An inequality between the diameter and the inverse dual degree of a tree

Let T be a nontrivial tree with diameter D(T) and radius R(T). Let I(T) be the inverse dual degree of T which is defined to be , where for uV(T). For any longest path P of T, denote by a(P) the number of vertices outside P with degree at least 2, b(P) the number of vertices on P with degree at least 3 and distance at least 2 to each of the end-vertices of P, and c(P) the number of vertices adjacent to one of the end-vertices of P and with degree at least 3. In this note we prove that . As a corollary we then get with equality if and only if T is a path of at least four vertices. The latter inequality strengthens a conjecture made by the program Graffiti.postprin

Efficiency versus linearity trade-off in an S-band class-AB power amplifier

This paper presents a design strategy to simultaneously optimize the efficiency and linearity of a single-device class-AB power amplifier, given minimum output power and gain requirements. The adopted linearity metric is the highest inter-modulation distortion in a two-tone test with 20MHz spacing. The simultaneous selection of optimum source and load terminations that provide the best trade-off among all of the requirements is described in detail, and the synthesis of the matching networks is then presented. A prototype is developed based on a 6W packaged GaN device around 3.5 GHz, manufactured and measured. According to the measured results, the amplifier achieves output power higher than 38dBm with associated gain higher than 12 dB and saturated power-added efficiency in excess of 73% in a single-tone test at 3.25 GHz, while providing a 33% power-added efficiency and -30 dBc inter-modulation distortion in the 20MHz two-tone test

Continuous Inverse Class-F GaN Power Amplifier with 70% Efficiency over 1.4-2 GHz Bandwidth

This work presents the design and experimental characterization of a wideband continuous inverse class-F power amplifier, covering several bands in the 5G FR1 frequency range, and thus suitable for base station applications. The design spaces of the class-F and inverse class-F in terms of input and output terminations are reviewed and compared, and the design choices relative to an implementation using a packaged device are described. Measurements show a saturated output power of 40 dBm, with corresponding efficiency and gain higher than 70% and 13 dB, respectively, over 1.4-2 GHz. The performance is well in line with the state of the art and is accurately predicted by simulations, proving the effectiveness of the design strategy

Shear enhanced heterogeneous nucleation in some Mg- and Al- alloys

Intensive shearing was applied to alloy melts at temperatures above their liquidus by using a twinscrew mechanism. The sheared melt was then cast into a TP1 mould for microstructural examination. Alloy melts with or without shearing were also filtered using the Prefil technique developed by N-Tech Ltd in order to analyse oxides and other second phase particles. The experimental results showed a significant grain refinement through enhancement of heterogeneous nucleation. The intensive melt shearing converted oxide films and agglomerates into well dispersed fine particles with a narrow size distribution. It was confirmed that the fine oxide particles can act as potent sites for nucleation during the solidification of the sheared melt. This paper presents the experimental results and theoretical analysis of shear enhanced heterogeneous nucleation during solidification of Mg- and Al-alloys. A multi-step heterogeneous nucleation mechanism has been proposed and discussed

An early Cambrian agglutinated tubular lophophorate with brachiopod characters.

The morphological disparity of lophotrochozoan phyla makes it difficult to predict the morphology of the last common ancestor. Only fossils of stem groups can help discover the morphological transitions that occurred along the roots of these phyla. Here, we describe a tubular fossil Yuganotheca elegans gen. et sp. nov. from the Cambrian (Stage 3) Chengjiang Lagerstätte (Yunnan, China) that exhibits an unusual combination of phoronid, brachiopod and tommotiid (Cambrian problematica) characters, notably a pair of agglutinated valves, enclosing a horseshoe-shaped lophophore, supported by a lower bipartite tubular attachment structure with a long pedicle with coelomic space. The terminal bulb of the pedicle provided anchorage in soft sediment. The discovery has important implications for the early evolution of lophotrochozoans, suggesting rooting of brachiopods into the sessile lophotrochozoans and the origination of their bivalved bauplan preceding the biomineralization of shell valves in crown brachiopods

Simultaneous determination of flavonoids and triterpenoids in Cyclocarya paliurus leaves using high-performance liquid chromatography

Background: Cyclocarya paliurus is an endangered plant and endemic to China. The leaves of C. paliurus have been used in drug formulations and as ingredients in functional foods in China. The aim of this study was to develop an effective method to extract most of the compounds and to establish a simplified HPLC analytical method to determine the contents of major bioactive compounds simultaneously.Materials and methods: High-performance liquid chromatography (HPLC) coupled with a photodiode array detector (PDA) was used for the simultaneous determination of the major flavonoids and triterpenoids in C. paliurus leaves.Results: Ultrasonic extraction in 100% methanol for 30 min was adopted as the optimal extraction method for C. paliurus leaves. The separation conditions were optimized using a Phenomenex C18 ODS column (250 mm × 4.6 mm, 5 μm) with a mobile phase of acetonitrile and 0.02% formic acid and a detection wavelength of 205 nm. The validation data indicated that this new HPLC analytical method successfully quantified the provenance and seasonal variations of seven major compounds (three flavonoids and four triterpenoids) in C. paliurus leaves.Conclusion: The study provided a novel and simplified approach to simultaneously determine the quantity of major flavonoids and triterpenoids in C. paliurus leaves. The results could promote the optimization of silvicultural systems for quality control of C. paliurus.Key words: Cyclocarya paliurus; HPLC; flavonoids; triterpenoid

Domain freezing in potassium dihydrogen phosphate, triglycine sulfate, and CuAlZnNi

The temperature dependence of the dielectric constant and dissipation in potassium dihydrogen phosphate (KDP), its deuterated compound (DKDP), triglycine sulfate (TGS), and TGS doped with α-alanine (LATGS) has been studied at various frequencies. It is found that the relaxation time of domain freezing in KDP and DKDP in the kHz range can be described by the Vogel-Fulcher relation. Evidence of domain freezing in TGS is presented through an analysis of relaxation time related to domain walls and a comparison between TGS and LATGS. Studies of internal friction and compliance show preliminary evidence of domain freezing in CuAlZnNi alloy. A domain-freezing model is proposed based upon the collective pinning of randomly distributed pinning centers to domain walls. Some key experiments related to domain freezing, such as (1) the Vogel-Fulcher relation for relaxation time; (2) the size effect of domain freezing; (3) two kinds of relaxation in low- and high-frequency ranges, respectively; and (4) the dependence of TF on defect density and applied field, etc., are explained.published_or_final_versio

Raman scattering and X-ray diffraction study of neutron irradiated GaN epilayers

Neutron irradiation induced defects and their effects on the carrier concentration of GaN epilayers are investigated with Raman scattering and X-ray diffraction techniques. Relative to the as-grown sample, the neutronirradiated samples exhibit a clear variation in the position and lineshape of the A 1(LO)-mode Raman peak as well as in the fullwidth at half-maximum height (FWHM) of the XRD rocking curves. Careful curve fitting and adequate calculations give the carrier concentrations of the irradiated GaN. It is found that the defects induced by neutron irradiation act as carrier trap centres which capture the electron carriers so that the carrier concentration of the irradiated GaN is reduced. © 2005 IEEE.published_or_final_versio

The stomach cancer pooling (STOP) project: a global consortium of epidemiological studies of gastric cancer, updated to 2021

The assessment of risk factors in cancer etiology is necessary for defining optimal preventive strategies, as well as for identifying high risk individuals, and it is therefore relevant for medical practice and cancer prevention. The Stomach cancer Pooling (StoP) Project is a consortium of epidemiological studies of gastric cancer (GC), established in year 2012. The StoP Project aims to examine the role of lifestyle, environmental and genetic determinants of GC through pooled analyses of subject-level data. The consortium is the major GC dataset globally, including original data from 35 studies – with case–control study design, including 5 nested case–control within cohort studies – conducted in the Americas, Asia and Europe (Table 1), for a total of about 13,500 cases and 32,000 controls, and it is continuously expanding. To date, the StoP Project contributed a detailed quantification of the risk of GC associated to several factors, including cigarette smoking (relative risk, RR, of 1.32 for heavy vs. never smokers), alcohol drinking (RR=1.48 for heavy vs. never drinkers), socio-economic status (RR=0.60 for high vs. low education), selected dietary factors (RR=1.30 for high vs. low meat intake; RR=0.65 for high vs. low vegetables consumption; RR=0.80 for high vs. low citrus fruit; RR=0.67 for high vs. low polyphenols intake) and occupational exposures (RR=1.70 for miners; RR=1.30 for construction workers; RR=1.33 for agricultural and animal husbandry workers; RR=1.41 for blacksmiths and machine-tool operators). Planned future developments are to analyze the role of rare exposures on GC risk and to examine risk factors in understudied patient subgroups (e.g., young onset GC, gastric cardia cancer, etc.); to integrate additional studies from East Asia; to develop a genome-wide modeling of polygenic risk score in GC; to include survival analyses and to apply machine learning methods in GC risk prediction and prognostication

Steel stress monitoring sensor based on elasto-magnetic effect and using magneto-electric laminated composite

Author name used in this publication: Yuan-Feng DuanAuthor name used in this publication: Siu Wing Or2011-2012 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe