863 research outputs found
A focus on focal surfaces
We make a systematic study of the focal surface of a congruence of lines in
the projective space. Using differential techniques together with techniques
from intersection theory, we reobtain in particular all the invariants of the
focal surface (degree, class, class of its hyperplane section, sectional genus
and degrees of the nodal and cuspidal curve). We study in particular the
congruences of chords to a smooth curve and the congruences of bitangents or
flexes to a smooth surface. We find that they possess unexpected components in
their focal surface, and conjecture that they are the only ones with this
property.Comment: Plain TeX, 33 pages with no figure
Proceedings from the ECFIN Workshop "The budgetary implications of structural reforms" - Brussels, 2 December 2005
Most of the reforms discussed within the framework of the Lisbon strategy will benefit public finances in the long term. However, in the short-term, there could a trade-off between some structural reforms and budgetary discipline. This possible tension between reforms and fiscal discipline was identified by academic economists as a possible drawback of the Stability and Growth Pact since its inception.budgetary discipline, Stability and Growth Pact, Lisbon strategy, fiscal discipline, Deroose, Flores, Turrini
Habitable Planet Formation in Binary-Planetary Systems
Recent radial velocity observations have indicated that Jovian-type planets
can exist in moderately close binary star systems. Numerical simulations of the
dynamical stability of terrestrial-class planets in such environments have
shown that, in addition to their giant planets, these systems can also harbor
Earth-like objects. In this paper, we study the late stage of terrestrial
planet formation in such binary-planetary systems, and present the results of
the simulations of the formation of Earth-like bodies in their habitable zones.
We consider a circumprimary disk of Moon- to Mars-sized objects and numerically
integrate the orbits of these bodies at the presence of the Jovian-type planet
of the system and for different values of the mass, semimajor axis, and orbital
eccentricity of the secondary star. Results indicate that, Earth-like objects,
with substantial amounts of water, can form in the habitable zone of the
primary star. Simulations also indicate that, by transferring angular momentum
from the secondary star to protoplanetary objects, the giant planet of the
system plays a key role in the radial mixing of these bodies and the water
contents of the final terrestrial planets. We will discuss the results of our
simulation and show that the formation of habitable planets in binary-planetary
systems is more probable in binaries with moderate to large perihelia.Comment: 27 pages, 11 figures, submitted for publicatio
Marine anthraquinones: Pharmacological and toxicological issues
The marine ecosystem, populated by a myriad of animals, plants, and microorganisms, is an inexhaustible reservoir of pharmacologically active molecules. Among the multiple secondary metabolites produced by marine sources, there are anthraquinones and their derivatives. Besides being mainly known to be produced by terrestrial species, even marine organisms and the uncount-able kingdom of marine microorganisms biosynthesize anthraquinones. Anthraquinones possess many different biological activities, including a remarkable antitumor activity. However, due to their peculiar chemical structures, anthraquinones are often associated with toxicological issues, even relevant, such as genotoxicity and mutagenicity. The aim of this review is to critically describe the an-ticancer potential of anthraquinones derived from marine sources and their genotoxic and mutagenic potential. Marine-derived anthraquinones show a promising anticancer potential, although clinical studies are missing. Additionally, an in-depth investigation of their toxicological profile is needed before advocating anthraquinones as a therapeutic armamentarium in the oncological area
Pengaruh Pemberian Probiotik Terhadap Trigliserida Darah, Lemak Abdominal, Bobot Dan Panjang Saluran Pencernaan Ayam Kampung
The objectives of this study were to evaluate the effects of probiotics in the ration on levels of serum triglycerides, abdominal fat weight, the weight and length of chicken digestive organs. The research was conducted in October through December 2011 in the poultry cage of Faculty of Animal Husbandry and Agriculture, Diponegoro University, Semarang.The material used in this study is Day Old Chick (DOC) of 200 chicken with initial body weight of an average of 33.58 ± 0.8 grams. Probiotics used are type of mold with each dose of 0.25 g, 0.50 g, and 0.75 g per 100 g ration. The feed used in this study has metabolizable energy (ME) 2750 kcal, 20.9% crude protein, 6.260% fat. Experimental design used was completely randomized design (CRD) consisting of 4 treatments with 5 replicates, each experimental unit 20. Treatment applied in this study is the addition of 0.25 g probiotic / 100 g ration for T1, the addition of 0.50 g probiotic / 100 g ration for T2, the addition of 0.75 g probiotic / 100 g ration for T3, and T0 without probiotics addition.The results showed that addition of probiotics in the ration significantly affected (P <0.05) the levels of serum triglycerides. In treatment T3 was the lowest levels of serum triglycerides and significantly different from T0, T1, and T2. Abdominal fat weight in treatment T1, T2, T3 was not significantly different (P> 0.05) to the control (T0). Digestive organ weights in treatment T0 significantly different (P <0.05) for T2, but not significantly different from T1 and T3. The length of the digestive organs are not significantly different at T0 to T1, T2, and T3. The conclusion of this research is the use of probiotics in chicken rations is capable in lowering serum triglyceride levels but did not affect the weight of abdominal fat. Adding probiotics in chicken rations can increase the digestive organ weight, but not on the length of the organ. The lowest serum triglyceride levels obtained at the level probiotics 0.75 g/100 g (T3). Digestive organ weights obtained at the highest level of probiotics 0.50 g/100 g (T2)
Who decides what: Spatial issues in environmental decisions
An integrated modelling approach is used in this work to assess the differences in defining air quality policies in spatial domains of different extensions. The tools used, SHERPA and RIAT+, are public domain and allow to rapidly define the emission scenario of the European area under examination and to solve a multi-objective problem to trade-off air quality improvement versus the costs of implementing the pollutant abatement measures. The territory considered is Northern Italy and the pollutant analysed in PM2.5, which is largely of secondary origin. The study demonstrates the importance of a proper definition of the administrative and physical boundaries of the air pollution problem, which may determine higher costs when the correct scale of decisions is missed.of the administrative and physical boundaries of the air pollution problem, which may determine highercosts when the correct scale of decisions is missed
Assessing the Economic Value of a Regional Air Quality Plan
When developing an air quality plan, environmental authorities usually devise a number of individual actions, constituted by the application of both technical (end-of-pipe) and energy efficiency measures.
They may range from the incentives to buy less polluting vehicles, to the enforcement of stricter rules on domestic heating. The assessment of the economic effectiveness for the society as a whole of the individual measures and of the overall plan requires a flexible support system able to quickly perform
air quality impact evaluations on the specific area. One such system is RIAT+, a software package developed and tested during a series of European research projects, which has been used to evaluate costs and benefits of the Lombardy Region Air Quality Plan (PRIA), constituted by about 90 different
actions to be implemented within 2020. The adoption of each measure means a certain change in the emission, which is distributed over the regional territory in different way, depending on the type of measure. A shift of the car fleet to a different EURO class, for instance, means an emission reduction only on the road network, while a reduced use of electricity may imply a lower emission of power
plants at specific sites.
To evaluate the effects of these emission changes, RIAT+ adopts a surrogate model approach, namely using a neural network calibrated on few results of a full chemical transport model. It is thus possible to rapidly evaluate the improvements in the population exposure and health and the consequent reduction of external costs.
The final economic assessment is obtained by comparing the sum of energy savings and external cost reductions with the implementation costs of the corresponding measures
Platelet-activating factor enhances complement-dependent phagocytosis of diamide-treated erythrocytes by human monocytes through activation of protein kinase C and phosphorylation of complement receptor type one (CR1).
Oligomerization of band 3 protein has been recently indicated as an early event in senescent or damaged red cell membrane followed by specific deposition of anti-band 3 antibodies and binding of complement C3 fragments. The band 3-anti-band 3-C3b complex is recognized by homologous monocytes, and phagocytosis ensues. This study shows that recognition of the anti-band 3-C3b complex by the monocyte C3b receptor type one (CR1) plays a crucial role in the process of removal of damaged red cells. Indeed, blocking of monocyte CR1 with an anti-CR1 monoclonal antibody abrogated phagocytosis of diamide-treated red cells. Platelet-activating factor (PAF) is a phospholipid mediator involved in inflammatory processes. Nanomolar (R)-PAF enhanced the CR1-dependent phagocytosis of diamide-treated human red cell and of sheep red cells coated with C3b, induced the fast translocation of protein kinase C to monocyte membrane compartment, and stimulated the phosphorylation of monocyte CR1. The biologically inert lyso-PAF and the enantiomer (S)-PAF were inactive. PAF receptor antagonists and inhibitors of protein kinase C blocked the enhancement of phagocytosis induced by PAF. Protein kinase C translocation, phosphorylation of CR1, and stimulation of this receptor to an active state capable of mediating phagocytosis represent a novel pathway by which PAF interferes with red cell homeostasis and possibly modulates inflammatory reactions and host mechanisms against infections
Oxygen depletion in giant planets with different formation histories
The atmospheric C/O ratio of exoplanets is widely used to constrain their formation. To guarantee that the C/O ratio provides robust information, we need to accurately quantify the amount of C and O in exoplanetary atmospheres. In the case of O, water and carbon monoxide are generally studied as the two key carriers. However, oxygen is a very reactive element and does not bind with carbon; depending on the temperature, it also binds to refractory elements. Estimating the amount of oxygen bound to refractory elements is therefore critical for unbiased estimates of the C/O ratio. In this work, we investigate the oxygen deficit due to refractory elements and its effects on the atmospheric C/O ratio of giant exoplanets as a function of their metallicity and equilibrium temperature. We model the composition of planetary atmospheres assuming chemical equilibrium and using as input physically justified elemental mixtures arising from detailed planet formation simulations. Our results show how the interplay between the atmospheric temperature and non-solar abundances of oxygen and refractory elements can sequester large fractions of oxygen, introducing significant biases in evaluating the C/O ratio when this effect is not accounted for. We apply our results to the case of Jupiter in the Solar System and show how the currently estimated water abundance points to a true oxygen abundance that is four times the solar one
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