CIRCULAR DICHROISM OF LIGHT-HARVESTING COMPLEXES FROM PURPLE PHOTOSYNTHETIC BACTERIA

The CD spectra of a range of antenna complexes from several different species of purple photosynthetic bacteria were recorded in the wavelength range of 190 to 930 nm. Analysis of the far UV CD (190 to 250 nm) showed that in each case except for the B800-850 from Chr. vinosum the secondary structure of the light-harvesting complexes contains a large amount of α-helix (50%) and very little 0-pleated sheet. This confirms the predictions of the group of Zuber of a high a-helical content based upon consideration of the primary structures of several antenna apoproteins. The CD spectra from the carotenoids and the bacteriochlorophylls show considerable variations depending upon the type of antenna complex. The different amplitude ratios in the CD spectrum for the bacteriochlorophyll Qy, Qx and Soret bands indicate not only different degrees of exciton coupling, but also a strong and variable hyperchromism (Scherz and Parson, 1984a, b)

Interfacing aptamers, nanoparticles and graphene in a hierarchical structure for highly selective detection of biomolecules in OECT devices

In several biomedical applications, the detection of biomarkers demands high sensitivity, selectivity and easy-to-use devices. Organic electrochemical transistors (OECTs) represent a promising class of devices combining a minimal invasiveness and good signal transduction. However, OECTs lack of intrinsic selectivity that should be implemented by specific approaches to make them well suitable for biomedical applications. Here, we report on a biosensor in which selectivity and a high sensitivity are achieved by interfacing, in an OECT architecture, a novel gate electrode based on aptamers, Au nanoparticles and graphene hierarchically organized to optimize the final response. The fabricated biosensor performs state of the art limit of detection monitoring biomolecules, such as thrombin-with a limit of detection in the picomolar range (≤ 5 pM) and a very good selectivity even in presence of supraphysiological concentrations of Bovine Serum Albumin (BSA-1mM). These accomplishments are the final result of the gate hierarchic structure that reduces sterich indrance that could contrast the recognition events and minimizes false positive, because of the low affinity of graphene towards the physiological environment. Since our approach can be easily applied to a large variety of different biomarkers, we envisage a relevant potential for a large series of different biomedical applications

Organic Bioelectronics Development in Italy: A Review

In recent years, studies concerning Organic Bioelectronics have had a constant growth due to the interest in disciplines such as medicine, biology and food safety in connecting the digital world with the biological one. Specific interests can be found in organic neuromorphic devices and organic transistor sensors, which are rapidly growing due to their low cost, high sensitivity and biocompatibility. This trend is evident in the literature produced in Italy, which is full of breakthrough papers concerning organic transistors-based sensors and organic neuromorphic devices. Therefore, this review focuses on analyzing the Italian production in this field, its trend and possible future evolutions

The Boltzmann equation for colourless plasmons in hot QCD plasma. Semiclassical approximation

Within the framework of the semiclassical approximation, we derive the Boltzmann equation describing the dynamics of colorless plasmons in a hot QCD plasma. The probability of the plasmon-plasmon scattering at the leading order in the coupling constant is obtained. This probability is gauge-independent at least in the class of the covariant and temporal gauges. It is noted that the structure of the scattering kernel possesses important qualitative difference from the corresponding one in the Abelian plasma, in spite of the fact that we focused our study on the colorless soft excitations. It is shown that four-plasmon decay is suppressed by the power of $g$ relative to the process of nonlinear scattering of plasmons by thermal particles at the soft momentum scale. It is stated that the former process becomes important in going to the ultrasoft region of the momentum scale.Comment: 41, LaTeX, minor changes, identical to published versio

Contribution to the Global Digital Compact: “Digital commons as a global public good. Internet as a free space, and methods for combating the spread of disinformation and misinformation.”

The Internet as a common good implies the absence of any restrictions, closures, and blockages with censorship being unacceptable in democratic societies. However, it can lead to the uncontrolled growth and spread of disinformation and misinformation, which can have negative effects on democratic processes, on emergency management, and on human rights. While part of society sees the Internet as the last free space and considers the restriction of the Internet an infringement of citizens’ rights to freedom of communication and information, another part of society advocates at least reasonable censorship of the Internet. Parallel to this is the question of who will be behind the censorship – will it be the government, private companies, platforms, or search engines, and what will be the rules and algorithms of censorship. As part of its participation in the CORE project (sCience&human factOr for Resilient sociEty), IIASA held an online consultation with project participants to discuss the topic of “Internet as a free space and methods for combating the spread of disinformation and misinformation” and to prepare key principles and commitments as a contribution to the Global Digital Compact. This report provides a comprehensive overview of the key points raised by the participants in the consultation proces

Computers from plants we never made. Speculations

We discuss possible designs and prototypes of computing systems that could be based on morphological development of roots, interaction of roots, and analog electrical computation with plants, and plant-derived electronic components. In morphological plant processors data are represented by initial configuration of roots and configurations of sources of attractants and repellents; results of computation are represented by topology of the roots' network. Computation is implemented by the roots following gradients of attractants and repellents, as well as interacting with each other. Problems solvable by plant roots, in principle, include shortest-path, minimum spanning tree, Voronoi diagram, $\alpha$-shapes, convex subdivision of concave polygons. Electrical properties of plants can be modified by loading the plants with functional nanoparticles or coating parts of plants of conductive polymers. Thus, we are in position to make living variable resistors, capacitors, operational amplifiers, multipliers, potentiometers and fixed-function generators. The electrically modified plants can implement summation, integration with respect to time, inversion, multiplication, exponentiation, logarithm, division. Mathematical and engineering problems to be solved can be represented in plant root networks of resistive or reaction elements. Developments in plant-based computing architectures will trigger emergence of a unique community of biologists, electronic engineering and computer scientists working together to produce living electronic devices which future green computers will be made of.Comment: The chapter will be published in "Inspired by Nature. Computing inspired by physics, chemistry and biology. Essays presented to Julian Miller on the occasion of his 60th birthday", Editors: Susan Stepney and Andrew Adamatzky (Springer, 2017

Impact of misinformation on social media on risk perception in a multi-risk environment

Misinformation is not a new phenomenon but, through social media, has gained new dynamics such as the rapidity of spread around the world within a few seconds. Past events have shown that misinformation can worsen the response to an emergency by leading to inappropriate behaviours, triggering fear and anxiety, or reducing the credibility of the measures by official actors. To better understand the dynamics of misinformation on social media or in the press and its effects on people’s beliefs and behaviour, we defined six case studies addressing different hazards and time periods. This allowed us to derive recommendations to prevent and fight the spread of and belief in misinformation along the entire communication chain - source, message, channel, receiver, effect, and feedback. Three of our key results are that: i) official actors should provide information on a regular basis to build credibility and trust, which will allow them to effectively communicate and counter misinformation during emergencies when people are under stressful conditions; ii) fragmented information on social media should be counterbalanced through external links to richer sources, where people can inform themselves about the broader context and details; and iii) the cultural context and ideological debates must be considered to address anchored beliefs and biases when developing strategies to prevent and fight misinformation

Двухдиапазонная отражательная антенная решетка Ka/Q-диапазонов частот

Introduction. Duplex satellite communication is commonly arranged using two spaced frequency bands, with one band receiving and the other band transmitting signals to a satellite. The main task of a communications satellite antenna system consists in providing an identical coverage area across all involved frequency bands, which is often a challenging task for conventional parabolic reflector antennas. Reflectarrays allow an independent control of the reradiated wave phase in spaced frequency bands, which can be used to create efficient multi-band antenna systems for modern communication satellites.Aim. To develop a Ka/Q-frequency range phase-correcting element and to create on its basis a dual-band reflectarray for operation with orthogonal circular polarizations and identical gains in a given sector of angles in significantly spaced frequency ranges.Materials and methods. Numerical studies were carried out using the finite element analysis method. Radiation patterns were measured using the near field scanning method.Results. A single-layer dual-band phase-correcting reflectarray element was developed for operation with orthogonal circular polarizations with low losses and a weak dependence of the relative position of the elements on the phase characteristic. On the basis of the proposed element, a reflectarray consisting of 24 465 two-frequency elements was synthesized and manufactured. The developed prototype of a single-layer dual-band reflectarray demonstrated good characteristics, with the efficiency reaching 56 and 36 % in the Ka- and Q-frequency ranges, respectively, and an almost identical minimum gain in the ±0.75° angle sector.Conclusion. The research results confirm the potential of the developed reflectarray to successfully replace conventional parabolic reflectors installed both on modern communication satellites and as part of ground-based satellite terminals in the millimeter wavelength range.Введение. Для организации дуплексной спутниковой связи, как правило, используются два разнесенных диапазона частот: один – для приема, второй – для передачи сигнала на спутник. Основной задачей антенной системы спутника связи является обеспечение идентичной зоны покрытия во всех задействованных диапазонах частот, что зачастую затруднительно с использованием традиционных параболических зеркальных антенн. Отражательные антенные решетки (ОАР) позволяют осуществлять независимое управление фазой переизлученной волны в разнесенных диапазонах частот, что может быть использовано для создания эффективных многодиапазонных антенных систем современной спутниковой связи.Цель работы. Разработка фазокорректирующего элемента Ka/Q-диапазонов частот и создание на его основе двухдиапазонной ОАР для работы с ортогональными круговыми поляризациями, обладающей идентичными коэффициентами усиления (КУ) в заданном секторе углов в значительно разнесенных диапазонах частот.Материалы и методы. Численные исследования проведены методом конечных элементов. Характеристики направленности измерялись методом сканирования в ближнем поле антенны.Результаты. Разработан однослойный двухдиапазонный фазокорректирующий элемент ОАР для работы с ортогональными круговыми поляризациями с малыми потерями и слабой зависимостью фазовой характеристики от взаимного расположения элементов. На основе предложенного элемента синтезирована и изготовлена ОАР, состоящая из 24 465 двухчастотных элементов. Разработанный макет однослойной двухдиапазонной ОАР продемонстрировал хорошую эффективность, коэффициент использования поверхности достигает 56 и 36 %, соответственно, в Ka- и Q-диапазонах частот при практически идентичном минимальном КУ в секторе углов ±0.75°.Заключение. Результаты исследований показывают возможность ОАР с успехом замещать традиционные параболические рефлекторы как на современных спутниках связи, так и в составе наземных спутниковых терминалов в миллиметровом диапазоне длин волн

Search for a common baryon source in high-multiplicity pp collisions at the LHC

We report on the measurement of the size of the particle-emitting source from two-baryon correlations with ALICE in high-multiplicity pp collisions at s=13 TeV. The source radius is studied with low relative momentum p–p, p‾–p‾, p–Λ, and p‾–Λ‾ pairs as a function of the pair transverse mass mT considering for the first time in a quantitative way the effect of strong resonance decays. After correcting for this effect, the radii extracted for pairs of different particle species agree. This indicates that protons, antiprotons, Λ s, and Λ‾ s originate from the same source. Within the measured mT range (1.1–2.2) GeV/c2the invariant radius of this common source varies between 1.3 and 0.85 fm. These results provide a precise reference for studies of the strong hadron–hadron interactions and for the investigation of collective properties in small colliding systems. © 2020 CERN for the benefit of the ALICE CollaborationPeer reviewe

Long- and short-range correlations and their event-scale dependence in high-multiplicity pp collisions at 1as = 13 TeV

Two-particle angular correlations are measured in high-multiplicity proton-proton collisions at s = 13 TeV by the ALICE Collaboration. The yields of particle pairs at short-( 06\u3b7 3c 0) and long-range (1.6 < | 06\u3b7| < 1.8) in pseudorapidity are extracted on the near-side ( 06\u3c6 3c 0). They are reported as a function of transverse momentum (pT) in the range 1 < pT< 4 GeV/c. Furthermore, the event-scale dependence is studied for the first time by requiring the presence of high-pT leading particles or jets for varying pT thresholds. The results demonstrate that the long-range \u201cridge\u201d yield, possibly related to the collective behavior of the system, is present in events with high-pT processes as well. The magnitudes of the short- and long-range yields are found to grow with the event scale. The results are compared to EPOS LHC and PYTHIA 8 calculations, with and without string-shoving interactions. It is found that while both models describe the qualitative trends in the data, calculations from EPOS LHC show a better quantitative agreement for the pT dependency, while overestimating the event-scale dependency. [Figure not available: see fulltext.