bluuebunny/crossref_metadata_2025 huggingface dataset:
Association between polymorphisms of folate- and methionine-metabolizing enzymes and susceptibility to malignant lymphoma
Authors: Matsuo Keitaro , Suzuki Ritsuro , Hamajima Nobuyuki , Ogura Michinori , Kagami Yoshitoyo , Taji Hirofumi , Kondoh Eisei , Maeda Satoko , Asakura Shoji , Kaba Sadayuki , Nakamura Shigeo , Seto Masao , Morishima Yasuo , Tajima Kazuo
Published: July 2002

Genetic alteration is considered a probable cause of malignant lymphoma. Folate and methionine metabolism play essential roles in DNA synthesis and DNA methylation, and their metabolic pathways might thus affect disease susceptibility. In the present study, 2 polymorphisms were evaluated for a folate metabolic enzyme, methylenetetrahydrofolate reductase (MTHFR), and one was evaluated for methionine synthase (MS). The 2 polymorphisms, MTHFR677 C→T and MTHFR1298 A→C, are reported to reduce the enzyme activity, which causes intracellular accumulation of 5,10-methylenetetrahydrofolate and results in a reduced incidence of DNA double-strand breakage. The MS2756 A→G polymorphism also reduces the enzyme activity and results in the hypomethylation of DNA. To evaluate the association between malignant lymphoma susceptibility and these polymorphisms, hospital-based case-control study was conducted in Aichi Cancer Center. Ninety-eight patients with histologically confirmed lymphoma and 243 control subjects without cancer were evaluated. Unconditional logistic regression analyses revealed a higher susceptibility with the MTHFR677 CC and the MTHFR1298 AA genotypes (odds ratio, 2.26; 95% confidence interval, 1.26-4.02) when those harboring at least one variant allele in either polymorphism of MTHFR were defined as the reference. For the MS polymorphism, the MS2756 GG genotype also showed a higher susceptibility (odds ratio, 3.83; 95% CI, 1.21-12.1) than those with MS2756 AA or AG types. The significance was not altered when these 3 polymorphisms were evaluated in combination, and the results suggest that folate and methionine metabolism play important roles in the occurrence of malignant lymphomas. Further studies to confirm the association and detailed biologic mechanisms are now required.
Nonablative neonatal marrow transplantation attenuates functional and physical defects of β-glucuronidase deficiency
Authors: Soper Brian W. , Lessard Mark D. , Vogler Carole A. , Levy Beth , Beamer Wesley G. , Sly William S. , Barker Jane E.
Published: July 2002

The toxicity of preparative regimens render neonatal bone marrow transplantation (BMT) for progressive childhood diseases a controversial treatment. Ablative BMT in neonatal mice with or without the lysosomal storage disease mucopolysaccharidosis type VII (MPS VII) show high morbidity and developmental disruption of both brain and bone structure. In this investigation, BMT was performed with a high dose of congenic, normal bone marrow into nonablated newborn mice. Recipients had lifelong, multilineage, peripheral blood chimerism with the donor β-glucuronidase-positive (GUS+) cells that was both well tolerated and therapeutic. Three daily injections of normal adult marrow increased the average life span by at least 6 months and corrected the functional breeding deficits typical of the MPS VII mice. Twelve months after injection, several structural features of femurs were more like that of normal mice than of untreated MPS VII mice. Periosteal circumference and bone cortical thickness were significantly improved in males and cortical density did not differ significantly from values in normal females. Significant reduction of lysosomal glycosaminoglycan storage corresponded directly with GUS enzyme activity and percentage of histochemically GUS+ cells in visceral organs and hematopoietic tissues such as thymus, spleen, peripheral blood, and bone marrow. By all criteria tested, BMT into neonatal MPS VII mice in the absence of any preparative regimen is a successful therapy.
Asymmetrical segregation of chromosomes with a normal metaphase/anaphase checkpoint in polyploid megakaryocytes
Authors: Roy Lydia , Coullin Philippe , Vitrat Natacha , Hellio Raymond , Debili Najet , Weinstein Jasminder , Bernheim Alain , Vainchenker William
Published: July 2002

During differentiation, megakaryocytes increase ploidy through a process called endomitosis, whose mechanisms remain unknown. As it corresponds to abortive mitosis at anaphase and is associated with a multipolar spindle, investigation of chromosome segregation may help to better understand this cell-cycle abnormality. To examine this variation, a new method was developed to combine primed in situ labeling to label centromeres of one chromosome category and immunostaining of tubulin. Human megakaryocytes were obtained from normal bone marrow culture. By confocal microscopy, this study demonstrates an asymmetrical distribution of chromosomes (1 or 7) either between the spindle poles at anaphase stage of endomitosis and between the different lobes of interphase megakaryocyte nuclei. The metaphase/anaphase checkpoint appears normal on the evidence that under nocodazole treatment megakaryocytes progressively accumulate in pseudo-metaphase, without spontaneous escape from this blockage. Immunostaining of p55CDC/hCDC20 with similar kinetochore localization and dynamics as during normal mitosis confirms this result. HCdh1 was also expressed in megakaryocytes, and its main target, cyclin B1, was normally degraded at anaphase, suggesting that the hCdh1-anaphase–promoting complex checkpoint was also functional. This study found the explanation for these unexpected results of an asymmetrical segregation coupled to normal checkpoints by careful analysis of multipolar endomitotic spindles: whereas each aster is connected to more than one other aster, one chromosome may segregate symmetrically between 2 spindle poles and still show asymmetrical segregation when the entire complex spindle is considered.
Platelet/polymorphonuclear leukocyte adhesion: a new role for SRC kinases in Mac-1 adhesive function triggered by P-selectin
Authors: Piccardoni Paola , Sideri Rita , Manarini Stefano , Piccoli Antonio , Martelli Nicola , de Gaetano Giovanni , Cerletti Chiara , Evangelista Virgilio
Published: July 2002

Adhesion of polymorphonuclear leukocytes (PMNLs) to activated platelets requires a P-selectin–triggered, tyrosine kinase–dependent adhesiveness of Mac-1 and is accompanied by tyrosine phosphorylation of a 110-kd protein (P-110) in PMNLs. Inhibitors of SRC tyrosine kinases were found to inhibit PMNL adhesion to activated platelets or to P-selectin expressing Chinese hamster ovary (CHO-P) cells and the tyrosine phosphorylation of P-110. Adhesion of PMNLs to activated platelets or to CHO-P cells stimulated activity of LYN and HCK. Monoclonal antibody blockade of P-selectin or β2-integrins reduced the activation of both kinases. In PMNLs either adherent to platelets or aggregated by P-selectin–IgG chimera, Mac-1 was rapidly redistributed to the Triton X-100–insoluble cytoskeletal fraction, and large clusters of Mac-1 colocalized with patches of F-actin at the sites of cell-cell contact. In PMNLs stimulated by P-selectin–IgG chimera, SRC kinase inhibition impaired Mac-1 clustering, F-actin accumulation, and CD18 redistribution to the cytoskeleton. Disruption of the actin filament network by cytochalasin D prevented PMNL-platelet adhesion and P-selectin–induced PMNL aggregation and impaired the clustering of Mac-1. In agreement with the requirement for the β2-integrin in the functional up-regulation of LYN and HCK, integrin blockade by monoclonal antibodies resulted in a complete inhibition of P-selectin–induced Mac-1 clustering and F-actin accumulation. Taken together, the results indicate that, after an initial P-selectin–triggered β2-integrin interaction with the ligand, SRC kinases are activated and allow the remodeling of cytoskeleton-integrin linkages and integrin clustering that finally strengthen cell-cell adhesion. This model highlights a new role for SRC kinases in a regulatory loop by which the Mac-1 promotes its own adhesive function.
Membrane localization is not required for Mpl function in normal hematopoietic cells
Authors: Otto Kevin G. , Broudy Virginia C. , Lin Nancy L. , Parganas Evan , Luthi Jennifer N. , Drachman Jonathan G. , Ihle James N. , Blau C. Anthony
Published: July 2002

Cellular trafficking of growth factor receptors, including cross-talk among receptors at the cell surface, may be important for signal transduction in normal hematopoietic cells. To test this idea, the signaling domain of Mpl (the thrombopoietin receptor) was targeted to the plasma membrane, or to the cytoplasm of murine marrow cells, and the ability of the cells to proliferate and differentiate in response to Mpl dimerized at the plasma membrane or free in the cytoplasm was assessed. Constructs encoding the signaling domain of Mpl linked to an FK506 binding protein domain (to permit dimerization by the membrane-permeable ligand AP20187) with or without a myristylation sequence (to target the receptor to the plasma membrane) and a hemagglutinin epitope tag were generated and introduced into murine marrow cells using a murine stem cell virus (MSCV)-based retroviral vector. Both populations of transduced marrow cells proliferated in Iscoves modified Dulbecco medium–10% FCS–100 nM AP20187 without exogenous growth factors for more than 100 days and achieved greater than a 107-fold expansion of cells by day 50 (n = 4 transductions). Growth was dimerizer dependent, and myeloid, erythroid, and megakaryocytic progenitors were generated. Activation of Mpl either at the plasma membrane or in the cytoplasm allowed for the terminal maturation of transduced progenitor cells. Introduction of membrane-targeted or cytoplasmic Mpl into fetal liver cells from homozygous JAK2 knock-out mice or wild-type littermates demonstrated that both forms of Mpl require JAK2 for signaling. These data show that the activation of Mpl independent of its normal plasma membrane location can support production of the full range of normal hematopoietic progenitor cells in vitro.
Identification of a candidate human neurohematopoietic stem-cell population
Authors: Shih Chu-Chih , Weng Yehua , Mamelak Adam , LeBon Thomas , Hu Mickey C.-T. , Forman Stephen J.
Published: July 2002

It was recently reported that transplantation of clonally derived murine neurosphere cells into sublethally irradiated allogeneic hosts leads to a donor-derived hematopoietic reconstitution. The confirmation of the existence of a common neurohematopoietic stem cell in the human brain will have a significant effect on stem cell research and on clinical transplantation. Here, it is demonstrated that the human fetal brain contains separate but overlapping epidermal growth factor (EGF)–responsive and basic fibroblast growth factor (FGF-2)–responsive neural stem cells. The majority (> 85%) of cells within these EGF- and/or FGF-2–generated neurospheres express characteristic neural stem/progenitor cell markers including nestin, EGF receptor, and FGF-2 receptor. These neural stem cells can be continuously passaged in vitro, and demonstrate a constant 20-fold expansion in every passage for up to the fifth passage (the longest period that has been carried out in the authors' laboratory). These neural stem cells are multipotential for neurons, astrocytes, and oligodendrocytes. After transplantation into SCID-hu mice, all neural stem cells, regardless of passages, culture conditions, and donors, are able to establish long-term hematopoietic reconstitution in the presence of an intact human bone marrow microenvironment.
Secretion of a unique peptide from interleukin-2–stimulated natural killer cells that induces endomitosis in immature human megakaryocytes
Authors: Angchaisuksiri Pantep , Grigus Shawn R. , Carlson Patricia L. , Krystal Geoffrey W. , Dessypris Emmanuel N.
Published: July 2002

When interleukin-2 (IL-2) was added to immature, low-ploidy (greater than 80% 2N+4N) megakaryocytes generated in IL-3 and stem cell factor (SCF)–containing liquid cultures of blood mononuclear cells highly enriched in hematopoietic progenitors, a 2- to 6-fold increase in the absolute number of polyploid (more than 8N) megakaryocytes was noted. This effect was found to be indirect and was mediated through natural killer (NK) cells that constitute the major lymphoid cell contaminating day 6 megakaryocyte cell populations. IL-2 had no effect on megakaryocytes generated from CD34+ cells stimulated with IL-3 and SCF. However, medium conditioned by IL-2–stimulated, but not resting, NK cells (NKCM) contained a trypsin-sensitive factor capable of increasing 2- to 5-fold the number of polyploid megakaryocytes generated in vitro from IL-3 and SCF-stimulated CD34+ cells. The activity in NKCM was dose dependent and could not be neutralized by an excess of antibodies to IL-6, IL-11, leukemia inhibitory factor (LIF), gp130, stromal cell derived factor-1a (SDF-1a), and thrombopoietin (TPO). Addition of IL-11, but not TPO, to NKCM-containing cultures resulted in further augmentation of polyploidy, with the generation of 50% to 70% polyploid megakaryocytes with a modal ploidy of 16N. This factor is distinct from TPO because it induces endomitosis in IL-3–generated megakaryocytes in vitro, whereas TPO does not, and its activity on megakaryocyte ploidy is not altered by optimal concentrations of TPO. In addition, no message for TPO is detectable in IL-2–stimulated NK cells by reverse transcription–polymerase chain reaction. These findings indicate that IL-2–stimulated NK cells produce a novel peptide, distinct from TPO, IL-6, IL-11, LIF, other gp130-associated interleukins, and SDF1a, that can induce in vitro endomitosis in immature human megakaryocytes in the presence of IL-3 and SCF.
Missense mutations in the β3 subunit have a different impact on the expression and function between αIIbβ3 and αvβ3
Authors: Tadokoro Seiji , Tomiyama Yoshiaki , Honda Shigenori , Kashiwagi Hirokazu , Kosugi Satoru , Shiraga Masamichi , Kiyoi Teruo , Kurata Yoshiyuki , Matsuzawa Yuji
Published: July 2002

αIIbβ3 and αvβ3 belong to the β3integrin subfamily. Although the β3 subunit is a key regulator for the biosynthesis of β3 integrins, it remains obscure whether missense mutations in β3 may induce the same defects in both αIIbβ3 and αvβ3. In this study, it is revealed that thrombasthenic platelets with a His280Pro mutation in β3, which is prevalent in Japanese patients with Glanzmann thrombasthenia, did contain significant amounts of αvβ3 (about 50% of control) using sensitive enzyme-linked immunosorbent assay. Expression studies showed that the His280Proβ3 mutation impaired αIIbβ3 expression but not αvβ3 expression in 293 cells. To extend these findings, the effects of several β3 missense mutations leading to an impaired αIIbβ3expression on αvβ3 function as well as expression was examined: Leu117Trp, Ser162Leu, Arg216Gln, Cys374Tyr, and a newly created Arg216Gln/Leu292Ser mutation. Leu117Trp and Cys374Tyr β3 mutations did impair αvβ3 expression, while Ser162Leu, Arg216Gln, and Arg216Gln/Leu292Ser mutations did not. With regard to ligand binding function, Ser162Leu mutation induced especially distinct effects between 2 β3 integrins: it markedly impaired ligand binding to αIIbβ3 but not to αvβ3 at all. These data clearly demonstrate that the biosynthesis and the ligand binding function of αIIbβ3 and those of αvβ3 are regulated in part by different mechanisms. Present data would be a clue to elucidate the regulatory mechanism of expression and function of β3 integrins.
Conformal Antennas
Authors: Sengupta Dipak L.
Published: November 2024

Specifically, this article describes the following:

The specific considerations that must be given to the performance of basic slot and microstrip or patch antenna elements when mounted on nonplanar conducting surfaces

A selected number of conformal antennas: for example, microstrip conformal antennas and dielectric‐filled edge slot (DFES) antennas

A class of wraparound antennas and antenna arrays

Cylindrical and spherical phased arrays used for omnidirectional and hemispherical coverage, respectively.
Electromagnetic Surface Waves
Authors: Wu Zhipeng
Published: November 2024

In this article, the electromagnetic surface waves propagating along an interface between two dielectric media or an interface between air and a multilayered structure in planar, cylindrical, and spherical geometries are introduced. Specific surface waves considered are (1) the Zenneck surface wave, (2) the surface wave on a conductor‐backed dielectric slab, (3) the radial cylindrical surface wave on a flat surface, (4) the axial cylindrical surface wave, (5) the surface wave on a dielectric‐coated conducting cylindrical, (6) Norton and trapped surface waves on flat ground interface, (7) surface‐wave propagation over an inhomogeneous flat surface, and (8) surface‐wave propagation over a spherical ground. Several examples are given to illustrate the propagation of surface waves in these geometric structures. The surface waves propagating along Earth's surface have been used for wireless communications and remote sensing. On the other hand, the surface waves on conductor‐backed dielectric slabs become a problem in microwave printed circuits and microstrip antenna systems. The understanding and control of surface waves are therefore important in radio systems.
Electromagnetic Waves in Ionosphere
Authors: Hunsucker Robert D.
Published: November 2024

Since the existence of the ionosphere was confirmed in 1925 using radio techniques, we have gained a good understanding of the basic physics and morphology of the solar–terrestrial environment. In this article we summarize the basic physics of the ionosphere and of the interaction of radiowaves with the ionosphere. The fundamental mechanisms of the various radio propagation modes and the effects of solar radiation and noise are described for specific radio services. The principal radio techniques for probing the ionosphere and “frontiers of ionospheric research” are summarized. Three of the principal journals that publish research in the subject of this article areRadio ScienceandJournal of Geophysical Research-Space Physics(published by the American Geophysical Union) andTransactions of the IEEE Group on Antennas and Propagation(published by the Institute of Electrical and Electronic Engineers).
Radio Direction Finding
Authors: Johnson Richard L. , Hipp Jackie E. , Sherrill William M.
Published: November 2024

Radio direction finding (DF) is a technique for estimating radiowave angle of arrival (AoA) and is based on prior knowledge of the antenna responses versus AoA.

Traditional DF systems exploit rotating antennas or sampled antenna arrays for which the antenna response patterns are very carefully controlled to provide support for closed‐form DF solutions or for the development of steered beams. Sources contributing to DF errors include local scattering, instrumentation, and propagation. Some more recent DF systems exploit array calibration and digital beamforming techniques to provide reliable AoA estimates while accomodating local scattering. Both of these DF system categories are designed for operation against single component plane waves. More sophisticated DF systems now exploit sampled arrays and DF processing to decompose the complex wavefields created by multiple simultaneous signal components.
Packaging RF Devices and Modules
Authors: Lee Y. C. , Zhang Wenge , Su Bingzhi , Feng Zhiping , Gupta K. C.
Published: November 2024

RF packaging technologies are advancing rapidly. This article provides basic knowledge to understand the technology advances. Most packaging issues common to those for microelectronics packaging will not be covered here, and they can be found in other articles. The following sections will focus on unique issues for RF packaging. Representative packages and assembly technologies will be reviewed. Critical consideration of RF performance and reliability will be introduced. The reliability section will cover both thermal management and mechanical integrity. A case study will be presented to illustrate a typical design procedure considering various factors. In addition, computer‐aided‐design (CAD) issues and advanced packaging concepts will be introduced, to understand future challenges.
MEI Method
Authors: Mei Kenneth K.
Published: November 2024

The basic principles of the measured equation of invariance (MEI) are presented. To apply the method, one needs to have fundamental knowledge of the finite difference and the integral representation of Maxwell's equations. The details of the formulas needed for solving specific problems are all contained in the cited references, so they are not included in this article. The purpose of this article is to inform the readers of the assumptions and reasoning of the method, the misgivings expressed by other researchers, what type of problems have already been solved by the method, and the latest developments in this method.
Magnetic Shielding
Authors: Fugate David W. , Young Frank S.
Published: November 2024

In traditional usage,
magnetic shielding
refers specifically to shields made of
magnetic
materials like iron and nickel. However, this article is more general because it covers not just traditional magnetic shielding but also shielding of alternating magnetic fields with conducting materials, such as copper and aluminum. In typical applications, shielding eliminates magnetic field interference with electron microscopes, computer displays (CRTs), sensitive electronics, or other devices affected by magnetic fields.
Generalized Scattering Matrix Technique
Authors: Monorchio Agostino , Mittra Raj , Manara Giuliano
Published: November 2024

The generalized scattering matrix (GSM) technique, which is a convenient method for analyzing complex microwave devices, consisting of separable and longitudinally uniform waveguiding structures, is presented in this article. GSM differs from the conventional scattering matrix used in circuit theory or microwave network theory in that it is extended to consider evanescent as well as propagating modes in each waveguide. Some numerical examples are provided to illustrate the importance of the inclusion of higher‐order modes for generating accurate solutions of waveguide discontinuity problems.
Magnetrons
Authors: Osepchuk John M. , Ruden Thomas E.
Published: November 2024

The magnetron has survived in an era when most electron tubes have been replaced by solid‐state devices in modern electronic systems.

A wide spectrum of related devices are being developed for specialized applications. These include crossed‐field amplifiers, voltage‐tuned magnetrons, beacon magnetrons, and relativistic magnetrons. Applications range from the classical radar through industrial heating to microwave weapons.

Future applications remain unpredictable, but many are being explored. Advances in computer modeling will eventually produce success.
Q‐Factor Measurements
Authors: Luiten Andre
Published: November 2024

This article presents a review of both traditional and modern methods ofQfactor measurement. Many of the techniques to be described were first developed in order to determine theQfactors of resonances falling in the microwave frequency domain.

The article commences with a definition of theQfactor and a description of the experimental parameters that need to be measured so as to determine theQfactor of resonance. The various methods for measuring these parameters will then be outlined, including the particular advantages and disadvantages of a technique, the equipment required for the measurement, and its potential for accuracy. Finally, some of the latest developments in the field ofQmeasurement will be presented.
Six‐Port Networks
Authors: Xu Xinyu , Wu Ke , Bosisio Renato G.
Published: November 2024

Software‐defined radio (SDR) has been identified as a potential method to enhance flexible wireless communication systems. The operation speed of an analog/digital converter (ADC) and processing ability of digital signal processing (DSP) chips are key factors in the development of SDR for useful commercial applications. More recent advances in semiconductor processing technology and the development of reconfigurable devices such as digital signal processors and field‐programmable gate arrays (FPGAs) reduce the development time of commercial products. SDR in conjunction with six‐port receivers has promising applications for use in wireless LANs, audio and television broadcasting, and interoperability between different radio services, as seen by new studies on the use of six‐port technology in various design aspects of a new SDR receiver. The objective is to realize an application of SDR to provide a multichannel, multimode wireless direct digital receiver.

The combination of SDR and six‐port technology provides great flexibility in system configuration; significant reduction in hardware cost, particularly at millimeter‐wave frequencies; and potential for software reuse. The six‐port receiver approach offers wideband accommodation to ever‐changing communication specifications required in a SDR as much of its functionality is defined in software. Different types of six‐port circuits have been designed, with center frequencies at 2.4, 5.8, 24, and 28 GHz, operating over wide frequency bands. Some six‐port circuits are based on microstrip structures and are fabricated with hybrid microwave integrated circuit (MHMIC) or monolithic microwave integrated circuit (MMIC) technology at both microwave and millimeter‐wave frequencies. Other circuits use a novel substrate‐integrated waveguide (SIW) structure allowing integration of planar integrated circuit structure with waveguide structure. The performances of these six‐port circuits in digital receivers are reported in relation to signal modulation schemes, noise performance analysis calibration, and coding. Bit error rate simulation and measurement results obtained with demodulation algorithms are given for QPSK and QAM‐16 signals under a variety of operating conditions. Initial results show promising applications of six‐port technology for direct digital conversion demodulation reception, needed in future low‐cost SDR communication systems. Measurement and simulated demodulation results obtained with coding algorithms are also given.
Artificial Magnetic Conductor
Authors: Diaz Rodolfo E. , Clavijo Sergio A.
Published: November 2024

The artificial magnetic conductor (AMC) is a textured ground plane that presents a high impedance to incident waves and nearby horizontal antennas over a prescribed frequency range. In addition, it suppresses the propagation of both transverse electric (TE) and transverse magnetic (TM) surface waves, thus concentrating the radiation from a horizontal antenna into the upper half‐space. The resulting reduced backlobe and reduced mutual coupling to any other antennas on the same surface, combined with the high input impedance, make the AMC an ideal gain‐enhancing ground plane for ultrathin antennas. It is shown that these desirable features of are derived from the AMC's effective anisotropic magnetodielectric constitutive properties. Analysis and design approaches are given that enable the control of these properties according to the desired frequency and bandwidth of operation and the amount of surface‐wave suppression needed. Examples of the latest applications of AMC are given, as well as a brief history of its inception.
Magnetic Materials
Authors: van Dover Robert B.
Published: November 2024

Since the early part of the twentieth century, magnetic materials have been the subject of deep and broad research and development because of their economic and scientific importance, and much of our knowledge is mature. Nevertheless, startling discoveries continue to be made, such as the discovery of Nd–Fe–B permanent magnets and the “giant magneto‐resistance” effect in thin‐film multilayers.
Microstrip Lines
Authors: Ma Zhewang , Yamashita Eikichi , Atsuki Kazuhiko
Published: November 2024

A microstrip line is a type of open planar transmission line that consists of a dielectric substrate medium with a ground plane on the lower side and a conducting strip on the upper side.

Microstrip line is now one of the most widely used transmission lines for MICs. Active devices (diodes and transistors), lumped circuit elements (capacitors, resistors, inductors), dielectric resonators, and antennas can be easily incorporated into the circuit. Compared with the traditional bulky and heavy metallic waveguides and coaxial lines, the planar microstrip structures are smallsize, lightweight, easy for mass production, and inexpensive.
Microwave Mixers
Authors: Tahim R. S.
Published: November 2024

The frequency conversion function of a mixer plays a critical role in RF and microwave systems in determining their overall performance. For example, the quality of data transmission in the wireless communication systems and the identification of targets using radar and sensor systems are entirely dependent on the mixer performance in the receiver systems. The microwave/millimeter‐wave systems that operate at a number of frequency bands are susceptible to intermodulation frequency products generated in mixers. Spurious signals or distortion in mixers continues to be a problem in virtually all the RF and microwave systems. Therefore, mixers are frequently the dominant components in the receiver in establishing the system's distortion free performance. As a result, microwave and millimeter‐wave mixers have been the subject of continuous research and development for the past several decades and will continue to be the subject of future research in order to make the systems more efficient.
Microwave Phase Shifters
Authors: White Joseph F.
Published: November 2024

This section treats the semiconductor phase shifter. While they could be built using a variety of semiconductors, diodes, and bipolar and field‐effect transistors, the principal development was with silicon pin diodes because of their relatively low cost, high microwave Q, and inherent inertia to changes in characteristics with applied microwave (RF) excitation.
Microwave Receivers
Authors: Bao-Yen Tsui James
Published: November 2024

In this article, intercept microwave receivers will be the main subject because of their similarities in design goals. Intercept receivers are very useful in military applications. Used in electronic warfare (EW), they are often referred to as EW receivers.

This article includes description of a generic receiver, followed by a discussion of the important terminology and definitions used in receiver design.
Surface Acoustic Wave Filters
Authors: Hashimoto Ken-ya , Yamaguchi Masatsune
Published: November 2024

Currently, surface acoustic wave (SAW) filters are widely used in RF stages as well as IF stages of modern telecommunication systems. With successful research and development of SAW devices since the early 1960s, the growth of mobile phone markets has accelerated, with surprising advances in SAW device technologies since the early 1990s. This article discusses how the filtering function of SAW devices is realized using various SAW propagation phenomena, and reviews the performance of current commercial SAW filters. First, SAW transversal filters are discussed. Starting from a brief discussion of their fundamentals, we describe achievable performance, impact of the substrate selection and the most recent advances of this type of filter. Next, filters based on SAW resonators are discussed. After giving basic ideas of SAW resonators, it is shown how SAW resonator filters are composed and designed using SAW resonators.
Transverse Resonance Techniques
Authors: Sorrentino Roberto , Mongiardo Mauro
Published: November 2024

The transverse resonance technique in its various forms is presented and discussed, from the analytical solutions for inhomogeneously filled rectangular waveguides to the conventional approximate solution for transversely discontinuous waveguides (e.g., the ridge waveguide), to the generalized rigorous formulation for waveguide discontinuities and junctions.
Waveguide Directional Couplers
Authors: Levy Ralph
Published: November 2024

Waveguide directional couplers are widely used as power monitors in microwave systems and test equipment. An even more important set of applications makes use of the 90° phase difference between the output signals, making them ideal for antenna feed networks, and as hybrid junctions or couplers for applications in balanced mixers, duplexers, and balanced amplifiers. Their common basic properties are outlined, and the design of the most common and useful types are described, namely, multiaperture and cross‐guide couplers, sidewall and topwall hybrids, and branch‐guide couplers. Modern design techniques based on exact synthesis are emphasized.
Radio on Fiber Systems (RoF Systems)
Authors: Komaki Shozo , Tsukamoto Katsutoshi
Published: November 2024

The radio‐on‐fiber (RoF) system involves the synergetic use of emerging wireless and photonic technologies and has advantages of both wide‐area radio access capability and the low‐loss long‐hop transmission capability of optical fibers simultaneously. Since the RoF system directly converts the RF signal to an optical signal, this system provides universal network solutions that are independent of frequency band and air interface types. In this section, the basic configurations of the RoF system, devices, performance, and present and future applications of networking have been described.
Ultra‐Wideband Wireless Systems
Authors: Donlan Brian M. , Buehrer R. Michael , Reed Jeffery H.
Published: November 2024

This article provides an overview of ultra‐wideband (UWB) wireless systems. System issues are discussed including modulation schemes, pulse shapes, interference issues, and channel characterization. Several communications‐ and radar‐specific implementation issues are also addressed. Much of the description is provided in the context of pulse‐based UWB or impulse radio. Furthermore, a section is dedicated to describing the role of the FCC and how current regulations are shaping UWB. The last section extends this discussion and presents several possible applications, providing examples of each.
Circuit Tuning
Authors: Schaumann Rolf
Published: November 2024

Circuit tuning
refers to the process of adjusting the values of electronic components in a circuit to ensure that the fabricated or manufactured circuit performs to specifications. In digital circuits, where signals are switched functions in the time domain and correct operation depends largely on the active devices switching all the way between their
ON
and
OFF
states, tuning in the sense discussed in this article is rarely necessary. In analog continuous‐time circuits, however, signals are continuous functions of time and frequency so that circuit performance depends critically on the component values. Consequently, in all except the most undemanding applications with wide tolerances, correct circuit operation almost always requires some form of tuning.
Radiotelemetry
Authors: Tsou Haiping , Cheung Kar-ming
Published: November 2024

Radiotelemetry, by definition, is the science and technology of automatically measuring and transmitting data by radio from remote sources, as from space vehicles, to receiving stations for recording and analysis. It involves preparing of data generated at remote sources, transmitting data through radio channels, and processing data at the receiving stations. Behind these three tasks, how to convey the information in a reliable and timely manner through a communication link is the most fundamental problem in this field.
Dynamic Treatment Regimes (Updated)
Authors: Moodie Erica E.M. , Stephens David A.
Published: November 2024

Dynamic treatment regimes describe a class of treatments or interventions, often given sequentially, that are tailored to the clinical, demographic, and related characteristics of an individual patient at the time the treatment is selected. In this article, we introduce dynamic treatment rules and point to important data sources for estimating outcomes under alternative treatment strategies. We also briefly discuss estimation strategies and recent innovations in the field.
An Update on Individual‐Moving Range (IMR) Control Charts
Authors: Knoth Sven
Published: November 2024

In the case that collecting samples with size is often not possible or sometimes not appropriate, the control chart user applies typically individual‐moving range (IMR) schemes. Here we report new results on their monitoring performance in terms of the average run length (ARL). Deploying these numerical algorithms, the IMR chart could be appropriately set up. Finally, the usefulness of adding the MR subchart is (re‐)evaluated.
Robust Statistical Monitoring of a Resistance Spot Welding Process
Authors: Capezza Christian , Centofanti Fabio , Lepore Antonio , Palumbo Biagio
Published: November 2024

Modern datasets are often contaminated with anomalous observations that can seriously decrease the performance of control charting procedures, especially in complex and high‐dimensional settings. To mitigate this issue, we show how to apply in a transparent set of steps a new general framework, named robust multivariate functional control chart (RoMFCC), for the statistical monitoring of a resistance spot welding process in the automotive industry that is robust to functional casewise and cellwise outliers. RoMFCC is implemented in the
R
package
funcharts
, available online on CRAN.
Quadrature Phase Shift Keying (QPSK) with Applications to Six‐Port Technology
Authors: Tatu Serioja O. , Bosisio Renato G.
Published: November 2024

Quadrature phase shift keying (QPSK) is a modulation technique used for sending data over radio or cable networks.

This article presents in detail the QPSK principle, as well as modulators and demodulators, using the conventional approach. A new concept to modulate or demodulate a QPSK signal using the six‐port circuit at microwave/millimeter‐wave frequencies is also presented.

The coherent carrier‐recovery circuit for the demodulation of QPSK signals is an important aspect to be considered. Three regeneration schemes (Costas loop, multiplication loop, and reverse‐modulation loop) are presented.

The probability of error for QPSK in the presence of noise is derived using the equations of I‐ and Q‐demodulated signals.
Impact of belly board immobilization devices and body mass factor on setup displacement using daily cone‐beam CT in rectal cancer radiotherapy
Authors: Ruan Junjie , Huang Xiaotong , Wang Tong , Mai Xiuying , Lin Chuyan , Li Fanghua , Li Yunfeng , Chi Feng , Li Bin
Published: November 2024

Objective

The objective of this study is to evaluate the impact of different belly board and daily changes in patient's body‐mass factor (BMF) on setup displacement in radiotherapy for rectal cancer.

Methods

Twenty‐five patients were immobilized using the thermoplastic mask with belly board (TM‐BB), and 30 used the vacuum bag cushion with belly board (VBC‐BB), performing daily cone‐beam computed tomography (CBCT) scans 625 times and 750 times, respectively. Daily pretreatment CBCT scans were registered to the planned CT images for BMF change determination and setup displacement measurement. Independent t‐tests compared setup displacement between the two groups in left‐right (LR), superior‐inferior (SI), and anterior‐posterior (AP) directions, as well as the BMF changes. The impact of daily BMF changes on setup displacement was evaluated using multivariate logistic regression and 10‐fold cross‐validation.

Results

The setup displacement for TM‐BB in the LR, SI, and AP directions were 0.31 ± 0.25, 0.58 ± 0.40, and 0.19 ± 0.18 cm, respectively, while VBC‐BB showed 0.19 ± 0.15, 0.26 ± 0.22, and 0.36 ± 0.29 cm in the corresponding directions, respectively. Margins of planning target volume (PTV) for TM‐BB were 8, 10, and 6 mm in LR, SI, and AP directions, while VBC‐BB showed margins of 5,7, and 8 mm, respectively. The daily BMF changes for both groups were ranked in descending order as follows: sacral rotation angle (RS), hip lateral diameter (HLD), and hip anterior‐posterior diameter (HAPD). HAPD was the main factor affecting setup displacement in both the AP and SI directions in TM‐BB, while RS was the primary factor for setup displacement in the AP direction in VBC‐BB.

Conclusion

Compared with TM‐BB, VBC‐BB had a larger AP displacement but smaller in LR and SI displacement. Daily changes in BMF have distinct effects on setup displacement in different immobilization devices. Image‐guided radiation therapy (IGRT) is highly recommended and BMF changes should be given consideration during radiotherapy.
Clinical use of Gafchromic EBT4 film for in vivo dosimetry for total body irradiation
Authors: Draeger Emily , Guan Fada , Lee Min‐Young , Han Dae Yup , Donahue William , Chen Zhe (Jay)
Published: November 2024

Purpose

In vivo dosimetry is a common requirement to validate dose accuracy/uniformity in total body irradiation (TBI). Several detectors can be used for in vivo dosimetry, including thermoluminescent dosimeters (TLDs), diodes, ion chambers, optically stimulated luminescent dosimeters (OSLDs), and film. TLDs are well established for use in vivo but required expertise and clinical system availability may make them impractical for multifractionated TBI. OSLDs offer quick readout, but recalls have restricted their use. The purpose of this work was to validate the newly available Gafchromic EBT4 film for TBI in vivo dosimetry.

Methods

Film calibration curves were created under standard conditions (6MV/15MV, 1.5/3.0 cm depth, 100 cm source‐to‐surface distance (SSD), 10 × 10 cm2 field), and films were scanned at several time points (0.5–24 h) to determine the shortest development time that yielded accurate dose measurements. 4 × 4 cm2 films were placed under 1.5 cm thick bolus on the anterior and posterior sides of a solid water phantom to measure entrance and exit dose under TBI conditions (∼600 cm SSD, 39.5 × 39.5 cm2 field, 6 MV/15 MV). These measurements were compared to ion chamber and diode readings for validation. Film measurements were also compared to OSLD measurements for three TBI patients.

Results

The shortest development time that resulted in accurate dosimetry and allowed for adequate physician review time was 4 h (± 4% dose accuracy). Film entrance and exit dose measurements were within ± 3.8% of ion chamber and diode readings for 6MV and 15MV beams. Patient film measurements were within ∼ ± 5% for the majority of anatomical measurement locations; however, film and OSLD readings for some anatomic locations deviated by > 10%.

Conclusions

These results indicate that EBT4 film can be utilized for accurate in vivo dosimetry for TBI patients and shows good agreement with diode and ion chamber measurements. Further investigation into film and OSLD differences was not possible due to OSLD recalls.
Highly Sensitive and Stable In Situ Acetylene Detection in Transformer Oil Using Polyimide‐Embedded Carbon Nanotubes
Authors: Kim Sihyeok , Choi Jin‐Myung , Novikov Ilya V. , Nam Jeong‐Seok , Lee Il‐hyun , Cai Liang , Yoon Jonghyuk , Lee Yeounggyu , Lee Jaehoon , Mikladal Bjorn , Kang Boseok , Kauppinen Esko I. , Lee Keekeun , Jeon Il
Published: November 2024

This study presents an acetylene gas sensor capable of in situ monitoring transformer oils. This sensor utilizes carbon nanotubes (CNTs) embedded in polyimide (PI) synthesized by floating catalyst chemical vapor deposition. Unlike conventional sensors that target hydrocarbon gases dissolved in oil and measure the gas extracted from the oil, the proposed CNT‐PI sensor detects gas within the oil in real time. The PI embedding technique effectively anchors and shields the CNT network against fluidic damage, ensuring stable sensing performance over 6 months, even under friction stress caused by oil convection. Decorating CNTs with gold nanoparticles further enhances the sensitivity and response of the sensor. The sensor achieves a high response (10.5% at 30 ppm) and fast response/recovery times (28 s/77 s), Furthermore, the sensor demonstrates good response (10.4% at 30 ppm) and moderate response/recovery times (444 s/670 s) in an oil medium, which qualifies for industrial applications. Additionally, a CNT‐PI‐based heater is integrated into the sensor as a multilayer component, maintaining an optimal operating temperature of 90 °C. The CNT‐PI sensor demonstrates consistent gas‐sensing performance even after 10,000 bending cycles and exhibits superior characteristics, indicating its compatibility with various forms of transformers.
Unveiling the Structure‐Fluorogenic Property Relationship of Seoul‐Fluor‐Derived Bioorthogonal Tetrazine Probes
Authors: Son Hayoung , Kim Dahham , Kim Sohee , Gi Byun Wan , Bum Park Seung
Published: November 2024

Tetrazine (Tz)‐embedded fluorescent probes, known for their fluorogenicity following bioorthogonal inverse electron‐demand Diels–Alder (iEDDA) reactions, are extensively used in bioimaging. Despite extensive research on fluorogenic Tz probes, there has been limited systematic exploration of their fluorogenic responses with various dienophiles. In this study, we elucidate the structure‐fluorogenic property relationship of bioorthogonal Tz probes. We synthesized a series of Seoul‐Fluor‐Tz (SFTz) probes designed to exhibit differentiated turn‐on fluorescence upon iEDDA reactions with three dienophiles: trans‐cyclooctene (TCO), bicyclo[6.1.0]nonyne (BCN), and spiro[2.3]hex‐1‐ene (Sph). Our findings revealed that the fluorogenic properties of the SFTz probes are highly dependent on the structures of Tz‐dienophile adducts. By systematically modifying the electronic properties and employing quantum chemical calculations, we developed a series of SFTz probes with optimal dienophile‐dependent fluorescence. These probes enabled simultaneous dual‐color imaging of different cellular targets using a single probe, providing a robust approach for advanced bioimaging applications that require precise and efficient multicolor labeling strategies.
Organic Electrolytes for Stable and Safe Potassium‐Ion Batteries
Authors: Xu Shu , Yi Xianhui , Fan Ling , Lu Bingan
Published: November 2024

Though lithium‐ion batteries (LIBs) are prevalent, the scarcity and uneven distribution of lithium resources have driven the search for complementary battery technologies. Potassium‐ion batteries (PIBs) have emerged as a promising contender in this quest due to their low‐cost, abundant resources, and potentially high voltage. The frequency of battery‐related accidents in recent years has heightened concerns about battery safety. The electrolyte, as a critical component of batteries, plays a pivotal role in determining safety, as it is directly linked to the formation of the solid electrolyte interphase (SEI), which is crucial for battery stability and security. Initially, enhancing battery safety often came at the cost of performance. However, thanks to the relentless efforts and in‐depth research, it is now possible to improve performance without compromising safety. This article provides an overview of organic electrolyte systems and introduces some state‐of‐the‐art electrolyte formulations, aiming to offer guidance on enhancing the safety and stability of PIBs.