Electronic properties of Fabre charge-transfer salts under various temperature and pressure conditions

Using density functional theory, we determine parameters of tight-binding Hamiltonians for a variety of Fabre charge transfer salts, focusing in particular on the effects of temperature and pressure. Besides relying on previously published crystal structures, we experimentally determine two new sets of structures; (TMTTF)$_2$SbF$_6$ at different temperatures and (TMTTF)$_2$PF$_6$ at various pressures. We find that a few trends in the electronic behavior can be connected to the complex phase diagram shown by these materials. Decreasing temperature and increasing pressure cause the systems to become more two-dimensional. We analyze the importance of correlations by considering an extended Hubbard model parameterized using Wannier orbital overlaps and show that while charge order is strongly activated by the inter-site Coulomb interaction, the magnetic order is only weakly enhanced. Both orders are suppressed when the effective pressure is increased.Comment: 12 pages, 16 figure

Bypassing rRNA methylation by RsmA/Dim1during ribosome maturation in the hyperthermophilic archaeon Nanoarchaeum equitans

In all free-living organisms a late-stage checkpoint in the biogenesis of the small ribosomal subunit involves rRNA modification by an RsmA/Dim1 methyltransferase. The hyperthermophilic archaeon Nanoarchaeum equitans, whose existence is confined to the surface of a second archaeon, Ignic-occus hospitalis, lacks an RsmA/Dim1 homolog. We demonstrate here that the I. hospitalis host possesses the homolog Igni_1059, which dimethylates the N-6-positions of two invariant adenosines within helix 45 of 16S rRNA in a manner identical to other RsmA/Dim1 enzymes. However, Igni_1059 is not transferred from I. hospitalis to N. equitans across their fused cell membrane structures and the corresponding nucleotides in N. equitans 16S rRNA remain unmethylated. An alternative mechanism for ribosomal subunit maturation in N. equitans is suggested by sRNA interactions that span the redundant RsmA/Dim1 site to introduce 2'-O-ribose methylations within helices 44 and 45 of the rRNA

Time-dependent energy absorption changes during ultrafast lattice deformation

The ultrafast time-dependence of the energy absorption of covalent solids upon excitation with femtosecond laser pulses is theoretically analyzed. We use a microscopic theory to describe laser induced structural changes and their influence on the electronic properties. We show that from the time evolution of the energy absorbed by the system important information on the electronic and atomic structure during ultrafast phase transitions can be gained. Our results reflect how structural changes affect the capability of the system to absorb external energy.Comment: 7 pages RevTeX, 8 ps figures, submitted to Journal of Appl. Physic

Numerical simulation of the electron beam distribution in tissueequivalent materials using GEANT4

The numerical model of the electron beam dose distribution in ABS and HIPS plastics was developed. The calculation results were compared with experimental data of depth dose distribution of electron beam in water phantom for applicability estimation of these polymer materials for the imitation of biological tissues

Analysis of 983 civilian blast and ballistic casualties and the generation of a template of injury burden : an observational study

Funding: The work was supported in part by a grant to LM from School of Medicine, University of St Andrews.Background Terrorism and armed conflict cause blast and ballistic casualties that are unusual in civilian practice. The immediate surgical response to mass casualty events, with civilians injured by these mechanisms, has not been systematically characterised. Standardising an approach to reacting to these events is challenging but is essential to optimise preparation for them. We aimed to quantify and assesses the surgical response to blast and ballistic injuries managed in a world-class trauma unit paradigm. Methods This was an observational study conducted at the UK-led military Medical Treatment Facility, Camp Bastion, Afghanistan from original theatre log-book entries between Nov 5, 2009, and Sept 21, 2014; a total of 10,891 consecutive surgical cases prospectively gathered by surgical teams were catalogued. Patients with combatant status/wearing body-armour to various degrees including interpreters were excluded from the study. Civilian casualties that underwent primary trauma surgery for blast and ballistic injuries were included (n=983). Surgical activity was analysed as a rate per 100 casualties, and patients were grouped according to adult vs. paediatric and ballistic vs. blast injury mechanisms to aid comparison. Findings The three most common surgical procedures for civilian blast injuries were debridement, amputation, and laparotomy. For civilian ballistic injuries, these were debridement, laparotomy and vascular procedures. Blast injuries generated more amputations in both adults and children compared to ballistic injuries. Blast injuries generated more removal of fragmentation material compared to ballistics injuries amongst adult casualties. Ballistic injuries lead to more chest drain insertions in adults. As a rate per 100 casualties, adults injured by blast underwent significantly more debridement (63·5); temporary skeletal stabilisation (13·2) and vascular procedures (12·8) compared to children (43·4, z=4·026, p=0·00007; 5·7, z=2·230, p=0·022; 4·9, z=2·468, p=0·014). Adults injured by ballistics underwent significantly more debridement (63·4); chest drain (12·3) and temporary skeletal fixation procedures (11·4) compared to children (50·0, z=2·058, p=0.040, p<0·05; 2·9, z=2·283, p=0.0230; 2·9, z=2·131, p=0.034 respectively). By comparison, children injured by ballistics underwent significantly more removal of fragmentation and ballistic materials (20·6) when compared to adults (7·7, z=−3·234; p=0.001). Interpretation This is the first evidence-based, template of the immediate response required to manage civilians injured by blast and ballistic mechanisms. The template presented can be applied to similar conflict zones and to prepare for terror attacks on urban populations.Publisher PDFPeer reviewe

Genarris: Random Generation of Molecular Crystal Structures and Fast Screening with a Harris Approximation

We present Genarris, a Python package that performs configuration space screening for molecular crystals of rigid molecules by random sampling with physical constraints. For fast energy evaluations Genarris employs a Harris approximation, whereby the total density of a molecular crystal is constructed via superposition of single molecule densities. Dispersion-inclusive density functional theory (DFT) is then used for the Harris density without performing a self-consistency cycle. Genarris uses machine learning for clustering, based on a relative coordinate descriptor (RCD) developed specifically for molecular crystals, which is shown to be robust in identifying packing motif similarity. In addition to random structure generation, Genarris offers three workflows based on different sequences of successive clustering and selection steps: the "Rigorous" workflow is an exhaustive exploration of the potential energy landscape, the "Energy" workflow produces a set of low energy structures, and the "Diverse" workflow produces a maximally diverse set of structures. The latter is recommended for generating initial populations for genetic algorithms. Here, the implementation of Genarris is reported and its application is demonstrated for three test cases

6G networks : is this an evolution or a revolution?

The lessons learned from the third industrial revolution taught us that the transformation from mechanical and analog technology to digital electronics have changed the world once and forever. While computers and communication networks have become the new oil that defines the wealth of countries, research and industrial communities have been the driving forces that have made this transition possible. In the future, the same communities and stakeholders are required to enable the transition to net-zero communication networks. With reference to mobile communications, 5G is an evolution from all previous networks with the adoption of new radio access technologies, multisliced architecture, cloud-native and automation, and so on. By definition, 5G is a network that adapts to user needs and dynamic changes in traffic, designed to serve a new class of users: “machines.” Therefore, latency has become a critical metric in 5G. Looking forward, 6G shall employ cell-less access networks, integrated nonterrestrial networks, joint sensing and communications, new spectrums such as terahertz (THz) communications, switching from traditional channel-based design paradigms to designing channels through novel technologies such as intelligent reconfigurable surfaces, open interfaces that interconnect all network functions, end-to-end orchestrators, and, most noticeably, artificial intelligence (AI) machines that govern all functional modules and operational services. The various network functions generate traces of various operations that are ingested into databases; then AI will leverage this data for optimized decisions that are reflected into network status transitions, resource utilization, service enhancement, and ultimately lead to self-synthesizing networks. Built upon commercial clouds, 6G will have the flexibility to scale and restructure for more resilient response to traffic fluctuations and user requirements. To this end, cybersecurity features will become an embedded part of network functions to shield the network services not only from external threats but also from hosting domains. From an air interface perspective, 6G will integrate nonterrestrial (space, air, drone, and ocean) communications technologies to connect and route new users such as drones and coastal trading vessels. Furthermore, future wireless networks need to make use of a spectrum that extends into the optical spectrum and includes the THz range. The channel becomes a critical component due to the impact of blockages and random orientations at these frequencies. Active and passive intelligent reflecting surfaces (IRSs) will become a new wireless system element that will help overcome new challenges related to coverage and the propagation channel

History and phylogeny of intermediate filaments: Now in insects

Intermediate filaments include the nuclear lamins, which are universal in metazoans, and the cytoplasmic intermediate filaments, which are much more varied and form cell type-specific networks in animal cells. Until now, it has been thought that insects harbor lamins only. This view is fundamentally challenged by the discovery, reported in BMC Biology, of an intermediate filament-like cytoplasmic protein, isomin, in the hexapod Isotomurus maculatus. Here we briefly review the history of research on intermediate filaments, and discuss the implications of this latest finding in the context of what is known of their structure and functions

Biological processes and links to the physics

Analysis of the temporal and spatial variability of biological processes and identification of the main variables that drive the dynamic regime of marine ecosystems is complex. Correlation between physical variables and long-term changes in ecosystems has routinely been identified, but the specific mechanisms involved remain often unclear. Reasons for this could be various: the ecosystem can be very sensitive to the seasonal timing of the anomalous physical forcing; the ecosystem can be contemporaneously influenced by many physical variables and the ecosystem can generate intrinsic variability on climate time scales. Marine ecosystems are influenced by a variety of physical factors, e.g., light, temperature, transport, turbulence. Temperature has a fundamental forcing function in biology, with direct influences on rate processes of organisms and on the distribution of mobile species that have preferred temperature ranges. Light and transport also affect the physiology and distribution of marine organisms. Small-scale turbulence determines encounter between larval fish and their prey and additionally influences the probability of successful pursuit and ingestion. The impact of physical forcing variations on biological processes is studied through long-term observations, process studies, laboratory experiments, retrospective analysis of existing data sets and modelling. This manuscript reviews the diversity of physical influences on biological processes, marine organisms and ecosystems and their variety of responses to physical forcing with special emphasis on the dynamics of zooplankton and fish stocks