the automated recognition of
activities of daily living at home and acts as a wellbeing and healthcare
personalized assistant. This abstract outlines the main concepts underlying its
features and capabilities.Comment: Paper accepted at the Eight Italian Forum on Ambient Assisted Living
(ForItAAL 2017
Back to Water: Signature of Adaptive Evolution in Cetacean Mitochondrial tRNAs
Abstract
The mitochondrion is the power plant of the eukaryotic cell, and tRNAs are the fundamental components of its translational machinery. In the present paper, the evolution of mitochondrial tRNAs was investigated in the Cetacea, a clade of Cetartiodactyla that retuned to water and thus had to adapt its metabolism to a different medium than that of its mainland ancestors. Our analysis focussed on identifying the factors that influenced the evolution of Cetacea tRNA double-helix elements, which play a pivotal role in the formation of the secondary and tertiary structures of each tRNA and consequently manipulate the whole translation machinery of the mitochondrion. Our analyses showed that the substitution pathways in the stems of different tRNAs were influenced by various factors, determining a molecular evolution that was unique to each of the 22 tRNAs. Our data suggested that the composition, AT-skew, and GC-skew of the tRNA stems were the main factors influencing the substitution process. In particular, the range of variation and the fluctuation of these parameters affected the fate of single tRNAs. Strong heterogeneity was observed among the different species of Cetacea. Finally, it appears that the evolution of mitochondrial tRNAs was also shaped by the environments in which the Cetacean taxa differentiated. This latter effect was particularly evident in toothed whales that either live in freshwater or are deep divers
Mars One-Year Mission Craft
A human Mars mission is more challenging to astronauts than the Apollo mission because of travel time, life support requirements, and the space environment. Although plans for Mars exploration by NASA and SpaceX based on conventional rockets have been presented, there are considerations that suggest alternatives for the mid-or long-term. The purpose of this paper is to outline a fast mission enabled by advanced (nuclear) propulsion and by internationally shared technology. Whether the destination is the Mars surface or Phobos, for a chemical powered spacecraft, the round trip takes about 990 days, including a 480-day surface stay, compared to only
370 days, including a 41-day surface stay, for the nuclear-powered spacecraft assumed here. Since nuclear propulsion can provide higher speed than chemical, the radiation dose can be drastically reduced. The logistics of such a mission involve one or more cargo craft that must precede the astronauts. Ballistic entry into Mars’ atmosphere depends on accurate knowledge of its features, to date poorly known, that may result in uncertainty in landing coordinates. For a single vehicle, this is not critical, but for a human crew ballistic landing kilometers away from cargo is unacceptable: walking for anything but the shortest distance cannot be afforded with current space suits. In this context, the concept of a modest L/D maneuvering cargo glider based on the past Russian “Kliper” is recommended and developed to ensure landing within a hundred meters of each spacecraft. The crewed lander vehicle is based on the high L/D, inherently stable USAF FDL-7C/D hypersonic glider experience
Reconstruction of time-dependent coefficients: a check of approximation schemes for non-Markovian convolutionless dissipative generators
We propose a procedure to fully reconstruct the time-dependent coefficients
of convolutionless non-Markovian dissipative generators via a finite number of
experimental measurements. By combining a tomography based approach with a
proper data sampling, our proposal allows to relate the time-dependent
coefficients governing the dissipative evolution of a quantum system to
experimentally accessible quantities. The proposed scheme not only provides a
way to retrieve full information about potentially unknown dissipative
coefficients but also, most valuably, can be employed as a reliable consistency
test for the approximations involved in the theoretical derivation of a given
non-Markovian convolutionless master equation.Comment: 11 pages, 4 figures, revised version published on PR
STILBENE ST18 AND TERFENYL TR4: IN VITRO ACTIVITY AGAINST TRYPANOSOMA CRUZI
Chagas disease is caused by the parasite Trypanosoma cruzi, which is transmitted to animals and people by insect vectors that are found only in the Americas. Chagas disease and Leishmaniasis are life-threatening illnesses caused by the protozoan parasites Leishmania spp. and Trypanosoma cruzi, respectively. They are known as “neglected diseases” due to the lack of effective drug treatments and the scarcity of research work devoted to them. Therefore, the development of novel and effective drugs is an important and urgent need. Natural products are an important source of bioactive molecules for the development of new drugs. Recently, studies showed an interesting cytotoxic action of Stilbene ST18 and the Terphenyl TR4 compounds in Leishmania.
In this study, we evaluated the in vitro trypanocidal activity of ST18 and TR4 and Nifurtimox, drug used for the treatment of Chagas disease. In addition, we evaluated the compounds action in infected macrophages with Trypanosoma cruzi. Results showed that three compounds exhibited significant activity against Trypanosoma compared to Nifurtimox. ST18 and TR4 compounds inhibited Trypanosoma growth with IC50 values of 4.5 and 32 ÎĽM, respectively. The treatment of infected macrophages with trypanosomes with the IC90 compounds showed a reduction of infection compared to control: ST18 reduced the infected cells to 52 %, TR4 reduced the infected cells to 63%. In conclusion, these news compounds could be considered as promising lead drugs for the development of new therapies for the treatment of Chagas disease
- …