Secondary Flux Research Articles

NAFLD: Diagnostic Algorithms for Regulating Patient Fluxes.

The global prevalence of NAFLD is estimated to be over 25% and it is already the leading cause of chronic liver disease in industrialized countries, as a consequence of the spread of obesity and metabolic syndrome. The prognosis of NAFLD is generally benign in the absence of fibrosis, but liver fibrosis rapidly progresses in 20% of the cases and can lead to cirrhosis and/or HCC. This review focuses on non-invasive fibrosis testing strategies for patients with NAFLD in order to increase the efficiency and effectiveness of diagnosis and care, regulating secondary care referral fluxes. An integrated management plan between primary care and secondary care with a defined algorithm of non-invasive testing to stratify the risk of NAFLD fibrosis is indispensable to increase the early diagnosis of fibrosis but also decrease unnecessary referrals.

Decrement of secondary gamma radiation flux during lunar eclipse June 16, 2011

The lunar eclipse at Udaipur (27◦ 43’ 12.00” N, 75◦ 28’ 48.01” E), India was experimentally observed on June16, 2011 using ground based NaI (Tl) Scintillation detector. We interpret such decrement of secondary gamma radiation flux (SGRF) on the basis of obstruction effect produced by Earth and Moon during lunar eclipse on radiation. Objective: To observe secondary gamma radiation flux during lunar eclipse day on comparison to pre and post eclipse days. Methods: For this experimental study we used ground based NaI (Tl) Scintillation detector. The data files were stored in computer for thirty minutes duration from 1.00 AM to 2.00 AM (Indian Time) on pre-eclipse normal days June 14 and 15, 2011 as well as on post eclipse normal day June 17 and also on eclipse day June 16, 2011. Finding: The analyzed data reveal significant decrement of secondary gamma radiation flux (SGRF) on lunar eclipse day about 6% on comparison to pre and post lunar eclipse days. Novelty: In this experimental study first time we reported about 6% decrement of secondary gamma radiation flux on lunar eclipse day on comparison to pre and post lunar eclipse days. Keywords: Lunar eclipse; cosmic radiation; reflected solar radiation; secondary gamma radiation; obstruction effect by Earth and Moon

A Compact Muon Telescope for Monitoring Secondary Cosmic Ray Fluxes

The cosmic ray laboratory of the Polar Geophysical Institute has created a simple and compact telescope with a modular design that is designed to detect ionizing particles in the energy range from 1 MeV to 100 GeV. The telescope consists of two scintillator plates separated by a layer of lead that are located one above the other. The electronic circuit creates a channel for counting the upper detector and a channel of coincidences with the lower one. The area of each detector is 0.25 m2; the average count rate of the upper detector is 3000 pulses/min.

A study of the secondary cosmic $\gamma $-ray flux in India during the Great American solar eclipse on 21st August 2017

We present the results from the measurement of secondary cosmic gamma-ray flux using a NaI(Tl) scintillator detector during a total solar eclipse. The unique feature of this experiment is that it was carried out at a place where the solar eclipse was not observable. The total solar eclipse of August 21, 2017, was visible in most of the regions of North America during the day, whereas India, falling on the other half of the globe missed this particular eclipse. Our aim was to measure and examine if there are any variations in the secondary cosmic ray (SCR) flux at Kolkata, India due to the occurrence of the eclipse in America. Detailed experimental techniques used for this experiment are mentioned in this article. Method of data analysis and results are presented. We observe unexpected dehancement and enhancement of SCR flux in certain energy regions.

Universal properties of primary and secondary cosmic ray energy spectra

Atomic nuclei appearing in cosmic rays (CRs) are typically classified as primary or secondary. However, a better understanding of their origin and propagation properties is still necessary. We analyse the flux of primary (He, C, O) and secondary nuclei (Li, Be, B) detected with rigidity (momentum/charge) between 2 GV and 3 TV by the alpha magnetic spectrometer on the International Space Station. We show that q-exponential distribution functions, as motivated by generalized versions of statistical mechanics with temperature fluctuations, provide excellent fits for the measured flux of all nuclei considered. Primary and secondary fluxes reveal a universal dependence on kinetic energy per nucleon for which the underlying energy distribution functions are solely distinguished by their effective degrees of freedom. All given spectra are characterized by a universal mean temperature parameter ∼200 MeV which agrees with the Hagedorn temperature. Our analysis suggests that QCD scattering processes together with nonequilibrium temperature fluctuations imprint universally onto the measured CR spectra, and produce a similar shape of energy spectra as high energy collider experiments on the Earth.

Heat priming improved heat tolerance of photosynthesis, enhanced terpenoid and benzenoid emission and phenolics accumulation in Achillea millefolium.

The mechanism of heat priming, triggering alteration of secondary metabolite pathway fluxes and pools to enhance heat tolerance is not well understood. Achillea millefolium is an important medicinal herbal plant, rich in terpenoids and phenolics. In this study, the potential of heat priming treatment (35°C for 1hr) to enhance tolerance of Achillea plants upon subsequent heat shock (45°C for 5min) stress was investigated through recovery (0.5-72 hr). The priming treatment itself had minor impacts on photosynthesis, led to moderate increases in the emission of lipoxygenase (LOX) pathway volatiles and isoprene, and to major elicitation of monoterpene and benzaldehyde emissions in late stages of recovery. Upon subsequent heat shock, in primed plants, the rise in LOX and reduction in photosynthetic rate (A) was much less, stomatal conductance (gs ) was initially enhanced, terpene emissions were greater and recovery of A occurred faster, indicating enhanced heat tolerance. Additionally, primed plants accumulated higher contents of total phenolics and condensed tannins at the end of the recovery. These results collectively indicate that heat priming improved photosynthesis upon subsequent heat shock by enhancing gs and synthesis of volatile and non-volatile secondary compounds with antioxidative characteristics, thereby maintaining the integrity of leaf membranes under stress.

Mercury dynamics in a changing coastal area over industrial and postindustrial phases: Lessons from the Venice Lagoon

During the industrial period, significant amounts of mercury (Hg) were discharged into the Venice Lagoon. Here, a spatially explicit model was implemented to reconstruct the temporal evolution of the total mercury (HgT) and methylmercury (MeHgT) concentrations in lagoon water and sediments over two centuries (1900–2100), from preindustrial to postindustrial phases. The model simulates the transport and transformations of particulate and dissolved Hg species. It is forced with time-variable Hg inputs and environmental conditions, including scenarios of future atmospheric deposition, reconstructed according to local and global socioeconomic scenarios. Since 1900, ~36 Mg of HgT and ~380 kg of MeHgT were delivered to the lagoon, and stored in the sediments. The deposition of Hg from the water to the seafloor increased during a period of eutrophication (1980s); however, the reverse fluxes increased during a period of high sediment resuspension caused by the unregulated fishing of Manila clams (1990s). In the current postindustrial phase, the lagoon sediments have acted as a secondary source to the lagoon waters, delivering Hg (~38 kg y−1) and MeHg (~0.07 kg y−1). The MeHg inputs from the watershed (~0.28 kg y−1) appear to be higher than the secondary fluxes from the sediments. The estimated HgT export to the Adriatic Sea is ~56 kg y−1. Since HgT and MeHgT outputs slightly exceed inputs, the concentrations are slowly decreasing. While the decreasing trend is maintained in all scenarios, the future level of atmospheric deposition will affect Hg concentrations and sediment recovery times. Though limited by inherent simplifications, this work results show that the reconstruction of historical dynamics using a holistic approach, supported by data, can improve our understanding of the pollutants distribution and the quantification of local emissions. Downscaling from trends predicted at the global scale taking into account for regional differences seems useful to investigate the pollutants fate.

Model uncertainty in accelerator application simulations

Monte-Carlo nuclear reaction and transport codes are widely used to devise accelerator-based nuclear physics experiments; at the same time, many experiments are performed to validate the Monte-Carlo codes, which can be used for the design of full-scale nuclear power applications or the design of new benchmark experiments. Dedicated model benchmark studies investigate a broad range of nuclear reactions and quantities. Examples of these include isotope formation or secondary particle fluxes that result from the interactions of GeV-range hadrons with monoisotopic targets, which can be used to assess the respective systematic uncertainty of models. Such benchmark studies, as well as many nuclear application experiments and simulations carried out by various groups over the last few decades, enable us to draw methodological lessons. In this work, model uncertainty determined based on available experimental data allow us to identify the effects of practitioner expertise as well as the design of codes (user access to micro-scale parameters) on the range of uncertainties. We found that in cases when simulations are performed by code developers or users that are very experienced in performing simulations, the model to experiment quantity ratios generally agree with the limits determined by dedicated benchmark studies. In other cases, the ratios generally tend to be either smaller (underestimation of model error) or larger (overestimation of model error). A plausible explanation of the aforementioned effects is suggested.

Estimation of the solar-induced natural variability of the tritium concentration of precipitation in the Northern and Southern Hemisphere

Abstract Tritium has been long recognized as a useful tracer for the study of atmospheric transport, ocean circulation, and the global water cycle. In addition, the application of tritium measurements in various fields has grown significantly in the last few decades. Since 1963, the atmospheric test-ban treaty, bomb tritium concentrations in precipitation have significantly declined. Therefore, in the last two decades, global tritium concentration of precipitation (including anthropogenic and natural sources) has almost reached a steady-state level. The aim of this study is to estimate the temporal variation of the natural tritium concentration of precipitation during the past decades. To do this, we use a backward predicting time-series model that exploits the correlation between precipitation tritium concentration and the secondary neutron flux in the atmosphere. The measured tritium time series of 21 Northern and two Southern Hemispheric stations are used, while neutron monitor (NM) data, which are widely compared to the production rate of cosmogenic isotopes in the atmosphere, is used as an external variable for the model. Backward predicting SARIMAX statistical models are fit on the period 2001–2018 and provide estimates of the natural precipitation tritium levels for the bomb peak period 1960–2000. Evaluation of backward estimations on the 1990–2000 test period yields RMSE measures between 0.5 and 4.6 TU for four of the 23 investigated stations, pointing out locations where the neutron flux is a good predictor of the precipitation tritium concentration.

Examining the Secondary Product Origin of Cosmic-Ray Positrons with the Latest AMS-02 Data

Abstract Measurements of cosmic-ray (CR) positron fractions by PAMELA and other experiments have found an excess above 10 GeV relative to the standard predictions for secondary production in the interstellar medium. Although the excess has been mainly suggested to arise from some primary sources of positrons (such as pulsars and or annihilating dark matter particles), the almost constant flux ratio of argues for an alternative possibility that the excess positrons and antiprotons up to the highest energies are secondary products generated in hadronic interactions. Recently, Yang & Aharonian revisited this possibility by assuming the presence of an additional population of CR nuclei sources. Here we examine this secondary product scenario using the DRAGON code, where the radiative loss of positrons is taken into account consistently. We confirm that the CR proton spectrum and the antiproton data can be explained by assuming the presence of an additional population of CR sources. However, the corresponding positron spectrum deviates from the measured data significantly above 100 GeV due to strong radiative cooling. This suggests that although hadronic interactions can explain the antiproton data, the corresponding secondary positron flux is still not enough to account for the Alpha Magnetic Spectrometer data. Hence the contribution from some primary positron sources, such as pulsars or dark matter, is nonnegligible.

What Feeds the Benthos in the Arctic Basins? Assembling a Carbon Budget for the Deep Arctic Ocean

Half of the Arctic Ocean is deep sea (> 1000 m), and this area is currently transitioning from being permanently ice-covered to being seasonally ice-free. Despite these drastic changes, it remains unclear how organisms are distributed in the deep Arctic basins, and particularly what feeds them. Here, we summarize data on auto- and heterotrophic organisms in the benthic, pelagic, and sympagic realm of the Arctic Ocean basins from the past three decades and put together an organic carbon budget for this region. Based on the budget, we investigate whether our current understanding of primary and secondary production and vertical carbon flux are balanced by the current estimates of the carbon demand by deep-sea benthos. At first glance, our budget identifies a mismatch between the carbon supply by primary production (3-46 g C m-2 yr-1), the carbon demand of organisms living in the pelagic (7-17 g C m-2) and the benthic realm (< 5 g C m-2 yr-1) versus the low vertical carbon export (at 200 m: 0.1-1.5 g C m-2 yr-1, at 3000-4000 m: 0.01-0.73 g C m-2 yr-1). To close the budget, we suggest that episodic events of large, fast sinking ice algae aggregates, export of dead zooplankton, as well as large food falls need to be quantified and included. This work emphasizes the clear need for a better understanding of the quantity, phenology, and the regionality of carbon supply and demand in the deep Arctic basins, which will allow us to evaluate how the ecosystem may change in the future.

A Search for IceCube Events in the Direction of ANITA Neutrino Candidates

Abstract During the first three flights of the Antarctic Impulsive Transient Antenna (ANITA) experiment, the collaboration detected several neutrino candidates. Two of these candidate events were consistent with an ultra-high-energy upgoing air shower and compatible with a tau neutrino interpretation. A third neutrino candidate event was detected in a search for Askaryan radiation in the Antarctic ice, although it is also consistent with the background expectation. The inferred emergence angle of the first two events is in tension with IceCube and ANITA limits on isotropic cosmogenic neutrino fluxes. Here we test the hypothesis that these events are astrophysical in origin, possibly caused by a point source in the reconstructed direction. Given that any ultra-high-energy tau neutrino flux traversing the Earth should be accompanied by a secondary flux in the TeV–PeV range, we search for these secondary counterparts in 7 yr of IceCube data using three complementary approaches. In the absence of any significant detection, we set upper limits on the neutrino flux from potential point sources. We compare these limits to ANITA’s sensitivity in the same direction and show that an astrophysical explanation of these anomalous events under standard model assumptions is severely constrained regardless of source spectrum.

Significant enhancements of secondary cosmic rays and electric field at the high mountain peak of Lomnick\xfd \u0160t\xedt in High Tatras during thunderstorms

High electric fields that occur in thunderstorm clouds in the Earth’s atmosphere might accelerate energetic charged particles produced by cosmic rays. Such energetic particles, especially electrons, can cause additional ionization as they are multiplied and thus form avalanche of relativistic electrons. These relativistic electrons emit Bremsstrahlung in the X- or gamma-ray spectral ranges as they lose their kinetic energy via collisions. Thunderstorm ground enhancements (TGEs) of secondary cosmic ray fluxes recorded at the top of a sharp rocky mountain of Lomnický Štít in High Tatras (2634 m, Slovak Republic) are compared with simultaneous measurements of electric field at the mountain top and on its slope at the observatory of Skalnaté Pleso (1780 m). Results of measurements performed from May to September in 2017 and from May to October in 2018 are presented. The cosmic ray flux is measured by Space Environment Viewing and Analysis Network (SEVAN) and by neutron monitor with 1-s resolution. The TGEs that persisted usually several minutes were mainly detected in the SEVAN channel 1 which has the lowest energy threshold, about 7–8 MeV. A statistical analysis shows that these enhancements usually occurred (not only) during large values of vertical, upward-pointing electric fields measured just above the detector. It is shown that the measurement of electric field at Skalnaté Pleso, distant about 1.86 km from the mountain top is also partly correlated with the enhancements and can provide additional useful information about the distance or dimension of charge structure and dynamics of electric field, especially on short time scales. The enhancements usually did not exceed several tens of percent of background values. However, events that exceeded the background values several times were also recorded. The most extreme event exceeded the background values about 215 times. This event was also detected by other SEVAN channels and by the neutron monitor (~ 130% enhancement), which indicates a possibility of photonuclear reactions. The enhancements were often terminated by a nearby lightning.

Secondary air distribution in a 600 MWe multi-injection multi-staging down-fired boiler: A comprehensive study

Multi-injection multi-staging combustion technology was designed to provide high boiler efficiency together with low pollutant emissions when employing hard-to-burn coal, and showed good application prospects. In this technology, to achieve the first staged air and more flexible combustion regulation on the arches, the secondary air employs a more complicated distribution surrounding the coal/air flows. This design concept significantly affects the flow and combustion characteristics of the actual boiler. Elucidating the underlying mechanisms by which the various secondary air parameters affect the boiler operation requires a comprehensive analysis of the secondary air distribution on the arches. In this work, small-scale cold modeling tests combined with industrial-scale trials using two actual 600 MWe down-fired boilers were conducted. The results show that the secondary air distribution can significantly affect the near-burner flow and mixing as well as the decay of the downward airflow velocity. High velocity secondary air, especially the secondary air surrounding the fuel-rich flow, evidently promotes the advanced mixing of fuel-rich and fuel-lean flows. Increasing the secondary air flux around the fuel-rich flow and raising the secondary air velocity decrease the pulverized coal heating rate, while a decreased inner secondary air velocity advances the coal ignition. Adjusting the secondary air also greatly affects the downward flame depth and the unburnt coal proportion in the near wall region of the furnace hopper, such that the flame kernel location and the temperatures near the hopper wall are modified. In addition, NOx formation can be accelerated by a high secondary air flux near the fuel-rich flow or a large contact area between the secondary air and the fuel-rich flow.

Direct Evidence for Electron Acceleration Within Ion‐Scale Flux Rope

AbstractEnergetic electrons have frequently been observed in small‐scale flux ropes. However, whether these energetic electrons were energized directly within the flux rope or not is unknown. In this paper, we present concrete evidence provided by the Magnetospheric Multiscale mission that a secondary flux rope provided strong acceleration for electrons expelled by the reconnection X line. We find that the energetic electron fluxes inside the ion‐scale flux rope were larger than those outside the flux rope. Electrons were adiabatically accelerated by betatron and Fermi mechanisms inside the flux rope. The highest energy electrons (&gt;100 keV) were produced by betatron acceleration, whereas Fermi acceleration was unable to accelerate the electrons to high energy probably due to the finite distance of the acceleration region along the field‐aligned direction. These results confirm the essential role of ion‐scale flux ropes in producing energetic electrons.

Some new hints on cosmic-ray propagation from AMS-02 nuclei spectra

In this work, we considered 2 schemes (a high-rigidity break in primary source injections and a high-rigidity break in diffusion coefficient) to reproduce the newly released AMS-02 nuclei spectra (He, C, N, O, Li, Be, and B) when the rigidity larger than 50 GV. The fitting results show that current data set favors a high-rigidity break at ∼ 325 GV in diffusion coefficient rather than a break at ∼ 365 GV in primary source injections. Meanwhile, the fitted values of the factors to rescale the cosmic-ray (CR) flux of secondary species/components after propagation show us that the secondary flux are underestimated in current propagation model. It implies that we might locate in a slow diffusion zone, in which the CRs propagate with a small value of diffusion coefficient compared with the averaged value in the galaxy. Another hint from the fitting results show that extra secondary CR nuclei injection may be needed in current data set. All these new hints should be paid more attention in future research.

The Dose from Secondary Neutrons during the Operation of Modern Medical Accelerators

A review of the experiments performed to date and calculations on the study of doses from secondary neutrons during the operation of medical electron accelerators of various manufacturers is presented. The fundamental differences between the heads of the three largest manufacturers (Varian, Elekta, and Siemens) are given. This article contains data on flux densities and doses for different accelerator models and operating modes. The data analysis showed that the dose from secondary neutrons when irradiating patients on a linear medical accelerator with bremsstrahlung should be taken into account, since its contribution can reach 2.04% at a maximum energy of up to 24 MeV. The contribution to the absorbed dose of secondary neutron fluxes must be evaluated when planning radiation therapy; all other things being equal, it is also necessary to choose modes of operation with the lowest rated energy for treating patients.

Расчет скорости ионизации вещества атмосферы Земли протонами галактических и солнечных космических лучей

This paper explores the applied use of the RUSCOSMICS software package [http://ruscosmics.ru] designed to simulate propagation of primary cosmic ray (CR) particles through Earth’s atmosphere and collect information about characteristics of their secondary component. We report the results obtained for proton fluxes with energy distributions corresponding to the differential spectra of galactic CR (GCR) and solar CR (SCR) during ground level enhancement (GLE) events GLE65 and GLE67. We examine features of the geometry of Earth’s atmosphere, parametrization methods, and describe a primary particle generator. The typical energy spectra of electrons obtained both for GCR and for GLE65 provide information that allows us to quantitatively estimate the SCR contribution to the enhancement of secondary CR fluxes. We also present altitude dependences of ionization rate for GCR and both the GLE events for several geomagnetic cutoff rigidity values. The conclusion summarizes and discusses the prospects for future research.

Calculating the ionization rate induced by GCR and SCR protons in Earth’s atmosphere

This paper explores the applied use of the RUSCOSMICS software package [http://ruscosmics.ru] designed to simulate propagation of primary cosmic ray (CR) particles through Earth’s atmosphere and collect information about characteristics of their secondary component. We report the results obtained for proton fluxes with energy distributions corresponding to the differential spectra of galactic CR (GCR) and solar CR (SCR) during ground level enhancement (GLE) events GLE65 and GLE67. We examine features of the geometry of Earth’s atmosphere, parametrization methods, and describe a primary particle generator. The typical energy spectra of electrons obtained both for GCR and for GLE65 provide information that allows us to quantitatively estimate the SCR contribution to the enhancement of secondary CR fluxes. We also present altitude dependences of ionization rate for GCR and both the GLE events for several geomagnetic cutoff rigidity values. The conclusion summarizes and discusses the prospects for future research.

Improvement of Fast Initial Speed Estimation Using Fuzzy Logic Control Technique for Induction Motors in the Low Speed Range

The paper presents a fast initial speed estimation method resolved by using a Fuzzy logic controller. This is applied for sensorless induction motor drives under low speed operation based on the second order differential of the secondary flux. At restarting time of an induction motor, it produces unwanted disturbance torque. This disturbance can be reduced by fast estimation based on FLC. The performance of proposed method is tested by using MATLAB/Simulink and estimation time has been compared with conventional controller like PI. Simulation results shows that FLC is more efficient than PI control.