2,744 research outputs found
Isolated resonances in conductance fluctuations in ballistic billiards
We study numerically quantum transport through a billiard with a classically
mixed phase space. In particular, we calculate the conductance and Wigner delay
time by employing a recursive Green's function method. We find sharp, isolated
resonances with a broad distribution of resonance widths in both the
conductance and the Wigner time, in contrast to the well-known smooth
conductance fluctuations of completely chaotic billiards. In order to elucidate
the origin of the isolated resonances, we calculate the associated scattering
states as well as the eigenstates of the corresponding closed system. As a
result, we find a one-to-one correspondence between the resonant scattering
states and eigenstates of the closed system. The broad distribution of
resonance widths is traced to the structure of the classical phase space.
Husimi representations of the resonant scattering states show a strong overlap
either with the regular regions in phase space or with the hierarchical parts
surrounding the regular regions. We are thus lead to a classification of the
resonant states into regular and hierarchical, depending on their phase space
portrait.Comment: 2 pages, 5 figures, to be published in J. Phys. Soc. Jpn.,
proceedings Localisation 2002 (Tokyo, Japan
Fractal Conductance Fluctuations of Classical Origin
In mesoscopic systems conductance fluctuations are a sensitive probe of
electron dynamics and chaotic phenomena. We show that the conductance of a
purely classical chaotic system with either fully chaotic or mixed phase space
generically exhibits fractal conductance fluctuations unrelated to quantum
interference. This might explain the unexpected dependence of the fractal
dimension of the conductance curves on the (quantum) phase breaking length
observed in experiments on semiconductor quantum dots.Comment: 5 pages, 4 figures, to appear in PR
Trapped ion mobility spectrometry and PASEF enable in-depth lipidomics from minimal sample amounts
A comprehensive characterization of the lipidome from limited starting material remains very challenging. Here we report a high-sensitivity lipidomics workflow based on nanoflow liquid chromatography and trapped ion mobility spectrometry (TIMS). Taking advantage of parallel accumulation-serial fragmentation (PASEF), we fragment on average 15 precursors in each of 100 ms TIMS scans, while maintaining the full mobility resolution of co-eluting isomers. The acquisition speed of over 100 Hz allows us to obtain MS/MS spectra of the vast majority of isotope patterns. Analyzing 1 mu L of human plasma, PASEF increases the number of identified lipids more than three times over standard TIMS-MS/MS, achieving attomole sensitivity. Building on high intra- and inter-laboratory precision and accuracy of TIMS collisional cross sections (CCS), we compile 1856 lipid CCS values from plasma, liver and cancer cells. Our study establishes PASEF in lipid analysis and paves the way for sensitive, ion mobility-enhanced lipidomics in four dimensions
Temporal-spatial Patterns of Noctuinae Communities (Lep. Noctuidae) in Hungarian Apple Orchards (Apple Ecosystem Research)
In our present study we aimed to recognize the temporal and spatial patterns of Noctuinae communities (Lep.Noctuidae) of four differently managed apple orchards laying in different localities of Hungary. Data were obtained by light trap collection. The quantitative data resulting from our investigations were analyzed by multivariate methods and were also analyzed by their diversity characteristics.As a result connections were found regarding the diversities of species and individuals, the patterns of occurrence and phenological properties. The studies were based on 8497 individuals of 39 species
Textural Properties and Structure of Starch-Reinforced Surimi Gels as Affected by Heat-Setting
The gel forming behavior of red hake (Urophycis chuss) surimi with and without starch and its relationship to the structure of the gel matrix were studied. For surimi gels without starch, a combination of preheat- setting at 40 C and cooking at 90 C resulted in significantly greater gel strength than cooking alone. However, preheat - setting of gels containing wheat or potato starch had no significant effect on gel strength demonstrating an opposite trend in gel strength due to the differences in swelling power, water holding ability and gelatinization temperature between potato and wheat starches. This difference in gel forming behavior due to the sources of starch and heat- setting prior to cooking correlated with changes in the structure of the matrix as evidenced by the results of image analysis. An examination of the microstructure of the gel matrix by light and electron microscopy showed that the structural differences may be due to the different protein matrix density as reflected in the increased gel strength
Textural and Microstructural Properties of Frozen Fish Mince as Affected by the Addition of Nonfish Proteins and Sorbitol
Changes in textural and microstructural properties of washed and unwashed frozen fish mince were studied as affected by the addition of non fish proteins (soy protein isolate, milk protein isolate, egg white, and wheat gluten at 2 , 4 or 6%) and 6% crystalline sorbitol. Soy and milk proteins and sorbitol reduced the hardness of frozen fish mince, while egg white and wheat gluten made the texture firmer without rubberiness developing after frozen storage. All nonfish proteins and sorbitol stabilized the myofibrillar organization by reducing freeze-induced contraction of myofibrils.
The mechanisms of reducing texture hardening appear to be different between sorbitol and nonfish proteins. Water binding properties and dispersibility made the difference among nonfish proteins in reducing freeze-contraction of myofibrils. Nonfish proteins not only reduced texture hardening during frozen storage, but also modified texture during cooki ng as they underwent thermal gelation specific to each protein used
Rainforests at the beginning of the 21st century
Rainforests are situated at low latitude where forests enjoy steady and strong radiation.
Biodiversity in rainforests has been very high, for historical and climatic reasons. The number of species
is very high and tends to increase with precipitation and decrease with seasonality. Disturbance, soil
fertility and forest stature also influence the species richness and high turnover of species contribute to
diversity. Field observation and studies revealed that large scale deforestation could alter the regional and
global climate significantly. Deforestation alters the surface albedo which leads to climate change.
Regional land use contributes to climate change through surface-energy budget, as well as the carbon
cycle. Forest fragmentation, logging, overhunting, fire and the expanding agriculture threaten the
biodiversity. Rainforest covered area has significantly shrunk in the last decades. It is hard to protect the
forests because of the growing demand for agricultural area and forest-derived products. Most measures
proved ineffective to slow down the destruction. Hence, more forest will be lost in the future.
Conservationists should take into consideration the secondary forests because biodiversity can be high
enough and it is worth protecting them
Derived Parameters for NGC 6791 from High-Metallicity Isochrones
We have computed 8, 10, and 12 Gyr isochrones and physically consistent
models of zero-age red horizontal branch stars for stellar masses between 0.55
and 1.3~\msun, all at [Fe/H] . Comparison to the NGC 6791 BVI
photometry of Ka{\l}u\.zny & Udalski (1992) and Montgomery, Janes & Phelps
(1994) yields an age of Gyr at an apparent distance modulus
13.49 < \dmv < 13.70. The color offsets required to fit the isochrones,
combined with the spectroscopic results of Friel & Janes, imply that the
foreground reddening to NGC 6791 lies in the range 0.24 > \ebv >0.19 with
[Fe/H] .
The zero-age horizontal branch models suggest that the red horizontal branch
stars of NGC 6791 have masses \lesssim 0.7\msun. The masses are similar to
those found for M67 red clump stars by Tripicco, Dorman & Bell (1993) and for
globular cluster red horizontal branch stars, despite higher and lower masses
(respectively) in those cases. This suggests the presence of a mechanism that
tends to reduce stellar envelopes on the zero-age horizontal branch {\it to} a
given mass rather than {\it by} a given amount.Comment: 23 pages, postscript fil
- …