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The visible world is founded on the proton, the only composite building block of matter that is stable in nature. Consequently, understanding the formation of matter relies on explaining the dynamics and the properties of the proton’s bound state. A fundamental property of the proton involves the response of the system to an external electromagnetic field. It is characterized by the electromagnetic polarizabilities1that describe how easily the charge and magnetization distributions inside the system are distorted by the electromagnetic field. Moreover, the generalized polarizabilities2map out the resulting deformation of the densities in a proton subject to an electromagnetic field. They disclose essential information about the underlying system dynamics and provide a key for decoding the proton structure in terms of the theory of the strong interaction that binds its elementary quark and gluon constituents. Of particular interest is a puzzle in the electric generalized polarizability of the proton that remains unresolved for two decades2. Here we report measurements of the proton’s electromagnetic generalized polarizabilities at low four-momentum transfer squared. We show evidence of an anomaly to the behaviour of the proton’s electric generalized polarizability that contradicts the predictions of nuclear theory and derive its signature in the spatial distribution of the induced polarization in the proton. The reported measurements suggest the presence of a new, not-yet-understood dynamical mechanism in the proton and present notable challenges to the nuclear theory.

The role of free passage distance (FPD: the distance between the avalanche region and surface detectors) in influencing the relative numbers of energetic electrons and gamma rays in Thunderstorm Ground Enhancements (TGEs) is reconsidered and focuses on the contrast between long (>100 m) versus short (<100 m) FPDs, respectively. Estimates of FPD are based on information from published balloon soundings of the electric field, from published profiles of radar reflectivity in TGEs, and from analyses of Japan winter storms. All these data sources support typical values of FPD >100 m. Neither the shortcomings of present particle detectors in distinguishing electrons from gamma rays, nor the dominance of gamma rays over electrons, are sufficient evidence to deny the robust presence of Compton electrons at FDP values greater than 100 m that have also been shown in earlier simulations as well as the present Comment. Problems with having sustained electric fields of breakeven magnitude within 100 m of the Earth's surface (in relatively rare TGEs) are identified. The resolution of these problems, and the prominent nocturnal presence of these rare events, may possibly be explained by the descent of a strong field region in a collapsing storm, and by a low cloud base that intercepts and immobilizes fast corona ions, thereby preserving the intense electric field. Thunderstorms are capable of accelerating electrons to large energy by a process called electron runaway. This process is often confined to the cold portion of the thunderstorm at higher altitude where ice particles are available to separate electric charge to produce the necessary electric field, and where so‐called avalanche electrons are present. As a result, the high field region in the storm is removed from the ground where measurements of energetic radiation are usually undertaken to diagnose electron acceleration aloft. Gamma rays are produced when the energetic electrons are decelerated in coming in contact with heavy nuclei in a process called bremsstrahlung. Electrons unaided by strong field have short range in the atmosphere: tens of meters and less, whereas gamma rays have larger range (hundreds of meters). Accordingly, energetic electrons cannot be expected far (>200 m) below the high field region. One possible scenario for reducing this gap is the descent of strong field to near cloud base in a collapsing storm and the protection of field dissipation by the capture of small corona ions by cloud droplets. Evidence from several research areas in the literature is used to support the arguments in this paper. Energetic Compton electrons are an inevitable accompaniment of the gamma ray flux of Thunderstorm Ground Enhancements (TGEs) but in numbers too small to be readily distinguished from the gamma rays with typical detectorsThe observations of avalanche electrons in TGEs is surprising, given the small free passage distance (FPD) (<50–100 m) requiredOne suggested scenario for creating small FPD is the lowering of negative charge in storm collapse and the capture of fast corona ions by cloud droplets Energetic Compton electrons are an inevitable accompaniment of the gamma ray flux of Thunderstorm Ground Enhancements (TGEs) but in numbers too small to be readily distinguished from the gamma rays with typical detectors The observations of avalanche electrons in TGEs is surprising, given the small free passage distance (FPD) (<50–100 m) required One suggested scenario for creating small FPD is the lowering of negative charge in storm collapse and the capture of fast corona ions by cloud droplets

Thunderstorm Ground Enhancements (TGEs) refer to correlated enhancements in surface electric field and gamma ray flux that are manifestations of electron runaway in the storm overhead. The electric field enhancements can be of positive or negative polarity. In this study, altitude‐resolved S‐band radar observations of graupel are used to demonstrate distinct differences in storm structure linked with these “positive” and “negative” TGEs. The physical interpretation rests on the well‐established temperature‐dependent tripole structure of thunderstorms, with the main negative charge of the tripole acting as an electron repeller. This interpretation is supported by case studies showing altitude‐stable convection, with shallow (deep) development linked with “positive” (“negative”) TGEs, and by case studies of collapsing storms that show upper dipole dominance early and lower inverted dipole dominance later when graupel particles descend from a colder to warmer temperature domain. In the case of many TGEs on Mt Aragats (3.2 km MSL), the temperature‐dependent altitude of downward electron acceleration and avalanching may be sufficiently distant (>500 m) from surface detectors that the energetic electrons (1–10 MeV) are not likely avalanche/runaway electrons. Instead, they are Compton‐scattered and pair‐produced electrons from bremsstrahlung gamma radiation emanating from the high‐field avalanche region aloft. These inferences are consistent with GEANT4 calculations that identify the physical origins of energetic electrons at the surface. Thunderstorm Ground Enhancements (TGEs) are indicative of downward electron acceleration within the storm and are manifest with both polarities of the electric fieldVertical development disclosed by RADAR is uniquely linked with "positive" and "negative" TGEsThese different vertical developments are attributed to a temperature‐dependent tripole structure of thunderclouds Thunderstorm Ground Enhancements (TGEs) are indicative of downward electron acceleration within the storm and are manifest with both polarities of the electric field Vertical development disclosed by RADAR is uniquely linked with "positive" and "negative" TGEs These different vertical developments are attributed to a temperature‐dependent tripole structure of thunderclouds

Despite the ubiquity of thunderstorms, lightning, and related electrical phenomena, many important electromagnetic processes in our atmosphere are poorly understood; the key questions about the thundercloud electrification and lightning initiation remain unanswered. The bulk information on particle fluxes correlated with thunderstorm can be used to better understand the electrical structure of thunderclouds. Only very specific electric configuration of the lower part of the cloud can support the sustainable acceleration of the electrons. Our analysis is based on the thunderstorm data from the Aragats Mountain in Armenia, 3200 m above sea level Varieties of particle detectors located at Aragats Space Environmental Center are registering neutral and charged particle fluxes correlated with thunderstorms, so-called Thunderstorm Ground Enhancements (TGEs). Simultaneously the electrical mills and lightning detectors are monitoring the near-surface electric field and type of lightning occurrences; weather stations are measuring plenty of meteorological parameters. In the present paper we relate particle fluxes to the electrical structure of thunderclouds, namely, to the origination of the Lower Positive Charged Region (LPCR) below the main negative charged layer in the middle of the thundercloud, and to lightning occurrences. Only after creation of the lower dipole in the thundercloud can the electrons be accelerated and particle flux be directed downward. Maturity of the LPCR is correlated with increasing particle fluxes. Thus, the temporal evolution of TGE gives direct evidence of the maturity of LPCR, its initiation, and its decaying. [ABSTRACT FROM AUTHOR]

Involvement of Chromosomes 7, 18 and X in Mitomycin C-Induced MicronucleiThe involvement of specific chromosomes in the formation of micronuclei (MN) is neither well studied nor understood. We studied the involvement of chromosomes 7, 18 and X in mitomycin C (MMC)-induced MN. A total of 1,202 female MN were studied by three-color fluorescence in situhybridization (FISH) using centromere-specific probes. After a second round of hybridization, using whole chromosome painting probes, 916 MN were evaluated. The frequency of MN containing whole chromosome painting signals for chromosomes X in 916 male MN was analyzed. Different frequency of involvement of selected chromosomes in MN formation was revealed. Chromosome interphase position, size and inactive (heterochromatinized) state of X chromosome in females was discussed as possible reasons of their non random involvement in MN formation. There was no clear relationship between chromosome interphase position and size and migration in MN. However, it was shown that X-chromosomal material was over represented in female- and under represented in male-derived MN. We speculated about a preferred inclusion of the inactive female X-chromosome into MN.

Characterization of Small Supernumerary Marker Chromosomes By A Simple Molecular and Molecular Cytogenetics ApproachSmall supernumerary marker chromosomes (sSMC) are still a major problem especially in prenatal cytogenetic diagnostics and counseling. These structurally abnormal chromosomes cannot be identified or characterized unambiguously by conventional banding cytogenetics alone, and are generally about the size of or smaller than a chromosome 20 in the same metaphase spread. We describe a straightforward algorithm, based on data from 2,211 reported cases (http://www.markerchromosomes.ag.vu) to quickly characterize the sSMC's chromosomal origin.

After having published the first thunderstorm ground enhancements (TGEs) catalog to explain long-lasting TGEs, we address here problems pertaining to TGE evolution (shape) and atmospheric conditions supporting the origination of the relativistic runaway electron avalanches. We also address the question of radon progeny gamma radiation and its contribution to overall TGE flux. We demonstrate that by using detectors with different energy thresholds we can identify and reliably separate both mechanisms of TGE origination. An analysis of measured energy spectra of TGEs reveals contributions of both processes to the TGE temporal evolution and shape. We also confirm the model of radon progeny radiation during a thunderstorm. [ABSTRACT FROM AUTHOR]