temporal behaviour
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2022 ◽  
Author(s):  
Paul Fruton ◽  
Aziza Nauruzbaeva ◽  
Henri Bataller ◽  
Cédric Giraudet ◽  
Alberto Vailati ◽  
...  

Abstract The sequestration of carbon dioxide (CO2) through storage into deep saline aquifers represents an indispensable support technology to achieve the zero-carbon target necessary to mitigate the impact of CO2 on climate change. The effectiveness of the sequestration process, partly driven by the convective dissolution of CO2 in brine, is nowadays well characterized for two-dimensional geometries, low permeabilities, and small pressures of injection of CO2. However, reliable predictions of process-efficiency are missing because of the lack of full understanding of the three-dimensional (3D) spatio-temporal behaviour of CO2-rich convective fingers in brine over a large range of injection pressures. Here, we show that the convective dissolution is determined by the instability of the boundary layer formed at the interface between the two phases and is totally independent of the overall vertical size. Experiments were conducted over a broad range of injection pressures, close to process-relevant conditions. The results show the formation of complex 3D structures, including interconnecting stream tubes at the CO2-liquid interface, which could not be detected in previous 2D Hele-Shaw studies, and fingerings. A scale-free theoretical modelling of the convective process allows us to remap our laboratory results to length-scales of relevance for geological reservoirs. The experiments and the model show that the times needed for the onset of convection and the convective flux are independent of the system size.


2022 ◽  
Vol 23 (1) ◽  
Author(s):  
Johannes Hettich ◽  
J. Christof M. Gebhardt

Abstract Background The temporal progression of many fundamental processes in cells and organisms, including homeostasis, differentiation and development, are governed by gene regulatory networks (GRNs). GRNs balance fluctuations in the output of their genes, which trace back to the stochasticity of molecular interactions. Although highly desirable to understand life processes, predicting the temporal progression of gene products within a GRN is challenging when considering stochastic events such as transcription factor–DNA interactions or protein production and degradation. Results We report a method to simulate and infer GRNs including genes and biochemical reactions at molecular detail. In our approach, we consider each network element to be isolated from other elements during small time intervals, after which we synchronize molecule numbers across all network elements. Thereby, the temporal behaviour of network elements is decoupled and can be treated by local stochastic or deterministic solutions. We demonstrate the working principle of this modular approach with a repressive gene cascade comprising four genes. By considering a deterministic time evolution within each time interval for all elements, our method approaches the solution of the system of deterministic differential equations associated with the GRN. By allowing genes to stochastically switch between on and off states or by considering stochastic production of gene outputs, we are able to include increasing levels of stochastic detail and approximate the solution of a Gillespie simulation. Thereby, CaiNet is able to reproduce noise-induced bi-stability and oscillations in dynamically complex GRNs. Notably, our modular approach further allows for a simple consideration of deterministic delays. We further infer relevant regulatory connections and steady-state parameters of a GRN of up to ten genes from steady-state measurements by identifying each gene of the network with a single perceptron in an artificial neuronal network and using a gradient decent method originally designed to train recurrent neural networks. To facilitate setting up GRNs and using our simulation and inference method, we provide a fast computer-aided interactive network simulation environment, CaiNet. Conclusion We developed a method to simulate GRNs at molecular detail and to infer the topology and steady-state parameters of GRNs. Our method and associated user-friendly framework CaiNet should prove helpful to analyze or predict the temporal progression of reaction networks or GRNs in cellular and organismic biology. CaiNet is freely available at https://gitlab.com/GebhardtLab/CaiNet.


2021 ◽  
Vol 21 (24) ◽  
pp. 18557-18572
Author(s):  
Niklas Illmann ◽  
Iulia Patroescu-Klotz ◽  
Peter Wiesen

Abstract. In order to enlarge our understanding of biomass burning plume chemistry, the OH-radical-initiated oxidation of 3-penten-2-one (3P2), identified in biomass burning emissions, and 2-hydroxypropanal (2HPr) was investigated at 298 ± 3 K and 990 ± 15 mbar in two atmospheric simulation chambers using long-path FTIR spectroscopy. The rate coefficient of 3P2 + OH was determined to be (6.2 ± 1.0) × 10−11 cm3 molec.−1 s−1 and the molar first-generation yields for acetaldehyde, methyl glyoxal, 2HPr, and the sum of peroxyacetyl nitrate (PAN) and CO2, used to determine the CH3C(O) radical yield, were 0.39 ± 0.07, 0.32 ± 0.08, 0.68 ± 0.27, and 0.56 ± 0.14, respectively, under conditions where the 3P2-derived peroxy radicals react solely with NO. The 2HPr + OH reaction was investigated using 3P2 + OH as a source of the α-hydroxyaldehyde adjusting the experimental conditions to shift the reaction system towards secondary oxidation processes. The rate coefficient was estimated to be (2.2 ± 0.6) × 10−11 cm3 molec.−1 s−1. Employing a simple chemical mechanism to analyse the temporal behaviour of the experiments, the further oxidation of 2HPr was shown to form methyl glyoxal, acetaldehyde, and CO2 with estimated yields of 0.27 ± 0.08, 0.73 ± 0.08, and 0.73 ± 0.08, respectively.


MAUSAM ◽  
2021 ◽  
Vol 47 (3) ◽  
pp. 275-280
Author(s):  
DHANNA SINGH ◽  
SUMAN GOYAL ◽  
C.V.V. BHADRAM ◽  
G. S. MANDAL

ABSTRACT. Based on 35 years' (1959-1993) data, the zonal and meridional wind components of selected Indian RS/RW statiomupto 100 hPa level were analysed for the pre-monsoon months of April and May in order to associate them with sub-regional monsoon rainfall of northeast India. Composite values of monsoon rainfall and meridional components for May for excess and deficient yean have revealed that anomaly of meridional components for the middle and upper troposphere is northerly/southerly preceding excees/deficient monsoon year. The meridional winds at most of the levels of Delhi and some of the levels of Jodhpur Nagpur, Bombay and Madras for the month of May showed significant correlations (significant at 0.1% to 5% level of significance) with sub-divisional monsoon rainfall in northeast India. The temporal behaviour of correlation coefficients for Punjab and Haryana for 16 and 20-year sliding windows has exhibited rasonable temporal stability except for first few years. Multiple rearession equations for 30 and 35 year period for Haryana, Punjab and contiguous northweat India were also developed. The regression model for Punjab sub-division has shown quite good  results for the independent period.  


2021 ◽  
Vol 23 (Supplement_G) ◽  
Author(s):  
Massimo Mapelli ◽  
Simona Romani ◽  
Damiano Magrì ◽  
Marco Merlo ◽  
Marco Cittar ◽  
...  

Abstract Aims Reduced cardiac output (CO) has been considered crucial in symptoms’ genesis in hypertrophic cardiomyopathy (HCM). We evaluated the cardiopulmonary exercise testing (CPET) response in HCM focusing on parameters strongly associated with stroke volume (SV) and cardiac output (CO), such as oxygen uptake (VO2) and O2-pulse, considering both their absolute values and temporal behaviour during physical exercise. Methods and results We enrolled 312 non-end stage HCM patients, divided according to left ventricle outflow tract obstruction (LVOTO) at rest or during Valsalva manoeuver (72% with LVOTO < 30; 10% between 30 and 49; and 18% ≥50 mmHg). Peak VO2 (percent of predicted), O2-pulse, and ventilation to carbon dioxide production (VE/VCO2) slope did not change across LVOTO groups. Ninety-six (31%) HCM patients presented an abnormal O2-pulse temporal behaviour, irrespective of LVOTO values. These patients showed lower peak systolic pressure, workload (106 ± 45 vs. 130 ± 49 W), VO2 (74 ± 17% vs. 80 ± 20%) and O2-pulse (12 [9–14] vs. 14 [11–17]ml/beat), with higher VE/VCO2 slope (28 [25–31] vs. 27 [24–31]) (P < 0.005 for all). Only two patients had an abnormal VO2/work slope. Conclusions None of CPET parameters, either as absolute values or dynamic relationships, were associated with LVOTO. Differently, an abnormal O2-pulse exercise behaviour, which is strongly related to inadequate SV during exercise, correlates with reduced functional capacity (peak and anaerobic threshold VO2 and workload) and increased VE/VCO2 slope, helping identifying more advanced disease irrespectively of LVOTO. Adding O2-pulse kinetics evaluation to standard CPET could lead to a potential incremental benefit in terms of HCM prognostic stratification and, then, therapeutic management.


2021 ◽  
Vol 10 (12) ◽  
pp. 808
Author(s):  
Pyae Phyoe Kyaw ◽  
David W. Macdonald ◽  
Ugyen Penjor ◽  
Saw Htun ◽  
Hla Naing ◽  
...  

The co-occurrence of felid species in Southeast Asia provides an unusual opportunity to investigate guild structure and the factors controlling it. Using camera-trap data, we quantified the space use, temporal activity, and multi-dimensional niche overlap of the tiger, clouded leopard, Asiatic golden cat, marbled cat, and leopard cat in the Htamanthi Wildlife Sanctuary, Myanmar. We hypothesised that the spatio-temporal behaviour of smaller cats would reflect the avoidance of the larger cats, and similar-sized guild members would partition their niches in space or time to reduce resource competition. Our approach involved modelling single-species occupancy, pairwise spatial overlap using Bayesian inference, activity overlap with kernel density estimation, and multivariate analyses. The felid assembly appeared to be partitioned mainly on a spatial rather than temporal dimension, and no significant evidence of mesopredator release was observed. Nonetheless, the temporal association between the three mesopredators was inversely related to the similarity in their body sizes. The largest niche differences in the use of space and time occurred between the three smallest species. This study offers new insight into carnivore guild assembly and adds substantially to knowledge of five of the least known felids of conservation concern.


2021 ◽  
Author(s):  
◽  
Annika Greve

<p>In order to understand the origin, temporal behaviour and spatial characteristics of Earth’s magnetic field, globally distributed records of the palaeomagnetic direction and absolute palaeointensity are required. However a paucity of data from the southern hemisphere significantly limits the resolution of global field models, particularly on short time-scales.  In this thesis new, high quality palaeomagnetic data from volcanic materials sampled within the Taupo Volcanic Zone, New Zealand are presented, with a focus on the Tongariro and Okataina Volcanic Centre.  New palaeomagnetic directions were obtained from 19 andesitic or rhyolitic lavas, of which 10 also produced successful palaeointensity results. Palaeointensity experiments were conducted using a combination of traditional Thellier-type thermal, and microwave techniques. Detailed magneto-mineralogical investigations carried out alongside these experiments helped to characterise the primary remanence carriers and to justify the reliability of the results.  The study also revises the age controls and results from earlier palaeomagnetic studies on Holocene volcanic materials from the area. All new or revised data are summarized into a new data compilation for New Zealand, which includes 24 directions and ten palaeointensities dated between 1886 AD and 15,000 yrs BP.  The new directional data reproduces the features of the most recently published continuous record from Lake Mavora (Fiordland, New Zealand), although with directions ranging in their extremes from 321° (west) to 26° (east) declination and -82 to -49° in inclination, the discrete dataset describes somewhat larger amplitude swings.  With few exceptions, the new palaeointensity dataset describes a steady increase in the palaeointensity throughout the Holocene, from 37.0 ± 5.7 μT obtained from a pre-8 ka lava to 70.6 ± 4.1 μT from the youngest (≤ 500 yrs BP) flows sampled. A similar trend is also predicted by the latest global field model pfm9k. Furthermore, the data falls within the range of palaeointensity variation suggested by the Mavora record. The dataset roughly agrees with a global VADM reconstruction in the early Holocene (> 5000 yrs BP), but yields values significantly above the global trend in the late Holocene (< 1000 yrs BP) which supports the presence of significant non-dipolar components over the SW Pacific region in the time period, visible in global field models and from continuous PSV records.  A comparison of the directional records with the Mavora Curve provided refinement of age estimates of five lava flows from the Tongariro Volcanic Centre, from uncertainties in the range of 2-3000 years. The new palaeomagnetic emplacement age estimates for these flows have age brackets as short as 500 years and thus highlight different phases of the young cone building eruptive activity on Ruapehu volcano.</p>


2021 ◽  
Author(s):  
◽  
Annika Greve

<p>In order to understand the origin, temporal behaviour and spatial characteristics of Earth’s magnetic field, globally distributed records of the palaeomagnetic direction and absolute palaeointensity are required. However a paucity of data from the southern hemisphere significantly limits the resolution of global field models, particularly on short time-scales.  In this thesis new, high quality palaeomagnetic data from volcanic materials sampled within the Taupo Volcanic Zone, New Zealand are presented, with a focus on the Tongariro and Okataina Volcanic Centre.  New palaeomagnetic directions were obtained from 19 andesitic or rhyolitic lavas, of which 10 also produced successful palaeointensity results. Palaeointensity experiments were conducted using a combination of traditional Thellier-type thermal, and microwave techniques. Detailed magneto-mineralogical investigations carried out alongside these experiments helped to characterise the primary remanence carriers and to justify the reliability of the results.  The study also revises the age controls and results from earlier palaeomagnetic studies on Holocene volcanic materials from the area. All new or revised data are summarized into a new data compilation for New Zealand, which includes 24 directions and ten palaeointensities dated between 1886 AD and 15,000 yrs BP.  The new directional data reproduces the features of the most recently published continuous record from Lake Mavora (Fiordland, New Zealand), although with directions ranging in their extremes from 321° (west) to 26° (east) declination and -82 to -49° in inclination, the discrete dataset describes somewhat larger amplitude swings.  With few exceptions, the new palaeointensity dataset describes a steady increase in the palaeointensity throughout the Holocene, from 37.0 ± 5.7 μT obtained from a pre-8 ka lava to 70.6 ± 4.1 μT from the youngest (≤ 500 yrs BP) flows sampled. A similar trend is also predicted by the latest global field model pfm9k. Furthermore, the data falls within the range of palaeointensity variation suggested by the Mavora record. The dataset roughly agrees with a global VADM reconstruction in the early Holocene (> 5000 yrs BP), but yields values significantly above the global trend in the late Holocene (< 1000 yrs BP) which supports the presence of significant non-dipolar components over the SW Pacific region in the time period, visible in global field models and from continuous PSV records.  A comparison of the directional records with the Mavora Curve provided refinement of age estimates of five lava flows from the Tongariro Volcanic Centre, from uncertainties in the range of 2-3000 years. The new palaeomagnetic emplacement age estimates for these flows have age brackets as short as 500 years and thus highlight different phases of the young cone building eruptive activity on Ruapehu volcano.</p>


2021 ◽  
Author(s):  
◽  
Nastasja Anais Scholz

<p>This study investigates the temporal behaviour of major earthquakes in the Vrancea Seismic Zone (VSZ)in Romania. I used the Romplus catalogue, which is a compilation of several sources and spans the time from 984 AD to the year 2005 and in which the data are of different quality. This catalogue contains only Vrancean earthquakes and consists of more than 8000 events. Qualities 'A', 'B' and 'C' were used to model the data. 'D' and '=' were found as too unreliable for modeling. Using the b-value, I concluded that 3.5 is the correct cut-off magnitude for earthquakes after 1980 and at depths of 60 km and greater. Thereby I detected an increase in the b-value after 1986 of about 0.2 units. The reason for this increase could not be found. Plotting the Gutenberg-Richter relation for several time and depth intervals, it was found that at larger depths than 60 km, there are too many M7 earthquakes as compared to small shocks. The shape of the Gutenberg-Richter relation is similar as to the one expected by the characteristic earthquake model (Schwarz and Coppersmith, 1984; Wesnousky, 1994). A strike of 53 degree was found and the earthquake coordinates were rotated correspondingly. The resulting view on the slab showed the confined volume in which the earthquakes happen and well as the 'aseismic part' of the slab between 40 km and 60 km of depth. The seismicity seems to reach a depth of 180 km. Only the earthquakes in the slab, below a depth of 60 km, show clustering behaviour. Furthermore, the M7 earthquakes all happened in the slab. Thus, a depth limit of 60 km was introduced for modeling. In order to find aftershocks in the catalogue, the temporal behaviour of the Vrancea earthquakes was examined. The mean magnitude increases after each major earthquake, indicating an aftershock process. This was confirmed by the rate of occurrence, which showed an increase in rate after the 1990 earthquakes. The rate of occurrence is too low for the first 580 days after 1980, possibly due to insufficient earthquake detection in this period of time. All the damaging M7 earthquakes all happened in the slab. Thus, shallow earthquakes had to be considered separately. A depth limit of 60 km was introduced and earthquake in shallower and deeper depths were considered separately. For the shallow earthquakes there was a sharp increase in the apparent b-value below the cut-off magnitude of 3.5. After reaching a value of 2.4, the b-value starts to fall steeply. This was attributed to biases in the magnitude calculation. I used the rounded value of 3.5 as a cut-off magnitude for the shallow earthquakes. Having found the magnitude cut-off, depth and time limit, modeling could be started. The model gives two important parameters: the proportion of aftershock and the time to the next earthquake. Using the Maximum Likelihood Method, a best fit was found for a data set starting at 1980 and consisting of earthquakes with a cut-off magnitude of 3.5 and a depth equal and greater than 60 km. According to the model, this data set consists of 13 plus or minus 5% aftershocks and has an inter-event time for new earthquakes of 13 plus or minus 1 days. Using several cut-off magnitudes, it was found that the calculated inter-event time for these earthquakes is consistent with the Gutenberg-Richter law. In contrast, the predicted value for the interevent time of M7 earthquakes does not match the one found in the catalogue. While the Maximum Likelihood Method leads to 814 years as recurrence time, the data shows a recurrence time of only 23 years. The model fits the data set of the 1990 aftershocks very well, too, leading to a aftershock proportion of 58 plus or minus 15%. The data set for the 1986 did not lead to good results, probably due to missing aftershocks shortly after the main shock. Comparing model and data with a pure Poisson model I could see that earthquakes tend to cluster in the first days after the major event. Several days later, their behaviour changes and then is similar to the one proposed by the seismic gap model. Looking at the ratio between the probabilities of the model of Smith and Christophersen and of the Poisson model, a clustering behaviour in the first 24 hours after the main shock was found, followed by a decreased seismicity, which reverts to be Poissonian after 100 days. Thus, I concluded that aftershock behaviour is only relevant after the first 24 hours following a major earthquake. After 24 hours, seismic hazard decreases to be less than as expected by the Poisson model in the following 100 days, until seismicity returns to be Poissonian again. Additionally, I suggest that the 1990 earthquake and its aftershocks should be considered as a 'model earthquake' for future earthquakes as it seems to be representative for earthquake behaviour in the VSZ.</p>


2021 ◽  
Author(s):  
◽  
Nastasja Anais Scholz

<p>This study investigates the temporal behaviour of major earthquakes in the Vrancea Seismic Zone (VSZ)in Romania. I used the Romplus catalogue, which is a compilation of several sources and spans the time from 984 AD to the year 2005 and in which the data are of different quality. This catalogue contains only Vrancean earthquakes and consists of more than 8000 events. Qualities 'A', 'B' and 'C' were used to model the data. 'D' and '=' were found as too unreliable for modeling. Using the b-value, I concluded that 3.5 is the correct cut-off magnitude for earthquakes after 1980 and at depths of 60 km and greater. Thereby I detected an increase in the b-value after 1986 of about 0.2 units. The reason for this increase could not be found. Plotting the Gutenberg-Richter relation for several time and depth intervals, it was found that at larger depths than 60 km, there are too many M7 earthquakes as compared to small shocks. The shape of the Gutenberg-Richter relation is similar as to the one expected by the characteristic earthquake model (Schwarz and Coppersmith, 1984; Wesnousky, 1994). A strike of 53 degree was found and the earthquake coordinates were rotated correspondingly. The resulting view on the slab showed the confined volume in which the earthquakes happen and well as the 'aseismic part' of the slab between 40 km and 60 km of depth. The seismicity seems to reach a depth of 180 km. Only the earthquakes in the slab, below a depth of 60 km, show clustering behaviour. Furthermore, the M7 earthquakes all happened in the slab. Thus, a depth limit of 60 km was introduced for modeling. In order to find aftershocks in the catalogue, the temporal behaviour of the Vrancea earthquakes was examined. The mean magnitude increases after each major earthquake, indicating an aftershock process. This was confirmed by the rate of occurrence, which showed an increase in rate after the 1990 earthquakes. The rate of occurrence is too low for the first 580 days after 1980, possibly due to insufficient earthquake detection in this period of time. All the damaging M7 earthquakes all happened in the slab. Thus, shallow earthquakes had to be considered separately. A depth limit of 60 km was introduced and earthquake in shallower and deeper depths were considered separately. For the shallow earthquakes there was a sharp increase in the apparent b-value below the cut-off magnitude of 3.5. After reaching a value of 2.4, the b-value starts to fall steeply. This was attributed to biases in the magnitude calculation. I used the rounded value of 3.5 as a cut-off magnitude for the shallow earthquakes. Having found the magnitude cut-off, depth and time limit, modeling could be started. The model gives two important parameters: the proportion of aftershock and the time to the next earthquake. Using the Maximum Likelihood Method, a best fit was found for a data set starting at 1980 and consisting of earthquakes with a cut-off magnitude of 3.5 and a depth equal and greater than 60 km. According to the model, this data set consists of 13 plus or minus 5% aftershocks and has an inter-event time for new earthquakes of 13 plus or minus 1 days. Using several cut-off magnitudes, it was found that the calculated inter-event time for these earthquakes is consistent with the Gutenberg-Richter law. In contrast, the predicted value for the interevent time of M7 earthquakes does not match the one found in the catalogue. While the Maximum Likelihood Method leads to 814 years as recurrence time, the data shows a recurrence time of only 23 years. The model fits the data set of the 1990 aftershocks very well, too, leading to a aftershock proportion of 58 plus or minus 15%. The data set for the 1986 did not lead to good results, probably due to missing aftershocks shortly after the main shock. Comparing model and data with a pure Poisson model I could see that earthquakes tend to cluster in the first days after the major event. Several days later, their behaviour changes and then is similar to the one proposed by the seismic gap model. Looking at the ratio between the probabilities of the model of Smith and Christophersen and of the Poisson model, a clustering behaviour in the first 24 hours after the main shock was found, followed by a decreased seismicity, which reverts to be Poissonian after 100 days. Thus, I concluded that aftershock behaviour is only relevant after the first 24 hours following a major earthquake. After 24 hours, seismic hazard decreases to be less than as expected by the Poisson model in the following 100 days, until seismicity returns to be Poissonian again. Additionally, I suggest that the 1990 earthquake and its aftershocks should be considered as a 'model earthquake' for future earthquakes as it seems to be representative for earthquake behaviour in the VSZ.</p>


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