An Examination of Three-dimensional Geometry in High School Curricula in the US and China

Geometry is an essential branch in mathematics that helps students learn to grasp their environment and leverage that grasp into abstract understanding and reasoning. There has been an observable decrease in geometrical content in secondary education curricula, and particularly a “puzzling scarcity” in three-dimensional geometry, which has led to a decline in students’ geometrical abilities, spatial thinking and deductive reasoning abilities. This study addresses this issue by scrutinizing the enacted curriculum standards and the most influential textbooks related to three-dimensional geometry in two prominent countries, the US and China, both of which embrace the interplay of both conventional and innovative practices. This qualitative study used both content analysis and cross-cultural comparison methods to inquire about and to understand the current situation of three-dimensional geometry in high school. I focused on probing the communication types, objects, concepts, and spatial thinking abilities related to three-dimensional geometry in the standards and texts. To understand spatial abilities, I synthesized a spatial thinking abilities framework with six attributes and used this framework to exam the affordance of these abilities in the texts and requirements in the standards. The result and analysis reveal the details of each text and standards individually and offer an examination of the alignment between the standards and texts. The comparison of the two countries’ different approaches also sharpens the understanding of the issue. I also worked to unveil students’ multiple ways of making sense of geometry concepts by two geometry learning models, Piaget’s model and van Hiele’s model, as well as spatial thinking abilities

シロイヌナズナにおける加水分解酵素を介したストリゴラクトン信号伝達経路に関する研究

要約のみTohoku University山口信次郎課

Generalized Deep Learning-based Proximal Gradient Descent for MR Reconstruction

The data consistency for the physical forward model is crucial in inverse problems, especially in MR imaging reconstruction. The standard way is to unroll an iterative algorithm into a neural network with a forward model embedded. The forward model always changes in clinical practice, so the learning component's entanglement with the forward model makes the reconstruction hard to generalize. The deep learning-based proximal gradient descent was proposed and use a network as regularization term that is independent of the forward model, which makes it more generalizable for different MR acquisition settings. This one-time pre-trained regularization is applied to different MR acquisition settings and was compared to conventional L1 regularization showing ~3 dB improvement in the peak signal-to-noise ratio. We also demonstrated the flexibility of the proposed method in choosing different undersampling patterns.Comment: Keywords: MRI reconstruction, Deep Learning, Proximal gradient descent, Learned regularization ter

Case report: Successful anesthesia management of noncardiac surgery in a patient with single atrium

BackgroundSingle atrium is very rare congenital cardiac anomaly in adults. The prognosis of patients with single atrium is very poor, with 50% of patients dying owing to cardiopulmonary complications in childhood. Herein, we focused on anesthesia management for noncardiac surgery in patients with single atrium.Case presentationA 58-year-old male with a history of bilateral varicocele underwent laparotomy for high-position ligation of the spermatic vein. The patient also had a history of single atrium, atrial fibrillation, chronic heart failure, pulmonary hypertension (PH), and complete right bundle branch block (CRBBB). Given the significant complications associated with general anesthesia in patients with PH, we preferred to use low-dose epidural anesthesia for this patient. Transthoracic echocardiography was used to assess cardiac function before and during surgery and guide perioperative fluid therapy. To limit the stress response, we used a regional nerve block for reducing postoperative pain. Furthermore, we used norepinephrine to appropriately increase the systemic vascular resistance in response to the reduction of systemic vascular resistance caused by epidural anesthesia.ConclusionLow-dose epidural anesthesia can be safely used in patients with single atrium and PH. The use of perioperative transthoracic echocardiography is helpful in guiding fluid therapy and effectively assessing the cardiac structure and function of patients. Prophylactic administration of norepinephrine before epidural injection may make it easier to maintain the patient’s BP

Pressure induced superconductivity bordering a charge-density-wave state in NbTe4 with strong spinorbit coupling

Transition-metal chalcogenides host various phases of matter, such as charge-density wave (CDW), superconductors, and topological insulators or semimetals. Superconductivity and its competition with CDW in low-dimensional compounds have attracted much interest and stimulated considerable research. Here we report pressure induced superconductivity in a strong spin-orbit (SO) coupled quasi-one-dimensional (1D) transition-metal chalcogenide NbTe$_4$, which is a CDW material under ambient pressure. With increasing pressure, the CDW transition temperature is gradually suppressed, and superconducting transition, which is fingerprinted by a steep resistivity drop, emerges at pressures above 12.4 GPa. Under pressure $p$ = 69 GPa, zero resistance is detected with a transition temperature $T_c$ = 2.2 K and an upper critical field $H_{c2}$= 2 T. We also find large magnetoresistance (MR) up to 102\% at low temperatures, which is a distinct feature differentiating NbTe$_4$ from other conventional CDW materials.Comment: https://rdcu.be/LX8

Mesoscopic study on the effect of CFRP layers on the mechanical properties of coal circular-columns

In order to study the effect of CFRP layers on the mechanical properties of coal cylinders. A discrete-continuous coupled meso-mechanical numerical model of CFRP passively confined coal cylinders was developed using a three-dimensional FLAC-PFC coupling method. The validity of the model was verified with experimental data of 0-2 layers of CFRP passively confined coal cylinders. On this basis, studies of the influence of 3-7 layers on mechanical properties and energy evolution of CFRP confined coal cylinders was carried out. The results show that the yield limit and the peak of the coal cylinders gradually coincide with the increase of CFRP layers, showing a state of yielding or failure without warning. With the increase of CFRP layers, the increment in the peak strength of coal cylinders first increases and then decreases. A function is obtained to characterize the evolution of the peak strength increment of CFRP confined coal cylinders under different layers. The increment in the peak strain shows a behavior of first increasing and then decreasing, and then increasing and decreasing again. When the elastic strain energy is constant, the axial strain of the coal cylinders has no correlation with CFRP layers, but its peak strain and ultimate strain both increase with the increase of CFRP layers. The dissipative energy conversion ratio at peak point increases first and then decreases with the increase of CFRP layers. A function is established to characterize the evolution of the dissipative energy conversion ratio of CFRP confined coal cylinders with different layers. The ductility characteristics of stress-strain curves, peak strength increment, peak strain increment, dissipative energy conversion ratio and total energy increment of coal cylinders are considered comprehensively, and taking into account the principles of economic cost and winding level, the three layers are determined as the optimal winding layers for CFRP confined coal circular-columns

Gut microbiota and acylcarnitine metabolites connect the beneficial association between estrogen and lipid metabolism disorders in ovariectomized mice

Decreased estrogen level is one of the main causes of lipid metabolism disorders and coronary heart disease in women after menopause. Exogenous estradiol benzoate is effective to some extent in alleviating lipid metabolism disorders caused by estrogen deficiency. However, the role of gut microbes in the regulation process is not yet appreciated. The objective of this study was to investigate the effects of estradiol benzoate supplementation on lipid metabolism, gut microbiota, and metabolites in ovariectomized (OVX) mice and to reveal the importance of gut microbes and metabolites in the regulation of lipid metabolism disorders. This study found that high doses of estradiol benzoate supplementation effectively attenuated fat accumulation in OVX mice. There was a significant increase in the expression of genes enriched in hepatic cholesterol metabolism and a concomitant decrease in the expression of genes enriched in unsaturated fatty acid metabolism pathways. Further screening of the gut for characteristic metabolites associated with improved lipid metabolism revealed that estradiol benzoate supplementation influenced major subsets of acylcarnitine metabolites. Ovariectomy significantly increased the abundance of characteristic microbes that are significantly negatively associated with acylcarnitine synthesis, such as Lactobacillus and Eubacterium ruminantium group bacteria, while estradiol benzoate supplementation significantly increased the abundance of characteristic microbes that are significantly positively associated with acylcarnitine synthesis, such as Ileibacterium and Bifidobacterium spp. The use of pseudosterile mice with gut microbial deficiency greatly facilitated the synthesis of acylcarnitine due to estradiol benzoate supplementation and also alleviated lipid metabolism disorders to a greater extent in OVX mice. IMPORTANCE Our findings establish a role for gut microbes in the progression of estrogen deficiency-induced lipid metabolism disorders and reveal key target bacteria that may have the potential to regulate acylcarnitine synthesis. These findings suggest a possible route for the use of microbes or acylcarnitine to regulate disorders of lipid metabolism induced by estrogen deficiency