High-visibility multi-photon interference of Hanbury Brown - Twiss type for classical light

Difference-phase (or Hanbury Brown - Twiss type) intensity interference of classical light is considered in higher orders in the intensity. It is shown that, while the visibility of sum-phase (NOON-type) interference for classical sources drops with the order of interference, the visibility of difference-phase interference has opposite behavior. For three-photon and four-photon interference of two coherent sources, the visibility can be as high as 81.8% and 94.4%, respectively. High-visibility three-photon and four-photon interference of space-time and polarization types has been observed in experiment, for both coherent and pseudo-thermal light.Comment: 11 pages, 9 figure

Laplace transformations of hydrodynamic type systems in Riemann invariants: periodic sequences

The conserved densities of hydrodynamic type system in Riemann invariants satisfy a system of linear second order partial differential equations. For linear systems of this type Darboux introduced Laplace transformations, generalising the classical transformations in the scalar case. It is demonstrated that Laplace transformations can be pulled back to the transformations of the corresponding hydrodynamic type systems. We discuss periodic Laplace sequences of with the emphasize on the simplest nontrivial case of period 2. For 3-component systems in Riemann invariants a complete discription of closed quadruples is proposed. They turn to be related to a special quadratic reduction of the (2+1)-dimensional 3-wave system which can be reduced to a triple of pairwize commuting Monge-Ampere equations. In terms of the Lame and rotation coefficients Laplace transformations have a natural interpretation as the symmetries of the Dirac operator, associated with the (2+1)-dimensional n-wave system. The 2-component Laplace transformations can be interpreted also as the symmetries of the (2+1)-dimensional integrable equations of Davey-Stewartson type. Laplace transformations of hydrodynamic type systems originate from a canonical geometric correspondence between systems of conservation laws and line congruences in projective space.Comment: 22 pages, Late

New Superhard Phases for 3D C60-based Fullerites

We have explored new possible phases of 3D C60-based fullerites using semiempirical potentials and ab-initio density functional methods. We have found three closely related structures - two body centered orthorhombic and one body centered cubic - having 52, 56 and 60 tetracoordinated atoms per molecule. These 3D polymers result in semiconductors with bulk moduli near 300 GPa, and shear moduli around 240 GPa, which make them good candidates for new low density superhard materials.Comment: To be published in Physical Review Letter

Quantitative Proteome Profiling of C. burnetii under Tetracycline Stress Conditions

The recommended antibiotic regimen against Coxiella burnetii, the etiological agent of Q fever, is based on a semi-synthetic, second-generation tetracycline, doxycycline. Here, we report on the comparison of the proteomes of a C. burnetii reference strain either cultured under control conditions or under tetracycline stress conditions. Using the MS-driven combined fractional diagonal chromatography proteomics technique, out of the 531 proteins identified, 5 and 19 proteins were found significantly up- and down-regulated respectively, under tetracycline stress. Although the predicted cellular functions of these regulated proteins did not point to known tetracycline resistance mechanisms, our data clearly reveal the plasticity of the proteome of C. burnetii to battle tetracycline stress. Finally, we raise several plausible hypotheses that could further lead to more focused experiments on studying tetracycline resistance in C. burnetii and thus reduced treatment failures of Q fever

The Radio Spectral Index of the Crab Nebula

We present the results of a new, comprehensive investigation of the radio spectral index of the Crab Nebula supernova remnant. New data at 74 MHz are combined with data at 327 MHz, 1.5 GHz and 5 GHz. In contrast to previous claims, little spatial variation in the spectral index is seen. In particular, between 327 MHz and 5 GHz we see no evidence of spectral steepening near the edge of the nebula, the ``jet'' or the ionized filaments. The rms limits on any spectral index variations in these regions amount to no more than 0.01. We believe that earlier reports of large steepening were the result of correlator bias and image registration problems. An elongated feature was detected 1\arcmin northwest of the pulsar which may be a continuation of the well-known wisp-like structures seen closer to the center of the nebula. At 74 MHz, we see for the first time evidence of free-free absorption by the thermal material in the Crab Nebula's filaments. Apart from some possible renewed acceleration occurring in the wisps, the dominant accelerator of relativistic electrons in the Crab Nebula is the pulsar itself.Comment: 20 pages, Latex, requires aaspp4.st

Detection of the Genetic Material of the Viruses Tacheng uukuvirus and Sara tick phlebovirus in Taiga Ticks Collected in the Sverdlovsk, Tomsk Regions and Primorsky Territory of Russia and Their Phylogeny

Extensive spread of tick-borne diseases poses a significant problem for public health and the health of the population living in endemic areas.The aim of the study was to search, analyze genetic material and identify new viral agents of the Phenuiviridae family in taiga ticks collected in Asian regions of Russia using the method of high throughput sequencing.Materials and methods. The study involved 1460 taiga ticks collected in suburban areas of the Tomsk, Yekaterinburg and Primorsky Territory. The genetic material isolated from ticks was sequenced using Illumina technology followed by phylogenetic analysis.Results and discussion. Analysis of the sequencing results made it possible to detect extended nucleotide sequences of the L-gene fragment characteristic of the Phenuiviridae family viruses. We were able to identify 20 nucleotide sequences the length of 250 bp on average in homogenates of Ixodes persulcatus ticks. Eighteen isolates have been identified as members of the genus Uukuvirus and two isolates have been assigned to the genus Phlebovirus, Phenuiviridae family. Phylogenetic analysis has shown that all isolates of the genus Uukuvirus fall under the cluster of Tacheng tick virus 2 belonging to the species Tacheng uukuvirus. They form a separate phylogenetic group which is closely related to two Romanian variants of 2019. Tacheng tick virus 2 was detected in all three surveyed regions of the Asian part of Russia. Two Tomsk isolates of phlebovirus were classified as Sara tick phlebovirus and they clustered with two isolates of phleboviruses from Karelia. Thus, the genetic material of Tacheng tick virus 2 and Sara tick phlebovirus belonging to two genera of the family Phenuiviridae was found in I. persulcatus ticks collected in three geographically different regions of the Asian part of Russia

Simulation vs. Reality: A Comparison of In Silico Distance Predictions with DEER and FRET Measurements

Site specific incorporation of molecular probes such as fluorescent- and nitroxide spin-labels into biomolecules, and subsequent analysis by Förster resonance energy transfer (FRET) and double electron-electron resonance (DEER) can elucidate the distance and distance-changes between the probes. However, the probes have an intrinsic conformational flexibility due to the linker by which they are conjugated to the biomolecule. This property minimizes the influence of the label side chain on the structure of the target molecule, but complicates the direct correlation of the experimental inter-label distances with the macromolecular structure or changes thereof. Simulation methods that account for the conformational flexibility and orientation of the probe(s) can be helpful in overcoming this problem. We performed distance measurements using FRET and DEER and explored different simulation techniques to predict inter-label distances using the Rpo4/7 stalk module of the M. jannaschii RNA polymerase. This is a suitable model system because it is rigid and a high-resolution X-ray structure is available. The conformations of the fluorescent labels and nitroxide spin labels on Rpo4/7 were modeled using in vacuo molecular dynamics simulations (MD) and a stochastic Monte Carlo sampling approach. For the nitroxide probes we also performed MD simulations with explicit water and carried out a rotamer library analysis. Our results show that the Monte Carlo simulations are in better agreement with experiments than the MD simulations and the rotamer library approach results in plausible distance predictions. Because the latter is the least computationally demanding of the methods we have explored, and is readily available to many researchers, it prevails as the method of choice for the interpretation of DEER distance distributions

ПЕРСПЕКТИВЫ ПОЛУЧЕНИЯ ПРОРОСТКОВ СЕМЯН ЛУКОВЫХ КУЛЬТУР, ОБОГАЩЕННЫХ СЕЛЕНОМ

Sprouts of agricultural crops seeds are considered to be functional food products with high content of antioxidants. Though seeds of Allium species plants are used in some countries as spices the possibilities of appropriate sprouts utilization have never been investigated so far. Evaluation of perennial and A. cepa seeds biofortification with selenium revealed high nutritional value of the resulting sprouts characterized not only by high selenium content exclusively in a form of selenomethyl selenocysteine (a natural anti carcinogen) but also with high levels of antioxidant activity and high polyphenol content. It was demonstrated that among seven studied representatives of Allium species Allium cepa variety Krasnoye krugevo and perennial onion Allium fistulosum give seeds sprouts with the highest levels of selenium (10500-11000 μg/kg d.w.), polyphenols (9.3-10.8 mg-eq GA/g d.w) and the largest values of antioxidant activity (14.7-17.1 mg-eq GA/g d.w.). Utilization of one g of dried seeds sprouts powder, fortified with selenium provides up to 15.7% of the adequate consumption level of selenium exclusively in a form of selenomethyl selenocysteine possessing powerful anti carcinogenic activity.Проростки семян сельскохозяйственных культур являются функциональными продуктами питания с высоким содержанием природных антиоксидантов. Хотя семена растений рода Allium используют в ряде стран в качестве приправы, однако возможности использования соответствующих проростков в пищу ранее не исследовались. Оценка эффективности обогащения семян многолетних луков и лука репчатого селеном выявила высокую пищевую ценность получаемого продукта, отличающегося не только высоким содержанием селена, причем преимущественно в виде селенометил селеноцистеина, мощного природного антиканцерогена, но также повышенным уровнем антиоксидантной активности и высоким содержанием полифенолов. Установлено, что среди 7 исследованных представителей рода Allium наиболее перспективными являются проростки семян лука репчатого Красное кружево и многолетнего лука батуна, содержащих наиболее высокие уровни селена (10500-11000 мкг/кг с.м), полифенолов (9,3-10,8 мг-экв ГК/1 г с.м.) и имеющих наибольший уровень антиоксидантной активности (14,7-17,1 мг-экв ГК/1 г с.м.). Использование 1 г порошка высушенных проростков лука, обогащенных селеном, обеспечивает поступление в организм человека до 15,7% суточной потребности человека в селене, причем в виде селенометил селеноцистеина, обладающего высокой антиканцерогенной активностью

Obtainment of Monoclonal Antibodies and Prospects of Their Application as Basis for Immunodiagnostic Aids for Crimean-Congo Hemorrhagic Fever Virus Detection

) as framework for the production of tools for CCHF virus detection and identification in artificially contaminated samples and clinical specimens containing CCHF antigens was proven efficient