Chemotherapy drugs react differently to radiation while in water (Vol. 50, No. 5-6)

A new study looked at the way certain molecules found in chemotherapy drugs react to radiation while in water, which is more similar to in the body, compared to previous research that studied them in gas.

Cancer treatment often involves a combination of chemotherapy and radiotherapy. Chemotherapy uses medication to stop cancer cells reproducing, but the medication affects the entire body. Radiotherapy uses radiation to kill the cancer cells, and it is targeted to the tumour site. In a recent study, published in the journal EPJD, the authors studied selected molecules of relevance in this context. They wanted to see how these molecules were individually affected by radiation similar to that used in radiotherapy.

S. E. Huber and A. Mauracher, Electron impact ionisation cross sections of fluoro-substituted nucleosides, Eur. Phys. J. D 73, 137 (2019)
[Article]

CHEP2018 Conference Proceedings (Vol. 51, No. 1)

The 23rd International Conference on Computing in High Energy and Nuclear Physics was held in the National Palace of Culture, Sofia, Bulgaria from 9th to 13th of July 2018. The program consisted of 27 plenary, 323 parallel presentations and 188 posters. The plenary talks covered topics such as HPC and cloud computing, machine learning in High Energy Physics (HEP), overviews of experiment software for data acquisition, high level triggering, reconstruction and analysis, experience from astro-particle and neutrino physics, as well as broader subjects like multithreading and vectorization in HEP, use of blockchains, quantum computing, software citation mechanisms. Progress on common and widely used tools and packages in HEP such as ROOT, EOS and CVMFS was also presented. A dedicated talk and a panel discussion were devoted to the implementation of a successful diversity program in the field of HEP and nuclear physics computing.

A. Forti, L. Betev, M. Litmaath, O. Smirnova and P. Hristov (Eds.),, 23^rd International Conference on Computing in High Energy and Nuclear Physics (CHEP 2018), Sofia, Bulgaria, July 9-13 , 2018',, EPJ Web of Conferences 214 (2019)
[Proceedings]

Chimera states are fragile under random links (Vol. 51, No. 2)

In a chimera state of large interactive systems the underlying symmetry of the dynamical system is spontaneously broken and the spatial profile splits into synchronised and desynchronised groups.

In this work the surprising fragility of chimeras in the presence of very few time-varying random links is demonstrated in wide-ranging examples. Spatial randomness restores the symmetry of the emergent spatial patterns, with chimeras giving way to uniform steady states or spatiotemporal chaos. The size of the basin of attraction of chimeras rapidly shrinks under increasing randomness, indicating its strong impact on the global stability of chimeras. These results impact the search for chimeras in real-world systems.

Sudeshna Sinha, Chimera states are fragile under random links, EPL 128, 40004 (2019)
[Abstract]

Chip-Based Frequency Shift Super-Resolution Imaging (Vol. 50, No. 4)

Current label-free super-resolution methods suffer from either limited resolution improvements, small field-of-views or complex implementations, and a method with high-resolution, high-throughput and easy configuration is desirable for the practical applications in materials, biology and medicine, etc. To break this limitation, the authors propose a Si₃N₄ waveguide platform design for multi-wavelength illuminated label-free super-resolution microscopy imaging. The deep-subwavelength resolution was enabled by large wave-vector evanescent illumination induced spatial frequency shift effect, which also provides the high throughput for its wide field implementation.

In the method, chip-based waveguide with high refractive index produced evanescent wave illumination on the upper surface, the high tangential wave vector shifted the high spatial frequency components into the passband of the detection system from the perspective of the reciprocal domain. Multi-wavelength illuminated method was employed to cover the complete detection in the frequency domain. This enlarged the detectable broad-band frequency spectrum range, and high-resolution image with high signal-to-noise-ratio could be achieved using reconstruction algorithm. The optimized waveguide design to realize single mode behaviour and low attenuation guaranteed uniform evanescent wave illumination for the low-noise wide-field imaging. The integrated device is cost-effective, mass-producible and can conveniently give super resolvability to conventional microscopy as a compact module.

X. Xu, X. Liu, Ch. Pang, Y. Ma, Ch. Meng, J. Zhang, X. Liu and Q. Yang, Si₃N₄ waveguide platform for label-free super-resolution imaging: simulation and analysis, J. Phys. D: Appl. Phys. 52, 284002 (2019)
[Abstract]

Classical and quantum approaches to the photon mass (Vol. 42, No. 4)

In new effects of the Aharonov-Bohm type, coherent superpositions of particles possessing opposite electromagnetic properties are used. For the one shown in this figure, charged particles interact with the magnetic vector potential A of a solenoid. If the photon mass is not zero, the electromagnetic interaction is modified. Measuring the corresponding change of quantum phase shift with an interferometer leads to an estimate of m_γ.

A survey of existing and proposed classical and quantum approaches to the photon mass
G. Spavieri, J. Quintero, G.T. Gillies and M. Rodriguez, Eur. Phys. J. D 61, 531 (2011)
[Abstract]

Clearer vision of the biochemical reaction that allows us to see (Vol. 49 No.5-6)

Physicists develop improved algorithms for simulating how complex molecules respond to excitation by photons, and explaining what happens when photons hit our eyes.

What makes it possible for our eyes to see? It stems from a reaction that occurs when photons come into contact with a protein in our eyes, called rhodopsin, which adsorbs the photons making up light. In a paper published recently the authors propose a refined approximation of the equation that describes the effect of this photo-excitation on the building blocks of molecules. Their findings also have implications for other molecules, such as azobenzene, a chemical used in dyes. The incoming photon triggers certain reactions, which can result, over time, in dramatic changes in the properties of the molecule itself. This study was included in a special anniversary issue of EPJB in honour of Hardy Gross.

F. Agostini, I.Tavernelli, and G. Ciccotti, Nuclear Quantum Effects in Electronic (Non)Adiabatic Dynamics, Eur. Phys. Jour. B 91, 139 (2018)
[Abstract]

Cocktail achieves superconducting boost (Vol. 44 No. 2)

Superconductivity occurs at 44 K

E.-W. Scheidt, V.R. Hathwar, D. Schmitz, A. Dunbar, W. Scherer, F. Mayr, V. Tsurkan, J. Deisenhofer, and A. Loidl, ‘Superconductivity at T_c = 44 K in Li_xFe₂Se₂(NH₃)_y’, Eur. Phys. J. B 85, 279 (2012)
[Abstract]

Coherent investigation of nuclear data at CEA DAM: a review (Vol. 43 No. 6)

Jezebel (a plutonium sphere) reactivity induced by components of the evaluated BRC09 and ENDF/B-VII.0 ²³⁹Pu file, demonstrates that two different evaluated data sets predict the same K_eff criticality for different underlying reasons; one or more of them (probably both) are in need of improvements.

E. Bauge + 28 co-authors, ‘Coherent investigation of nuclear data at CEA DAM: Theoretical models, experiments and evaluated data’, Eur. Phys. J. A 48, 113 (2012)
[Abstract]

Cold Fusion Mechanism in Nanoscale Catalysis? (Vol. 41, No. 6)

Novel mechanism for nanoscale catalysis
A.Z. Msezane, Z. Felfli and D. Sokolovski, J. Phys. B: At. Mol. Opt. Phys., 43, 201001 (2010)
[Abstract]

Collagen fibres grow like a sunflower (Vol. 50, No. 4)

Collagen fibrils are a major component of the connective tissues found throughout the animal kingdom. The cable-like assemblies of long biological molecules combine to form tissues as varied as skin, corneas, tendons or bones. The development of these complex tissues is the subject of a variety of research efforts, focusing on the steps involved and the respective contributions of genetics and physical chemistry to their development. Now, the authors have shed new light on how complex collagen fibrils form. In a new study published recently, they focus on one of the hierarchical steps, in which molecules spontaneously associate in long and dense axisymmetric fibres, known as type I collagen fibrils. In this study, the spontaneous association step under scrutiny is unique because the diameter of the fibre remains constant throughout its growth, while the end of growth manifests a characteristic parabolic profile. After studying several possible models, the researchers concluded the most likely explanation is that the fibres spread out from the fibre axis, along a stem, similar to how a sunflower’s florets grow.

J. Charvolin, and J-F. Sadoc, Type I collagen fibrils: from growth morphology to local order, Eur. Phys. J. E 42, 49 (2019)
[Abstract]

Combining experimental data to test models of new physics that explain dark matter (Vol. 49, No. 1)

The most statistically consistent and versatile tool to date is designed to gain insights into dark matter from models that extend the standard model of particle physics, rigorously comparing them with the latest experimental data.

In chess, a gambit refers to a move in which a player risks one piece to gain an advantage. The quest to explain dark matter, a missing ingredient from the minimal model that can describe the fundamental particles we have observed (referred to as the standard model of particle physics), has left many physicists eager to gain an advantage when comparing theoretical models to as many experiments as possible. In particular, maintaining calculation speed without sacrificing the number of parameters involved is a priority. Now the GAMBIT collaboration, an international group of physicists, has just published a series of papers that offer the most promising approach to date to understanding dark matter. The collaboration has developed the eponymous GAMBIT software, designed to combine the growing volume of experimental data from multiple sources—a process referred to as a global fit—in a statistically consistent manner. Such data typically comes from astrophysical observations and experiments that collide subatomic particles, such as those involving the Large Hadron Collider (LHC), based at CERN in Geneva, Switzerland.

The GAMBIT Collaboration, Status of the scalar singlet dark matter model, Eur. Phys. J. C 77, 568 (2017)
[Abstract]

Compact Stark slower for polar molecules (Vol. 41, No. 5)

Photograph of the hand-held wire Stark decelerator

Slowing polar molecules using a wire Stark decelerator
A. Marian, H. Haak, P. Geng and G. Meijer, Eur. Phys. J. D 59, 179 (2010)
[Abstract] | [PDF]

COMPASS: Radiative widths of the a2(1320) and π2(1670) (Vol. 45 No.3)

Intensity of the 2−+ partial-wave in π−γ ->π−π−π+, interpreted as radiative width of the π2(1670)

Radiative transitions are among the most important and insightful processes for the investigation of atomic, nuclear and hadronic systems. They reveal the electromagnetic substructure of the involved particles. The meson is known since the 1980s to decay radiatively with a branching of about 0.3% into a pion and a photon. Theoretically this can be linked, for example through the vector meson dominance model, to the main hadronic decay channels.

Experimentally, it is difficult to observe rare decays involving a single photon directly, over an abundant neutral pion background. The way out is to measure the reverse process, the production of the resonance in a pion-photon collision. The COMPASS experiment at CERN has taken high-statistics data of pion-nucleus collisions π-Pb->π-π-π+Pb of which the photon-exchange contribution, so-called Primakoff scattering, was singled out.. The radiative coupling of the a2(1320) resonance was determined with unprecedented precision, employing partial-wave analysis of the three-pion final state. The latter proved the radiative coupling of the 10-times less intensive π2(1670) resonance, π2(1670) -> πγ, and made possible the first measurement of its radiative width. This challenges theoretical descriptions, that aim at linking this transition intensity to the inner structure of the π2(1670).

C. Adolph et al., “Measurement of radiative widths of a2 (1320) and π2 (1670)“, Eur. Phys. J. A, 50, 79 (2014)
[Abstract]

Computer and brain-logic gates (Vol. 45 No. 1)

An illustration for the differences between computer and brain logic-gates.

This year we are celebrating the 70th anniversary of the publication of the seminal work by McCulloch and Pitts "A logical calculus of the ideas immanent in nervous activity". They suggested that the brain is composed of threshold units, neurons, composing reliable logic-gates similar to the logic at the core of today's computers. This suggested computational framework had a tremendous impact on the development of artificial neural networks and machine learning theory, but had limited impact on neuroscience, since neurons exhibit far richer dynamics. Here we propose a new experimentally corroborated paradigm in which the functionality of the brain's logic-gates depends on the history of their activity, the stimulation frequencies of their input neurons, as well as the activity of their interconnections. Our results are based on an experimental procedure where conditioned stimulations were enforced on circuits of neurons embedded within a large-scale network of cortical cells in-vitro. We demonstrate that the underlying biological mechanism is the unavoidable increase of neuronal response latency to ongoing stimulations, which imposes a non-uniform gradual stretching of network delays. This computational paradigm is anticipated to lead to better understanding of the brain's functionalities.

R. Vardi, S. Guberman, A. Goldental and I. Kanter, “An experimental evidence-based computational paradigm for new logic-gates in neuronal activity”, EPL, 103, 66001 (2013).
[Abstract]

Conductivity at the edges of graphene bilayers (Vol. 50, No. 5-6)

The conductivity of dual layers of graphene greatly depends on the states of carbon atoms at their edges; a property which could have important implications for information transmissions on quantum scales.

Made from 2D sheets of carbon atoms arranged in honeycomb lattices, graphene displays a wide array of properties regarding the conduction of heat and electricity. When two layers of graphene are stacked on top of each other to form a ‘bilayer’, these properties can become even more interesting. At the edges of these bilayers, for example, atoms can sometimes exist in an exotic state of matter referred to as the ‘quantum spin Hall’ (QSH) state, depending on the nature of the interaction between their spins and their motions, referred to as their ‘spin-orbit coupling’ (SOC). While the QSH state is allowed for ‘intrinsic’ SOC, it is destroyed by ‘Rashba’ SOC. In an article recently published, the authors showed that these two types of SOC are responsible for variations in the ways in which graphene bilayers conduct electricity.

P. Sinha, and S. Basu, Study of edge states and conductivity in spin-orbit coupled bilayer graphene, Eur. Phys. J. B 92, 207 (2019)
[Article]