56 research outputs found
Quasiparticle Spectrum of Vortices in Cuprates
The quasiparticle excitation spectrum of an isolated vortex in a clean
layered d-wave superconductor is calculated, using both the Bogoliubov--de
Gennes and the quasiclassical Eilenberger equations. Analytical solutions are
obtained within the model of step-variation of the gap function, adjusting the
Caroli, de Gennes and Matricon approach for low-lying excitations in cuprates.
A large peak in the density of states in the "pancake" vortex core is found,
caused by the two-dimensional and strong coupling nature of high-temperature
superconductivity.Comment: 8 pages, Latex, uses spie1.sty, 6 eps figures, published in SPIE
Proceedings, Vol. 3481 (SPIE, Bellingham, 1998), p. 106-11
Asteroid proper elements and secular resonances
In a series of papers (e.g., Knezevic, 1991; Milani and Knezevic, 1990; 1991) we reported on the progress we were making in computing asteroid proper elements, both as regards their accuracy and long-term stability. Additionally, we reported on the efficiency and 'intelligence' of our software. At the same time, we studied the associated problems of resonance effects, and we introduced the new class of 'nonlinear' secular resonances; we determined the locations of these secular resonances in proper-element phase space and analyzed their impact on the asteroid family classification. Here we would like to summarize the current status of our work and possible further developments
Asteroid family ages
A new family classification, based on a catalog of proper elements with numbered asteroids and on new methods is available. For the
dynamical families with members identified in this classification, we
present an attempt to obtain statistically significant ages: we succeeded in
computing ages for collisional families. We used a rigorous method,
including a least squares fit of the two sides of a V-shape plot in the proper
semimajor axis, inverse diameter plane to determine the corresponding slopes,
an advanced error model for the uncertainties of asteroid diameters, an
iterative outlier rejection scheme and quality control. The best available
Yarkovsky measurement was used to estimate a calibration of the Yarkovsky
effect for each family. The results are presented separately for the families
originated in fragmentation or cratering events, for the young, compact
families and for the truncated, one-sided families. For all the computed ages
the corresponding uncertainties are provided. We found 2 cases where two
separate dynamical families form together a single V-shape with compatible
slopes, thus indicating a single collisional event. We have also found 3
examples of dynamical families containing multiple collisional families, plus a
dubious case. We have found 2 cases of families containing a conspicuous
subfamily, such that it is possible to measure the slope of a distinct V-shape,
thus the age of the secondary collision. We also provide data on the central
gaps appearing in some families.
The ages computed in this paper are obtained with a single and uniform
methodology, thus the ages of different families can be compared, providing a
first example of collisional chronology of the asteroid main belt
Asteroid families classification: exploiting very large data sets
The number of asteroids with accurately determined orbits increases fast. The
catalogs of asteroid physical observations have also increased, although the
number of objects is still smaller than in the orbital catalogs. We developed a
new approach to the asteroid family classification by combining the
Hierarchical Clustering Method (HCM) with a method to add new members to
existing families. This procedure makes use of the much larger amount of
information contained in the proper elements catalogs, with respect to
classifications using also physical observations for a smaller number of
asteroids. Our work is based on the large catalog of the high accuracy
synthetic proper elements (available from AstDyS). We first identify a number
of core families; to these we attribute the next layer of smaller objects.
Then, we remove all the family members from the catalog, and reapply the HCM to
the rest. This gives both halo families which extend the core families and new
independent families, consisting mainly of small asteroids. These two cases are
discriminated by another step of attribution of new members and by merging
intersecting families. By using information from absolute magnitudes, we take
advantage of the larger size range in some families to analyze their shape in
the proper semimajor axis vs. inverse diameter plane. This leads to a new
method to estimate the family age (or ages). The results from the previous
steps are then analyzed, using also auxiliary information on physical
properties including WISE albedos and SDSS color indexes. This allows to solve
some difficult cases of families overlapping in the proper elements space but
generated by different collisional events. We analyze some examples of
cratering families (Massalia, Vesta, Eunomia) which show internal structures,
interpreted as multiple collisions. We also discuss why Ceres has no family
Bacterial microbiota isolated from cysts of Globodera rostochiensis (Nematoda: Heteroderidae).
The potato cyst nematode (PCN) Globodera rostochiensis is a plant parasite of potato classified into a group of quarantine organisms causing high economic losses worldwide. Due to the long persistence of the parasite in soil, cysts harbor numerous bacteria whose presence can lead to cyst death and population decline. The cysts of G. rostochiensis found in two potato fields were used as a source of bacteria. The universal procedure was applied to extract DNA from bacteria which was then sequenced with 16S primers. The aims of the study were to identify bacterial microbiota associated with the PCN populations and to infer their phylogenetic relationships based on the maximum likelihood and Bayesian phylogeny of the 16S sequences. In addition, the impact of the most significant climate and edaphic factors on bacterial diversity were evaluated. Regarding the higher taxonomy, our results indicate that the prevalent bacterial classes were Bacilli, Actinobacteria and Alphaproteobacteria. Phylogenetic analyses clustered Brevibacterium frigoritolerans within the family Bacillaceae, confirming its recent reclassification. Long-term climate factors, such as air temperature, insolation hours, humidity and precipitation, as well as the content of soil organic matter, affected the bacterial diversity. The ability of cyst nematodes to persist in soil for a long time qualifies them as a significant natural source to explore the soil bacterial microbiota
Can a presepsin (SCD14-ST) obtained from tracheal aspirate be a biomarker for early-onset neonatal sepsis
© 2020, University of Kragujevac, Faculty of Science. All rights reserved. In absence of clear clinical signs and clear definition, neonatal sepsis is still one of the major cause of morbidity and mortality. Most researchs in past time was directional on finding new biomarkers with greater sensitivity and specific-ity in detection of neonatal sepsis. The aim of our study was to investigate if presepsin obtained from tracheal asprate in intubated newborns, can be a novel biomarker of systemic bacterial infection. Our ‘’case control’’ study included 60 newborns, 11 with suspected neonatal sepsis. Tracheal aspirate for examination was taken in the usual toilets, in asep-tic conditions, by lavage with 2 ml of 0.9% NaCl in Mucus suction set. In the same day were mesured presepsin (blood), CRP, PCT, leukocytes and neutrophyls, as well as blood cul-ture. Our research showed higher levels for PCT and prese-psin (blood) in septic newborns, as well as in newborns with clinical signs of SIRS. Presepsin obtained from a tracheal aspirate had high score for septic newborns. As the coefficients of simple linear correlation showed, there was quantitative agreement between presepsin (blood) with presepsin (trache-al aspirate)-increase in the value of one leads to an increase in other. In conjunction with an already validated markers of infection, presepsin obtained from tracheal aspirate cam be turned on in diagnostic procedures
Transgeni organizmi-biotehnološka moć
Creation of transgenic organisms should be endeavored necessary amount of food
for the elimination of mankind hunger, increase yield and quality, resistance to diseases
and pests, tolerance to high and low temperature properties and improvement of
transportation and storage. Transgenic organisms are characterized by a higher content
of protein, oil, and starch specific structure. Their use in the diet can have different
effects on human health from uncontrolled use. Due to the relatively short period since
the creation of transgenic organisms and for greater security man and the ecosystem of
their production and trade is within the legal regulations and legislation.Čovek je tokom svog istorijskog razvoja do danas bio, između ostalog,
kreativno biće u interakciji sa spoljašnjom sredinom. Birao je najbolje vrste, najbolje
plodove, najbolja staništa i u tom ambijentu je proizvodio i kreirao bolje od postojećeg pa
i u živom svetu. Transgeni oganizmi su kreirani u cilju povećanja prinosa, kvaliteta i
adaptivnosti a time i obezbeđenje hrane za ljudsku populaciju koja se brojno umnožava.
Za neke transgene organizme je ustanovljeno negativno delovanje na druge organizme i
ekosistem. Tako su se u oblasti biotehnologije postigli vrhunski rezultati koji ne ostavljaju
ravnodušnim pojedince, grupe i udruženja u naučnoj, stručnoj i široj javnosti kod nas i u
svetu
Kako poplave modifikuju genotoksični odgovor slatkovodnih riba?
U ovom radu ispitivan je potencijal dve vrste roda Abramis (Abramis bjoerkna i Abramis sapa) kao bioindikatora genotoksičnog potencijala vode reke Save primenom komet testa. Izabrani lokalitet pripada oblasti intezivne poljoprivredne aktivnosti, izložen je otpadnim vodama grada Obrenovca i nalazi se u blizini najveće termoelektrane u Srbiji, “Nikola Tesla”. Uzorkovanje je vršeno od januara do avgusta 2014. godine, obuhvatajući mesec maj kada je došlo do intezivnih poplava u slivu reke Save. Dobijeni rezultati ukazuju da se ispitivane vrste mogu koristiti za procenu genotoksičnog potencijala
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