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"Ding Lin, Ding Lin"
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Design of a Compact Multiband Monopole Antenna with MIMO Mutual Coupling Reduction
In this article, the authors present the design of a compact multiband monopole antenna measuring 30 × 10 × 1.6 mm3, which is aimed at optimizing performance across various communication bands, with a particular focus on Wi-Fi and sub-6G bands. These bands include the 2.4 GHz band, the 3.5 GHz band, and the 5–6 GHz band, ensuring versatility in practical applications. Another important point is that this paper demonstrates effective methods for reducing mutual coupling through two meander slits on the common ground, resembling a defected ground structure (DGS) between two antenna elements. This approach achieves mutual coupling suppression from −6.5 dB and −9 dB to −26 dB and −13 dB at 2.46 GHz and 3.47 GHz, respectively. Simulated and measured results are in good agreement, demonstrating significant improvements in isolation and overall multiple-input multiple-output (MIMO) antenna system performance. This research proposes a compact multiband monopole antenna and demonstrates a method to suppress coupling in multiband antennas, making them suitable for internet of things (IoT) sensor devices and Wi-Fi infrastructure systems.
Journal Article
Negative association of C-reactive protein-albumin-lymphocyte index (CALLY index) with all-cause and cause-specific mortality in patients with cancer: results from NHANES 1999–2018
Background
The CALLY index, which is derived from C-reactive protein (CRP) content, serum albumin level, and total lymphocyte count, reflects the immune, nutritional, and inflammatory status of the body. Lack of sufficient evidence on the correlation between the CALLY index and the prognosis of cancer patients with various cancer forms. This study seeks to elucidate the association between the CALLY index and mortality from all causes as well as specific causes in cancer patients within a U.S. population.
Methods
This investigation encompassed 3511 cancer-afflicted adults from the National Health and Nutritional Examination Surveys (NHANES) spanning 1999 to 2018. The CALLY index was measured at baseline only. The relationship between the CALLY index and mortality from both all causes and cancer specifically was examined using Cox proportional hazards models. Additionally, restricted cubic spline, piecewise linear regression, and various subgroup and sensitivity analyses were employed.
Results
Over a median follow-up of 103 months, 1,355 deaths occurred, and the incidence of all-cause mortality for these participants was 38.34%. Our findings indicate that an elevated CALLY index correlates with a diminished risk of all-cause mortality. Upon applying a natural logarithmic transformation to the CALLY index, the comprehensively adjusted model revealed that each one-unit increment in ln CALLY corresponded to a 18% decrease in all-cause mortality risk among cancer patients (HR = 0.82, 95% CI:0.79–0.86). Analyses of mortality due to cardiac and cancer-related causes yielded consistent results, which were robust across various subgroup and sensitivity analyses.
Conclusion
The CALLY index demonstrated a linear and negative association with all-cause mortality, as well as mortality caused by cancer and cardiac conditions, highlighting its significant prognostic value in patients with oncological conditions.
Journal Article
A Review of Critical Issues in High-Speed Vat Photopolymerization
Vat photopolymerization (VPP) is an effective additive manufacturing (AM) process known for its high dimensional accuracy and excellent surface finish. It employs vector scanning and mask projection techniques to cure photopolymer resin at a specific wavelength. Among the mask projection methods, digital light processing (DLP) and liquid crystal display (LCD) VPP have gained significant popularity in various industries. To upgrade DLP and LCC VPP into a high-speed process, increasing both the printing speed and projection area in terms of the volumetric print rate is crucial. However, challenges arise, such as the high separation force between the cured part and the interface and a longer resin refilling time. Additionally, the divergence of the light-emitting diode (LED) makes controlling the irradiance homogeneity of large-sized LCD panels difficult, while low transmission rates of near ultraviolet (NUV) impact the processing time of LCD VPP. Furthermore, limitations in light intensity and fixed pixel ratios of digital micromirror devices (DMDs) constrain the increase in the projection area of DLP VPP. This paper identifies these critical issues and provides detailed reviews of available solutions, aiming to guide future research towards developing a more productive and cost-effective high-speed VPP in terms of the high volumetric print rate.
Journal Article
Uncovering spin-orbit coupling-independent hidden spin polarization of energy bands in antiferromagnets
Many textbook physical effects in crystals are enabled by some specific symmetries. In contrast to such ‘apparent effects’, ‘hidden effect X’ refers to the general condition where the nominal global system symmetry would disallow the effect X, whereas the symmetry of local sectors within the crystal would enable effect X. Known examples include the hidden Rashba and/or hidden Dresselhaus spin polarization that require spin-orbit coupling, but unlike their apparent counterparts are demonstrated to exist in non-magnetic systems even in inversion-symmetric crystals. Here, we discuss hidden spin polarization effect in collinear antiferromagnets without the requirement for spin-orbit coupling (SOC). Symmetry analysis suggests that antiferromagnets hosting such effect can be classified into six types depending on the global vs local symmetry. We identify which of the possible collinear antiferromagnetic compounds will harbor such hidden polarization and validate these symmetry enabling predictions with first-principles density functional calculations for several representative compounds. This will boost the theoretical and experimental efforts in finding new spin-polarized materials.
A hidden effect can occur in materials where locally a symmetry is broken, even though global symmetry is preserved. An example is hidden spin-polarization, arising from local inversion symmetry breaking in otherwise globally centro-symmetric materials. Here, Yuan et al uncover a hidden spin-polarization that can occur in antiferromagnets without spin-orbit coupling and identify the key material requirements for this to occur.
Journal Article
Non-Contact Monitoring and Classification of Breathing Pattern for the Supervision of People Infected by COVID-19
During the pandemic of coronavirus disease-2019 (COVID-19), medical practitioners need non-contact devices to reduce the risk of spreading the virus. People with COVID-19 usually experience fever and have difficulty breathing. Unsupervised care to patients with respiratory problems will be the main reason for the rising death rate. Periodic linearly increasing frequency chirp, known as frequency-modulated continuous wave (FMCW), is one of the radar technologies with a low-power operation and high-resolution detection which can detect any tiny movement. In this study, we use FMCW to develop a non-contact medical device that monitors and classifies the breathing pattern in real time. Patients with a breathing disorder have an unusual breathing characteristic that cannot be represented using the breathing rate. Thus, we created an Xtreme Gradient Boosting (XGBoost) classification model and adopted Mel-frequency cepstral coefficient (MFCC) feature extraction to classify the breathing pattern behavior. XGBoost is an ensemble machine-learning technique with a fast execution time and good scalability for predictions. In this study, MFCC feature extraction assists machine learning in extracting the features of the breathing signal. Based on the results, the system obtained an acceptable accuracy. Thus, our proposed system could potentially be used to detect and monitor the presence of respiratory problems in patients with COVID-19, asthma, etc.
Journal Article
Efficacy and safety of early prone positioning combined with HFNC or NIV in moderate to severe ARDS: a multi-center prospective cohort study
Background
Previous studies suggest that prone positioning (PP) can increase PaO
2
/FiO
2
and reduce mortality in moderate to severe acute respiratory distress syndrome (ARDS). The aim of our study was to determine whether the early use of PP combined with non-invasive ventilation (NIV) or high-flow nasal cannula (HFNC) can avoid the need for intubation in moderate to severe ARDS patients.
Methods
This prospective observational cohort study was performed in two teaching hospitals. Non-intubated moderate to severe ARDS patients were included and were placed in PP with NIV or with HFNC. The efficacy in improving oxygenation with four support methods—HFNC, HFNC+PP, NIV, NIV+PP—were evaluated by blood gas analysis. The primary outcome was the rate of intubation.
Results
Between January 2018 and April 2019, 20 ARDS patients were enrolled. The main causes of ARDS were pneumonia due to influenza (9 cases, 45%) and other viruses (2 cases, 10%). Ten cases were moderate ARDS and 10 cases were severe. Eleven patients avoided intubation (success group), and 9 patients were intubated (failure group). All 7 patients with a PaO
2
/FiO
2
< 100 mmHg on NIV required intubation. PaO
2
/FiO
2
in HFNC+PP were significantly higher in the success group than in the failure group (125 ± 41 mmHg vs 119 ± 19 mmHg,
P
= 0.043). PaO
2
/FiO
2
demonstrated an upward trend in patients with all four support strategies: HFNC < HFNC+PP ≤ NIV < NIV+PP. The average duration for PP was 2 h twice daily.
Conclusions
Early application of PP with HFNC, especially in patients with moderate ARDS and baseline SpO
2
> 95%, may help avoid intubation. The PP was well tolerated, and the efficacy on PaO
2
/FiO
2
of the four support strategies was HFNC < HFNC+PP ≤ NIV < NIV+PP. Severe ARDS patients were not appropriate candidates for HFNC/NIV+PP.
Trial registration
ChiCTR,
ChiCTR1900023564
. Registered 1 June 2019 (retrospectively registered)
Journal Article
Theoretical perspectives of quantitative physics education research
The notion of quantitative physics education research (PER) so far has been mostly limited to the mere use of statistical methods or use of computational tools for analyzing numerical data. Little attention, in fact, has been given to the underpinnings of this research paradigm. To fill the gap, this theoretical paper addresses key and yet often tacit (or even misunderstood) principles of three commonly used quantitative genres in PER, which I, respectively, refer to as measurement (quantification of individual constructs), controlled exploration of relations (quantification of relationships between multiple constructs through controlled experiments), and data mining (quantification of new information from large datasets). For each genre, I elucidate the paradigmatic basis by focusing on its ontological assumptions (theories about the reality under quantitative investigation), epistemological commitments (views about the knowledge gained through quantitative investigation), and methodological implications for empirical investigations. Although framed in the context of physics education research, the discussions herein are applicable to other discipline-based or general education research employing quantitative methods. [This paper is part of the Focused Collection on Quantitative Methods in PER: A Critical Examination.]
Journal Article
Processes of initial collision and suturing between India and Asia
The initial collision between Indian and Asian continents marked the starting point for transformation of land-sea thermal contrast,uplift of the Tibet-Himalaya orogen,and climate change in Asia.In this paper,we review the published literatures from the past 30 years in order to draw consensus on the processes of initial collision and suturing that took place between the Indian and Asian plates.Following a comparison of the different methods that have been used to constrain the initial timing of collision,we propose that the tectono-sedimentary response in the peripheral foreland basin provides the most sensitive index of this event,and that paleomagnetism presents independent evidence as an alternative,reliable,and quantitative research method.In contrast to previous studies that have suggested collision between India and Asia started in Pakistan between ca.55 Ma and50 Ma and progressively closed eastwards,more recent researches have indicated that this major event first occurred in the center of the Yarlung Tsangpo suture zone（YTSZ） between ca.65 Ma and 63 Ma and then spreading both eastwards and westwards.While continental collision is a complicated process,including the processes of deformation,sedimentation,metamorphism,and magmatism,different researchers have tended to define the nature of this event based on their own understanding,an intuitive bias that has meant that its initial timing has remained controversial for decades.Here,we recommend the use of reconstructions of each geological event within the orogenic evolution sequence as this will allow interpretation of collision timing on the basis of multidisciplinary methods.
Journal Article
Direct bandgap emission from strain-doped germanium
Germanium (Ge) is an attractive material for Silicon (Si) compatible optoelectronics, but the nature of its indirect bandgap renders it an inefficient light emitter. Drawing inspiration from the significant expansion of Ge volume upon lithiation as a Lithium (Li) ion battery anode, here, we propose incorporating Li atoms into the Ge to cause lattice expansion to achieve the desired tensile strain for a transition from an indirect to a direct bandgap. Our first-principles calculations show that a minimal amount of 3 at.% Li can convert Ge from an indirect to a direct bandgap to possess a dipole transition matrix element comparable to that of typical direct bandgap semiconductors. To enhance compatibility with Si Complementary-Metal-Oxide-Semiconductors (CMOS) technology, we additionally suggest implanting noble gas atoms instead of Li atoms. We also demonstrate the tunability of the direct-bandgap emission wavelength through the manipulation of dopant concentration, enabling coverage of the mid-infrared to far-infrared spectrum. This Ge-based light-emitting approach presents exciting prospects for surpassing the physical limitations of Si technology in the field of photonics and calls for experimental proof-of-concept studies.
The authors proposed a Silicon technology-compatible approach to convert Germanium from an indirect bandgap to a direct bandgap via doping. This is done to expand the lattice to produce tunable effective tensile strain, aiming towards the on-chip light sources.
Journal Article