Subatomic Research Articles

On the needs for combining physiological principles and mathematics to improve crop models

• Basic concepts of crop modelling founders are fading into oblivion since the mid-1990s. • The multi-model ensemble approach does not facilitate the models as a heuristic tool. • A bottom-up approach that assembles all biological elements is not conducive to simulating the crop. • An intermediate approach combining physiology and mathematics is recommended. • Leaf area index and radiation use efficiency are used as showcases. • Outstanding areas for further model development and caveats are outlined. Major crop models were developed before the 1990s and many of their algorithms are (semi-)empirical. In the recent two decades, the number of models has grown rapidly, but the increase in their quality does not match the growth in number. Often, an ensemble of multiple models is required to make a useful prediction. This ensemble approach does not facilitate the improvement of models as a tool to understand crop physiological mechanisms. On the other hand, following a bottom-up approach that tries to assemble all elements along different scales of biological organisation may result in numerically clumsy models that are not necessarily more robust than existing models in simulating phenotypes at the crop scale. We argue that to model complex crop phenotypes in a simple yet accurate manner, crop modellers should be inspired by experiences in some fundamental sciences. For example, physicists used sound theories and solid mathematics in thought experiments, and came up with seemingly simple equations to explain the behaviour of very diverse systems, from sub-atomic particles to the largest clusters of galaxies. We review examples, where biological insights and mathematics are combined to derive simple equations that apply to different processes of crop growth. The essence of this modelling approach is a combination of simplicity , elegance and robustness . Models integrating those equations can predict crop phenotypes as well as generate hypotheses or emerging properties to assist in knowing the unknowns. Thus, crop models should not only provide practical predictions, but should especially be considered as a research tool for data interpretation, system design, and heuristic understanding.

Effect of a Model of the Electron Angular Scattering on the Electron Runaway Rate in Helium

It is known that, in the strong electric field, electrons undergo continuous acceleration [runaway electrons (REs)] even in dense media, receiving from the field more energy than lose via interactions with the ambient atomic particles. We, here, analyze the effect of the angular scattering of electrons in inelastic interactions on the runaway process. For this purpose, we developed a Monte Carlo (MC) code and, having carried out simulations of electron transport in the helium of atmospheric density, calculated the runaway rate at the field strengths of 50–300 kV cm−1. We show that different models of the electron scattering lead to a tenfold difference in the runaway rate magnitudes.

The Life after Texts, the Life within Them

The Life after Texts, the Life within Them

Relation between the Density of States in Different Cases and the Corresponding Examples

The study of particle system is inevitable to study its statistical law, and understanding the distribution of particles is fundamental and important. In this paper, the author points out the relation between the number of states of free particles in the relativistic and non-relativistic cases, and gives formulae for each case. Furthermore, the author enumerates some popular and basic particle systems, as well as classifies them in terms of relativistic and non-relativistic cases, also their basic formulae are deduced and enumerated in this paper. These particle systems are applicable to different formulae for the density of states for relativistic or non-relativistic cases. It is concluded that the different densities of states in different cases are related to each other through the de Broglie relation and the energy formula.

Experimental investigation on emission characteristics of non-road diesel engine equipped with integrated DOC + CDPF + SCR aftertreatment

The non-road emission regulations are getting more and more rigorous, which make it necessary for Original Equipment Manufacturers (OEMs) to adopt aftertreatment systems. In this paper, an integrated aftertreatment system consisting of Diesel Oxidation Catalyst (DOC), Catalytic Diesel Particulate Filter (CDPF) and Selective Catalytic Reduction (SCR) was proposed aiming to reduction of non-road diesel engine emissions. The effects of DOC + CDPF + SCR on engine performance and emission characteristics including HC, CO, NOX, PM, PN and NH3 slip were investigated under steady operations and transient cycle. The results showed that DOC + CDPF + SCR had little influence on engine power and economic performance. In initial DOC reduced HC and CO emissions by the efficiency of 89% and 91% respectively, CDPF dealt with the remained inheritance of HC and CO by 75% and 80% respectively latterly. The DOC + CDPF specifically raised the ratio of NO2/NOx although there was barely the influence on NOx emission. The efficiencies of DOC + CDPF filtering PM and PN were over 95%, and CDPF had better performance of filtering accumulation particles than it applied on nuclear particles. SCR NOx reduction efficiency was 90% and ammonia slip was 14 ppm on average. The emissions factors of CO, HC, NOx, PN and PM, lower than non-road China-IV limits of non-road steady cycle (NRSC) under all test operations except for 10% load, due to the equipped integrated DOC + CDPF + SCR aftertreatment, decreased by 97.6%, 98.1%, 90%, 97% and 98% respectively. In the whole hot non-road transient cycle (NRTC), HC and CO reduction efficiencies were 57.1% and 55% in average in DOC. In addition, the efficiencies of 68.3% and 19.8% could be further achieved in CDPF respectively in average. It is especially important that CDPF-out NO2/NOx ratio fluctuated and did increase at some special time due to the lack of adequate PM and NO2 reaction time in transient cycle although CDPF-out NO2/NOx ratio decreased under steady operations. The SCR NOx reduction in average was 57.7% and ammonia slip was less than 10 ppm. PM and PN diminished by 95% and 98.3% respectively in the DOC + CDPF and the transient operation fluctuation had little effect on filtration efficiency.

About the Altitude Profile of the Atmospheric Cut-Off of Cosmic Rays: New Revised Assessment

Cosmic rays, high-energy subatomic particles of extraterrestrial origin, are systematically measured by space-borne and ground-based instruments. A specific interest is paid to high-energy ions accelerated during solar eruptions, so-called solar energetic particles. In order to build a comprehensive picture of their nature, it is important to fill the gap and inter-calibrate ground-based and space-borne instruments. Here, we focus on ground-based detectors, specifically neutron monitors, which form a global network and provide continuous recording of cosmic ray intensity and its variability, used also to register relativistic solar energetic particles. The count rate of each neutron monitor is determined by the geomagnetic and atmospheric cut-offs, both being functions of the location. Here, on the basis of Monte Carlo simulations with the PLANETOCOSMICS code and by the employment of a new verified neutron monitor yield function, we assessed the atmospheric cut-off as a function of the altitude, as well as for specific stations located in the polar region. The assessed in this study altitude profile of the atmospheric cut-off for primary cosmic rays builds the basis for the joint analysis of strong solar proton events with different instruments and allows one to clarify recent definitions and related discussions about the new sub-class of events, so-called sub-ground-level enhancements (sub-GLEs).

The Neutrino Decay of the Free Neutron and the Neutrino Structure According to the Planck Vacuum Theory


 
 
 The Planck vacuum (PV) theory derives equations for the neutrino and antineutrino, and relates them to the unstable free neutron and antineutron. Remarkably, these neu- trons and neutrinos share the same wavefunction solutions that describe the proton and electron and their antiparticle cores.
 The neutrino and antineutrino are chargeless and massless; so their propagation through matter goes unnoticed, making these neutrinos invisible. The equations to follow that describe these pseudo-particles are the theoretical embodiment of the circa 1930 Pauli neutrino hypothesis.
 Finally, depending on one’s perspective, the neutrons can be viewed as decaying meta-particles or as stable nuclear particles.
 
 

The Neutrino Decay of the Free Neutron and the Neutrino Structure According to the Planck Vacuum Theory


 
 
 The Planck vacuum (PV) theory derives equations for the neutrino and antineutrino, and relates them to the unstable free neutron and antineutron. Remarkably, these neu- trons and neutrinos share the same wavefunction solutions that describe the proton and electron and their antiparticle cores.
 The neutrino and antineutrino are chargeless and massless; so their propagation through matter goes unnoticed, making these neutrinos invisible. The equations to follow that describe these pseudo-particles are the theoretical embodiment of the circa 1930 Pauli neutrino hypothesis.
 Finally, depending on one’s perspective, the neutrons can be viewed as decaying meta-particles or as stable nuclear particles.
 
 

The Theoretical Value of the Hubble Constant Ho and Unification of the Fundamental Forces of Nature

The Hubble constant Ho represents the speed of expansion of the universe and various cosmological observations and modeling methods were utilized by astronomers for a century to pin down its exact value. Determining Ho from cosmological observations is a long and tedious process requiring highly accurate datasets. To circumvent this need, a simple theoretical approach is introduced in this study which uses the concept of gravitational weakening and seismic-induced recession. As tremors occur among celestial objects, their gravitational fields would also change. This resulted in a fundamental relation of Ho and the computed rate of recession that gives a theoretical value for Ho=69.921 Km/s/Mpc. Using the newly discovered seismic-induced gravitational weakening and time dilation, it is possible that various astrophysical methods using different measurement methods would converge to this theoretical Ho value when cosmological distances and time delay measurements are corrected with the simple formulas we derived. The new model assumes that, as quakes occur in celestial objects, luminosity-induced acceleration and high-energy collision of protons and electrons may produce a massive number of neutrinos, quarks and other subatomic particles. Furthermore, the fine structure constant was found to be inversely proportional to Ho-squared and that the fine-structure constant obtained in this study gives a new physical interpretation of α. New relations for the speed of light, orbital velocity, gravitational force and the Hubble constant were further derived from the new recession constant using approximate relations for the Newtonian and electric force constant. This resulted in a modified gravitational law that is both repulsive and attractive and a theoretical explanation of the phenomenon of light-induced gravitation analogous to the electromagnetic force where photon is the force-carrier. Finally, the fundamental forces of gravitation, electromagnetism and strong nuclear force are now unified.

Comparison of spray characteristics of gasoline and water-in-gasoline mixture at elevated fuel temperature conditions

With the advent of the era of ultra-high thermal efficiency and ultra-low emission internal combustion engines, water injection technology is the key to solving the knocking problem and breaking the technical bottleneck. Water-in-oil mixture shows great potential as a special water injection technology for avoiding the huge cost of engine modification and the application of the flash-boiling spray, which brings more possibilities for the improvement of atomization quality, the formation of fuel–air mixture and the combustion. In this work, the spray development process of gasoline(G100) and water-in-gasoline(G70) was explored. Spray characteristics, including spray penetration, spray cone angle, spray area, minimum energy for atomization and spray particle size distribution, were investigated at elevated fuel temperature conditions (25 ~ 140 °C). The results show that as the temperature of the mixture rises, the spray pattern gradually assumes a collapsed shape, which will be prominent at the initial injection by the intervention of water after 100 °C. There are critical temperatures of 75 °C(G100) and 90 °C(G70), above which the spray penetration is remarkably reduced and the spray cone angle and spray area of G70 are enormously increased but that of G100 are diminished. The minimum energy for atomization and SMD (Sauter Mean Diameter) decrease as the temperature of the mixture rises. There exists a critical temperature of 90 °C, above which the particle size span decreases sharply and the small particle size droplets disappear quickly.

Transformations of actinides fission product yields due to post-scission emission of nuclear particles: 232Th

The “many ensembles” method was proposed to investigate the influence of nuclear particles’ post-scission emission on mass and charge distributions of fission products. The post-scission approximation was used: each of these ensembles consists of the fission fragments after emission of chains of different lengths, both the beta (β±) particles and neutrons. The theory allows one to find the most probable two-fragment clusters of fission products and study their evolution after the post-scission emission of nuclear particles. The isotope 232Th was chosen as an example, the fission fragments of which have been intensively studied experimentally. It is shown that the post-scission emission of nuclear particles eventually leads to the convergence of the asymmetric peaks, which looks like enhanced symmetric fission mode over the asymmetric mode for fission product yields. A comparison of the theoretical results and experimental data for the 232Th fission fragments indicates their satisfactory matching.

Noncomunicable/Aging Diseases with the Perspective of Quantum Physics

The leading cause of illness in aging is a group known as Noncommunicable Diseases. There should be some meeting points that modify the cells homeostasis and impaired the cell physiology developing different diseases. Quantum physics studied the atomic and subatomic particles and revolutionized the reality perception with paradoxical and weird concepts. Heisenberg's uncertainty principle established that it is not possible to determine the two characteristic properties of particles with accuracy. Subatomic particles have a wave-particle duality. Two subatomic particles are entangled, something happening over here can have an instantaneous effect over there, no matter how far away there are. All these concepts have tried to apply to biology and life sciences, quantum biology is behind photosynthesis, mitochondrial respiration, enzyme activity, the sense of smell, animal migration, heredity's fidelity, and consciousness. We can apply all these concepts to diseases pathogeny. So, we describe quantum phenomena in oxidative stress, calcification, signal transduction, vitamin D production and cancer mutations. Aging diseases also could be explained by applying quantum physics concepts. It is a new, hard to believe, and an incredible path to be built, but we need to open the treatment options to our patients with new perspectives. Keywords: Oxidative stress; Calcification; Signal transduction; Vitamin D; Cancer mutations; Quantum phenomena

Müge Kasanmascheff.

"Science is fun because it is full of surprises … My science 'heroes' are JoAnne Stubbe and Marina Bennati …" Find out more about Müge Kasanmascheff in her Introducing … Profile.

Müge Kasanmascheff

Müge Kasanmascheff

Structure of the TELO2-TTI1-TTI2 complex and its function in TOR recruitment to the R2TP chaperone.

SummaryThe R2TP (RUVBL1-RUVBL2-RPAP3-PIH1D1) complex, in collaboration with heat shock protein 90 (HSP90), functions as a chaperone for the assembly and stability of protein complexes, including RNA polymerases, small nuclear ribonucleoprotein particles (snRNPs), and phosphatidylinositol 3-kinase (PI3K)-like kinases (PIKKs) such as TOR and SMG1. PIKK stabilization depends on an additional complex of TELO2, TTI1, and TTI2 (TTT), whose structure and function are poorly understood. The cryoelectron microscopy (cryo-EM) structure of the human R2TP-TTT complex, together with biochemical experiments, reveals the mechanism of TOR recruitment to the R2TP-TTT chaperone. The HEAT-repeat TTT complex binds the kinase domain of TOR, without blocking its activity, and delivers TOR to the R2TP chaperone. In addition, TTT regulates the R2TP chaperone by inhibiting RUVBL1-RUVBL2 ATPase activity and by modulating the conformation and interactions of the PIH1D1 and RPAP3 components of R2TP. Taken together, our results show how TTT couples the recruitment of TOR to R2TP with the regulation of this chaperone system.

Lessons Learned from Using Competency Based Assessment (CBA) in a First Year Engineering Statics Course

During the Fall term of 2020, the first year Statics course in the College of Engineering at theUniversity of Saskatchewan was taught remotely, and synchronously, using a competency-based assessment (CBA) implementation. CBA is commonly used in other professions, especially medical education and teacher education, but it has yet to see widespread use in engineering education.CBA can involve a number of key differences from conventional assessment practices. In this pilot, it involved the following key differences. Whereas previous versions of the course had involved assignments, labs, a midterm, and a final exam, each worth a certain weight in the overallcourse grade, the 2020 CBA version was broken into three modules, each with a “module test”. The module tests were superficially similar to a midterm, and there was no cumulative final exam. Open book assignments, quizzes, labs, and module tests consisted of questions and exercises that addressed a variety of learning outcomes (LOs) within the modules. The LOs were assigned weights in the overall course grade, as opposed to assigning weights to assessments themselves as in a conventional assessment system. Students could therefore overcome poor performances in early assessments of LOs, as better later results on the same LOs would replace the earlier results.A key feature of this approach was that students had at least two and typically three or more opportunities to exhibit competence with respect to the course’s LOs. Another key aspect of this CBA implementation was the division of course material into three levels or “types”. Type A materials were the most basic building blocks of the course i.e. basic definitions, calculations, and concepts. Type B materials were basic integrative problems e.g. solving a basic 2D or 3D particle or rigid body equilibrium question, or solving a basic truss. Type C materials were advanced or “tricky” integrative problems that probed deeper understanding and required more adaptive problem solving. Students were required to meet competency thresholds for Type A and B materials i.e. theyneeded to exhibit a minimal level of competency in the LOs in order to pass the course.Overall, the class excelled in this assessment format and anecdotal evidence suggests that the students enjoyed it. A summary description of the complete system will be presented in this paper, including how grades were determined, how assessments were conducted and evaluated, how LOs were determined, and how the three levels of material were arranged. As well, basic statisticalresults from the class’ performance will be presented, along with a number of observations made by the instructors and some anecdotal impressions conveyed to them by students. The observed outcomes will be compared with the CBA literature for related STEM contexts, although the remote learning/COVID context did obscure the causes and origins of some of the observed outcomes. Changes that will be made in next year’s implementation of the course will also be discussed.

Multi-Objective Optimization of a Mine Water Reuse System Based on Improved Particle Swarm Optimization.

This paper proposes a general hierarchical dispatching strategy of mine water, with the aim of addressing the problems of low reuse rate of coal mine water, and insufficient data analysis. First of all, water quality and quantity data of the Narim River No. 2 mine were used as the research object; the maximum reuse rate of mine water and the system operation rate comprised the objective function; and mine water quality information, mine water standard, and mine water treatment speed were the constraints. A multi-objective optimization scheduling mathematical model of water supply system was established. Then, to address the problems of premature convergence and ease of falling into a local optimum in the iterative process of particle swarm optimization, the basic particle swarm optimization was improved. Using detailed simulation research, the superiority of the improved algorithm was verified. Eventually, the mine water grading dispatching strategy proposed in this paper is compared with the traditional dispatching method. The results show that the hierarchical dispatching system can significantly improve the mine water reuse rate and system operating efficiency.

When in Need of an ESCRT: The Nature of Virus Assembly Sites Suggests Mechanistic Parallels between Nuclear Virus Egress and Retroviral Budding.

The proper assembly and dissemination of progeny virions is a fundamental step in virus replication. As a whole, viruses have evolved a myriad of strategies to exploit cellular compartments and mechanisms to ensure a successful round of infection. For enveloped viruses such as retroviruses and herpesviruses, acquisition and incorporation of cellular membrane is an essential process during the formation of infectious viral particles. To do this, these viruses have evolved to hijack the host Endosomal Sorting Complexes Required for Transport (ESCRT-I, -II, and -III) to coordinate the sculpting of cellular membrane at virus assembly and dissemination sites, in seemingly different, yet fundamentally similar ways. For instance, at the plasma membrane, ESCRT-I recruitment is essential for HIV-1 assembly and budding, while it is dispensable for the release of HSV-1. Further, HSV-1 was shown to recruit ESCRT-III for nuclear particle assembly and egress, a process not used by retroviruses during replication. Although the cooption of ESCRTs occurs in two separate subcellular compartments and at two distinct steps for these viral lifecycles, the role fulfilled by ESCRTs at these sites appears to be conserved. This review discusses recent findings that shed some light on the potential parallels between retroviral budding and nuclear egress and proposes a model where HSV-1 nuclear egress may occur through an ESCRT-dependent mechanism.

β-decay and isospin symmetry breaking

<p indent=0mm>The elegant concept of isospin symmetry is of fundamental importance in nuclear and elementary particle physics. As a β-decay process changes an up quark to a down quark or <italic>vice versa</italic>, studies of nuclei with exchanged numbers of neutrons and protons, known as mirror nuclei, can be a powerful means to probe isospin symmetry breaking. A series of β-decay experiments of sd-shell nuclei near the proton drip line produced by projectile fragmentation were performed at the Radioactive Ion Beam Line of the Heavy Ion Research Facility in Lanzhou (HIRFL-RIBLL1) using a silicon array with a high detection efficiency and a low detection threshold. The secondary ions were identified by the combination of Δ<italic>E</italic>-TOF and magnetic rigidity (<italic>Bρ</italic>) in which the time of flight (TOF) was measured by two plastic scintillators at the second and fourth focal planes of the RIBLL1 and the energy loss (Δ<italic>E</italic>) was measured by two silicon detectors in the front of the silicon array. Double-sided silicon strip detectors (DSSDs) in the center of the array served to measure the residual energies of secondary ions on an event-by-event basis and study their decay properties with an implantation-decay correlation. Several quadrant silicon detectors (QSDs) placed behind DSSDs were used for anticoincidences of the penetrating fragments and light particles coming along with the beam, and measurements of β particles and high-energy protons. The β-delayed proton peaks with known energies and their corresponding absolute intensities were used for the energy and detection efficiency calibrations of the DSSDs. The system allows us to measure protons with energies down to about <sc>200 keV</sc> without obvious β background in the proton spectrum and was successful to measure the energies, time, and positions of implanted ions and decay protons efficiently, supporting researchers to study the decay properties of nuclei towards the proton drip line. The β-decay data, together with the large-scale shell-model calculations, allows detailed investigations on the mirror-nuclei systems resulting in the systematic study of isospin symmetry breaking in the sd-shell nuclear region. It was found that the mirror asymmetry parameters become larger due to the smaller separation energies while approaching the proton drip line for the extremely proton-rich sulfur nuclei ^27,28,29S and the Coulomb forces and other isospin-symmetry nonconserving forces acting between protons would lead to extended proton wave functions and cause mirror asymmetries. The properties of ²²Si β-decay for the transitions to the low-lying states of ²²Al were measured, and the reduced transition probabilities were determined. Comparing with the data on the β-decay of the mirror nucleus ²²O, we found a mirror asymmetry of <italic>δ</italic>=209(96)% in the transition to the first 1⁺ excited state of the respective daughters. This is by far the largest value of <italic>δ</italic> observed in the low-lying states. Shell-model calculations with isospin-nonconserving forces, including the <italic>T</italic>=1,<italic> J</italic>=2, 3 interactions related to the s_1/2 orbit that introduces explicitly the isospin-symmetry breaking force and describes the loosely bound nature of the wave functions of the s_1/2 orbit, can reproduce the observed data well and demonstrate that this dramatically large mirror asymmetry is attributed to the significant proton occupation and loosely bound nature of the wave functions of the s_1/2 orbit, which suggests that ²²Al is a proton-halo nucleus.

Optimization of copper detection based on polarization-resolved laser-induced breakdown spectroscopy.

In order to obtain stable spectral data of copper plasma, a detection platform of polarization-resolved laser-induced breakdown spectroscopy (PRLIBS) was built. The PRLIBS characteristic function of copper was constructed by combining the spectral path of plasma discrete spectrum and contact spectrum. The system can not only measure the original data, but also obtain the polarization information in the spectral data. By analyzing the extraction method of spatial polarized light information, the characteristic model of S-wave intensity information in PRLIBS was derived. The results show that in the decay process of plasma energy, the anisotropy of plasma recombination under local thermal equilibrium makes the number of deflected particles of atoms and electrons different in unit time, which leads to the polarization of radiation. The polarization characteristics of the plasma spectrum decreased with the increase of laser energy density. The S-wave was very active, and the polarization of continuous media was much stronger than that of discrete line emission. The advantages were helpful to obtain more stable characteristic peak signals. As a plasma element identification method, PRLIBS makes up for the deficiency of plasma detection technology, and can provide a scientific basis for the safety and non-destructive detection of heavy metals.