101 research outputs found

    A stand-level growth and yield model for thinned and unthinned even-aged Scots pine forests in Norway

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    Management of Scots pine (Pinus sylvestris L.) in Norway requires a forest growth and yield model suitable for describing stand dynamics of even-aged forests under contemporary climatic conditions with and without the effects of silvicultural thinning. A system of equations forming such a stand-level growth and yield model fitted to long-term experimental data is presented here. The growth and yield model consists of component equations for (i) dominant height, (ii) stem density (number of stems per hectare), (iii) total basal area, (iv) and total stem volume fitted simultaneously using seemingly unrelated regression. The component equations for stem density, basal area, and volume include a thinning modifier to forecast stand dynamics in thinned stands. It was shown that thinning significantly increased basal area and volume growth while reducing competition related mortality. No significant effect of thinning was found on dominant height. Model examination by means of various fit statistics indicated no obvious bias and improvement in prediction accuracy in comparison to existing models in general. An application of the developed stand-level model comparing different management scenarios exhibited plausible long-term behavior and we propose this is therefore suitable for national deployment.publishedVersio

    Stand-level growth models for long-term projections of the main species groups in Norway

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    Stand-level growth and yield models are important tools that support forest managers and policymakers. We used recent data from the Norwegian National Forest Inventory to develop stand-level models, with components for dominant height, survival (number of survived trees), ingrowth (number of recruited trees), basal area, and total volume, that can predict long-term stand dynamics (i.e. 150 years) for the main species in Norway, namely Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.), and birch (Betula pubescens Ehrh. and Betula pendula Roth). The data used represent the structurally heterogeneous forests found throughout Norway with a wide range of ages, tree size mixtures, and management intensities. This represents an important alternative to the use of dedicated and closely monitored long-term experiments established in single species even-aged forests for the purpose of building these stand-level models. Model examination by means of various fit statistics indicated that the models were unbiased, performed well within the data range and extrapolated to biologically plausible patterns. The proposed models have great potential to form the foundation for more sophisticated models, in which the influence of other factors such as natural disturbances, stand structure including species mixtures, and management practices can be included.publishedVersio

    In-silico enhanced animal study of pulmonary artery pressure sensors: assessing hemodynamics using computational fluid dynamics

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    To assess whether in-silico models can be used to predict the risk of thrombus formation in pulmonary artery pressure sensors (PAPS), a chronic animal study using pigs was conducted. Computed tomography (CT) data was acquired before and immediately after implantation, as well as one and three months after the implantation. Devices were implanted into 10 pigs, each one in the left and right pulmonary artery (PA), to reduce the required number of animal experiments. The implantation procedure aimed at facilitating optimal and non-optimal positioning of the devices to increase chances of thrombus formation. Eight devices were positioned non-optimally. Three devices were positioned in the main PA instead of the left and right PA. Pre-interventional PA geometries were reconstructed from the respective CT images, and the devices were virtually implanted at the exact sites and orientations indicated by the follow-up CT after one month. Transient intra-arterial hemodynamics were calculated using computational fluid dynamics. Volume flow rates were modelled specifically matching the animals body weights. Wall shear stresses (WSS) and oscillatory shear indices (OSI) before and after device implantation were compared. Simulations revealed no relevant changes in any investigated hemodynamic parameters due to device implantation. Even in cases, where devices were implanted in a non-optimal manner, no marked differences in hemodynamic parameters compared to devices implanted in an optimal position were found. Before implantation time and surface-averaged WSS was 2.35 ± 0.47 Pa, whereas OSI was 0.08 ± 0.17, respectively. Areas affected by low WSS magnitudes were 2.5 ± 2.7 cm², whereas the areas affected by high OSI were 18.1 ± 6.3 cm². After device implantation, WSS and OSI were 2.45 ± 0.49 Pa and 0.08 ± 0.16, respectively. Surface areas affected by low WSS and high OSI were 2.9 ± 2.7 cm², and 18.4 ± 6.1 cm², respectively. This in-silico study indicates that no clinically relevant differences in intra-arterial hemodynamics are occurring after device implantation, even at non-optimal positioning of the sensor. Simultaneously, no embolic events were observed, suggesting that the risk for thrombus formation after device implantation is low and independent of the sensor position

    Stepwise investigation of the influences of steric groups versus counter ions to target Cu/Dy complexes

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    From an investigation of varying the steric bulk of a flexible ligand, we have produced a family of structures using similar reaction conditions. Even small changes from a hydrogen atom to a methyl to an ethyl group on the ligand influences the structural outcome, which can also be steered by the nature of the metal source. We employed Schiff base ligands by combining o-vanillin and three different 2-amino-1,3-propandiol units, leading to H3L1 (R=hydrogen), H3L2 (R=methyl) and H3L3 (R=ethyl). The differing nuclearities of the three clusters, 1 to 3, originate mainly from the steric influence, while this effect is not seen in complex 4 to 6, where the general butterfly motif is maintained. We present here the synthesis, crystal structures and magnetic properties of six new CuII-LnIII complexes, providing valuable insight into future synthetic directions. The topological part includes a table of all CuII-DyIII complexes with nuclearities higher than four and their topological motif. The investigation of the magnetic behaviors reveal that all six complexes show frequency dependent signals in the out-of phase ac susceptibility, which is indicative for SMM behavior

    Hemodynamic changes during physiological and pharmacological stress testing in patients with heart failure: a systematic review and meta-analysis

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    Although disease etiologies differ, heart failure patients with preserved and reduced ejection fraction (HFpEF and HFrEF, respectively) both present with clinical symptoms when under stress and impaired exercise capacity. The extent to which the adaptation of heart rate (HR), stroke volume (SV), and cardiac output (CO) under stress conditions is altered can be quantified by stress testing in conjunction with imaging methods and may help to detect the diminishment in a patient’s condition early. The aim of this meta-analysis was to quantify hemodynamic changes during physiological and pharmacological stress testing in patients with HF. A systematic literature search (PROSPERO 2020:CRD42020161212) in MEDLINE was conducted to assess hemodynamic changes under dynamic and pharmacological stress testing at different stress intensities in HFpEF and HFrEF patients. Pooled mean changes were estimated using a random effects model. Altogether, 140 study arms with 7,248 exercise tests were analyzed. High-intensity dynamic stress testing represented 73% of these data (70 study arms with 5,318 exercise tests), where: HR increased by 45.69 bpm (95% CI 44.51–46.88; I2 = 98.4%), SV by 13.49 ml (95% CI 6.87–20.10; I2 = 68.5%), and CO by 3.41 L/min (95% CI 2.86–3.95; I2 = 86.3%). No significant differences between HFrEF and HFpEF groups were found. Despite the limited availability of comparative studies, these reference values can help to estimate the expected hemodynamic responses in patients with HF. No differences in chronotropic reactions, changes in SV, or CO were found between HFrEF and HFpEF. When compared to healthy individuals, exercise tolerance, as well as associated HR and CO changes under moderate-high dynamic stress, was substantially impaired in both HF groups. This may contribute to a better disease understanding, future study planning, and patient-specific predictive models. Systematic Review Registration: [https://www.crd.york.ac.uk/prospero/], identifier [CRD42020161212]

    Studi Efisiensi Sistem Prasedimentasi Dan Free Water Surface Wetland Dalam Menurunkan Kadar Nitrat, Fosfat, Kekeruhan, Zat Organik Dan Total Coli

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    Boezem Wonorejo saat ini telah dikembangkan menjadi tempat wisata yaitu Ekowisata Mangrove. Sampai saat ini pihak pengelola boezem masih kesulitan dalam penyediaan air bersihnya Sungai Jagir yang mengalir di sekitar wilayah Ekowisata tersebut merupakan sumber air permukaan yang berpotensi sebagai pemenuhan kebutuhan tersebut secara kuantitatif. Agar dapat terpenuhi secara kualitatif, maka Perlu dilakukan penelitian awal untuk mengetahui efisiensi penurunan kadar Nitrat, Fosfat, Zat Organik, Kekeruhan maupun Total Coli. Dalam penelitian ini akan digunakan rangkaian suatu sistem pengolahan Prasedimentasi dan Free Water Surface wetland skala laboratoium, Dengan variabel ukuran media pasir (16-32 mesh dan lolos 32 mesh) dan umur mangrove (3 bulan dan 6 bulan) yang akan di analisis di laboratorium Teknik Lingkungan ITS. Dari hasil analisis didapat removal maksimum untuk kekeruhan pada prasedimentasi 46,5%, sedangkan pada wetland yaitu pada media pasir mesh 16-32 dan mangrove 6 bulan yaitu 94,8%. Presentase maksimum removal nitrat pada prasedimentasi yaitu 17,8%, removal maksimum pada wetland dengan mangrove 6 bulan dan media pasir lolos 32 mesh yaitu 53,6%. Pada mangrove sendiri removal makismum terdapat pada umur 6 bulan dengan besar removal 36,5%. Removal maksimum fosfat terbesar pada prasedimentasi yaitu 64,3%, untuk Reaktor Wetland yaitu pada wetland dengan mangrove 6 bulan dan media pasir lolos mesh 32 sebesar 90,5%. Untuk . Mangrovenya sendiri mampu meremoval maksimum pada umur 6 bulan dengan besar 53,8%. Presentase removal maksimum zat organik pada prasedimentasi sebesar 35,7%, pada reaktor wetland sebesar 21,8% dengan ukuran media pasir mesh 16-32 dan umur mangrove 3 bulan

    In-silico enhanced animal study of pulmonary artery pressure sensors: assessing hemodynamics using computational fluid dynamics

    Get PDF
    To assess whether in-silico models can be used to predict the risk of thrombus formation in pulmonary artery pressure sensors (PAPS), a chronic animal study using pigs was conducted. Computed tomography (CT) data was acquired before and immediately after implantation, as well as one and three months after the implantation. Devices were implanted into 10 pigs, each one in the left and right pulmonary artery (PA), to reduce the required number of animal experiments. The implantation procedure aimed at facilitating optimal and non-optimal positioning of the devices to increase chances of thrombus formation. Eight devices were positioned non-optimally. Three devices were positioned in the main PA instead of the left and right PA. Pre-interventional PA geometries were reconstructed from the respective CT images, and the devices were virtually implanted at the exact sites and orientations indicated by the follow-up CT after one month. Transient intra-arterial hemodynamics were calculated using computational fluid dynamics. Volume flow rates were modelled specifically matching the animals body weights. Wall shear stresses (WSS) and oscillatory shear indices (OSI) before and after device implantation were compared. Simulations revealed no relevant changes in any investigated hemodynamic parameters due to device implantation. Even in cases, where devices were implanted in a non-optimal manner, no marked differences in hemodynamic parameters compared to devices implanted in an optimal position were found. Before implantation time and surface-averaged WSS was 2.35±0.47 Pa, whereas OSI was 0.08±0.17, respectively. Areas affected by low WSS magnitudes were 2.5±2.7 cm2, whereas the areas affected by high OSI were 18.1±6.3 cm2. After device implantation, WSS and OSI were 2.45±0.49 Pa and 0.08±0.16, respectively. Surface areas affected by low WSS and high OSI were 2.9±2.7 cm2, and 18.4±6.1 cm2, respectively. This in-silico study indicates that no clinically relevant differences in intra-arterial hemodynamics are occurring after device implantation, even at non-optimal positioning of the sensor. Simultaneously, no embolic events were observed, suggesting that the risk for thrombus formation after device implantation is low and independent of the sensor position

    Prohormones in the early diagnosis of cardiac syncope

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    Background--The early detection of cardiac syncope is challenging. We aimed to evaluate the diagnostic value of 4 novel prohormones, quantifying different neurohumoral pathways, possibly involved in the pathophysiological features of cardiac syncope: midregional-pro-A-type natriuretic peptide (MRproANP), C-terminal proendothelin 1, copeptin, and midregionalproadrenomedullin. Methods and Results--We prospectively enrolled unselected patients presenting with syncope to the emergency department (ED) in a diagnostic multicenter study. ED probability of cardiac syncope was quantified by the treating ED physician using a visual analogue scale. Prohormones were measured in a blinded manner. Two independent cardiologists adjudicated the final diagnosis on the basis of all clinical information, including 1-year follow-up. Among 689 patients, cardiac syncope was the adjudicated final diagnosis in 125 (18%). Plasma concentrations of MRproANP, C-terminal proendothelin 1, copeptin, and midregional-proadrenomedullin were all significantly higher in patients with cardiac syncope compared with patients with other causes (P < 0.001). The diagnostic accuracies for cardiac syncope, as quantified by the area under the curve, were 0.80 (95% confidence interval [CI], 0.76-0.84), 0.69 (95% CI, 0.64-0.74), 0.58 (95% CI, 0.52-0.63), and 0.68 (95% CI, 0.63-0.73), respectively. In conjunction with the ED probability (0.86; 95% CI, 0.82-0.90), MRproANP, but not the other prohormone, improved the area under the curve to 0.90 (95% CI, 0.87-0.93), which was significantly higher than for the ED probability alone (P=0.003). An algorithm to rule out cardiac syncope combining an MRproANP level of < 77 pmol/L and an ED probability of < 20% had a sensitivity and a negative predictive value of 99%. Conclusions--The use of MRproANP significantly improves the early detection of cardiac syncope among unselected patients presenting to the ED with syncope
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