140 research outputs found
Radiative corrections to muon decay in leading and next to leading approximation for electron spectrum
We have noted that the electron spectrum of muon decay in the leading
logarithmic approximation calculated in two lowest orders of the perturbation
theory in the paper of Berman (1958), can be reproduced by the parton language.
This fact permits one to generalize the result to all orders of the
perturbation theory using the structure function method.Comment: 4 pages, 1 figur
Virulence of wheat leaf rust (Puccinia triticina Eriks.) in the years 2013–2015 and resistance of wheat cultivars in Slovakia
In 2013–2015 virulence in the wheat leaf rust population was evaluated on 17 Thatcher near-isogenic lines with leaf rust resistance genes. A total of 110 wheat leaf rust isolates were analyzed. Resistance genes Lr9 and Lr19 were effective to all tested isolates. Genes Lr24 and Lr28 conditioned resistance to 92% of the tested rust isolates. Thirty-seven winter wheat cultivars registered in Slovakia were analyzed for the presence of Lr10, Lr24, Lr26, Lr34 and Lr37 using tightly linked molecular markers. Gene Lr37 was the most common in the tested cultivars. Leaf rust resistance was also tested in 13 wheat cultivars at the seedling stage with representative pathotypes of leaf rust
Semiconductor Bloch equation analysis of optical Stark and Bloch-Siegert shifts in monolayers WSe and MoS
We report on the theoretical and experimental investigation of
valley-selective optical Stark and Bloch-Siegert shifts of exciton resonances
in monolayers WSe and MoS induced by strong circularly polarized
nonresonant optical fields. We predict and observe transient shifts of both 1sA
and 1sB exciton transitions in the linear interaction regime. The theoretical
description is based on semiconductor Bloch equations. The solutions of the
equations are obtained with a modified perturbation technique, which takes into
account many-body Coulomb interaction effects. These solutions allow to explain
the polarization dependence of the shifts and calculate their values
analytically. We found experimentally the limits of the applicability of the
theoretical description by observing the transient exciton spectra change due
to many-body effects at high field amplitudes of the driving wave.Comment: 20 pages, 9 figures, this manuscript is related to the "Giant
valley-selective Stark and Bloch-Siegert shifts of exciton resonances in
WSe and MoS monolayers" manuscrip
Giant valley-selective Stark and Bloch-Siegert shifts of exciton resonances in WSe and MoS monolayers
In this letter we demonstrate that the valley degeneracy of exciton states in
monolayers of WSe and MoS can be lifted by the interaction with strong
circularly-polarized infrared pulses with durations of only few periods of the
electric field whose photon energy is much lower than the energy of the
excitonic transition. The observed valley-sensitive blue shifts of excitonic
absorption lines are consequences of optical Stark and Bloch-Siegert shifts
acting exclusively on the opposite valleys of the monolayer. We measured the
transient valley-selective changes of sample reflectivity for 1sA as well as
for 1sB exciton transitions corresponding to the two most intensive resonances
in the studied materials. For the studied phenomena we developed a theoretical
description based on semiconductor Bloch equations, which goes beyond the
simple two-level model used in previous investigations. The theoretical
approach takes into account Coulomb many-body effects in the monolayer and
provides a unified description of both types of shifts. The detected
room-temperature excitonic energy shifts of up to 30\,meV pave the way for
practical applications of these effects.Comment: 6 pages, 3 figures, the manuscript is related to the "Semiconductor
Bloch equation analysis of optical Stark and Bloch-Siegert shifts in
monolayers WSe and MoS" manuscrip
Effect of Different Factors on Proliferation of Antler Cells, Cultured In Vitro
Antlers as a potential model for bone growth and development have become an object of rising interest. To elucidate processes explaining how antler growth is regulated, in vitro cultures have been established. However, until now, there has been no standard method to cultivate antler cells and in vitro results are often opposite to those reported in vivo. In addition, many factors which are often not taken into account under in vitro conditions may play an important role in the development of antler cells. In this study we investigated the effects of the antler growth stage, the male individuality, passaged versus primary cultures and the effect of foetal calf serum concentrations on proliferative potential of mixed antler cell cultures in vitro, derived from regenerating antlers of red deer males (Cervus elaphus). The proliferation potential of antler cells was measured by incorporation of 3H thymidine. Our results demonstrate that there is no significant effect of the antler growth stage, whereas male individuality and all other examined factors significantly affected antler cell proliferation. Furthermore, our results suggest that primary cultures may better represent in vivo conditions and processes occurring in regenerating antlers. In conclusion, before all main factors affecting antler cell proliferation in vitro will be satisfactorily investigated, results of in vitro studies focused on hormonal regulation of antler growth should be taken with extreme caution
Footprint of publication selection bias on meta-analyses in medicine, environmental sciences, psychology, and economics
Publication selection bias undermines the systematic accumulation of evidence. To assess the extent of this problem, we survey over 68,000 meta-analyses containing over 700,000 effect size estimates from medicine (67,386/597,699), environmental sciences (199/12,707), psychology (605/23,563), and economics (327/91,421). Our results indicate that meta-analyses in economics are the most severely contaminated by publication selection bias, closely followed by meta-analyses in environmental sciences and psychology, whereas meta-analyses in medicine are contaminated the least. After adjusting for publication selection bias, the median probability of the presence of an effect decreased from 99.9% to 29.7% in economics, from 98.9% to 55.7% in psychology, from 99.8% to 70.7% in environmental sciences, and from 38.0% to 29.7% in medicine. The median absolute effect sizes (in terms of standardized mean differences) decreased from d = 0.20 to d = 0.07 in economics, from d = 0.37 to d = 0.26 in psychology, from d = 0.62 to d = 0.43 in environmental sciences, and from d = 0.24 to d = 0.13 in medicine
Footprint of publication selection bias on meta-analyses in medicine, environmental sciences, psychology, and economics
Publication selection bias undermines the systematic accumulation of
evidence. To assess the extent of this problem, we survey over 68,000
meta-analyses containing over 700,000 effect size estimates from medicine
(67,386/597,699), environmental sciences (199/12,707), psychology (605/23,563),
and economics (327/91,421). Our results indicate that meta-analyses in
economics are the most severely contaminated by publication selection bias,
closely followed by meta-analyses in environmental sciences and psychology,
whereas meta-analyses in medicine are contaminated the least. After adjusting
for publication selection bias, the median probability of the presence of an
effect decreased from 99.9% to 29.7% in economics, from 98.9% to 55.7% in
psychology, from 99.8% to 70.7% in environmental sciences, and from 38.0% to
29.7% in medicine. The median absolute effect sizes (in terms of standardized
mean differences) decreased from d = 0.20 to d = 0.07 in economics, from d =
0.37 to d = 0.26 in psychology, from d = 0.62 to d = 0.43 in environmental
sciences, and from d = 0.24 to d = 0.13 in medicine
Dogs Discriminate Identical Twins
Earlier studies have shown variation among experimental attempts to establish whether human monozygotic twins that are genetically identical also have identical individual scents. In none of the cases were the dogs able to distinguish all the individual scents of monozygotic twins living in the same environment if the scents were presented to them separately. Ten specially trained police German Shepherd dogs of three Czech Republic Police Regional Headquarters were used for scent identification in our study. The dogs were supposed to match scents of two monozygotic pairs (5 and 7 years old) and two dizygotic twin pairs (8 and 13 years old). Scents were collected on cotton squares stored in glass jars. Dog handlers were blind to the experiment details. In each trial (line-up), one scent was used as a starting scent and the dog was then sent to determine if any of the 7 presented glass jars contained a matching scent. Scents of children of similar ages were used as distractors. In the matching procedure, the dogs matched correctly the scent of one twin with the other, as well as two scents collected from every single identical and non-identical twin to prove their efficacy and likewise, the presence of the matching twin scent in any given glass jar. All dogs in all trials distinguished correctly the scents of identical as well as non-identical twins. All dogs similarly matched positively two scents collected from the same individuals. Our findings indicated that specially trained German Shepherd dogs are able to distinguish individual scents of identical twins despite the fact that they live in the same environment, eat the same food and even if the scents are not presented to them simultaneously
Brain antigens in functionally distinct antigen-presenting cell populations in cervical lymph nodes in MS and EAE
Drainage of central nervous system (CNS) antigens to the brain-draining cervical lymph nodes (CLN) is likely crucial in the initiation and control of autoimmune responses during multiple sclerosis (MS). We demonstrate neuronal antigens within CLN of MS patients. In monkeys and mice with experimental autoimmune encephalomyelitis (EAE) and in mouse models with non-inflammatory CNS damage, the type and extent of CNS damage was associated with the frequencies of CNS antigens within the cervical lymph nodes. In addition, CNS antigens drained to the spinal-cord-draining lumbar lymph nodes. In human MS CLN, neuronal antigens were present in pro-inflammatory antigen-presenting cells (APC), whereas the majority of myelin-containing cells were anti-inflammatory. This may reflect a different origin of the cells or different drainage mechanisms. Indeed, neuronal antigen-containing cells in human CLN did not express the lymph node homing receptor CCR7, whereas myelin antigen-containing cells in situ and in vitro did. Nevertheless, CLN from EAE-affected CCR7-deficient mice contained equal amounts of myelin and neuronal antigens as wild-type mice. We conclude that the type and frequencies of CNS antigens within the CLN are determined by the type and extent of CNS damage. Furthermore, the presence of myelin and neuronal antigens in functionally distinct APC populations within MS CLN suggests that differential immune responses can be evoked
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