Transduction properties of tracheal stretch receptors

1. Using single fibre vagal afferent recording, we have studied the behavior of slowly adapting stretch receptors located in an isolated, in situ, segment of the trachea in dogs. Responses to positive and negative steady and oscillating transmural pressures were investigated. 2. Seventy-eight per cent of the receptors studied were tonically active at resting tracheal volume. Ninety per cent showed a more pronounced response to positive than to negative transmural pressures. 3. During pressure oscillations the majority of the receptors had a higher discharge frequency at any given pressure during the ascending phase of the pressure wave than at the same pressure under static conditions. During most of the ensuing descent of pressure toward zero the discharge frequency led transmural pressure. 4. With increasing frequency of oscillation the differences from the static responses increased (dP/dt sensitivity), especially during the ascending limb of the pressure oscillation (rectifying behavior). 5. In a small number of receptors, discharge frequency lagged behind transmural pressure or was in phase with it ("no loop" pattern). 6. In three cases the same receptor exhibited dP/dt sensitivity during positive pressure oscillations, whereas discharge frequency lagged behind pressure during negative pressure oscillations. This indicates that the lack of dP/dt sensitivity exhibited under negative pressure conditions does not represent an intrinsic property of these receptors, but reflects some aspect of their mechanical arrangement within the airway wall. 7. THESE PATTERNS OF RESPONSE ARE DISCUSSed in terms of intrinsic and extrinsic characteristics of the receptors. 8. The physiological implications of stretch receptor behaviour are also considered.     

The cheating and intention of a partner as determinants of evaluative decisions among juvenile offenders

A 17 year-old male, who was mentally and bodily retarded from the age of 7 years. At the age of 16 years, several neurological signs appeared. Pathologically, there was widespread myelin loss and tissue sponginess in the white matter of the cerebrum and cerebellum, bilaterally and symmetrically. A great many Alzheimer type II glia and Opalski glia were widely distributed in the cerebral cortex and the basal ganglia. Despite severe destruction of the white matter, mesenchymal and gliofibre proliferation were not noticed. In the liver, Laennec's cirrhosis and a great many copper granules in the cytoplasm of the parenchymal cells were identified. From the above mentioned findings the present case, being a new type, could be called "Demyelinating type of Wilson's disease".     

An Energy-Efficient OOK Transceiver for Wireless Sensor Networks

A 1-Mb/s 916.5-MHz on-off keying (OOK) transceiver for short-range wireless sensor networks has been designed in a 0.18-mum CMOS process. The receiver has an envelope detection based architecture with a highly scalable RF front-end. Untuned RF circuits are leveraged and optimized in the receiver to achieve superior energy efficiency compared to tuned RF circuits. The receiver power consumption scales from 0.5 mW to 2.6 mW, with an associated sensitivity of -37 dBm to -65 dBm at a BER of 10 ^-3. The transmitter consumes 3.8 mW to 9.1 mW with output power from -11.4 dBm to -2.2 dBm. The receiver achieves a startup time of 2.5 mus, allowing for efficient duty cycling     

The spatially averaged electric field in the near field and far field of a circular aperture

This paper presents a theoretical and numerical investigation of the spatially averaged electric field in the beam of a circular aperture. The investigation leads to closed-form analytical expressions, based on scalar diffraction theory, which describe the spatially averaged electric field in the Fresnel region of a circular aperture excited by a spatially uniform, harmonic plane wave. The expressions ultimately permit rapid, practical, and efficient prediction of certain routine electromagnetic measurements. Because the expressions are valid in the Fresnel region, they are also valid in the near field, the far field, and the Fraunhofer region of a circular aperture. In fact, it is shown that the closed-form expressions contain, as special cases, classic on-axis and far-field results associated with a circular aperture. The analytical expressions are based on a generalization of Fresnel diffraction originally developed by Lommel in the late 1800s. Hence, a thorough review of the literature on the Lommel diffraction formulation is presented. Finally, it is shown that results obtained from the closed-form expressions compare quite favorably to results obtained from the exact solution computed via the dyadic Green's function approach.     

改进光电晶体管线性运行的反馈电路

当设计者用光电晶体管将一个调制后的光信号转换成电信号时,如果有高亮度的背光使光电晶体管饱和,就会遇到麻烦.当光电晶体管基极端悬浮时,其集电极/射极电压只取决于信号与背光重叠而产生的光电流.光电晶体管增益及其作用区范围由R1阻值(见图1)确定.R1阻值较高时,电路的增益增加,但光电晶体管会很快饱和.图1中没有背光照射时,晶体管工作在其线性区的偏置点φ2,Q1的集电极电压围绕VCE作线性变化.其输出VOUT准确地重复使调制光信号产生幅度波动.当施加外部稳定的背光照明时,电路的工作点移至偏置点φ3,输出电压被压缩并出现失真.     

锁存继电器的CMOS电路

控制应用经常要求将一只继电器锁存定位,直到需要改变其状态时为止。完成这个任务的是锁存继电器。当给它们发送一个脉冲时,它们可能保持在当前状态,也可能改变状态,具体取决于脉冲的极性以及继电器当前状态。图1中电路会根据一     

Technologies for Ultradynamic Voltage Scaling

Energy efficiency of electronic circuits is a critical concern in a wide range of applications from mobile multimedia to biomedical monitoring. An added challenge is that many of these applications have dynamic workloads. To reduce the energy consumption under these variable computation requirements, the underlying circuits must function efficiently over a wide range of supply voltages. This paper presents voltage-scalable circuits such as logic cells, SRAMs, ADCs, and dc–dc converters. Using these circuits as building blocks, two different applications are highlighted. First, we describe an H.264/AVC video decoder that efficiently scales between QCIF and 1080p resolutions, using a supply voltage varying from 0.5 V to 0.85 V. Second, we describe a 0.3 V 16-bit microcontroller with on-chip SRAM, where the supply voltage is generated efficiently by an integrated dc–dc converter.      

Self‐Assembly of Atomically Thin Chiral Copper Heterostructures Templated by Black Phosphorus

The fabrication of 2D systems for electronic devices is not straightforward, with top‐down low‐yield methods often employed leading to irregular nanostructures and lower quality devices. Here, a simple and reproducible method to trigger self‐assembly of arrays of high aspect‐ratio chiral copper heterostructures templated by the structural anisotropy in black phosphorus (BP) nanosheets is presented. Using quantitative atomic resolution aberration‐corrected scanning transmission electron microscopy imaging, in situ heating transmission electron microscopy and electron energy‐loss spectroscopy arrays of heterostructures forming at speeds exceeding 100 nm s^?1 and displaying long‐range order over micrometers are observed. The controlled instigation of the self‐assembly of the Cu heterostructures embedded in BP is achieved using conventional electron beam lithography combined with site specific placement of Cu nanoparticles. Density functional theory calculations are used to investigate the atomic structure and suggest a metallic nature of the Cu heterostructures grown in BP. The findings of this new hybrid material with unique dimensionality, chirality, and metallic nature and its triggered self‐assembly open new and exciting opportunities for next generation, self‐assembling devices.     

Fiber Optic Intermodulation Distortion

In analog frequency-division multiplexed fiber optic systems, laser nonlinearities transfer energy between the different carriers, resulting in intermodulation distortion and interference. A third-order polynomial without memory is used to model the nonlinearity. The FM frequency-division multiplexed (FM/FDM) signal consists of a set of FM carriers at frequencies.N_{omega 0}, whereN = L, L + 1, L +2, ... , M. The video distortion introduced by the nonlinearity is determined for various types of second- and third-order intermodulation terms. The intermodulation distortion frequency spectrum is determined for FM signals with assumed Gaussian spectra.     

Development of a prototype,experimental single-channel sequencing navstar gps receiver: Part I—Hardware implementation

Late in 1988 the Navstar GPS satellite navigation operational phase is planned to commence, offering world-wide, continuous and precise position-fixing and timing information to observers on land, sea, air and in space. This paper describes the development of a particular type of Navstar receiver—a single-channel, single-frequency, sequencing C/A code unit—and results of various tests carried out on the present phase-II satellite constellation. Part I of the paper deals essentially with the NAVSTAR satellite system and receiver hardware implementation, whereas Part II concentrates on receiver software and system performance.