Two-stage Concept Research Articles

Continual Pre-Training of Language Models for Concept Prerequisite Learning with Graph Neural Networks

Prerequisite chains are crucial to acquiring new knowledge efficiently. Many studies have been devoted to automatically identifying the prerequisite relationships between concepts from educational data. Though effective to some extent, these methods have neglected two key factors: most works have failed to utilize domain-related knowledge to enhance pre-trained language models, thus making the textual representation of concepts less effective; they also ignore the fusion of semantic information and structural information formed by existing prerequisites. We propose a two-stage concept prerequisite learning model (TCPL), to integrate the above factors. In the first stage, we designed two continual pre-training tasks for domain-adaptive and task-specific enhancement, to obtain better textual representation. In the second stage, to leverage the complementary effects of the semantic and structural information, we optimized the encoder of the resource–concept graph and the pre-trained language model simultaneously, with hinge loss as an auxiliary training objective. Extensive experiments conducted on three public datasets demonstrated the effectiveness of the proposed approach. Our proposed model improved by 7.9%, 6.7%, 5.6%, and 8.4% on ACC, F1, AP, and AUC on average, compared to the state-of-the-art methods.

ELLIPSIS IN COMPARATIVES IN ENGLISH

This paper presents an analysis of certain properties of ellipsis within comparative clauses in English. The analysis has shown that the comparative clauses contain gradable expressions and establish a connection between two-stage concepts related to gradable properties. In other words, what is claimed in the matrix clause is compared to claims from subordinated clauses, so that the corresponding linguistic structures are usually omitted in a comparative clause. An elliptical comparative clause usually consists only of an expanded complement introduced with than, like, as ... as. The omitted parts, most often phrases, parts of predicates (or the whole predication) and clauses, are present in the text as antecedents. We have not limited our research only to the syntactic and / or semantic level in the reconstruction of ellipted content, but to all contexts and situations from which recoverability is possible, regardless of the type of ellipsis. We have examined the conditions and constraints of ellipsis within comparative clauses in the theoretical part, and the properties of the comparative ellipsis in the analysis on the corpus of contemporary English.

Responsible Lending Policy of Green Investments in the Energy Sector in Poland

The paper concerns the issue of responsible involvement of commercial banks in Poland in green financing of the energy sector. The main reason for undertaking this topic is the observed increased interest of domestic banks in green financing of investments on the energy market in Poland. Therefore, the main objective are to explore the determinants of changes in the level and structure of bank loans under the influence of green investments in the energy sector in Poland. The article verifies the research hypothesis which assumes that an increase in financing green investments by bank loans in the energy market in Poland requires strengthening the synergy of responsible financing of sustainable development of the economy. For this purpose, a two-stage concept of the empirical research was adopted. On the first stage, questionnaire surveys were conducted among the largest Polish commercial banks to examine the respondents’ acceptance degree of the concept of sustainable financing and greening the loan portfolio. On the second stage, case studies were analyzed along with the analysis of selected secondary quantitative data. It was proven that commercial banks in Poland increase their commitment to sustainable financing, which is observed in the sectorally progressing process of “greening” the credit offer. There is also a noticeable change in their approach to social responsibility, especially in the context of the energy market, where financing of traditional, ecologically harmful projects is still dominant. However, this trend is slowly being reversed, towards supporting investments in the area of modern, environmentally-friendly energy solutions. However, “greening” of loan portfolios in the native banking sector requires a responsible lending policy based on various complex business decisions. Increasing their pro-ecological awareness of financing the economy is only a prerequisite, albeit inadequate, of further energy transformation in Poland.

Conceptual design of an off-momentum collimation system in the CERN Super Proton Synchrotron for High-Luminosity Large Hadron Collider proton beams

The CERN accelerator complex is undergoing an upgrade in order to meet the requirements of the High-Luminosity Large Hadron Collider (HL-LHC). One of the key needs is to increase the intensity of beams injected into the LHC from the current $1.15\ifmmode\times\else\texttimes\fi{}{10}^{11}$ to $2.3\ifmmode\times\else\texttimes\fi{}{10}^{11}\text{ }\text{ }{\mathrm{p}}^{+}/\mathrm{bunch}$. This requires a beam intensity at injection in the Super Proton Synchrotron (SPS), the last injector before the LHC, as high as $2.6\ifmmode\times\else\texttimes\fi{}{10}^{11}\text{ }\text{ }{\mathrm{p}}^{+}/\mathrm{bunch}$, given that a budget for losses of about 10% is included in the design. However, previous experience with high intensity beams suggests that the total amount of losses in the SPS can be even higher, causing an increased activation, faster aging, and consequent early failure of machine equipment, in addition to an increase in the requirements for preinjectors in order to still meet the HL-LHC target in spite of higher losses. In this paper, we propose a collimation system to be used with HL-LHC proton beams in the SPS in order to intercept and safely dispose of beam losses in ad hoc locations and therefore provide the machine with protection against activation and equipment aging. The design is based on a two-stage concept, where the primary stage intercepts particles that otherwise would be lost, and the secondary stage employing an absorber where lost particles are finally disposed of. Numerical simulations prove a cleaning efficiency of the proposed system of at least 80%, substantially reducing the spreading of particle losses around the machine. Furthermore, the performance of the collimation system has a low sensitivity to common machine errors, and the design is cost efficient, with minimal hardware changes.

Maintenance Optimization of a 2-Component Swappable Series System Using the Delay-Time Concept

In the 2-component swappable series system, the two components undertake tasks with different loads and degrade at different speeds. To prolong the lifetime of the series system, these two components are swapped in the operating process of the system in practice. This is common in the maintenance of duplexing steelmaking systems, tires of vehicles, and steel rails in curves. The failure process of each component in the system is modeled based on a two-stage delay-time concept and divided into two stages: normal and defective. Inspections are carried out periodically on the system. Two components may be swapped once at an inspection time that the two components are both in the normal stage. Due to the increase or decrease of loads, normal and defective time distributions after the swap are assumed to be different from those prior to the swap. The system is subjected to failure, inspection, and age-based renewals. The number of inspections over the maximum usage time of the system and the swap time are optimized jointly by minimizing the expected cost per unit time in a long run. A numerical example is presented to demonstrate the model.

Fast Pyrolysis of Wheat Straw—Improvements of Operational Stability in 10 Years of Bioliq Pilot Plant Operation

The bioliq process developed at the Karlsruhe Institute of Technology (KIT) aims at the conversion of lignocellulosic biomass into synthetic biofuels and chemicals. The process follows a two-stage concept combining decentralized pretreatment of biomass via fast pyrolysis and centralized large-scale gasification and synthesis. The process was specifically designed to convert ash-rich biomass residues, such as wheat straw, requiring special design features at least in the upstream processes. The 2 MW fast pyrolysis pilot plant at KIT was operated with wheat straw from 2009 to 2018 and since then with miscanthus. A substantial increase from less than 5 tons of wheat straw converted per test run in 2012 to more than 50 tons in 2018 was achieved. In total, up to 2018, more than 260 tons of wheat straw were converted to pyrolysis products within a total of 500 h of steady operation. Representative results of the product yields and properties were presented for test campaigns from 2015 to 2018 and compared to a process demonstration unit of the same design but with a downscale factor of 50 (10 kg/h). Mass yields from both plants are in good agreement and consistent with literature data. Experience from longer-term operation and major technical modifications made to improve the operational stability of the plant are described.

MECHATRONIC DEVICE FOR TWO-STAGE CLAMPING OF CYLINDRICAL OBJECTS IN MACHINE TOOL SPINDLES

The design of an electromechanical device for fixing cylindrical objects in the spindle units of technological equipment is presented. The new two-stage concept of the clamping process with a separated first stage is developed. The design of the presented mechanism provides advanced capabilities for control and regulation of its operating characteristics. The control system with the possibility of carrying out the first stage of clamping in automatic mode and without connecting to the upper-level control system in a technological machine is proposed. The involvement of electrical devices for the conversion and transmission of energy instead of their mechanical analogues is used as one of the promising ways to increase the performance efficiency of machine units. It helps to simplify and expand control capabilities, as well as reduce energy losses during intermediate transformations. The absence of mechanical energy converters in the proposed structure helps to reduce energy losses on intermediate transformations. The simplicity of the design expands the possibilities of integration of the proposed clamping mechanism into the structure of both new and existing technological machines in order to modernize it. This allows to achieve technical results, such as an expansion of the metalworking machines functionality, increase the level of automation of the clamping process and the accuracy of clamping objects in spindle units. The task is achieved by equipping the jaw of the clamping chuck with a special mechanism for identifying the presence of the object for clamping. For this goal, the clamping jaw is equipped with a probe that is capable of simultaneous force interaction with the object and the plunger. The plunger is rigidly attached to the magnetic element whose magnetic field has the possibility to interact with the magnetic field sensor. The sensor transmits its electrical signals to the control system of the device. The research results are aimed at meeting the requirements for effective control of clamping mechanisms with the possibility of automatic operation according to a preset algorithm for maintenance of optimal characteristics of a clamping process and a wide range of optional settings.

Combination of cryothermy with radiofrequency energy sources during hybrid atrial fibrillation ablation- impact on lesion quality and outcomes

Abstract Background Whereas pulmonary vein isolation lays the groundwork of endocardial atrial fibrillation (AF) ablation, it leaves patients undertreated. Additional substrate modification of the left atrium is often required, but lesion gaps and non-transmurality limit restoration of sinus rhythm. Moreover, some low voltage areas and conduction abnormalities are located exclusively on the epicardial aspect, and endocardial ablation alone does not address these issues. Our hybrid endo-/epicardial ablation strategy overcomes all these shortcomings. Purpose To test if the combination of epicardial cryo and radiofrequency (RF) ablation (dual) further improves the quality of ablation lines, and if the combined endo-/epicardial ablation can treat intractable cases of AF. Methods Twenty-six patients (13 paroxysmal, 13 long-persistent; 20 patients with 1–5 prior endocardial AF ablations) first underwent epicardial, total thoracoscopic beating heart ablation (TTA). Lesion sets included bilateral PVI, left atrial appendage closure, as well as superior (roof) and inferior (floor) interpulmonary vein lines. Roof and floor lines were alternatingly ablated by dual energy or RF only. Three months post TTA, endocardial mapping with optional gap closure completed this two-stage hybrid concept. Results Intraoperatively, 24 of 40 (60%) previous left or right endocardial PVIs were found incomplete. Apart from two post-TTA pacemaker insertions and one mini-thoracotomy for bleeding, respectively, no major morbidity was observed during follow up. The full protocol of the hybrid concept was applied in 24 patients. Forty-five of 47 (96%) epicardial PVIs were found gap-less during endocardial mapping, and the remaining 2 PVIs were readily re-ablated. In contrast, only 32 of 46 (70%) roof and floor lines were complete, and endocardial touch up was required in one of three patients. Of note, dual energy lines were more likely to be complete than RF only lines (17 of 22, 77%, vs. 15 of 24, 62%; p NS). Among 19 patients with continuous monitoring, only 4 (21%) had any AF burden including two patients within blanking period and before endocardial gap closure. The remaining 7 patients without continuous monitoring never experienced any symptoms related to recurrent AF, and serial Holter EKG were without pathology. Conclusions Hybrid ablation and dual energy provides a strong armamentarium for extra-pulmonary venous triggers of AF. Linear ablation lines were more likely to be gap-less and transmural, if dual energy sources were used. Dual energy TTA is highly efficient to restore sinus rhythm in patients with prior failed endocardial AF ablation. However, one of three patients will require endocardial gap closure to realize the full benefit of our two-stage hybrid concept. Further study will evaluate if dual energy lines outside the box can improve outcome in these challenging cases of intractable AF. Funding Acknowledgement Type of funding source: None

Advanced ORC architecture for geothermal combined heat and power generation

Several approaches to enhance the performance of Organic Rankine Cycles (ORC) have been investigated in literature, including architecture, working fluid selection and part-load optimization together with combined heat and power (CHP) generation. To contribute to these developments, the design and the first operation of an advanced ORC-CHP architecture is being presented in this study. This architecture extends the state of the art by a two-stage concept with turbine bleeding and a regenerative direct contact preheater. The aim of this architecture is to increase the heat source utilization, flexibility and part-load efficiency. To evaluate the performance of this concept, a test rig has been constructed. It is heated with a 200 kW electrical heater and a twin-screw expander is being used. The low-GWP fluid R1233zd(E) is applied as working fluid. In order to analyze the system in its full operating range, experiments are conducted with varying heat loads of the district heating network. Furthermore, an operating strategy of the system is being developed. With this first operation, a very high operational range of the novel ORC-CHP architecture down to a minimum load of 15.3% is being demonstrated. Furthermore, is could be proven that thermal efficiency increases during part-load operation.

The Determination and Assessment of the Appropriateness of Interest Rates in the Case of Cross-Border Financial Transactions between Related Parties – A Case Study

Assessing the appropriateness of interest rates for loan relationships in multinational groups or corporate groups may be the subject of controversial discussions in tax audits. On the basis of a two-stage concept, the case study is intended to provide the practical determination of the interest rates for such transactions. This gradually developed case study serves as a fruitful instruction for consulting practice, administration and jurisdiction, while realizing an appropriate arms’ length interest rate.

“Flip-over flap” in two-stage cleft palate repair

PurposeThis study served to evaluate a two-stage concept in cleft palate repair, including key use of a triangular hinge (“flip-over”) flap, in order to prevent palatal fistulae. It uses data from a prospective registry established in 1991. Materials and methodsThe concept entails Furlow soft palate repair (at 1 year of age) and hard palate closure (at 4 years) by a three-pronged approach [paring of the edges with or without postero-lateral relaxing incisions, peninsula (Veau) flap(s)], plus a triangular hinge flap. The latter is elevated from the oral layer of the already-repaired soft palate, stays based anteriorly, and is flipped over to close the posterior nasal layer defect. The case series is compared with data from the literature. ResultsThe palatal fistula rate for Veau II to IV types (two-stage surgeries) was 4.3%. The overall fistula rate in the cleft population (Veau I–IV) was 2.9%. Meta-analyses describe 4.9 and 8.6% on average. There was no difference between sample A in which the flip-over flaps were used only when modified Veau flaps were indicated (until 2006) and sample B in which it was used regardless of the technique of hard palate closure applied (2006–2018). The fistula rate decreased to zero after 2010, which may reflect also an influence of other factors such as the interpositioning of a collagen membrane and also of improved surgical judgment. ConclusionsUsing a flip-over flap in two-stage cleft palate repair may contribute to prevent fistula formation at the hard/soft palate junction. Level of evidenceIII.

Flexible TwoStage biomass gasifier designs for polygeneration operation

As increasing amounts of wind and solar are integrated into the energy system, there is a growing need for the development of flexible and efficient biomass-based energy plants. Currently, a Polygeneration concept is being investigated: a system based on thermal biomass gasification and solid oxide cells that can either produce power or biofuels depending on the electricity prices. This study investigates gasifier design opportunities for large-scale and fuel flexible TwoStage concepts that only applies partial oxidation for tar conversion. Thermodynamic modeling is carried out for a total of 12 gasifier cases, featuring 3 main systems that each can process wood/straw and use air/oxygen. It was found that despite the varying operation conditions, process parameters remained relatively stable and that partial oxidation could be effectively applied as the only tar reducing measure. The systems all achieved high cold gas efficiencies of 84–88% and were found to be significantly more effective than competing technologies, while also obtaining higher fuel flexibility.

A Sequential Selection Normalized Subband Adaptive Filter with Variable Step-Size Algorithms

This letter proposes a sequential selection normalized subband adaptive filter (SS-NSAF) in order to reduce the computational complexity. In addition, a variable step-size algorithm is also proposed using the mean-square deviation analysis of the SS-NSAF. To enhance the performance in terms of the convergence speed, we propose an improved variable step-size SS-NSAF using a two-stage concept. The simulation results show the low computational complexity and low misalignment errors using the proposed algorithm.

The nepionic stage of Solenomeris Douvillé, 1924 (Acervulinidae, Foraminiferida): new observations from the uppermost Maastrichtian-early Danian of Austria (Kambühel Formation, Northern Calcareous Alps)

In the shallow-water limestone succession of the Kambuhel Formation (upper Maastrichtian to upper Thanetian, Northern Calcareous Alps), the benthic-vagile to encrusting-sessile acervulinid foraminifer Solenomeris Douville was identified in upper Maastrichtian and, more commonly, lower Danian rocks. We report on the free nepionic (juvenile) stage of this foraminifer, its relation to the adult encrusting stage, and competitive interaction with coralline algae. Whereas morphology and chamber arrangement of the free nepionts clearly assign the Alpine specimens to Solenomeris, the chamber shape in axial sections differs from the Eocene type-species S. ogormani, accounting for classification in open nomenclature. Nepiont chamber shape can be used as a further specific criterion besides size of adult chambers and, perhaps, growth habit. A two-stage concept of ontogenetic development is presented. Solenomeris flourished in early Danian high-stress environments (perhaps related to cooler waters and/or elevated nutrient level) under conditions less favorable for encrusting corallines that competed for substrate. Absence of Solenomeris in upper Danian limestones and in upper Thanetian coralgal limestones that form the top of the Kambuhel Formation may be related to recovery of coralline algae in shallow-marine environments of low to moderate nutrient level.

Perforated Diverticulitis with Generalized Peritonitis: Low Stoma Rate Using a "Damage Control Strategy".

Optimal surgical management of perforated diverticulitis of the sigmoid colon has yet to be clearly defined. The purpose of this study was to evaluate efficacy of a "Damage Control Strategy" (DCS). Patients with perforated diverticulitis of the sigmoid colon complicated by generalized peritonitis (Hinchey III and IV) surgically treated according to a damage control strategy between May 2011 and February 2017 were enrolled in the present multicenter retrospective cohort study. Data were collected at three surgical centers. DCS comprises a two-stage concept: [1] limited resection of the perforated colon segment with oral and aboral blind closure during the emergency procedure and [2] definitive reconstruction at scheduled second laparotomy (anastomosis ∓ loop ileostomy or a Hartmann's procedure) after 24-48 h. Fifty-eight patients were included into the analysis [W:M 28:30, median age 70.1years (30-92)]. Eleven patients (19%) initially presented with fecal peritonitis (Hinchey IV) and 47 patients with purulent peritonitis (Hinchey III). An anastomosis could be created during the second procedure in 48 patients (83%), 14 of those received an additional loop ileostomy. In the remaining ten patients (n = 17%), an end colostomy was created at second laparotomy. A fecal diversion was performed in five patients to treat anastomotic complications. Thus, altogether, 29 patients (50%) had stoma at the end of the hospital stay. The postoperative mortality was 9% (n = 5), and median postoperative hospital stay was 18.5days (3-66). At the end of the follow-up, 44 of 53 surviving patients were stoma free (83%). The use of the Damage Control strategy leads to a comparatively low stoma rate in patients suffering from perforated diverticulitis with generalized peritonitis.

Two-step values for games with two-level communication structure

TU games with two-level communication structure, in which a two-level communication structure relates fundamentally to the given coalition structure and consists of a communication graph on the collection of the a priori unions in the coalition structure, as well as a collection of communication graphs within each union, are considered. For such games we introduce two families of two-step values inspired by the two-step procedures staying behind the Owen value (Owen, in: Henn, Moeschlin (eds) Essays in mathematical economics and game theory, Springer, Berlin, pp 76–88, 1977) and the two-step Shapley value (Kamijo in Int Game Theory Rev 11:207–214, 2009) for games with coalition structure. Our approach is based on the unified treatment of several component efficient values for games with communication structure and it generates two-stage solution concepts that apply component efficient values for games with communication structure on both distribution levels. Comparable axiomatic characterizations are provided.

«Back to the Future»: the main historiographical themes and topical problems of the Neolithic of the Urals

The following paper deals with some problems of Trans-Urals Neolithic which are associated with the formation and development of basic cultural and chronological concepts. Three stages in conceptual historiography are identified. The first one refers to the mid-second half of the 20th century and is associated with the formation of the first cultogenesis schemes of the late Trans-Urals Stone Age by V.N. Chernetsov, O.N. Bader and L.Ya. Krizhevskaya. At the second stage at the end of the 19th beginning of the 21st century their ideas were revised by V.T. Kovaleva in the framework of a two-stage and two-line concept. At the same time the hypothesis of V.A. Zakh was developed. Later V.S. Mosin proposed a socio-cultural scheme for the formation of an integrated society in the Neolithic Trans-Urals. The third the modern stage began approximately in the second decade of the 21st century when natural scientific data growth forced to reconsider a number of established ideas about the chronology and typology of Neolithic ceramics and ornamental traditions. At the regional level there was a return to the classical three-term periodization; there was a trend towards regionalization of research to clarify the notions of local variants and the chronological position of material complexes, specifics of historical and cultural processes. It is concluded that it is necessary to form a new research paradigm by synthesizing middle-level theories with empirical generalizations.

Reduce odor and NH3 emission: condensation of the carbonatation vapors

At beet sugar production, vapors from first and second carbonatation contain a significant amount of odor components, NH3 and waste heat, which are normally directly released into the environment. Due to sustainability motivations, obligations regarding odor nuisance and expected stricter regulations regarding NH3 emission limits, Suiker Unie decided to take measures to reduce emission via the carbonatation vapors. During the 2015 beet campaign, pilot scale plant trials have been performed to investigate the effectiveness of indirect contact and direct contact condensation of these vapors. Based on this experimental work a two-stage gas scrubbing concept was designed: in the first stage main goal is condensing the vapors and reuse the heat of condensation to heat up limed juice, while the actual scrubbing takes place in the second scrubber. This two-stage gas scrubbing installation has been built at the Vierverlaten factory and was started up in the 2016 beet campaign. The background, pilot scale trials, concept of design and achieved reductions in odor and NH3 emission at industrial scale are discussed.

Recommendations for education in ultrasound in medical intensive care and emergency medicine: position paper of DGIIN, DEGUM and DGK

Point-of-care ultrasound in acute care medicine is aprerequisite for diagnosis and therapy monitoring of critically ill patients. There is currently no uniform education strategy for medical intensive care and emergency medicine. As part of the basic level, the trainee takes theoretical and clinical training covering abdominal and thoracic ultrasonography and focused cardiovascular ultrasound. In asecond step, special knowledge and skills can be acquired at an expert level. This two-stage concept is intended to guarantee quality assurance in ultrasound education in medical intensive care and emergency medicine.

Primäre Lebertumoren

Chronic liver parenchymal diseases as well as cholestasis are established risk factors for liver failure after partial hepatectomy. As hepatocellular (HCC) and cholangiocellular (CCC) carcinoma often require extended resection due to the often considerable size of tumors - in an often priorly damaged liver - surgery for these entities is usually demanding. Due to the lack of potent systemic treatment for primary liver tumors, surgery remains the only potentially curative treatment option for CCC and most HCC; therefore, perioperative risk factors for liver failure should be reduced as far as possible. In this study measures for reducing the risk of liver failure after extended liver resections were analyzed. This analysis was based on a selective literature search in the Pubmed databank. Medical measures can be used to lower the degree of steatosis or the inflammatory reaction of ischemia/reperfusion injury. In particular, biliary decompression should be achieved in obstructive jaundice prior to liver surgery, e.g. for hilar cholangiocarcinoma, as cholestasis impairs liver regeneration. Moreover, the future liver remnant volume after extended liver resection can be increased by embolization (PVE) or ligation of major branches of the portal vein. Similar results as for PVE regarding liver hypertrophy have been reported from unilateral selective internal radiotherapy (SIRT) although this effect appears prolonged and less impressive than after PVE. In addition, two-stage concepts for liver surgery, which are also based on the regenerative potential of the liver, may lower the complication rate and increase patient safety by increasing liver volume. However, conventional two-stage procedures harbor the risk of disease progression during the time lapse to the second step which contraindicates complete resection in 20-30 % of patients. In contrast to this, a complete tumor resection is possible in nearly all patients treated by the associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) procedure but long-term results regarding tumor recurrence rate are scarce due to the limited experience with this novel technique. The perioperative risks of extended liver resection can be lowered by technical and medical measures.