743 research outputs found
Preparation and biological investigation of luminescent water soluble CdTe nanoparticles
In this study CdTe quantum dots have been successfully prepared in aqueous medium using several different thiol stabilizers. The resulting nanocrystals were purified and the photoluminescence efficiency was subsequently enhanced through post preparative procedures such as photochemical etching and ageing. An optical study was carried out on the resulting CdTe nanocrystals as proof as their improvement. Preliminary tests of the thiol stabilised QDs as potential biolabels have been performed. It has been shown that L-cysteine stabilised QDs localising to the outer cell membrane in living cells. TGA stabilised CdTe QDs can potentially serve as live cell imaging tools as they exhibit strong luminescence and excellent photostability. In addition, the ability of TGA stabilised CdTe QDs to traverse the cell membrane of macrophages is a formidable quality that may potentially be harnessed for imaging and therapeutics. Modulating the delivery of QDs to subcellular locations in living cells opens a myriad of potential applications ranging from drug delivery to examination of intracellular processes
Nanostructured metal-fullerene field emission cathode
One of the important properties of carbon nanostructures is their cold electron
emission ability. Carbon nanotubes and other nanostructures are capable of
emitting high currents at relatively low electrical fields. They are already
used in functional devices such as field emitters. The conventional method of
carbon nanostructured cathodes manufacturing is thin film nanocarbon deposition
using CVD process on electrically conducting substrate like metal or doped
silicon plates. The alternative way of manufacturing of carbon field emission
cathodes is based on a special processing of carbon microfibers or composite materials in metal holders. We used the similar approach to produce composite
metal-nanocarbon material which may be easily processed and shaped to
produce an effective field emission cathode which can be easily fixed an any
environment.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2058
Π‘ΠΎΠ²ΡΠ΅ΠΌΠ΅Π½Π½ΡΠ΅ ΠΌΠ΅ΡΠΎΠ΄Ρ ΠΈΠ΄Π΅Π½ΡΠΈΡΠΈΠΊΠ°ΡΠΈΠΈ Π²ΠΎΠ·Π±ΡΠ΄ΠΈΡΠ΅Π»Ρ Π³ΠΎΠ½ΠΎΠΊΠΎΠΊΠΊΠΎΠ²ΠΎΠΉΠΈΠ½ΡΠ΅ΠΊΡΠΈΠΈ
The authors present the data on the current laboratory methods and recommendations for identifying the gonorrhea
pathogen applied in Russia and abroad: microscopy method, cultural (bacteriological) study method, nucleic acid
amplification techniques and DNA chip technology. The benefits and shortcomings of each of the techniques have been
compared. The authors emphasize the cultural method is currently considered to be the key one for diagnosing gonorrhea
due to its high specificity and sensitivity making it possible to define the N.gonorrhoeae sensitivity to antimicrobial
drugs, which is very important taking into consideration the N. gonorrhoeae resistance to antibiotics. The nucleic acid
amplification techniques and, first of all, polymerase chain reaction, can be used in Russia as screening methods. The
results obtained by using the techniques need confirmation by the cultural method.ΠΡΠΈΠ²Π΅Π΄Π΅Π½Ρ Π΄Π°Π½Π½ΡΠ΅ ΠΎ ΡΠΎΠ²ΡΠ΅ΠΌΠ΅Π½Π½ΡΡ
Π»Π°Π±ΠΎΡΠ°ΡΠΎΡΠ½ΡΡ
ΠΌΠ΅ΡΠΎΠ΄Π°Ρ
ΠΈ ΡΠ΅ΠΊΠΎΠΌΠ΅Π½Π΄Π°ΡΠΈΡΡ
ΠΏΠΎ ΠΈΠ΄Π΅Π½ΡΠΈΡΠΈΠΊΠ°ΡΠΈΠΈ Π²ΠΎΠ·Π±ΡΠ΄ΠΈΡΠ΅Π»Ρ
Π³ΠΎΠ½ΠΎΡΠ΅ΠΈ, ΠΏΡΠΈΠΌΠ΅Π½ΡΠ΅ΠΌΡΡ
Π² Π ΠΎΡΡΠΈΠΈ ΠΈ Π·Π° ΡΡΠ±Π΅ΠΆΠΎΠΌ: ΠΌΠ΅ΡΠΎΠ΄Π΅ ΠΌΠΈΠΊΡΠΎΡΠΊΠΎΠΏΠΈΠΈ, ΠΊΡΠ»ΡΡΡΡΠ°Π»ΡΠ½ΠΎΠΌ (Π±Π°ΠΊΡΠ΅ΡΠΈΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΎΠΌ)
ΠΌΠ΅ΡΠΎΠ΄Π΅ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ, ΠΌΠ΅ΡΠΎΠ΄Π°Ρ
Π°ΠΌΠΏΠ»ΠΈΡΠΈΠΊΠ°ΡΠΈΠΈ Π½ΡΠΊΠ»Π΅ΠΈΠ½ΠΎΠ²ΡΡ
ΠΊΠΈΡΠ»ΠΎΡ, ΡΠ΅Ρ
Π½ΠΎΠ»ΠΎΠ³ΠΈΠΈ ΠΠΠ-ΡΠΈΠΏΠΎΠ²; Π² ΡΡΠ°Π²Π½ΠΈΡΠ΅Π»ΡΠ½ΠΎΠΌ
Π°ΡΠΏΠ΅ΠΊΡΠ΅ ΠΎΡΡΠ°ΠΆΠ΅Π½Ρ Π΄ΠΎΡΡΠΎΠΈΠ½ΡΡΠ²Π° ΠΈ Π½Π΅Π΄ΠΎΡΡΠ°ΡΠΊΠΈ ΠΊΠ°ΠΆΠ΄ΠΎΠ³ΠΎ ΠΌΠ΅ΡΠΎΠ΄Π°. ΠΠΎΠ΄ΡΠ΅ΡΠΊΠ½ΡΡΠΎ, ΡΡΠΎ ΠΎΡΠ½ΠΎΠ²ΠΎΠΉ Π΄ΠΈΠ°Π³Π½ΠΎΡΡΠΈΠΊΠΈ Π³ΠΎΠ½ΠΎΡΠ΅ΠΈ
Π² Π½Π°ΡΡΠΎΡΡΠ΅Π΅ Π²ΡΠ΅ΠΌΡ ΡΠ²Π»ΡΠ΅ΡΡΡ ΠΊΡΠ»ΡΡΡΡΠ°Π»ΡΠ½ΡΠΉ ΠΌΠ΅ΡΠΎΠ΄, ΠΎΠ±Π»Π°Π΄Π°ΡΡΠΈΠΉ Π²ΡΡΠΎΠΊΠΎΠΉ ΡΠΏΠ΅ΡΠΈΡΠΈΡΠ½ΠΎΡΡΡΡ ΠΈ ΡΡΠ²ΡΡΠ²ΠΈΡΠ΅Π»ΡΠ½ΠΎΡΡΡΡ,
ΠΏΠΎΠ·Π²ΠΎΠ»ΡΡΡΠΈΠΉ ΠΎΠΏΡΠ΅Π΄Π΅Π»ΡΡΡ ΡΡΠ²ΡΡΠ²ΠΈΡΠ΅Π»ΡΠ½ΠΎΡΡΡ N. gonorrhoeae ΠΊ Π°Π½ΡΠΈΠΌΠΈΠΊΡΠΎΠ±Π½ΡΠΌ ΠΏΡΠ΅ΠΏΠ°ΡΠ°ΡΠ°ΠΌ, ΡΡΠΎ ΠΎΡΠΎΠ±Π΅Π½Π½ΠΎ Π°ΠΊΡΡΠ°Π»ΡΠ½ΠΎ
Π²Π²ΠΈΠ΄Ρ Π²ΠΎΠ·ΡΠ°ΡΡΠ°Π½ΠΈΡ Π² ΠΏΠΎΡΠ»Π΅Π΄Π½ΠΈΠ΅ Π³ΠΎΠ΄Ρ ΡΠ΅Π·ΠΈΡΡΠ΅Π½ΡΠ½ΠΎΡΡΠΈ N. gonorrhoeae ΠΊ Π°Π½ΡΠΈΠ±ΠΈΠΎΡΠΈΠΊΠ°ΠΌ. ΠΠ΅ΡΠΎΠ΄Ρ Π°ΠΌΠΏΠ»ΠΈΡΠΈΠΊΠ°ΡΠΈΠΈ
Π½ΡΠΊΠ»Π΅ΠΈΠ½ΠΎΠ²ΡΡ
ΠΊΠΈΡΠ»ΠΎΡ ΠΈ ΠΏΡΠ΅ΠΆΠ΄Π΅ Π²ΡΠ΅Π³ΠΎ ΠΏΠΎΠ»ΠΈΠΌΠ΅ΡΠ°Π·Π½Π°Ρ ΡΠ΅ΠΏΠ½Π°Ρ ΡΠ΅Π°ΠΊΡΠΈΡ Π² Π ΠΎΡΡΠΈΠΈ ΠΌΠΎΠ³ΡΡ ΠΏΡΠΈΠΌΠ΅Π½ΡΡΡΡΡ Π² ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅
ΡΠΊΡΠΈΠ½ΠΈΠ½Π³ΠΎΠ²ΡΡ
ΠΌΠ΅ΡΠΎΠ΄ΠΎΠ²; ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΡ, ΠΏΠΎΠ»ΡΡΠ΅Π½Π½ΡΠ΅ ΠΏΡΠΈ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠΈ ΡΡΠΈΡ
ΠΌΠ΅ΡΠΎΠ΄ΠΎΠ², ΡΡΠ΅Π±ΡΡΡ ΠΏΠΎΠ΄ΡΠ²Π΅ΡΠΆΠ΄Π΅Π½ΠΈΡ
ΠΊΡΠ»ΡΡΡΡΠ°Π»ΡΠ½ΡΠΌ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠΌ
The numerical study of hydrogen-air mixture ignition under laser photo-dissociation of O2 molecules
Determination of the parameters of semiconducting CdF2:In with Schottky barriers from radio-frequency measurements
Physical properties of semiconducting CdF_2 crystals doped with In are
determined from measurements of the radio-frequency response of a sample with
Schottky barriers at frequencies 10 - 10^6 Hz. The dc conductivity, the
activation energy of the amphoteric impurity, and the total concentration of
the active In ions in CdF_2 are found through an equivalent-circuit analysis of
the frequency dependencies of the sample complex impedance at temperatures from
20 K to 300 K. Kinetic coefficients determining the thermally induced
transitions between the deep and the shallow states of the In impurity and the
barrier height between these states are obtained from the time-dependent
radio-frequency response after illumination of the material. The results on the
low-frequency conductivity in CdF_2:In are compared with submillimeter (10^{11}
- 10^{12} Hz) measurements and with room-temperature infrared measurements of
undoped CdF_2. The low-frequency impedance measurements of semiconductor
samples with Schottky barriers are shown to be a good tool for investigation of
the physical properties of semiconductors.Comment: 9 pages, 7 figure
The possible variant of pulsed RF-discharge cleaning mode of the Uragan-3m torsatron
The cleaning regime with the use of pulsed RF-discharges in hydrogen-nitrogen mixture was examined over the nitrogen concentration range from 4 at.% to 96 at.% at the same parameters of RF-generator as for pure hydrogen. The analysis of obtained preliminary data has shown that even about 2x10Β³ discharge pulses in Hβ-Nββ mixture causes drastic decrease of partial hydrogen pressure and ultimate base pressure. But, in contrast, to revert initial high hydrogen partial pressure in the U-3M torsatron vacuum chamber, it is needed more than 2x10β΄ pulsed discharges in pure hydrogen. The possible reasons of effective hydrogen removing in RF-discharges in hydrogen-nitrogen mixtures are discussed.ΠΠΎΡΠ»ΡΠ΄ΠΆΡΠ²Π°Π²ΡΡ ΡΠ΅ΠΆΠΈΠΌ ΡΠΈΡΠ΅Π½Π½Ρ ΡΠΌΠΏΡΠ»ΡΡΠ½ΠΈΠΌΠΈ ΠΠ§-ΡΠΎΠ·ΡΡΠ΄Π°ΠΌΠΈ Π² ΡΡΠΌΡΡΡ Π²ΠΎΠ΄Π½Ρ ΠΉ Π°Π·ΠΎΡΡ ΠΏΡΠΈ ΠΊΠΎΠ½ΡΠ΅Π½ΡΡΠ°ΡΡΡΡ
Π°Π·ΠΎΡΡ Π²ΡΠ΄ 4 at. % to 96 at. % ΠΏΡΠΈ ΡΠΈΡ
ΠΆΠ΅ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠ°Ρ
ΠΠ§-Π³Π΅Π½Π΅ΡΠ°ΡΠΎΡΠ°, ΡΠΎ Ρ Π΄Π»Ρ ΡΠΈΡΡΠΎΠ³ΠΎ Π²ΠΎΠ΄Π½Ρ. ΠΠ½Π°Π»ΡΠ· ΠΎΡΡΠΈΠΌΠ°Π½ΠΈΡ
Π΄Π°Π½ΠΈΡ
ΠΏΠΎΠΊΠ°Π·Π°Π², ΡΠΎ Π²ΠΆΠ΅ Π±Π»ΠΈΠ·ΡΠΊΠΎ 2x10Β³ ΡΠΌΠΏΡΠ»ΡΡΡΠ² Ρ Hβ-Nβ ΡΡΠΌΡΡΡ Π²ΠΈΠΊΠ»ΠΈΠΊΠ°Ρ ΠΏΠΎΠΌΡΡΠ½Π΅ Π·Π½ΠΈΠΆΠ΅Π½Π½Ρ ΠΏΠ°ΡΡΡΠ°Π»ΡΠ½ΠΎΠ³ΠΎ ΡΠΈΡΠΊΡ Π²ΠΎΠ΄Π½Ρ Ρ Π³ΡΠ°Π½ΠΈΡΠ½ΠΎΠ³ΠΎ ΡΠΈΡΠΊΡ Π² ΠΊΠ°ΠΌΠ΅ΡΡ Π£-3Π. ΠΠ°Π²ΠΏΡΠΎΡΠΈ, ΡΠΎΠ± ΠΏΠΎΠ²Π΅ΡΠ½ΡΡΠΈ Π²ΠΈΡΠΎΠΊΠΈΠΉ ΠΏΠ°ΡΡΡΠ°Π»ΡΠ½ΠΈΠΉ ΡΠΈΡΠΊ Π²ΠΎΠ΄Π½Ρ Ρ Π²Π°ΠΊΡΡΠΌΠ½ΡΠΉ ΠΊΠ°ΠΌΠ΅ΡΡ Π£-3Π Π½Π΅ΠΎΠ±Ρ
ΡΠ΄Π½ΠΎ Π±ΡΠ»ΡΡ Π½ΡΠΆ 2x10β΄ ΡΠΌΠΏΡΠ»ΡΡΠ½ΠΈΡ
ΡΠΎΠ·ΡΡΠ΄ΡΠ² Ρ ΡΠΈΡΡΠΎΠΌΡ Π²ΠΎΠ΄Π½Ρ. ΠΠ±Π³ΠΎΠ²ΠΎΡΡΡΡΡΡΡ ΠΌΠΎΠΆΠ»ΠΈΠ²Ρ ΠΏΡΠΈΡΠΈΠ½ΠΈ Π΅ΡΠ΅ΠΊΡΠΈΠ²Π½ΠΎΠ³ΠΎ Π²ΠΈΠ΄Π°Π»Π΅Π½Π½Ρ Π²ΠΎΠ΄Π½Ρ ΡΠΎΠ·ΡΡΠ΄Π°ΠΌΠΈ Π² ΡΡΠΌΡΡΡ Π²ΠΎΠ΄Π½Ρ ΠΉ Π°Π·ΠΎΡΡ.ΠΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π»ΡΡ ΡΠ΅ΠΆΠΈΠΌ ΡΠΈΡΡΠΊΠΈ ΠΈΠΌΠΏΡΠ»ΡΡΠ½ΡΠΌΠΈ ΠΠ§-ΡΠ°Π·ΡΡΠ΄Π°ΠΌΠΈ Π² ΡΠΌΠ΅ΡΠΈ Π²ΠΎΠ΄ΠΎΡΠΎΠ΄Π° ΠΈ Π°Π·ΠΎΡΠ° ΠΏΡΠΈ ΠΊΠΎΠ½ΡΠ΅Π½ΡΡΠ°ΡΠΈΡΡ
Π°Π·ΠΎΡΠ° ΠΎΡ 4 at.% to 96 at.% ΠΏΡΠΈ ΡΠ΅Ρ
ΠΆΠ΅ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠ°Ρ
ΠΠ§-Π³Π΅Π½Π΅ΡΠ°ΡΠΎΡΠ°, ΡΡΠΎ ΠΈ Π΄Π»Ρ ΡΠΈΡΡΠΎΠ³ΠΎ Π²ΠΎΠ΄ΠΎΡΠΎΠ΄Π°. ΠΠ½Π°Π»ΠΈΠ· ΠΏΠΎΠ»ΡΡΠ΅Π½Π½ΡΡ
Π΄Π°Π½Π½ΡΡ
ΠΏΠΎΠΊΠ°Π·Π°Π», ΡΡΠΎ ΡΠΆΠ΅ ΠΎΠΊΠΎΠ»ΠΎ 2x10Β³ ΠΈΠΌΠΏΡΠ»ΡΡΠΎΠ² Π² Hβ-Nβ ΡΠΌΠ΅ΡΠΈ Π²ΡΠ·ΡΠ²Π°Π΅Ρ Π·Π°ΠΌΠ΅ΡΠ½ΠΎΠ΅ ΡΠ½ΠΈΠΆΠ΅Π½ΠΈΠ΅ ΠΏΠ°ΡΡΠΈΠ°Π»ΡΠ½ΠΎΠ³ΠΎ Π΄Π°Π²Π»Π΅Π½ΠΈΡ Π²ΠΎΠ΄ΠΎΡΠΎΠ΄Π° ΠΈ ΠΏΡΠ΅Π΄Π΅Π»ΡΠ½ΠΎΠ³ΠΎ Π΄Π°Π²Π»Π΅Π½ΠΈΡ Π² ΠΊΠ°ΠΌΠ΅ΡΠ΅ Π£-3Π. ΠΠ°ΠΏΡΠΎΡΠΈΠ², ΡΡΠΎΠ±Ρ Π²Π΅ΡΠ½ΡΡΡ Π²ΡΡΠΎΠΊΠΎΠ΅ ΠΏΠ°ΡΡΠΈΠ°Π»ΡΠ½ΠΎΠ΅ Π΄Π°Π²Π»Π΅Π½ΠΈΠ΅ Π²ΠΎΠ΄ΠΎΡΠΎΠ΄Π° Π² Π²Π°ΠΊΡΡΠΌΠ½ΠΎΠΉ ΠΊΠ°ΠΌΠ΅ΡΠ΅ Π£-3Π Π½Π΅ΠΎΠ±Ρ
ΠΎΠ΄ΠΈΠΌΠΎ Π±ΠΎΠ»Π΅Π΅ ΡΠ΅ΠΌ 2x10β΄ ΠΈΠΌΠΏΡΠ»ΡΡΠ½ΡΡ
ΡΠ°Π·ΡΡΠ΄ΠΎΠ² Π² ΡΠΈΡΡΠΎΠΌ Π²ΠΎΠ΄ΠΎΡΠΎΠ΄Π΅. ΠΠ±ΡΡΠΆΠ΄Π°ΡΡΡΡ Π²ΠΎΠ·ΠΌΠΎΠΆΠ½ΡΠ΅ ΠΏΡΠΈΡΠΈΠ½Ρ ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΠΎΠ³ΠΎ ΡΠ΄Π°Π»Π΅Π½ΠΈΡ Π²ΠΎΠ΄ΠΎΡΠΎΠ΄Π° ΡΠ°Π·ΡΡΠ΄Π°ΠΌΠΈ Π² ΡΠΌΠ΅ΡΠΈ Π²ΠΎΠ΄ΠΎΡΠΎΠ΄Π° ΠΈ Π°Π·ΠΎΡΠ°
Space-time dynamics of low frequency plasma density fluctuations in URAGAN-3 torsatron
Experimentally investigated the space-time dynamics of low-frequency plasma density fluctuations for two regimes of discharges in torsatron U-3M and with laser-ablation-injection of carbon.ΠΠΊΡΠΏΠ΅ΡΠΈΠΌΠ΅Π½ΡΠ°Π»ΡΠ½ΠΎ Π΄ΠΎΡΠ»ΡΠ΄ΠΆΠ΅Π½Π° ΠΏΡΠΎΡΡΠΎΡΠΎΠ²ΠΎ-ΡΠ°ΡΠΎΠ²Π° Π΄ΠΈΠ½Π°ΠΌΡΠΊΠ° Π½ΠΈΠ·ΡΠΊΠΎ-ΡΠ°ΡΡΠΎΡΠ½ΠΈΡ
ΡΠ»ΡΠΊΡΡΠ°ΡΡΠΉ Π³ΡΡΡΠΈΠ½ΠΈ Π΅Π»Π΅ΠΊΡΡΠΎΠ½ΡΠ² Ρ Π΄Π²ΠΎΡ
ΡΠ΅ΠΆΠΈΠΌΠ°Ρ
ΡΠΎΠ·ΡΡΠ΄ΡΠ² ΡΠ° Π· Π»Π°Π·Π΅ΡΠ½ΠΎΡ ΡΠ½ΠΆΠ΅ΠΊΡΡΡΡ Π΄ΠΎΠΌΡΡΠΎΠΊ Π²ΡΠ³Π»Π΅ΡΡ Π² ΡΠΎΡΡΠ°ΡΡΠΎΠ½Ρ Π£-3Π.ΠΠΊΡΠΏΠ΅ΡΠΈΠΌΠ΅Π½ΡΠ°Π»ΡΠ½ΠΎ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½Π° ΠΏΡΠΎΡΡΡΠ°Π½ΡΡΠ²Π΅Π½Π½ΠΎ-Π²ΡΠ΅ΠΌΠ΅Π½Π½Π°Ρ Π΄ΠΈΠ½Π°ΠΌΠΈΠΊΠ° Π½ΠΈΠ·ΠΊΠΎ-ΡΠ°ΡΡΠΎΡΠ½ΡΡ
ΡΠ»ΡΠΊΡΡΠ°ΡΠΈΠΉ ΠΏΠ»ΠΎΡΠ½ΠΎΡΡΠΈ ΡΠ»Π΅ΠΊΡΡΠΎΠ½ΠΎΠ² Π² Π΄Π²ΡΡ
ΡΠ΅ΠΆΠΈΠΌΠ°Ρ
ΡΠ°Π·ΡΡΠ΄ΠΎΠ² ΠΈ Ρ Π»Π°Π·Π΅ΡΠ½ΠΎΠΉ ΠΈΠ½ΠΆΠ΅ΠΊΡΠΈΠ΅ΠΉ ΠΏΡΠΈΠΌΠ΅ΡΠΈ ΡΠ³Π»Π΅ΡΠΎΠ΄Π° Π² ΡΠΎΡΡΠ°ΡΡΠΎΠ½Π΅ Π£-3Π
Self-optimization, community stability, and fluctuations in two individual-based models of biological coevolution
We compare and contrast the long-time dynamical properties of two
individual-based models of biological coevolution. Selection occurs via
multispecies, stochastic population dynamics with reproduction probabilities
that depend nonlinearly on the population densities of all species resident in
the community. New species are introduced through mutation. Both models are
amenable to exact linear stability analysis, and we compare the analytic
results with large-scale kinetic Monte Carlo simulations, obtaining the
population size as a function of an average interspecies interaction strength.
Over time, the models self-optimize through mutation and selection to
approximately maximize a community fitness function, subject only to
constraints internal to the particular model. If the interspecies interactions
are randomly distributed on an interval including positive values, the system
evolves toward self-sustaining, mutualistic communities. In contrast, for the
predator-prey case the matrix of interactions is antisymmetric, and a nonzero
population size must be sustained by an external resource. Time series of the
diversity and population size for both models show approximate 1/f noise and
power-law distributions for the lifetimes of communities and species. For the
mutualistic model, these two lifetime distributions have the same exponent,
while their exponents are different for the predator-prey model. The difference
is probably due to greater resilience toward mass extinctions in the food-web
like communities produced by the predator-prey model.Comment: 26 pages, 12 figures. Discussion of early-time dynamics added. J.
Math. Biol., in pres
Reflection, radiation and interference for black holes
Black holes are capable of reflection: there is a finite probability for any
particle that approaches the event horizon to bounce back. The albedo of the
black hole depends on its temperature and the energy of the incoming particle.
The reflection shares its physical origins with the Hawking process of
radiation, both of them arise as consequences of the mixing of the incoming and
outgoing waves that takes place on the event horizon.Comment: 10 pages, 1 figure, Revte
Quantum Inequalities for the Electromagnetic Field
A quantum inequality for the quantized electromagnetic field is developed for
observers in static curved spacetimes. The quantum inequality derived is a
generalized expression given by a mode function expansion of the four-vector
potential, and the sampling function used to weight the energy integrals is
left arbitrary up to the constraints that it be a positive, continuous function
of unit area and that it decays at infinity. Examples of the quantum inequality
are developed for Minkowski spacetime, Rindler spacetime and the Einstein
closed universe.Comment: 19 pages, 1 table and 1 figure. RevTex styl
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