Direct Interaction Processes Research Articles

LEARNING LOSS IN THE TEACHING OF ENGLISH SUBJECT AT A VOCATIONAL SCHOOL IN TANJUNG JABUNG BARAT: TEACHERS’ PERCEPTION

Abstract
 The covid-19 Pandemic has caused an unexpected shift in teaching and learning at schools around the world. The teaching and learning process has mostly switched to distance learning and causes problems for all parties involved, including students and their parents, teachers, and school management. While research has been carried out to observe the implementation of distance learning and its challenges and problems, only a few studies have been focused on investigating a possible phenomenon called ‘learning loss’. Learning loss is generally defined as a lack of student interest in the learning process because there is only little to zero direct interaction process during their learning. This research is designed to investigate the possible occurrence of learning loss in a vocational school in Tanjung Jabung Barat. The research was carried out qualitatively. Data were collected through in-depth interviews with participants that consist of two English teachers in the school. Questions addressed in the interview were focused on investigating the shift in the teachers’ teaching process and students’ learning activities, including the signs of a decrease or loss of interest in learning and the impact on learning achievement. Teachers’ understanding of students’ situations and efforts to mitigate them will also be investigated. Data collected from the interview was analyzed using theories relevant to the issues.
 Key Word: Pandemic, English Teaching, Teachers Perception, Learning Loss

Transformation of Public Services Through Electronic-Based Government System in Malang City

The electronic-based government system is a transformation in the process of providing public services, both internally and externally through technical operations of information and communication technology to improve the quality of public services. It has also been explained, in Presidential Regulation no. 95 of 2018 concerning the Electronic-Based Government System which regulates the National SPBE Master Plan and the integration of electronic services. Thus, public services that have been able to be carried out through a direct interaction process, then with the presence of increasingly sophisticated information and communication technology can provide convenience in providing services through digital devices. The purpose of this study was to determine how effective and efficient the implementation of the model related to Transformation of Public Services through Electronic-Based Government Systems in Malang is. The research method used is a literature study method, where the sources and data are through journals, books, and other written sources. The results of research on Transformation of Public Services Through Electronic-Based Government Systems in Malang City can use vertical and horizontal integration models to improve public services from Old Public Administration to New Public Service.

Studying trophic interactions between a plant pathogen and two different antagonistic microorganisms using a 13C‐labeled compound and isotope ratio mass spectrometry

The study of the interactions among microorganisms, especially between pathogens and other microorganisms, is a very useful way to identify possible biocontrol agents (BCAs). In this study we verified the capability of δ(13)C analysis using isotope ratio mass spectrometry (IRMS) to detect active parasitism or metabolic assimilation of (13)C-labeled Armillaria mellea (plant pathogen) by Trichoderma atroviride and Pseudomonas fluorescens (two BCAs). The three microorganisms were labeled in pure-culture using a specific medium to which D-glucose (13)C was added. The δ(13)C analysis of mycelia/cells and DNA was undertaken using IRMS at different times, to study the uptake kinetics of (13)C. The mechanisms of interaction were studied by implementing dual-culture tests and measuring the δ(13)C values of the two BCAs after 29 days of contact with the labeled pathogen. A. mellea absorbed (13)C more slowly (plateau at 21 days) than T. atroviride and P. fluorescens (3 and 1 day, respectively) in pure-culture. The maximum δ(13)C values were higher in A. mellea and T. atroviride mycelia (8,019.9‰ and 10,383.7‰, respectively) than in P. fluorescens (953.4‰ in cells). In dual-culture the mycelia of T. atroviride which remained in direct contact with labeled A. mellea showed an increased δ(13)C value with respect to the unlabeled treatment (66.4‰ and -26.6‰, respectively), due to active interaction. Lower assimilation of (13)C was detected in P. fluorescens. This work demonstrates that IRMS can be used for the in-depth study of direct parasitism and interaction process between biocontrol agents and labeled pathogens, allowing the screening of potential new BCAs.

Direct exchange and interaction of 3d impurities on the (0 0 1) surface of iron

We present a detailed ab-initio study of direct exchange and interaction processes of 3d atoms on the Fe(0 0 1) surface. The calculations are based on local density functional theory and apply a KKR-Green's function method for impurities on surfaces. For practically all 3d transition metal impurities on Fe(0 0 1) we find a strong tendency for a direct exchange mechanism into the first surface layer. The early 3d impurities V, Cr and Mn strongly repel each other on neighbouring positions within the first layer, while Ni and Cu atoms show a moderate repulsion. The ab-initio results are in good agreement with STM studies for Cr/Fe(0 0 1) by the NIST group and present valuable predictions for all 3d/Fe(0 0 1) systems.

Fast Neutron Inelastic Scattering Cross Sections of238U for States between 680 and 1530 keV

Neutron inelastic scattering cross sections for /sup 238/U levels between 680- and 1530-keV excitation energy have been measured in the incident neutron energy range from 0.9 to 2.2 MeV. The (n,n') time-of-flight (TOF) technique was used to obtain direct differential inelastic cross sections. Neutrons were generated using the /sup 7/Li(p,n)/sup 7/Be reaction. Experimental parameters were optimized to achieve an energy resolution of <15 keV. Level cross sections were deduced from the measured 125-deg differential scattering cross sections. The validity of this procedure was confirmed by measuring the angular distributions for nine levels at En=1.5 and 2.0 MeV. Background due to fission induced by fast neutrons was subtracted. The TOF spectra were unfolded using the method of the response function. The data were corrected for multiple scattering and neutron attenuation in disk scattering geometry using an analytic method. Theoretical calculations of the cross sections were carried out using reaction models appropriate to the description of compound nucleus and direct interaction processes. The data are compared to (n,n'..gamma..) results and the ENDF/B-V evaluation.

Hydrogen and oxygen isotope geochemistry of Ascension Island lavas and granites: variation with crystal fractionation and interaction with sea water

Lavas and pyroclastics on Ascension Island contain plutonic blocks that include fluid-inclusion-bearing peralkaline-granite. 18O/16O ratios, F and Cl have been analysed on whole rocks and/or minerals for lavas and granites, and D/H ratios and H2O+ for comenditic obsidians and granites. Whole rock 18O/16O ratios of fresh alkali-basalt, hawaiite, trachyandesite, trachyte and comendite range from 6.0 to 6.9‰ with 18O tending to increase with increase in SiO2. The δ18O values of the granites are from 0.0 to 0.3‰ depleted in 18O relative to the comendites. Comenditic obsidians have δD= −80±4‰ and H2O+ ∼0.3 wt.% while amphiboles from the granites have δD= −56±2‰ The O-isotope trend of the lavas is consistent with a crystal fractionation model. Fresh igneous rocks with δ18O values greater than 7‰ involve processes in addition to crystal fractionation of a basaltic magma. The D/H ratios and Cl contents (∼ 3,000 ppm) of the H2O-poor comenditic obsidians represent undegassed primary magmatic values. The H-isotope compositions and low H2O and Cl (167 ppm) contents of the granites are consistent with the major degassing (loss of >90% of initial H2O) of an H2Osaturated magma derived from the interaction of sea (or possibly meteoric) water with the H2O-undersaturated comenditic melt. It is proposed that, associated with caldera subsidence and stoping, water was sucked in around the residual magma before the system had time to be sealed up. The H2O-undersaturated magma consumed this H2O with possibly some minor partial dehydration and dewatering of the hydrated volcanic roof blocks, at a pressure of about 1.5 kb. The granites are the plutonic equivalents of rhyolitic pyroclastics and not directly of the comendites. Granites from oceanic islands may, in general, be a result of generating an H2O-saturated acid melt by such direct or indirect crustal water-magma interaction processes.

Imprints of compound-nucleus and direct-interaction processes in energy-averaged cross sections and durations of nuclear reactions

New analytical expressions for the energy-averaged S-matrix and nuclear-reaction cross sections are obtained on the basis of the unitary S-matrix parametrization. Some approximations are analyzed when compound-nucleus cross sections are described with and without the Hauser-Feshbach formula with the partial-width-fluctuation correction. The connection of the S-matrix parameters in the Simonius representation with the dynamics of compound-nucleus processes is clarified. An explicit expression for the averaged duration of the nuclear reaction is obtained for the range of closely situated resonances. Possible methods of obtaining information on some compound-nucleus and direct-interaction characteristics from the averaged cross sections and durations are examined.

The scavenging of particles by electrified drops: radar echo intensification following lightning

A series of laboratory experiments were performed in an effort to improve our understanding of the physics of the echo-intensification phenomenon, in which the radar reflectivity of a region of a thundercloud increases rapidly immediately following the occurrence of lightning within it. Measurements were made of the charges, q, deposited on falling water drops when they engage in direct interactions with positive corona streamers in a uniform electric field, E, just above the limit for propagation, E0. As the drop radius increased from 12 to 950/μm, q increased from about 10−13 to about 10−10C; and q increased as E was raised above E0. These measurements yielded an estimate of 30μm and 108, respectively, for the radius of, and the number of elementary charges contained in, the tip of a propagating streamer at a pressure of one atmosphere. The collection efficiencies of drops in the radius range 40 to 120 μm carrying charges appropriate to the direct interaction process, for uncharged droplets of radius around 12 μm, were found to be about four times the non-electrical values. It was concluded that this enhancement in collection resulted largely from dipole rather than coulomb forces. A simple analysis indicates that reported echo-intensification observations cannot be explained in terms of these enhanced collection efficiencies, but could possibly be a consequence of the greatly enhanced velocities (and hence growth rates) of drops of radius ∼ 100 μm highly charged by direct interaction with corona streamers in the intense electric fields of a thundercloud.

The scavenging of particles by electrified drops: Radar echo intensification following lightning

AbstractA series of laboratory experiments were performed in an effort to improve our understanding of the physics of the echo‐intensification phenomenon, in which the radar reflectivity of a region of a thundercloud increases rapidly immediately following the occurrence of lightning within it. Measurements were made of the charges, q, deposited on falling water drops when they engage in direct interactions with positive corona streamers in a uniform electric field, E, just above the limit for propagation, E0. As the drop radius increased from 12 to 950/μm, q increased from about 10−13 to about 10−10C; and q increased as E was raised above E0. These measurements yielded an estimate of 30μm and 108, respectively, for the radius of, and the number of elementary charges contained in, the tip of a propagating streamer at a pressure of one atmosphere.The collection efficiencies of drops in the radius range 40 to 120 μm carrying charges appropriate to the direct interaction process, for uncharged droplets of radius around 12 μm, were found to be about four times the non‐electrical values. It was concluded that this enhancement in collection resulted largely from dipole rather than coulomb forces. A simple analysis indicates that reported echo‐intensification observations cannot be explained in terms of these enhanced collection efficiencies, but could possibly be a consequence of the greatly enhanced velocities (and hence growth rates) of drops of radius ∼ 100 μm highly charged by direct interaction with corona streamers in the intense electric fields of a thundercloud.

Dynamics of CO2+−D2 collisions

We have measured complete velocity vector distributions for several of the products of collisions between CO2+ and D2. The reactions CO2+(D2,D)DCO2+ and CO2+(D2,OD)DCO+ are the principal chemical processes in the range of relative energies from 1 to 15 eV. The former proceeds principally by a direct interaction mechanism, with some smaller contribution from the decay of a D2CO2+ persistent complex. The DCO+ appears to come exclusively from the decay of this persistent complex at low relative energies, and from a complicated direct interaction process at very high energies. Other energetically accessible products such as CO+, O+, D2O+, and OD+ prove to be of minor or no importance.

Fast neutron induced [( n, t) + ( n, n′ t)] reaction cross-sections in the medium and heavy mass regions

Cross-sections have been measured for the formation of tritium via ( n, t) and ( n, n′ t) reactions on Ti, Mn, Cu, Ga, Nb, 92Mo, Ag, In, Sb, Ta, Re, Au and Bi with fast neutrons produced via break-up of 53 MeV deuterons on a Be-target (maximum intensity of the neutrons at E n ∼ 22·5 MeV). The activation technique in combination with vacuum extraction and “low-level” gas phase β −-counting of tritium was employed. The cross-sections lie between 3·5 and 5·5 mbarn and decrease only slightly with increasing Z of the target element. A comparison of the cross-section systematics at E n = 14·6 and 22·5 MeV suggests that at the latter energy possibly a greater contribution from direct interaction processes is involved.

Quasistatistical Complexes in Chemical Reactions

The S matrix for inelastic and rearrangement collisions derived within Feshbach's theory of resonances can be written as the sum of SD and SC, where SD refers to direct interaction processes, and SC refers to complex (resonant) processes. For collision times short compared to characteristic times of internal motions of reactants, models of direct interactions, which assume SC to be zero, have been developed. For collision times long compared to all characteristic times of internal motion, statistical models of complex formation, which assume SD to be zero, have been formulated. Although much experimental work can be classified with either of these extreme models, intermediate cases do occur. We examine a possible method for making quasistatistical (or partial statistical) approximations on SC (for inelastic and reactive scattering), and indicate how well-known statistical models can be modified with this method to describe quasistatistical behavior. The concept of doorway states provides another category of intermediate cases and is developed briefly. The classification of experimental results into the various categories (direct interaction, complete statistical complex, partial statistical complex, doorway states, and combinations of all of these) requires a number of different measurements. Possible deductions from the various experiments are discussed and examples of reactions for the different categories are cited.

Activation cross-sections for some 14·8 MeV neutron-induced nuclear reactions on caesium: Isomer ratios of 134Cs, 133Xe and 130I

Absolute cross-sections for 14·8 MeV neutron-induced reactions on 133Cs were determined using the activation technique. The results, with maximum errors of 15 per cent, are: ρ(n,γ)=7·1 mb (ρ(n,γ) 134m Cs=1·82 mb, ρ(n,γ) 134g Cs=5·3 mb ; ρ(n,2n) 132 Cs=1620 mb ; ρ(n,p)=10·5 mb (ρ(n,p) 133m Xe=4·8 mb, ρ(n,p) 133g Xe=5·7 mb ; ρ(n,α)=1·14 mb (ρ(n,α) 130m I=0·54 mb, ρ(n,α) 130g I=0·6 mb ; ρ(n, 3 He) 131 I=3·2 μ barn ; ρ(n,2p) 132 I⩽12 μ barn . At this particle energy direct interaction processes also contribute. The isomer cross-section ratios σ m σ g for 134Cs, 133Xe and 130I are 0·34±0·08, 0·85±0·15 and 0·91±0·2 respectively. A reinvestigation of the alleged 127I ( n, 3 n) 125I reaction showed that the earlier measurement was in error.

(n, α) Reaction on 12C Induced by 14.1 MeV Neutrons

The ( n , α) reaction on 12 C has been investigated by bombarding a thin polyethylene film with 14.1 MeV neutrons. The emitted α-particles were detected by a CsI(T1) scintillation detector and distinguished from other particles by applying the pulse-shape discrimination method. The angular distribution of the α-particles leaving the residual nucleus 9 Be in the ground state was strongly peaked at about 40° and at the backward hemisphere in the center-of-mass angles, predicting the presence of direct interaction processes. The ground state transition cross section of 76±11 mb was obtained. The forward peaking was compared with the plane wave theory, for both the pick-up and knock-on processes. The reduced width amplitude of the α-cluster at the nuclear surface of 12 C was determined by attempting the theoretical fit to the backward peak of the angular distribution in terms of the heavy-particle stripping model. Comparing this value with those obtained from other reactions on light nuclei, it seems that the...

Half-lives and activation cross-sections of some radio-isotopes of iodine, tellurium and antimony formed in the interactions of iodine with 14·7 MeV neutrons

Accurate half-lives and absolute activation cross-sections have been estimated for some of the isotopes formed in the interactions of iodine with 14·7 MeV neutrons. They are as follows: 128 I:25·5±0.3 min; ρ n,y=7·2±1·2 mb 126 I:13·02±0.07 day; ρ n,2n=1128±120 mb 125 I:58±2 day; ρ n,3n=40±15 mb 127 Te:9·23±0.13 hr; ρ n,p=8·9±1·0 mb 124m Sb:21·3±0.8 min; ρ n,α=1·5±0·2 mb At this particle energy direct interaction processes also contribute. A search for the alleged 2·6 hr isomeric state in 126I showed that this activity probably does not exist.

Investigation of the 9Be( 3He, n) 11C reaction in the energy range 3.5–10 MeV

The excitation functions and angular distributions of neutrons from the 9Be( 3He, n) 11C reaction leading to the ground and first excited states of 11C have been measured in the energy range 3.49–9.96 MeV. The behaviour of the excitation cruves and the oscillatory pattern of angular distributions indicate that a direct interaction process is predominant in the 9Be( 3He, n) 11C reaction especially at the incident energies above 5 MeV. The angular distributions obtained at several bombarding energies have been compared with the results of DWBA calculations based on a two-nucleon stripping process, and good agreement is obtained for the data taken at 9.93 MeV. The agreement is not satisfactory at lower incident energy region, where the reaction process seems to be more complex. The neutron group leading to the first excited state of 11C shows a L = 2 pattern in higher energy region in contrast with the L = 0 pattern of the photon group observed in the mirror reaction 9Be( 3He, p) 11B. This is consistent with a selection rule for the di-proton stripping reaction and indicates that the two-nucleon stripping process is predominant in the 9Be 3He reaction.

Nuclear Polarization in theB11(d,p)B12Reaction. II

Measurements have been made of the polarization of the ${\mathrm{B}}^{12}$ recoil nuclei resulting from the ${\mathrm{B}}^{11}(d,p){\mathrm{B}}^{12}$ reaction for ${E}_{d}$ in the range 0.90 to 3.20 MeV. The polarization is observed by measuring the $\ensuremath{\beta}$-decay asymmetries of the ${\mathrm{B}}^{12}$ recoil nuclei with respect to the reaction plane. The ${\mathrm{B}}^{12}$ recoil nuclei formed in the ground state are separated kinematically from those in excited states and are then stopped in various solids in the presence of a small magnetic field normal to the reaction plane. The sign of the observed polarization for all measurements is in the direction of the vector ${\mathbf{k}}_{d}\ifmmode\times\else\texttimes\fi{}{\mathbf{k}}_{p}$. The magnitude of the polarization is strongly dependent on ${E}_{d}$, the recoil emission angle and the material used to stop the recoils. It is found that the polarization of ${\mathrm{B}}^{12}$ nuclei can be maintained in either metallic Pd or Au at room temperature, using holding fields smaller than 20 G. For recoils stopped in Pt metal, a magnetic field of about 200 G is required to maintain the nuclear polarization. The ${\mathrm{B}}^{12}$ recoil polarization plotted as a function of ${E}_{d}$ shows definite structure. Polarization resonances are observed at 1.5, 2.1, and 3.0 MeV. At these energies the measured relative polarizations are +(8.01\ifmmode\pm\else\textpm\fi{}0.30)%, +(4.29\ifmmode\pm\else\textpm\fi{}0.30)%, and +(3.86\ifmmode\pm\else\textpm\fi{}0.27)%, respectively, for a Pt metal recoil stopper and a 49\ifmmode^\circ\else\textdegree\fi{} (lab) recoil angle. These resonances are tentatively identified with states of the ${\mathrm{C}}^{13}$ compound nucleus near 20.0 MeV and at 20.52 and 21.28 MeV. It is believed that the polarization resonances may result from an interference between direct interaction and two-particle compound resonance processes.

Réactions entre protons de 30 à 155 MeV et noyaux lourds complexes

Excitation functions have been established between 20 and 156 MeV for twelve (p, xn) reactions and nine (p, p xn) reactions induced on Bi by protons . In order to determine the cross sections for light polonium isotopes, new identifications were made for the disintegration schemes on 197–202Po. New isomeric states were found for 203Po, 201Po, 199Po and 197Po. The experimental excitation functions have been compared to theoretical values which were deduced from the two-step mechanism (Serber model). It has been shown that the experimental data are in agreement with a direct-interaction model in which prompt cascades are calculated in a diffusive-edge nucleus. However a model in which reflections and refractions are included for the penetration and the exit of the prompt nucleons, yields much too high proportions of compound nucleus, and therefore a simple model in which the impulse approximation is strictly applied for all collisions is a better description of the direct-interaction process than more elaborate calculations. The de-excitation process is described with great success by the statistical theory when at each step of the neutron evaporation chain, a competition is introduced for charged-particle evaporation and for fission. The best fit is obtained with level density parameters a = 13 MeV −1 for the particle emission and a f = 13.5 MeV − for fission. The agreement with experimental data obtained for all excitation functions along such a large energy range (20–155 MeV) seems to be a great success of the Serber-Goldberger model for the description of medium-energy, nuclear reactions.

Investigation of theAl27(α,p)Reaction by Cross-Section Fluctuation Studies

Cross sections for the reaction ${\mathrm{Al}}^{27}(\ensuremath{\alpha},p){\mathrm{Si}}^{30}$ have been measured with energy resolutions which, in the incoming alpha-particle channel, are finer than the energy width of the overlapping levels of the compound system ${\mathrm{P}}^{31}$. Fluctuations in these cross sections were analyzed for the coherence widths of this compound nucleus and for details of the reaction mechanism, such as the behavior of reaction amplitudes as shown by the form of the frequency distribution of the cross section, the independence of the reactions leading to the different magnetic substates, and the amounts of compound-nucleus and direct-interaction processes. Cross sections were measured at 11 angles between 0\ifmmode^\circ\else\textdegree\fi{} and 175\ifmmode^\circ\else\textdegree\fi{} and at 5-keV energy steps for energies between 5.8 and 8.6 MeV. Lack of a cross correlation between the yields of protons to the ground (${0}^{+}$) and first excited (${2}^{+}$) states of ${\mathrm{Si}}^{30}$ confirmed the expected overlapping of levels of the compound nucleus, which is a basic requirement of fluctuation analysis. The coherence width of the compound-nucleus ${\mathrm{P}}^{31}$ was found to increase from 8 to 18 keV over the range of excitation energy 14.7 to 17.1 MeV. At the back angles of 175\ifmmode^\circ\else\textdegree\fi{} and 170\ifmmode^\circ\else\textdegree\fi{} the frequency distributions of cross sections for protons to the ground state of ${\mathrm{Si}}^{30}$ agree with ${\ensuremath{\chi}}^{2}$ distributions with only slightly more than two effective degrees of freedom. This number corresponds to the slightly more than one effective magnetic substate allowed by angular-momentum properties near 180\ifmmode^\circ\else\textdegree\fi{}. This agreement substantiates cross-section fluctuation theory and indicates negligible direct interaction at these back angles. At 140\ifmmode^\circ\else\textdegree\fi{} and 160\ifmmode^\circ\else\textdegree\fi{} direct interactions were assumed still to be negligible, and then from the frequency distributions of cross sections the number of independent magnetic quantum states at these angles was found to be less than expected from an analysis based on angular-momentum properties and a Hauser-Feshbach calculation. This difference is a consequence of the small orbital angular momenta involved in the ($\ensuremath{\alpha},p$) reaction at these energies. These effective numbers of magnetic substates were used at the corresponding forward angles to determine the amounts of compound-nucleus and direct-interaction processes from fluctuations in cross sections. At the lowest energies of incident alpha particles the amount of direct interaction was too low to be determined with accuracy, but at the highest energies the maximum direct-interaction cross section was roughly equal to the compound-nucleus cross section. The direct-interaction cross section was found to vary with angle roughly as expected from distorted-wave Born-approximation calculations.

(p, p′γ) Angular Correlations inTi48

The angular correlations between the protons inelastically scattered from the first excited state of ${\mathrm{Ti}}^{48}$ and the associated de-excitation gamma rays have been measured as absolute second differential cross sections at bombarding energies of 4.63 and 5.25 MeV. These measurements were made both in the scattering plane and at angles of 30, 45, 60, and 90\ifmmode^\circ\else\textdegree\fi{} relative to the scattering plane. Special attention was directed to studies of the symmetry predictions of the compound nucleus and direct interaction processes, and comparison is made with the statistical-theory computations of Sheldon. For a given proton detector angle, the azimuthal symmetries agree in shape though not in magnitude with statistical-theory predictions. However, results for complementary proton-detector angles are incommensurate with the symmetries predicted by statistical theory.