High Collisions Research Articles

An overview of scholarly literature on navigation hazards in Arctic shipping routes.

Maritime transport plays a crucial role in international trade. As the number and tonnage of ships continue to increase, traditional shipping routes are becoming progressively congested. The development of Arctic shipping routes has the potential to significantly improve trade efficiency and decrease reliance on traditional shipping routes. At the same time, the harsh navigation conditions in the Arctic pose a huge challenge to ships crossing the Arctic shipping routes. To address the above issues, this paper reviews the natural, navigational environment and unique navigational modes of ships in the Arctic shipping routes. Furthermore, the navigational risks caused by factors including low temperature, sea ice, poor visibility, communication, lack of infrastructure, lack of navigational experience, lack of historical data, high collision risk, and complex navigational environment are summarized and analyzed, providing a reference for researchers and policymakers to conduct research related to Arctic shipping routes.

Ceragenin-CSA13 loaded high strength coatings of nano- and micro-SrHA implanted N-Carboxymethyl chitosan – Polyetheretherketone by low temperature high speed collision approach: In vitro pro-osteogenicity and bactericidal activity against MRSA

Cationic steroid antimicrobials (CSA13) loaded in the uniform coatings synthesized by micro and nano sized particles of strontium substituted hydroxyapatite implanted into the surface of N-carboxymethyl chitosan (N-CMCh) pre-embedded on polyetheretherketone (PEEK) substrate and their biocompatibility and antibacterial efficacy were investigated. Release of CSA13 from the nano SrHA implanted substrate showed faster release of the drug till 48 h with a release of 48% of total drug. It was found that CSA13 rich nano SrHA implanted substrate damaged the Methicillin Resistant Staphylococcus Aureus biofilm mass in 30 h, while micron sized SrHA implanted substrate reduced the biofilm mass to 27% at the same culture period. MG63 cell viability on these specimens exhibited significant cell growth even in the presence of CSA13. Nano SrHA implanted substrate showed better biocompatibility simultaneously providing antibacterial efficacy than the micro sized coating. The sustained release of CSA13 from the nano Sr-HA coating could be beneficial for long term eradication of infection. In silico docking approach between CSA13 and 1VQQ penicillin binding protein 2a from MRSA strain showed strong negative binding energy of (−) 68.78 kcal/mol demonstrating an in-visual predicting anti-bacterial efficacy.

Results on light (anti)hypernuclei production with ALICE at the LHC

The high collision energies reached at the LHC lead to significant production yields of light (anti)hypernuclei in proton–proton (pp), proton–lead (p–Pb) and, in particular, Pb–Pb collisions. The lightest known hypernucleus is the hypertriton, which is a bound state of a proton, a neutron, and a Λ hyperon. It decays weakly with a decay length of a few centimeters. The excellent tracking and particle identification capabilities of the ALICE detector, exploiting the energy loss measurement of the Time Projection Chamber (TPC) and using the Inner Tracking System (ITS) to distinguish between primary and secondary (decay) vertices, allow for the determination of the hypertriton yield across different collision systems, its lifetime, and its binding energy. The latest hypertriton lifetime measurement in Pb–Pb collisions performed in the 2-body decay channel will be presented. This measurement contributes to the solution of the hypertriton lifetime puzzle. In addition, the hypertriton production in different collision systems and at different energies will be compared to model predictions. Due to its low binding energy, and hence to its large size, the hypertriton is the ideal candidate to distinguish between statistical hadronization and coalescence models. With the precision of the presented yield measurements some variants of the aforementioned models can be excluded.

Intramolecular Accelerated Assembly of Molecular Beacons: A DNA Nanoarchitecture-based Spatial Confinement Strategy toward Terminal Deoxynucleotidyl Transferase Biosensing.

Physiological function analysis of terminal deoxynucleotidyl transferase (TdT) in clinical medicine and hematopathology highlights its significance to be extensively utilized as a diagnostic biomarker for leukemia diagnosis. Herein, taking advantage of the spatial-confinement effect on a three-dimensional (3D) DNA nanoarchitecture, we reported a target-triggered intramolecular accelerated molecular beacon (MB) assembly for rapid and real-time analysis of TdT activity. In this strategy, the 3D DNA nanoarchitecture is first engineered via a cross-linking network hybridization chain reaction (HCR). A number of MBs, which were designed with a polythymine (poly-T) loop, were then conjugated on the scaffold DNA nanoarchitecture, allowing the obtained MB-DNA nanoarchitecture to contain lots of free 3'-hydroxyl (OH) termini inside or outside the super DNA nanostructure. Moreover, the distance between different MBs is closed, and the local concentration of MB is significantly improved owing to the confinement of MBs on this DNA nanoarchitecture. Once encountered with target TdT, the free -OH groups can be recognized by TdT immediately to catalyze the template-independent incorporation of adenine nucleotides, which results in the generation of multiple poly-A chains that rapidly react with many MBs via an intramolecular accelerated assembly process. The time-dependent substantial enhancement of the fluorescence from MBs can thus be applied for robustly analyzing TdT. Our observations suggest that the DNA nanostructure-based spatial confinement effect enables a high molecular collision frequency to accelerate the reaction kinetics, and the super DNA nanoarchitecture exhibits a better nuclease resistance to maintain signal stability. With these advantages, TdT can be rapidly detected with high sensitivity, specificity, and biostability.

Efficiency of Magnetohydrodynamic Wave Generation in Weakly Ionized Atmospheres

The generation of Alfvén and slow magnetoacoustic waves in weakly ionized atmospheres by excitation of the charges-only component of the two-fluid (charge and neutral) plasma is shown to be more or less efficient depending on the energy fraction initially allocated to the three stationary flow differential modes, which characterize the inter-species drift. This is explained via detailed analysis of the full 10-dimensional spectral description of two-fluid linear magnetohydrodynamics. Excitation via the velocity of the charges only is found to be very inefficient, in accord with previous results, while excitation via the magnetic field perturbation alone is highly efficient. All 10 eigenvalues and eigenvectors are presented analytically in the high collision frequency regime.

Decomposition of multi-particle azimuthal correlations in Q-cumulant analysis* *Supported by the Ministry of Education Science and Technological Development, Republic of Serbia, the National Natural Science Foundation of China (12035006, 12075085, 12147219), and the U.S. Department of Energy (de-sc0012910).

The method of Q-cumulants is a powerful tool for studying the fine details of azimuthal anisotropies in high energy nuclear collisions. This paper presents a new method, based on mathematical induction, to evaluate the analytical form of high-order Q-cumulants. The capability of this method is demonstrated via a toy model that uses the elliptic power distribution to simulate the anisotropic emission of particles, quantified in terms of Fourier flow harmonics . The method can help in studying the large amount of event statistics that can be collected in the future and allow measurements of the very high central moments of the distribution. This can, in turn, facilitate progress in understanding the initial geometry, the input to the hydrodynamic calculations of medium expansion in high energy nuclear collisions, and the constraints on it.

Heavy-ion physics with Compact Muon Solenoid detector

Recent results on heavy-ion physics at the LHC (CERN) by the Compact Muon Solenoid (CMS) collaboration are analyzed. The tests of quark-gluon plasma carried out with the CMS detector provide valuable information about the behavior of matter in the extreme regime of very high energy nucleus-nucleus collisions.

Unbinned deep learning jet substructure measurement in high Q2ep collisions at HERA

The radiation pattern within high energy quark- and gluon-initiated jets (jet substructure) is used extensively as a precision probe of the strong force as well as an environment for optimizing event generators with numerous applications in high energy particle and nuclear physics. Looking at electron-proton collisions is of particular interest as many of the complications present at hadron colliders are absent. A detailed study of modern jet substructure observables, jet angularities, in electron-proton collisions is presented using data recorded using the H1 detector at HERA. The measurement is unbinned and multi-dimensional, using machine learning to correct for detector effects. All of the available reconstructed object information of the respective jets is interpreted by a graph neural network, achieving superior precision on a selected set of jet angularities. Training these networks was enabled by the use of a large number of GPUs in the Perlmutter supercomputer at Berkeley Lab. The particle jets are reconstructed in the laboratory frame, using the kT jet clustering algorithm. Results are reported at high transverse momentum transfer Q2>150GeV2, and inelasticity 0.2<y<0.7. The analysis is also performed in sub-regions of Q2, thus probing scale dependencies of the substructure variables. The data are compared with a variety of predictions and point towards possible improvements of such models.

First Measurement of Antideuteron Number Fluctuations at Energies Available at the Large Hadron Collider.

The first measurement of event-by-event antideuteron number fluctuations in high energy heavy-ion collisions is presented. The measurements are carried out at midrapidity (|η|<0.8) as a function of collision centrality in Pb-Pb collisions at sqrt[s_{NN}]=5.02 TeV using the ALICE detector. A significant negative correlation between the produced antiprotons and antideuterons is observed in all collision centralities. The results are compared with a state-of-the-art coalescence calculation. While it describes the ratio of higher order cumulants of the antideuteron multiplicity distribution, it fails to describe quantitatively the magnitude of the correlation between antiproton and antideuteron production. On the other hand, thermal-statistical model calculations describe all the measured observables within uncertainties only for correlation volumes that are different with respect to those describing proton yields and a similar measurement of net-proton number fluctuations.

A novel distributed multi-slot TDMA-based MAC protocol for LED-based UOWC networks

Underwater optical wireless communication (UOWC) networks are promising for many civilian and industrial applications due to underwater high-speed data transmission demand. This paper focuses on the distributed time division multiple access (TDMA) protocol design for UOWC networks. Unlike existing research, we focus on a more general underwater communication scenario where nodes are scattered, and node mobility is considered. We propose a distributed TDMA-based medium access control(MAC) protocol, called cluster-based cross-layer multi-slot MAC(CCM-MAC), which can assign multiple slots to each node according to the slot-occupying information. When using CCM-MAC, the network is divided into clusters. Each node maintains knowledge of the cluster topology and slot-occupying information of surrounding nodes through routing techniques; by updating this knowledge, collisions can also be detected and eliminated dynamically. Analysis results are presented to evaluate the performance of CCM-MAC, and simulations show that high network throughput and low collision rate can be realized in comparison with existing contention-based MAC protocols.

Assessing the role of asymmetric charge transfer reactions in analytical glow discharges in argon

Charge transfer reactions between argon ions and analyte atoms occur at a much higher rate in analytical glow discharges than in other similar plasmas, as follows from experimental Boltzmann plots of glow discharge emission spectra and the spectra generated by an inductively coupled plasma. A simple model of a Grimm-type discharge suggests that charge transfer-excited emission of the analyte elements comes largely from the cathode sheath, due to a high collision rate between the sputtered analyte atoms and argon ions accelerated in the cathode fall. The contribution to this radiation from the negative glow is several times lower. The mentioned enhancement of the charge transfer-excited emission in the cathode sheath is, however, not sufficiently high to explain the anomalously high rates of those charge transfer reactions relative to other plasmas. The different characteristics of emission from the cathode sheath and the negative glow also means that Boltzmann plots of glow discharge spectra cannot be interpreted in the conventional way. Further work is needed to explain the observed features of glow discharge excitation, as reflected in the emission spectra.

PH and H-bonding energy for pure water

This paper is devoted to the estimation of pH for pure water. We assume that the dissociation of water molecules is mainly caused by binary high energetic collisions. The dissociation energy in liquid water is identified with the energy of H-bonding. The density dependence of the dissociation energy TD is described. It is shown that this dependence allows to successfully reproduce the experimental values of pH up to the boiling temperature.

He+ +N2 Charge Transfer Reaction: An Ab initio Analysis.

An ab initio analysis on the involved potential energy surfaces is presented for the investigation of the charge transfer mechanism for the He+ +N2 system. At high collision energy, as many as seven low-lying electronic states are observed to be involved in the charge transfer mechanism. Potential energy surfaces for these low-lying electronic states have been computed in the Jacobi scattering coordinates, applying multireference configuration interaction level of theory and aug-cc-pVQZ basis sets. Asymptotes for the ground and various excited states are assigned to mark the entrance (He+ +N2 ) and charge transfer channels (He+N2 + ). Nonadiabatic coupling matrix elements and quasi-diabatic potential energy surfaces have been computed for all seven states to rationalize the available experimental data on the charge transfer processes and to facilitate dynamics studies.

Wildlife mortality on roads crossing a protected area: The case of Dadia-Lefkimi-Soufli National Park in north-eastern Greece

Wildlife-vehicle collisions have been identified as an important ecological problem in most countries around the world, during the last decades. In the present work we examined the impacts on wildlife arising from two road categories crossing and adjoining the Dadia-Lefkimi-Soufli National Park (DLS NP), in north-eastern Greece. The study area is consisted of one of the most diverse fauna in Europe, with 202 bird species including 36 out of 38 European diurnal raptors, 60–65 mammal species, 29 reptiles and 13 amphibians. Vehicle collisions was the highest mortality factor in the study (83.9%) among five recorded categories, poison, electrocution, drowning, vehicle collisions and unidentified causes. 204 vehicle casualties were recorded out of 243 in total. Mammals (90.7%) were the vertebrates that mainly suffered from road mortality, including 11 species. The stone marten Martes foina contributed with the highest numbers, followed by the red fox Vulpes vulpes, the hedgehog Erinaceus roumanicus and the wild cat Felis silvestris. Although the contribution of birds on the road casualties was low, nine species were identified, including five diurnal and four nocturnal species, with raptors predominating. Most road casualties were observed in the national road network (71.6%), mainly during holidays (58.3%). Traffic volume, road category, season and blind bend were all dominant factors with different effects determining high wildlife-vehicle collision values. Mitigation measures that can reduce the harmful effects of roads on wildlife in the DLS NP are also discussed.

Are the Gas-Phase Structures of Molecular Elephants Enduring or Ephemeral? Results from Time-Dependent, Tandem Ion Mobility.

The structural stability of biomolecules in the gas phase remains an important topic in mass spectrometry applications for structural biology. Here, we evaluate the kinetic stability of native-like protein ions using time-dependent, tandem ion mobility (IM). In these tandem IM experiments, ions of interest are mobility-selected after a first dimension of IM and trapped for up to ∼14 s. Time-dependent, collision cross section distributions are then determined from separations in a second dimension of IM. In these experiments, monomeric protein ions exhibited structural changes specific to both protein and charge state, whereas large protein complexes did not undergo resolvable structural changes on the timescales of these experiments. We also performed energy-dependent experiments, i.e., collision-induced unfolding, as a comparison for time-dependent experiments to understand the extent of unfolding. Collision cross section values observed in energy-dependent experiments using high collision energies were significantly larger than those observed in time-dependent experiments, indicating that the structures observed in time-dependent experiments remain kinetically trapped and retain some memory of their solution-phase structure. Although structural evolution should be considered for highly charged, monomeric protein ions, these experiments demonstrate that higher-mass protein ions can have remarkable kinetic stability in the gas phase.

Exploring the versatile reactivity of the F- + SiH3Cl system on a full-dimensional coupled-cluster potential energy surface.

We develop a full-dimensional analytical potential energy surface (PES) for the F- + SiH3Cl reaction using Robosurfer for automatically sampling the configuration space, the robust [CCSD-F12b + BCCD(T) - BCCD]/aug-cc-pVTZ composite level of theory for computing the energy points, and the permutationally invariant polynomial method for fitting. Evolution of the fitting error and the percentage of the unphysical trajectories are monitored as a function of the iteration steps/number of energy points and polynomial order. Quasi-classical trajectory simulations on the new PES reveal rich dynamics resulting in high-probability SN2 (SiH3F + Cl-) and proton-transfer (SiH2Cl- + HF) products as well as several lower-probability channels, such as SiH2F- + HCl, SiH2FCl + H-, SiH2 + FHCl-, SiHFCl- + H2, SiHF + H2 + Cl-, and SiH2 + HF + Cl-. The Walden-inversion and front-side-attack-retention SN2 pathways are found to be competitive, producing nearly racemic products at high collision energies. The detailed atomic-level mechanisms of the various reaction pathways and channels as well as the accuracy of the analytical PES are analyzed along representative trajectories.

Injury patterns in patients with severe traumatic brain injuries from motor crashes admitted to Mulago hospital accidents & emergency unit.

The global burden of Road Traffic Crashes (RTC) is increasing. Uganda has one of the highest rates of RTCs in Sub-Sahara. Victims of RTCs sustain varying degrees of injuries depending on factors including the velocity at time of impact, protective gear; and if it was a motorcycle-motorcycle or motorcycle-vehicle crash. High speed collisions can result in severe forms of injuries and polytrauma. Some injuries are undetected. A cross sectional study was carried at Mulago Hospital Accidents & Emergency Unit, between November 2021 and February 2022; on all adult patients (≥18 years) with severe head injury from motor road traffic crashes. The study looked at injury patterns and assessed the relationship of polytrauma in patients with severe head injury to the mechanism of injury (motorcycles versus vehicles). Data were extracted from patient charts using a validated data abstraction tool and complete head to toe physical examination was carried out and injuries recorded. Data were analysed to determine the relationship of polytrauma in patients with severe head injury to the mechanism of injury. The participants were predominantly males with a population median age of 32 (25-39). The commonest modes of transportation of patients to the hospital were Police Pickup trucks (40%) and ambulance (36.1%). Among motorcycle RTCs, (19.2%) wore helmets; 21.2% had protective gear; with injury identified mainly in; the limbs (84.8%), neck (76.8%), chest (39.4%), and abdomen (26.3%). Patients from vehicle RTCs were 19% more likely to have polytrauma compared to patients from motorcycle RTCs. This study showed that patients who sustain severe traumatic brain injuries from vehicle crashes have an increased likelihood of having multiple injuries, compared to patients from motorcycle RTCs. For motorcycle users, injuries mostly affect the limbs. At particular risk are motorcyclists who do not wear helmets and protective coveralls.

Molecular mechanism in the solubility reduction of elemental sulfur in H2S/CH4 mixtures: A molecular modeling study

The solubility evolution of elemental sulfur in sour gas is key to study the occurrence and inhibition of sulfur deposition in the exploitation of high-sulfur gas reservoirs. Elemental sulfur mainly dissolves in H2S, and its solubility decreases dramatically in the presence of methane. As both methane and H2S are the main components in high-sulfur gas, it is essential to understand the molecular mechanism of the solubility reduction in H2S/CH4 mixtures. Molecular dynamics simulations are carried out for the S8, H2S and CH4 mixtures to reproduce the solubility reduction upon methane addition, and then used to reveal the reduction mechanism at the level of intermolecular interaction. The simulations reveal that both the strong competitiveness and high collision probability of H2S–CH4 pairs reduce the average densities of H2S–S(S8) and H2S–H2S pairs, which reduce the sulfur solubility in a direct/indirect but cooperative way. The role of methane in the solubility reduction is then discussed and the molecular mechanism of sulfur dissolution and precipitation in the sour gasses is addressed.

Three‐dimensional scan‐based algorithm for directional neighbor discovery in ad hoc networks

SummaryIn recent years, neighbor discovery techniques using directional antennas have attracted widespread attention. Most currently available directional neighbor discovery techniques are designed based on two‐dimensional (2D) space. Although these algorithms can accomplish the discovery between nodes, the algorithm portability is poor for three‐dimensional (3D) platforms, and the application scenarios are limited since new communication scenarios such as unmanned aerial vehicle (UAV) groups and maritime fleets emerge where information needs to be delivered in real time and nodes are located in 3D space. This paper proposes a new deterministic directional neighbor discovery algorithm in 3D space named 3D scan‐based algorithm (3D‐SBA) to meet the needs of the line‐of‐sight (LOS) scenes. Four existing neighbor discovery algorithms, namely, SBA‐based random mode selection (SBA‐R), quorum, complete random algorithm (CRA), and SBA‐based leader election algorithm (LE), have been extended to our proposed 3D algorithm model for simulation and comparative analysis with 3D‐SBA. The simulation results show that the 3D‐SBA algorithm consumes 51.15%, 180.20%, 9.48%, and 17.49% of the time slots compared with the four existing algorithms mentioned above. However, the quorum algorithm has a very high node collision rate, up to 92.11%. Ultimately, the 3D‐SBA algorithm has the best performance considering the conflicts and the density of network nodes.

Electron trajectories in a collisional crossed-field gap

The Hull cutoff represents the maximum magnetic field in a vacuum crossed-field gap (CFG) such that an electron emitted from the cathode reaches the anode. Prior studies demonstrated that introducing ions into a CFG always causes increased excursion of electrons toward the anode. In this paper, we assess a collisional CFG by incorporating collision frequency into the electron force law. The theoretical electron trajectories agree well with a one-dimensional particle-in-cell simulation and demonstrate that emitted electrons always cross a collisional CFG. We derive a modified Hull cutoff condition for a collisional CFG corresponding to an electron reaching the anode with zero velocity in the direction of the electric field. Rather than representing the threshold for magnetic insulation, this condition gives the maximum magnetic field and maximum collision frequency for which an electron reaches the anode without turning around; higher magnetic fields and/or collision frequencies cause the electron to turn around before crossing the gap. Further increasing either quantity causes the electron to change direction more frequently as it crosses the gap, noticeably increasing the transit time with each change in electron direction. In the limit of high collision frequency, the electron velocity across the gap approaches a constant, meaning that electrons will reach the anode at nonzero velocity. The transit time above this condition increases smoothly and monotonically with increasing magnetic field or collision frequency. These results elucidate the implications of collisions on magnetic insulation for future assessments of the limiting current in a collisional CFG.