Reaction kinetics determined from core flooding and steady state principles for Stevns Klint and Kansas chalk injected with MgCl2 brine at reservoir temperature

A methodology is presented for determining reaction kinetics from core flooding: A core is flooded with reactive brine at different compositions with injection rates varied systematically. Each combination is performed until steady state, when effluent concentrations no longer change significantly with time. Lower injection rate gives the brine more time to react. We also propose shut-in tests where brine reacts statically with the core a defined period and then is flushed out. The residence time and produced brine composition is compared with the flooding experiments. This design allows characterization of the reaction kinetics from a single core. Efficient modeling and matching of the experiments can be performed as the steady state data are directly comparable to equilibrating the injected brine gradually with time and does not require spatial and temporal modeling of the entire dynamic experiments. Each steady state data point represents different information that helps constrain parameter selection. The reaction kinetics can predict equilibrium states and time needed to reach equilibrium. Accounting for dispersion increases the complexity by needing to find a spatial distribution of coupled solutions and is recommended as a second step when a first estimate of the kinetics has been obtained. It is still much more efficient than simulating the full dynamic experiment. Experiments were performed injecting 0.0445 and 0.219 mol/L MgCl2 into Stevns Klint chalk from Denmark, and Kansas chalk from USA. The reaction kinetics of chalk are important as oil-bearing chalk reservoirs are chemically sensitive to injected seawater. The reactions can alter wettability and weaken rock strength which has implications for reservoir compaction, oil recovery and reservoir management. The temperature was 100 and 130°C (North Sea reservoir temperature). The rates during flooding were varied from 0.25 to 16 PV/d while shut-in tests provided equivalent rates down to 1/28 PV/d. The results showed that Ca2+ ions were produced and Mg2+ ions retained (associated with calcite dissolution and magnesite precipitation, respectively). This occurred in a substitution-like manner, where the gain of Ca was similar to the loss of Mg2+. A simple reaction kinetic model based on this substitution with three independent tuning parameters (rate coefficient, reaction order and equilibrium constant) was implemented together with advection to analytically calculate steady state effluent concentrations when injected composition, injection rate and reaction kinetic parameters were stated. By tuning reaction kinetic parameters, the experimental steady state data could be fitted efficiently. From data trends, the parameters were determined relatively accurate for each core. The roles of reaction parameters, pore velocity and dispersion were illustrated with sensitivity analyses. The steady state method allows computationally efficient matching even with complex reaction kinetics. Using a comprehensive geochemical description in the software PHREEQC, the kinetics of calcite and magnesite mineral reactions were determined by matching the steady state concentration changes as function of (residence) time. The simulator predicted close to identical production of Ca as loss of Mg. The geochemical software predicted much higher calcite solubility in MgCl2 than observed at 100 and 130°C for Stevns Klint and Kansas.acceptedVersio

Long-term survival and quality of life after intensive care for patients 80 years of age or older

Background: Comparison of survival and quality of life in a mixed ICU population of patients 80 years of age or older with a matched segment of the general population. Methods: We retrospectively analyzed survival of ICU patients ≥80 years admitted to the Haukeland University Hospital in 2000–2012. We prospectively used the EuroQol-5D to compare the health-related quality of life (HRQOL) between survivors at follow-up and an age- and gender-matched general population. Follow-up was 1–13.8 years. Results: The included 395 patients (mean age 83.8 years, 61.0 % males) showed an overall survival of 75.9 (ICU), 59.5 (hospital), and 42.0 % 1 year after the ICU. High ICU mortality was predicted by age, mechanical ventilator support, SAPS II, maximum SOFA, and multitrauma with head injury. High hospital mortality was predicted by an unplanned surgical admission. One-year mortality was predicted by respiratory failure and isolated head injury. We found no differences in HRQOL at follow-up between survivors (n = 58) and control subjects (n = 179) or between admission categories. Of the ICU non-survivors, 63.2 % died within 2 days after ICU admission (n = 60), and 68.3 % of these had life-sustaining treatment (LST) limitations. LST limitations were applied for 71.3 % (n = 114) of the hospital non-survivors (ICU 70.5 % (n = 67); post-ICU 72.3 % (n = 47)). Conclusions: Overall 1-year survival was 42.0 %. Survival rates beyond that were comparable to those of the general octogenarian population. Among survivors at follow-up, HRQOL was comparable to that of the age- and sex-matched general population. Patients admitted for planned surgery had better short- and long-term survival rates than those admitted for medical reasons or unplanned surgery for 3 years after ICU admittance. The majority of the ICU non-survivors died within 2 days, and most of these had LST limitation decisions

3D Masked Modelling Advances Lesion Classification in Axial T2w Prostate MRI

Masked Image Modelling (MIM) has been shown to be an efficient self-supervised learning (SSL) pre-training paradigm when paired with transformer architectures and in the presence of a large amount of unlabelled natural images. The combination of the difficulties in accessing and obtaining large amounts of labeled data and the availability of unlabelled data in the medical imaging domain makes MIM an interesting approach to advance deep learning (DL) applications based on 3D medical imaging data. Nevertheless, SSL and, in particular, MIM applications with medical imaging data are rather scarce and there is still uncertainty around the potential of such a learning paradigm in the medical domain. We study MIM in the context of Prostate Cancer (PCa) lesion classification with T2 weighted (T2w) axial magnetic resonance imaging (MRI) data. In particular, we explore the effect of using MIM when coupled with convolutional neural networks (CNNs) under different conditions such as different masking strategies, obtaining better results in terms of AUC than other pre-training strategies like ImageNet weight initialization.publishedVersio

Selectivity of eurasian lynx Lynx lynx and recreational hunters for age, sex and body condition in roe deer Capreolus capreolus

tional hunters for age, sex and condition in roe deerCapreolus capreolus.-Wildl. Biol. 13: 467-474. Data on the age, sex and condition of roe deer Capreolus capreolus killed by Eurasian lynx Lynx lynx and human hunters were collected in two study areas in the counties of Nord-Trøndelag and Hedmark in central and southeastern Norway, respectively. Data on the age and sex structure of the standing population were also collected. No differences in the age or sex structure of roe deer killed by lynx were found between the two study areas or between years with differing snow depths which was ex-pected to affect age-class vulnerability. The profile of 151 lynx-killed roe deer (24 % adult males, 44 % adult females, 11 % male fawns and 21% female fawns) was not statistically different from that of the standing population. In contrast, hunters killed a significantly larger proportion of adult animals, especially males (44 % adult males, 28 % adult females, 15 % male fawns and 13 % female fawns). The detailed age structure of lynx killed and hunter killed animals was not different within the adult age class. The body condition of roe deer declined during late winter (more so for males than for females), however, there was no difference in the con-dition of roe deer killed by lynx or hunters during early winter (the hunt-ing season ends on 24 December). The overall picture is typical of a stalk-ing predator that has few options to select individuals based on condition, age or sex in a prey species with no sexual dimorphism and which is relatively small in relation to the size of the predator (lynx are 50-70% the size of an adult roe deer). Human hunters, on the other hand, are clearly harvesting a non-random section of the population. The result is that hunting does not replicate natural predation, although lynx preda-tion is likely to have a higher per capita impact on roe deer growth rates

Permeability evolution of shear failing chalk cores under thermochemical influence

Development of petroleum reservoirs, including primary depletion of the pore pressure and repressurization during water injection naturally, leads to changes in effective stresses of the formations. These changes impose mechanical deformation of the rock mass with subsequent altering of its petrophysical properties. Besides mechanical compaction, chalk reservoirs on the Norwegian Continental Shelf also seem susceptible to mineralogical and textural changes as an effect of the injecting fluid’s chemical composition and temperature. Understanding such chemical and thermal effects and how they interplay with the mechanical response to changes in effective stresses could contribute to improved prediction of permeability development during field life. This article presents results from mechanical testing of chalk cores of medium-porosity (32%) outcrop chalk (Niobrara Formation, Kansas) in triaxial cells. The experimental setup allows systematic combinations of fluctuating deviatoric stress, temperature (50 and 130 °C), and injecting fluid (calcite-equilibrated sodium chloride, calcite-equilibrated sodium sulfate, and reactive synthetic seawater) intended to replicate in situ processes, relevant to the North Sea chalk reservoirs. Deviatoric loading above yield resulted in a shear failure with a steeply dipping fracture of the core and a simultaneous increase in permeability. This occurred regardless of the brine composition. The second and third deviatoric loadings above yield did not have the same strong effect on permeability. During creep and unloading, the permeability changes were minor such that the end permeability remained higher than the initial values. However, sodium sulfate-injected cores retained most of the permeability gain after shear fracturing compared to sodium chloride and synthetic seawater series at both temperatures. Synthetic seawater-injected cores registered the most permeability loss compared to the other brines at 130 °C. The results indicate that repulsive forces generated by sulfate adsorption contribute to maintain the fracture permeability.publishedVersio

ACCELERATED LEARNING BERBANTUAN SOFTWARE MAPLE SEBAGAI UPAYA MENINGKATKAN KEMAMPUAN KOMUNIKASI MATEMATIS DAN MINAT BELAJAR SISWA SMA

Penelitian ini dilatarbelakangi oleh pentingnya kemampuan komunikasi matematis dan minat belajar. Namun kenyataan di lapangan menunjukkan bahwa kemampuan komunikasi matematisdan minat belajarsiswa masih rendah. Agar permasalahan tersebut dapat diatasi, diperlukan sebuah model pembelajaran yang dapatmeningkatkankemampuan komunikasi matematis dan minat belajarsiswa.Olehkarenaitu, dipilih modelAccelerated Learning Berbantuan Software Maple. Penelitian ini bertujuan untuk menelaahpeningkatan kemampuan komunikasi matematis dan minat belajarsiswa, danmenelaahhubunganantara kemampuan komunikasi dan minat belajar.Penelitianinimerupakanpenelitiankuasieksperimendenganpretest-postest control group design. Populasi pada penelitian ini adalah seluruh siswa kelas X pada salah satu SMA Negeri di Kota Purwokerto. Sampel terdiri dari dua kelas yang dipilih secara purposive sampling.Instrumen yang digunakan berupa tes kemampuan komunikasi matematis dan angket minat belajar, lembar observasi, serta pedoman wawancara. Analisis data dilakukan secara kuantitatif.Analisis data tersebutmenggunakanMann-Whitney U Testdan uji asosiasi Chi Square. Berdasarkan analisis data, ditemukan bahwa: (1)pencapaian kemampuan komunikasi matematis siswa yang memperoleh Accelerated LearningBerbantuanSoftware Maplelebih baik daripada siswa yang memperoleh pembelajaran biasa;(2) peningkatan kemampuan komunikasi matematis siswa yang memperoleh Accelerated LearningBerbantuanSoftware Maplelebih baik daripada siswa yang memperoleh pembelajaran biasa, (3) pencapaian kemampuan minat belajar siswa yang memperoleh Accelerated LearningBerbantuanSoftware Maplelebih baik daripada siswa yang memperoleh pembelajaran biasa; (4) peningkatan kemampuan minat belajar siswa yang memperoleh Accelerated LearningBerbantuanSoftware Maplelebih baik daripada siswa yang memperoleh pembelajaran biasa; dan(5) terdapat asosiasi antara kemampuan komunikasi dan minat belajarsiswadengan kategori rendah. ---------- This research was motivated by the importance of mathematical communication learning interest of students. Mathematical communication ability and learning interest of students is still low. In order that this problemscan be solved, alearning modelthatcan enhancemathematical communication and learning interest ofstudents is required.In this research, Maple-Assisted Accelerated Learning was selected. This studyaims to analyzetheenhancement of mathematical communication learning interest of students, and to analyzetheassociationbetween mathematical communication ability andlearning interest of students. This research was aquasi-experimentalwithpretest-posttest control group design. The population was students at tenth gradein one of senior high schools in Purwokerto, Central Java. The sample consisted oftwoclasses which wasselected bypurposivesampling. This research used fourinstruments: testof mathematicalcommunication ability, learning interestquestionnaire, observation sheets, and interview guide.Data analyzed was done quantitatively. The data were analyzed by usingMann-Whitney U TestandChi Squaren test. Based on the data analyze, it is found that: (1) the achievement of mathematical communication ability of students who receivedthe Maple-Assisted Accelerated Learning is betterthan the achievement of students who receivedconventionallearning;(2) The enhancement of mathematical communication ability of students who receivedthe Maple-Assisted Accelerated Learning is betterthan the enhancement of students who receivedconventionallearning; (3)the achievement oflearning interestability of students who receivedthe Maple-Assisted Accelerated Learning is betterthan the achievement of students who receivedconventionallearning; (4)the enhancement oflearning interestof students who receivedthe Maple-Assisted Accelerated Learning is betterthan the enhancement of students who receivedconventionallearning; and(5) there is anassociation between students’ mathematical communication ability and learning interest of student

Tangled up in fibers: How a lytic polysaccharide monooxygenase binds its chitin substrate

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Time series covering up to four decades reveals major changes and drivers of marine growth and proportion of repeat spawners in an Atlantic salmon population

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Bile acids are important direct and indirect regulators of the secretion of appetite- and metabolism-regulating hormones from the gut and pancreas.

OBJECTIVE: Bile acids (BAs) facilitate fat absorption and may play a role in glucose and metabolism regulation, stimulating the secretion of gut hormones. The relative importance and mechanisms involved in BA-stimulated secretion of appetite and metabolism regulating hormones from the gut and pancreas is not well described and was the purpose of this study. METHODS: The effects of bile acids on the secretion of gut and pancreatic hormones was studied in rats and compared to the most well described nutritional secretagogue: glucose. The molecular mechanisms that underlie the secretion was studied by isolated perfused rat and mouse small intestine and pancreas preparations and supported by immunohistochemistry, expression analysis, and pharmacological studies. RESULTS: Bile acids robustly stimulate secretion of not only the incretin hormones, glucose-dependent insulinotropic peptide (GIP), and glucagon-like peptide-1 (GLP-1), but also glucagon and insulin in vivo, to levels comparable to those resulting from glucose stimulation. The mechanisms of GLP-1, neurotensin, and peptide YY (PYY) secretion was secondary to intestinal absorption and depended on activation of basolateral membrane Takeda G-protein receptor 5 (TGR5) receptors on the L-cells in the following order of potency: Lithocholic acid (LCA) >Deoxycholicacid (DCA)>Chenodeoxycholicacid (CDCA)> Cholic acid (CA). Thus BAs did not stimulate secretion of GLP-1 and PYY from perfused small intestine in TGR5 KO mice but stimulated robust responses in wild type littermates. TGR5 is not expressed on α-cells or β-cells, and BAs had no direct effects on glucagon or insulin secretion from the perfused pancreas. CONCLUSION: BAs should be considered not only as fat emulsifiers but also as important regulators of appetite- and metabolism-regulating hormones by activation of basolateral intestinal TGR5