Miracle-dz/UniFAR-FTUs huggingface dataset:
What should be the object of research with respect to the notion of mathematical proof?

Despite its central place in the mathematics curriculum the notion mathematical proof has failed to permeate the curriculum at all scholastic levels. While the concept of mathematical proof can serve as a vehicle for mathematical thinking, studies have revealed that students experience serious difficulties with proving that include: not knowing how to begin the proving process, the proclivity to use empirical verifications for tasks that call for axiomatic methods of proving, resorting to rote memorization of uncoordinated fragments of proof facts. While several studies have been conducted with the aim of addressing students’ fragile grasp of mathematical proof the majority of such studies have been based on activities that involve students reflecting and expressing their level of convincement in arguments supplied by the researchers thereby compromising the voice of the informants. Further, research focus has been on the front instead of the back of mathematics. Hence, there is a dearth in research studies into students’ thinking processes around mathematical proof that are grounded in students’ own proof attempts. Therefore current research strides should aim at identifying critical elements of students’ knowledge of the notion of proof that should be informed by students’ actual individual proof construction attempts.
Barriers to digital government and the COVID-19 crisis – A comparative study of federal government entities in the United States and Austria

Digital government has been an evolving topic in research and practice, and during the COVID-19 crisis, different tools emerged as crucial elements in tackling the crisis. Comparing the federal level in the United States (Anglo-Saxon public interest culture) and in Austria (continental European rule-of-law culture), this article looks at how different barriers to digital government were affected by the COVID-19 crisis. Fourteen semi-structured interviews with experts in United States departments and their Austrian counterparts are conducted. The results show strong similarities between the United States and Austria in cultural barriers (bureaucratic culture, resistance to change, risk aversion) but also in structural barriers (political commitment and resources, workforce) to digital government. The main difference lies in laws and regulations as structural barriers, stemming from the different administrative traditions. Furthermore, the study highlights the dynamic nature of barriers. It shows that a crisis can result in the lowering of both structural as well as cultural barriers. Deliberate removal of structural barriers in experimentation spaces may therefore enhance digital government in ‘orderly’ times as well. Points for practitioners Knowing how to overcome certain barriers is essential in innovation processes. This study shows that windows of opportunity can be opened by a crisis, but also provides key learnings for policy measures that can be taken in ‘orderly’ times. Public administrations require space where structural barriers are deliberately removed in order to experiment and learn, which can lower cultural barriers to digital government as well.
Development of Virtual Inertia Control with State-of-Charge Recovery Strategy Using Coordinated Secondary Frequency Control for Optimized Battery Capacity in Isolated Low Inertia Grid

Integrating renewable energy through inverter-based generators has decreased the power system’s inertia. Reduced inertia may lead to frequency instability during power imbalance disturbances, particularly in an isolated power system with limited inertia. The Battery Energy Storage System (BESS) and a virtual inertia (VI) emulation control system have become popular to mitigate this issue. Nonetheless, the BESS utilization for VI emulation is highly dependent on the availability of BESS capacity, which may affect the energy cost. Therefore, developing a VI emulation control strategy that requires less energy and can recover the state of charge (SoC) to a desired level to optimize BESS utilization is required. This paper proposes a VI control with an SoC recovery strategy through coordination with the generators’ secondary frequency control. Instead of relying on the frequency, such as in the conventional approach, the controlled signal of the generators’ secondary frequency control also includes the VI power and BESS SoC. Hence, the generators can contribute to lowering the VI required energy and recovering the BESS SoC. The results show that the proposed method outperforms the conventional method by requiring around 36% lower energy and the ability to maintain the BESS SoC.
Effective Online Portfolio Selection for the Long-Short Market Using Mirror Gradient Descent

Online portfolio selection has been actively studied to maximise overall returns by selecting the optimal portfolio weights using online algorithms. However, most work has focused on long-only portfolios, and developing efficient algorithms with loose portfolio constraints remains a challenge. In this letter, the classical online portfolio selection problem is reformulated to allow long/short and margin. For this problem, conventional gradient-based online algorithms face the challenges of high regret and computational complexity due to non-optimal gradients and high-dimensional projections. To tackle this, we propose a novel online algorithm that introduces mirror descent to achieve dimension-free regret in a non-Euclidean space. Specifically, a Bregman divergence is introduced to replace the $\ell _{2}$ norm as a valid proximal setup for the problem to achieve uniform gradients and reduce projection computations. Furthermore, a smoothing technique is developed to reduce the variance of the gradients. The evaluation shows that our algorithm achieves low regret bound and computational complexity, which guarantees a 30% advantage over other strategies in Chinese futures market.
Transcriptome Dynamics during Spike Differentiation of Wheat Reveal Amazing Changes in Cell Wall Metabolic Regulators

Coordinated cell proliferation and differentiation result in the complex structure of the inflorescence in wheat. It exhibits unique differentiation patterns and structural changes at different stages, which have attracted the attention of botanists studying the dynamic regulation of its genes. Our research aims to understand the molecular mechanisms underlying the regulation of spike development genes at different growth stages. We conducted RNA-Seq and qRT-PCR evaluations on spikes at three stages. Our findings revealed that genes associated with the cell wall and carbohydrate metabolism showed high expression levels between any two stages throughout the entire process, suggesting their regulatory role in early spike development. Furthermore, through transgenic experiments, we elucidated the role of the cell wall regulator gene in spike development regulation. These research results contribute to identifying essential genes associated with the morphology and development of wheat spike tissue.
An ex vivo Model of Paired Cultured Hippocampal Neurons for Bi-directionally Studying Synaptic Transmission and Plasticity

Synapses provide the main route of signal transduction within neuronal networks. Many factors regulate critical synaptic functions. These include presynaptic calcium channels, triggering neurotransmitter release, and postsynaptic ionotropic receptors, mediating excitatory and inhibitory postsynaptic potentials. The key features of synaptic transmission and plasticity can be studied in primary cultured hippocampal neurons. Here, we describe a protocol for the preparation and electrophysiological analysis of paired hippocampal neurons. This model system allows the selective genetic manipulation of one neuron in a simple neuronal network formed by only two hippocampal neurons. Bi-directionally analyzing synaptic transmission and short-term synaptic plasticity allows the analysis of both pre- and postsynaptic effects on synaptic transmission. For example, with one single paired network synaptic responses induced by both, a wild-type neuron and a genetically modified neuron can be directly compared. Ultimately, this protocol allows experimental modulation and hence investigation of synaptic mechanisms and thereby improves previously developed methods of studying synaptic transmission and plasticity in ex vivo cultured neurons. Key features Preparation of ex vivo paired cultured hippocampal neurons. Bi-directional electrophysiological recordings of synaptic transmission and plasticity. Genetic modulation of synaptic network formation (demonstrated by presynaptic viral overexpression of the auxiliary calcium channel α2δ-2 subunit). Graphical overview
SO-IMCKD processed signal improving MSCNN model’s fault diagnosis accuracy for drilling pump fluid end

Drilling pump is the ‘heart’ of drilling construction. The key to accurate fault diagnosis is to extract useful fault features from noisy raw signals. In order to improve the accuracy of fault diagnosis of drilling pump fluid end, this paper proposes a fault diagnosis method based on multi-scale convolutional neural network (MSCNN) combined with the snake optimization optimized maximum correlation kurtosis deconvolution (SO-IMCKD). First, the SO algorithm is employed to optimize the filter length and the shift number of IMCKD to process the raw signal, enhancing the fault features from the raw signal. Second, the continuous wavelet transform is used to convert the enhanced signals into time-frequency images which are input into an established MSCNN to extract the fault feature more effectively. Finally, by changing the training batchsize of the MSCNN model, the identification effect of the model to the normal state, minor damage, and serious damage of the fluid end is analyzed. The identification of nine states of the fluid end is successfully carried out, with an average diagnostic accuracy of 99.93%. Moreover, the adaptability of the proposed method is verified with the Mechanical Failure Prevention Technology Association dataset. The method has high accuracy and good adaptability, which has desired prospect for drilling pump fault diagnosis and bearing fault diagnosis.
Simultaneous Achievement of Open and Closed Loop Diagonal Dominance Through Constant Feedback

This paper proposes a new and low complexity technique for the simultaneous achievement of open and closed loop diagonal dominance for uncertain plants. The method is based on the introduction of a static high gain inner feedback which modifies the plant to attain a diagonal dominant open loop compensated plant. The sufficient, easy to use, conditions derived for the open loop diagonal dominance also assure the simultaneous achievement of closed loop diagonal dominance under soft assumptions on the diagonal elements of the decoupled controller robustly stabilizing the plant. These assumptions agree with the usual closed‐loop performance specifications, so that closed‐loop diagonal dominance is achieved without any extra complication on the controller design procedure. The main merits of the present method are: applicability to uncertain plants, ease of implementation and low computational cost. Three examples taken from the relevant literature, are given to show the effectiveness of the proposed approach.
Assessing higher education students’ critical thinking with the PENCRISAL test - Portuguese short version: a psychometric study

The development of critical thinking in higher education is fundamental, preparing students to think well, find explanations, make decisions and solve problems. Given the importance of its promotion, its assessment is crucial, since the two are inseparable. Moreover, the number of instruments that are validated to assess critical thinking in the Portuguese language and culture are scarce. We present the validation psychometric study of the PENCRISAL test (short version) to the Portuguese language, a critical thinking assessment test for higher education students, designed and validated in Spain (full and short version), which presents adequate reliability and validity psychometric characteristics to assess key-dimensions of critical thinking. A sample of 225 Portuguese higher education students from three universities (two public and one private) performed a reduced version of the PANCRISAL test. The results obtained allowed replicating the Spanish reduced version in Portugal (only changing one of the six items), and the confirmatory factorial analysis permits to identify two factors intercorrelated, legitimizing the combination of the six items in a global score. This short version can be used as a screening test, and its potential is pointed out to assess students critical thinking to support teaching and research in higher education.
Aeroelastic tailoring for static and dynamic loads with blending constraints

In the present paper the authors want to investigate the effect of different load configuration in order to identify the ones driving the optimization. A set of static loads, gust loads and static loads with maneuver load alleviation (MLA) are tested. Gust loads have been included in the optimization via an equivalent static load (ESL). Composite blending is tackled by means of continuous constraints and a two phases approach is proposed to find a blended stacking sequence table. Results show that region of influence can be identified for specific loads and that MLA can be beneficial for structural weight reduction. Finally, the blending constraints prove their effectiveness by significantly reducing the error in retrieving a blended stacking sequence.
Recent advances in endogenous neural stem/progenitor cell manipulation for spinal cord injury repair

Traumatic spinal cord injury (SCI) can cause severe neurological impairments. Clinically available treatments are quite limited, with unsatisfactory remediation effects. Residing endogenous neural stem/progenitor cells (eNSPCs) tend to differentiate towards astrocytes, leaving only a small fraction towards oligodendrocytes and even fewer towards neurons; this has been suggested as one of the reasons for the failure of autonomous neuronal regeneration. Thus, finding ways to recruit and facilitate the differentiation of eNSPCs towards neurons has been considered a promising strategy for the noninvasive and immune-compatible treatment of SCI. The present manuscript first introduces the responses of eNSPCs after exogenous interventions to boost endogenous neurogenesis in various SCI models. Then, we focus on state-of-art manipulation approaches that enhance the intrinsic neurogenesis capacity and reconstruct the hostile microenvironment, mainly consisting of pharmacological treatments, stem cell-derived exosome administration, gene therapy, functional scaffold implantation, inflammation regulation, and inhibitory element delineation. Facing the extremely complex situation of SCI, combined treatments are also highlighted to provide more clues for future relevant investigations.
Comparative phenotype of circulating versus tissue immune cells in human lung and blood compartments during health and disease

Abstract The lung is a dynamic mucosal surface constantly exposed to a variety of immunological challenges including harmless environmental antigens, pollutants, and potentially invasive microorganisms. Dysregulation of the immune system at this crucial site is associated with a range of chronic inflammatory conditions including asthma and Chronic Pulmonary Obstructive Disease (COPD). However, due to its relative inaccessibility, our fundamental understanding of the human lung immune compartment is limited. To address this, we performed flow cytometric immune phenotyping of human lung tissue and matched blood samples that were isolated from 115 donors undergoing lung tissue resection. We provide detailed characterization of the lung mononuclear phagocyte and T cell compartments, demonstrating clear phenotypic differences between lung tissue cells and those in peripheral circulation. Additionally, we show that CD103 expression demarcates pulmonary T cells that have undergone recent TCR and IL-7R signalling. Unexpectedly, we discovered that the immune landscape from asthmatic or COPD donors was broadly comparable to controls. Our data provide a much-needed expansion of our understanding of the pulmonary immune compartment in both health and disease.
Association Between Inflammatory Burden Index and Unfavorable Prognosis After Endovascular Thrombectomy in Acute Ischemic Stroke

Background Inflammatory burden index (IBI) is a systemic inflammation indicator that reflects the inflammatory status. We aimed to investigate the prognostic value of IBI after endovascular thrombectomy (EVT) in patients with acute ischemic stroke. Methods We enrolled patients treated with EVT from a multicenter cohort between June 2020 and December 2021. The IBI was calculated as C-reaction protein × neutrophil / lymphocyte count. The primary outcome was the unfavorable functional outcome (90-day modified Rankin scale score 3–6). C-statistics and net reclassification indexes were used to assess the predictive accuracy. Multivariable logistic regression models were used to investigate the association between IBI and unfavorable outcome. Results A total of 295 patients (mean age, 64.0 ± 12.8 years; male, 63.7%) were enrolled in this study. In multivariable models, higher IBI levels were associated with an increased risk of 90-day unfavorable outcome after EVT (per 1-SD: odds ratio, 1.754; 95% confidence interval, 1.241–2.587; P = 0.002). Restricted cubic spline curve displayed a linear relationship between the IBI level and 90-day unfavorable outcome (P for nonlinearity = 0.410). Besides, IBI was a more accurate biomarker for predicting unfavorable outcomes with the highest predictive accuracy and reclassification indexes. Conclusion This study demonstrated that higher IBI was associated with an increased risk of 90-day unfavorable outcome in acute ischemic stroke treated with EVT.
3D Multi-Ion Corrosion Model in Hierarchically Structured Cementitious Materials Obtained from Nano-XCT Data

Corrosion of steel reinforcements in concrete constructions is a worldwide problem. To assess the degradation of rebars in reinforced concrete, an accurate description of electric current, potential and concentrations of various species present in the concrete matrix is necessary. Although the concrete matrix is a heterogeneous porous material with intricate microstructure, mass transport has been treated in a homogeneous material so far, modifying bulk transport coefficients by additional factors (porosity, constrictivity, tortuosity), which led to so-called effective coefficients (e.g., diffusivity). This study presents an approach where the real 3D microstructure of concrete is obtained from high-resolution X-ray computed tomography (XCT), processed to generate a mesh for finite element method (FEM) computations, and finally combined with a multi-species system of transport and electric potential equations. This methodology allows for a more realistic description of ion movements and reactions in the bulk concrete and on the rebar surface and, consequently, a better evaluation of anodic and cathodic currents, ultimately responsible for the loss of reinforcement mass and its location. The results of this study are compared with a state-of-the-art model and numerical calculations for 2D and 3D geometries.
A second‐order semiparametric method for survival analysis, with application to an acquired immune deficiency syndrome clinical trial study

Motivated by the recent acquired immune deficiency syndrome clinical trial study A5175, we propose a semiparametric framework to describe time‐to‐event data, where only the dependence of the mean and variance of the time on the covariates are specified through a restricted moment model. We use a second‐order semiparametric efficient score combined with a non‐parametric imputation device for estimation. Compared with an imputed weighted least squares method, the approach proposed improves the efficiency of the parameter estimation whenever the third moment of the error distribution is non‐zero. We compare the method with a parametric survival regression method in the A5175 study data analysis. In the data analysis, the method proposed shows a better fit to the data with smaller mean‐squared residuals. In summary, this work provides a semiparametric framework in modelling and estimation of survival data. The framework has wide applications in data analysis.
Isolation of phosphorus-hyperaccumulating microalgae from revolving algal biofilm (RAB) wastewater treatment systems

Excess phosphorus (P) in wastewater effluent poses a serious threat to aquatic ecosystems and can spur harmful algal blooms. Revolving algal biofilm (RAB) systems are an emerging technology to recover P from wastewater before discharge into aquatic ecosystems. In RAB systems, a community of microalgae take up and store wastewater P as polyphosphate as they grow in a partially submerged revolving biofilm, which may then be harvested and dried for use as fertilizer in lieu of mined phosphate rock. In this work, we isolated and characterized a total of 101 microalgae strains from active RAB systems across the US Midwest, including 82 green algae, 9 diatoms, and 10 cyanobacteria. Strains were identified by microscopy and 16S/18S ribosomal DNA sequencing, cryopreserved, and screened for elevated P content (as polyphosphate). Seven isolated strains possessed at least 50% more polyphosphate by cell dry weight than a microalgae consortium from a RAB system, with the top strain accumulating nearly threefold more polyphosphate. These top P-hyperaccumulating strains include the green alga Chlamydomonas pulvinata TCF-48 g and the diatoms Eolimna minima TCF-3d and Craticula molestiformis TCF-8d, possessing 11.4, 12.7, and 14.0% polyphosphate by cell dry weight, respectively. As a preliminary test of strain application for recovering P, Chlamydomonas pulvinata TCF-48 g was reinoculated into a bench-scale RAB system containing Bold basal medium. The strain successfully recolonized the system and recovered twofold more P from the medium than a microalgae consortium from a RAB system treating municipal wastewater. These isolated P-hyperaccumulating microalgae may have broad applications in resource recovery from various waste streams, including improving P removal from wastewater.
Saddle-node bifurcations of multiple homoclinic solutions in ODES

We study codimension 3 degenerate homoclinic bifurcations under periodic perturbations. Assume that among the 3 bifurcation equations, one is due to the homoclinic tangecy along the orbital direction. To the lowest order, the bifurcation equations become 3 quadratic equations. Under generic conditions on perturbations of the normal and tangential directions of the homoclinic orbit, up to 8 homoclinic orbits can be created through saddle-node bifurcations. Our results generate the homoclinic tangency bifurcation in Guckenheimer and Holmes [ 8 ].