There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

An introduction to heat transfer

International Technology Roadmap for Semiconductors 2003の要求清浄度について － シリコンウエハ表面と雰囲気環境に要求される清浄度, 分析方法の現状について －

The stability of two-dimensional (2D) layers and membranes is subject of a long standing theoretical debate. According to the so called Mermin-Wagner theorem, long wavelength fluctuations destroy the long-range order for 2D crystals. Similarly, 2D membranes embedded in a 3D space have a tendency to be crumpled. These dangerous fluctuations can, however, be suppressed by anharmonic coupling between bending and stretching modes making that a two-dimensional membrane can exist but should present strong height fluctuations. The discovery of graphene, the first truly 2D crystal and the recent experimental observation of ripples in freely hanging graphene makes these issues especially important. Beside the academic interest, understanding the mechanisms of stability of graphene is crucial for understanding electronic transport in this material that is attracting so much interest for its unusual Dirac spectrum and electronic properties. Here we address the nature of these height fluctuations by means of straightforward atomistic Monte Carlo simulations based on a very accurate many-body interatomic potential for carbon. We find that ripples spontaneously appear due to thermal fluctuations with a size distribution peaked around 70 \AA which is compatible with experimental findings (50-100 \AA) but not with the current understanding of stability of flexible membranes. This unexpected result seems to be due to the multiplicity of chemical bonding in carbon.

Intrinsic ripples in graphene

Magnetocaloric effect: From materials research to refrigeration devices

Commercial CMOS chips routinely operate at frequencies up to 5 GHz and exciting new opportunities exists in higher frequency bands such as 3-10 GHz, 17 GHz, 24 GHz, and 60 GHz. Many research groups have already demonstrated CMOS circuit operation beyond 100 GHz. Will circuit design and compact modeling continue along the same course, or is a new microwave design methodology required? This paper will highlight the design and modeling challenges in moving up to these higher frequencies. A merger of RF and microwave design perspectives will be used to offer insight into the problem. The paper will discuss requirements for a next generation compact model to meet these challenges and offer potential solutions.

https://briefs.techconnect.org/wp-content/volumes/Nanotech2005WCM/pdf/1234.pdf

Challenges in Compact Modeling for RF and Microwave Applications

A weakly-coupled few-mode gain-flattening filter (FM-GFF) based on long-period fiber gratings (LPFGs) in double-cladding few-mode fiber is proposed. Utilizing the FM-GFF, we demonstrate that the gain spectra of each core mode can be independently flattened.

Weakly-Coupled Few-Mode Gain-Flattening Filter Using Long-Period Fiber Grating in Double-Cladding FMF

Background Postoperative myocardial injury (PMI) is associated with short- and long-term mortality. The incidence of PMI in very old patients is currently unknown. There is currently neither known effective prophylaxis nor a uniform strategy for the elderly with PMI. Objective To share our 10 years of experience in the comprehensive management of PMI after non-cardiac surgery in patients aged ≥ 80 years. Methods In this case series, we retrospectively collected and assessed the 2,984 cases aged ≥ 80 years who accepted non-cardiac surgery from 2011 to 2021 at the second Medical Center, Chinese PLA General Hospital. The incidence, risk factors, management strategy, and prognosis of surgical patients with PMI were analyzed. Results A total of 2,984 patients met our inclusion criteria. The overall incidence of PMI was 14%. In multivariable analysis, coronary artery disease, chronic heart failure, and hypotension were independently associated with the development of PMI. The patients with PMI were at a higher risk of death (OR, 2.69; 95% CI, 1.78–3.65). They were more likely to have received low molecular heparin, anti-plantlet therapy, beta-blocker, early coronary angiography, and statin than patients without PMI. The 30-day (0.96% vs. 0.35%; OR 3.46; 95% CI, 1.49–7.98; P < 0.001) and 1-year mortality (5.37% vs. 2.60%; OR 2.35; 95% CI, 1.12–6.53; P < 0.001) was significantly higher in patients with PMI compared with those without PMI. Conclusions The incidence of PMI in very old patients was high. The PMI is associated with an increased risk of 30 days and 1-year mortality. These patients can benefit from intensification of assessment and individualized care of multi-morbidities during the perioperative period. Especially cardiovascular medical treatments, such as antiplatelet, anticoagulation, β-blockers, and statins are very important for patients with PMI.

Management of Postoperative Myocardial Injury After Non-cardiac Surgery in Patients Aged ≥ 80 Years: Our 10 Years' Experience

Most of the existing multi-lead electrocardiogram (ECG) detection methods are based on all 12 leads, which undoubtedly results in a large amount of calculation and is not suitable for the application in portable ECG detection systems. Moreover, the influence of different lead and heartbeat segment lengths on the detection is not clear. In this paper, a novel Genetic Algorithm-based ECG Leads and Segment Length Optimization (GA-LSLO) framework is proposed, aiming to automatically select the appropriate leads and input ECG length to achieve optimized cardiovascular disease detection. GA-LSLO extracts the features of each lead under different heartbeat segment lengths through the convolutional neural network and uses the genetic algorithm to automatically select the optimal combination of ECG leads and segment length. In addition, the lead attention module (LAM) is proposed to weight the features of the selected leads, which improves the accuracy of cardiac disease detection. The algorithm is validated on the ECG data from the Huangpu Branch of Shanghai Ninth People’s Hospital (defined as the SH database) and the open-source Physikalisch-Technische Bundesanstalt diagnostic ECG database (PTB database). The accuracy for detection of arrhythmia and myocardial infarction under the inter-patient paradigm is 99.65% (95% confidence interval: 99.20–99.76%) and 97.62% (95% confidence interval: 96.80–98.16%), respectively. In addition, ECG detection devices are designed using Raspberry Pi, which verifies the convenience of hardware implementation of the algorithm. In conclusion, the proposed method achieves good cardiovascular disease detection performance. It selects the ECG leads and heartbeat segment length with the lowest algorithm complexity while ensuring classification accuracy, which is suitable for portable ECG detection devices.

/pdf/optimized-solutions-of-electrocardiogram-lead-and-segment-5kfbt1qi.pdf

Optimized Solutions of Electrocardiogram Lead and Segment Selection for Cardiovascular Disease Diagnostics

Background Germline mutation in the BMPR2 gene is common in patients with pulmonary arterial hypertension (PAH). However, its association with imaging findings in these patients is, to the knowledge of the authors, unknown. Purpose To characterize distinctive pulmonary vascular abnormalities at CT and pulmonary artery angiography in patients with and without BMPR2 mutation. Materials and Methods In this retrospective study, chest CT scans, pulmonary artery angiograms, and genetic test data were acquired for patients diagnosed with idiopathic PAH (IPAH) or heritable PAH (HPAH) between January 2010 and December 2021. Perivascular halo, neovascularity, centrilobular ground-glass opacity (GGO), and panlobular GGO were evaluated at CT and graded on a four-point severity scale by four independent readers. Clinical characteristics and imaging features between patients with BMPR2 mutation and noncarriers were analyzed using the Kendall rank-order coefficient and the Kruskal-Wallis test. Results This study included 82 patients with BMPR2 mutation (mean age, 38 years ± 15 [SD]; 34 men; 72 patients with IPAH and 10 patients with HPAH) and 193 patients without the mutation, all with IPAH (mean age, 41 years ± 15; 53 men). A total of 115 patients (42%; 115 of 275) had neovascularity, and 56 patients (20%; 56 of 275) had perivascular halo at CT, and so-called frost crystals were observed on pulmonary artery angiograms in 14 of 53 (26%) patients. Compared with patients without BMPR2 mutation, patients with BMPR2 mutation more frequently showed two distinctive radiographic manifestations, perivascular halo and neovascularity (38% [31 of 82] vs 13% [25 of 193] in perivascular halo [P < .001] and 60% [49 of 82] vs 34% [66 of 193] in neovascularity [P < .001], respectively). "Frost crystals" were more frequent in patients with BMPR2 mutation compared with noncarriers (53% [10 of 19] vs 12% [four of 34]; P < .01). Severe perivascular halo frequently coexisted with severe neovascularity in patients with BMPR2 mutation. Conclusion Patients with PAH with BMPR2 mutation showed distinctive features at CT, specifically perivascular halo and neovascularity. This suggested a link between the genetic, pulmonary, and systemic manifestations that underly the pathogenesis of PAH. © RSNA, 2023 Supplemental material is available for this article.

Jin He

Papers

Challenges in Compact Modeling for RF and Microwave Applications

Weakly-Coupled Few-Mode Gain-Flattening Filter Using Long-Period Fiber Grating in Double-Cladding FMF

Management of Postoperative Myocardial Injury After Non-cardiac Surgery in Patients Aged ≥ 80 Years: Our 10 Years' Experience

Optimized Solutions of Electrocardiogram Lead and Segment Selection for Cardiovascular Disease Diagnostics

Imaging Features in BMPR2 Mutation-associated Pulmonary Arterial Hypertension.