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

抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

This paper describes the contents of the 2016 edition of the HITRAN molecular spectroscopic compilation. The new edition replaces the previous HITRAN edition of 2012 and its updates during the intervening years. The HITRAN molecular absorption compilation is composed of five major components: the traditional line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, infrared absorption cross-sections for molecules not yet amenable to representation in a line-by-line form, collision-induced absorption data, aerosol indices of refraction, and general tables such as partition sums that apply globally to the data. The new HITRAN is greatly extended in terms of accuracy, spectral coverage, additional absorption phenomena, added line-shape formalisms, and validity. Moreover, molecules, isotopologues, and perturbing gases have been added that address the issues of atmospheres beyond the Earth. Of considerable note, experimental IR cross-sections for almost 300 additional molecules important in different areas of atmospheric science have been added to the database. The compilation can be accessed through www.hitran.org. Most of the HITRAN data have now been cast into an underlying relational database structure that offers many advantages over the long-standing sequential text-based structure. The new structure empowers the user in many ways. It enables the incorporation of an extended set of fundamental parameters per transition, sophisticated line-shape formalisms, easy user-defined output formats, and very convenient searching, filtering, and plotting of data. A powerful application programming interface making use of structured query language (SQL) features for higher-level applications of HITRAN is also provided.

/pdf/the-hitran-2008-molecular-spectroscopic-database-1ud8clpej3.pdf

The HITRAN 2008 molecular spectroscopic database

Preface to the Second Edition. Preface to the First Edition. 1 Introduction. 2 Network Analysis. 2.1 Network Variables. 2.2 Scattering Parameters. 2.3 Short-Circuit Admittance Parameters. 2.4 Open-Circuit Impedance Parameters. 2.5 ABCD Parameters. 2.6 Transmission-Line Networks. 2.7 Network Connections. 2.8 Network Parameter Conversions. 2.9 Symmetrical Network Analysis. 2.10 Multiport Networks. 2.11 Equivalent and Dual Network. 2.12 Multimode Networks. 3 Basic Concepts and Theories of Filters. 3.1 Transfer Functions. 3.2 Lowpass Prototype Filters and Elements. 3.3 Frequency and Element Transformations. 3.4 Immittance Inverters. 3.5 Richards' Transformation and Kuroda Identities. 3.6 Dissipation and Unloaded Quality Factor. 4 Transmission Lines and Components. 4.1 Microstrip Lines. 4.2 Coupled Lines. 4.3 Discontinuities and Components. 4.4 Other Types of Microstrip Lines. 4.5 Coplanar Waveguide (CPW). 4.6 Slotlines. 5 Lowpass and Bandpass Filters. 5.1 Lowpass Filters. 5.2 Bandpass Filters. 6 Highpass and Bandstop Filters. 6.1 Highpass Filters. 6.2 Bandstop Filters. 7 Coupled-Resonator Circuits. 7.1 General Coupling Matrix for Coupled-Resonator Filters. 7.2 General Theory of Couplings. 7.3 General Formulation for Extracting Coupling Coefficient k. 7.4 Formulation for Extracting External Quality Factor Qe. 7.5 Numerical Examples. 7.6 General Coupling Matrix Including Source and Load. 8 CAD for Low-Cost and High-Volume Production. 8.1 Computer-Aided Design (CAD) Tools. 8.2 Computer-Aided Analysis (CAA). 8.3 Filter Synthesis by Optimization. 8.4 CAD Examples. 9 Advanced RF/Microwave Filters. 9.1 Selective Filters with a Single Pair of Transmission Zeros. 9.2 Cascaded Quadruplet (CQ) Filters. 9.3 Trisection and Cascaded Trisection (CT) Filters. 9.4 Advanced Filters with Transmission-Line Inserted Inverters. 9.5 Linear-Phase Filters. 9.6 Extracted Pole Filters. 9.7 Canonical Filters. 9.8 Multiband Filters. 10 Compact Filters and Filter Miniaturization. 10.1 Miniature Open-Loop and Hairpin Resonator Filters. 10.2 Slow-Wave Resonator Filters. 10.3 Miniature Dual-Mode Resonator Filters. 10.4 Lumped-Element Filters. 10.5 Miniature Filters Using High Dielectric-Constant Substrates. 10.6 Multilayer Filters. 11 Superconducting Filters. 11.1 High-Temperature Superconducting (HTS) Materials. 11.2 HTS Filters for Mobile Communications. 11.3 HTS Filters for Satellite Communications. 11.4 HTS Filters for Radio Astronomy and Radar. 11.5 High-Power HTS Filters. 11.6 Cryogenic Package. 12 Ultra-Wideband (UWB) Filters. 12.1 UWB Filters with Short-Circuited Stubs. 12.2 UWB-Coupled Resonator Filters. 12.3 Quasilumped Element UWB Filters. 12.4 UWB Filters Using Cascaded Miniature High- And Lowpass Filters. 12.5 UWB Filters with Notch Band(s). 13 Tunable and Reconfigurable Filters. 13.1 Tunable Combline Filters. 13.2 Tunable Open-Loop Filters without Via-Hole Grounding. 13.3 Reconfigurable Dual-Mode Bandpass Filters. 13.4 Wideband Filters with Reconfigurable Bandwidth. 13.5 Reconfigurable UWB Filters. 13.6 RF MEMS Reconfigurable Filters. 13.7 Piezoelectric Transducer Tunable Filters. 13.8 Ferroelectric Tunable Filters. Appendix: Useful Constants and Data. A.1 Physical Constants. A.2 Conductivity of Metals at 25 C (298K). A.3 Electical Resistivity rho in 10-8 m of Metals. A.4 Properties of Dielectric Substrates. Index.

Microstrip filters for RF/microwave applications

A new type of metallic electromagnetic structure has been developed that is characterized by having high surface impedance. Although it is made of continuous metal, and conducts dc currents, it does not conduct ac currents within a forbidden frequency band. Unlike normal conductors, this new surface does not support propagating surface waves, and its image currents are not phase reversed. The geometry is analogous to a corrugated metal surface in which the corrugations have been folded up into lumped-circuit elements, and distributed in a two-dimensional lattice. The surface can be described using solid-state band theory concepts, even though the periodicity is much less than the free-space wavelength. This unique material is applicable to a variety of electromagnetic problems, including new kinds of low-profile antennas.

/pdf/high-impedance-electromagnetic-surfaces-with-a-forbidden-3vtu72a5an.pdf

High-impedance electromagnetic surfaces with a forbidden frequency band

Total-power radiometry is applied over a wide-frequency band (26-40 GHz) to measure homogeneous and emulsified (40%:60% oil:water composition) oil films on water. The resulting brightness-temperature (T/sub B/) spectra contain substantially more information about the film than the spot-frequency measurements of previous work. In thin homogeneous films (/spl sim/3 mm or less), the T/sub B/ spectra have the same monotonically increasing frequency dependence as the bare-water spectrum, but are distinguishable from the water by a positive T/sub B/ offset. For thicker homogeneous films, oscillations in the T/sub B/ spectra occur that have a period inversely related to the thickness of the film. For emulsified films, the T/sub B/ offset is greater than that of a homogeneous film of the same thickness, and oscillations in T/sub B/ occur, even for the thinnest (1 mm) emulsion tested. However, the amplitude of these oscillations is much smaller than for homogeneous films because of losses in the emulsion. Hence, the key result of this paper is that wide-band radiometry enables both the unambiguous determination of the thickness of homogeneous oil and the discrimination of homogeneous oil from emulsified films, at least in the range of thickness >1 mm.

Wide-band radiometry for remote sensing of oil films on water

The experimental and simulated switching behavior across the negative differential resistance (NDR) region of GaN/AlN double-barrier resonant tunneling diodes (RTDs) is presented. The shortest 10%–90% experimental switching time was ~55 ps. The experimental results are also studied with P-SPICE circuit models, which show that the relatively low peak-to-valley current ratio (~1.5), relatively high specific contact resistance ( $\geq \textsf {1}\times \textsf {10}^{-\textsf {6}}\,\,\Omega $ -cm2), and relatively large specific capacitance limit the switching time.

Investigation of Switching Time in GaN/AlN Resonant Tunneling Diodes by Experiments and P-SPICE Models

Embodiments of the invention are directed to retrodirective radio-frequency systems wherein a transmit antenna array includes at least one row of N transmit elements and a receive antenna array includes at least one row of N receive elements that correspond one-to-one to the transmit elements and wherein the transmit and receive elements are located on spaced planes, and centered about a common axis and located at common transmit distance and a common receive distance, respectively. In some embodiments the one row of transmit and receive elements comprises “n” rows of elements, where “n” is an integer greater than one, thereby forming a two-dimensional array. In some embodiments the total transmit radiation pattern provides an azimuth coverage of 360 degrees. In other embodiments, it may provide less coverage but be operable as independent sectors. In some embodiments, the desired transmit wave form will be identical between all transmit elements of the array, one possible example being pseudo random noise imparted on a sinusoidal carrier.

Low-profile omnidirectional retrodirective antennas

A imaging ultrasonic device has a flexible, conformal transducer array. The flexible, conformal transducer array has a flexible printed circuit and a plurality of piezoelectric elements. Each piezoelectric element of the plurality of piezoelectric elements is electrically connected to the flexible printed circuit, and each of the piezoelectric elements is suitable to transmit and/or receive an ultrasound signal. The flexible transducer array can be configured into a plurality of shapes for forming a corresponding plurality of conformal images, each conformal image of the plurality of conformal images being formed free from scanning the flexible, conformal transducer array over an object being imaged.

A flexible conformal ultrasonic imaging transducer and system

We report experimental results for the optical responsivity and noise-equivalent power (NEP) of quasi-optically 
coupled, room-temperature ErAs-InGaAlAs rectifier diodes. Four-micron-diameter diodes were flip-chip coupled to 
self-complementary log-periodic and square-spiral antennas, and characterized with a 104-GHz Gunn diode oscillator 
coupled to the rectifiers through variable attenuators, a feedhorn, an aspherical polymeric lens, and a Si 
hyperhemisphere. The log-periodic mounted device displayed a responsivity and specific NEP' of 0.9x10 3 V/W and 
1.2x10 -12 W/Hz 1/2 , respectively. The square-spiral mounted device displayed a responsivity and NEP' of 1.2x10 3 V/W 
and 2.0x10 -12 W/Hz 1/2 , respectively. All values were measured at a post-detection center frequency of 33 Hz.

Elliott R. Brown

Papers

Wide-band radiometry for remote sensing of oil films on water

Investigation of Switching Time in GaN/AlN Resonant Tunneling Diodes by Experiments and P-SPICE Models

Low-profile omnidirectional retrodirective antennas

A flexible conformal ultrasonic imaging transducer and system

High-sensitivity, quasi-optically-coupled semimetal-semiconductor detectors at 104 GHz