The effects of maturation on early and late phases of phrenic neurogram during eupnea

In this paper, we investigate the effects of maturation on the early and late phases of the phrenic neurogram. We have used the matching pursuit (MP) method to examine the effects of maturation on breathing patterns in both time and frequency domains. The MP was chosen since the wavelet transform method may not represent signals whose Fourier transforms have a narrow high-frequency support. The phrenic neurogram was recorded from 25 piglets (3-35 days) during eupnea (normal breathing) at three postnatal age groups: young (3-7 days (n = 9)), (middle) 10-21 days (n = 6), and old (29-35 days (n = 10)). The energy percentage of atoms representing the nonperiodic neural activities (NPNAs) significantly decreased from young age to middle age groups (p<0.01) and from young age to old age groups (p<0.01), and from middle age to old age groups (p<0.055) in the early phase (the first half) of the phrenic neurogram, but these changes were not statistically significant in the late phase (the second half) of the phrenic neurogram as maturation proceeded. However, the energy percentage of atoms representing the periodic neural activities (PNAs) decreased with maturation, but these changes were not statistically significant in the early phase of the phrenic neurogram. The energy percentage of (PNAs) increased in the late phase of the phrenic neurogram as maturation proceeded although these changes were only significant between young and old age groups (p<0.01). These results suggest that the significant decrease of the NPNAs in the early phase and the increase in the late phase of the phrenic neurogram could be a sign of maturation in piglets.     

Influence of the vagus nerve on respiratory patterns during early maturation

Nonlinear dynamical analysis was performed on the phrenic neurogram before and after vagotomy in order to study the influence of the vagus nerve on the complexity of the phrenic neurogram in piglets in three age groups: 3-7 days (n = 7); 11-19 days (n = 6); and 29-34 days (n = 8). The phrenic neurogram, generated by the respiratory neural networks in the medulla, projects on the diaphragm muscles and initiate the respiratory movement. On the other hand, the vagus nerves carry the information from mechanoreceptors, located at the lower airway and lungs, to the medulla. The data was recorded during normal breathing (eupnea) before and after vagotomy while piglets were ventilated with 40% O2 in N2 and analyzed using the approximate entropy (ApEn) method. The mean values of the approximate entropy before and after vagotomy during the first 7 days of the postnatal age were 1.32 +/- 0.1 (standard deviation) and 1.34 +/- 0.07, respectively. These values before and after vagotomy during the 11-19 days age group were 1.15 +/- 0.09 and 1.12 +/- 0.05, respectively. For the 29-34 days age group, they were 1.14 +/- 0.05 before vagotomy and 1.19 +/- 0.08 after vagotomy. These differences in the ApEn (complexity) values of the phrenic neurogram before and after vagotomy are not statistically different at each age group. However, the mean mean approximate entropy (complexity) values between the 3-7 days age group and the other two groups were significantly different both before and after vagotomy (p < 0.05) using an analysis off variance test. These results suggest that the vagus nerve may not be mature during early maturation in piglets.     

The effects of defects on the early failure of metal interconnects

A method that predicts the effect of particular defects on the failure rate of metal interconnections in semiconductor integrated circuits due to electromigration is presented. The defects of interest are missing material that reduces the effective cross section of the conductor at the point of the defect. Reliability measures for the conductor are computed from a given defect distribution. These defects appreciably increase conductor failure rate during early life but have little effect on median life for linewidths above 1 μm. However, for defect densities typically encountered in current semiconductor manufacturing environments a rapid decrease in median life is predicted for conductors less than 0.30 μm wide. This result extends the practical data for submicron conductors. Poorer median life as well as poorer yield due to these defects will ultimately limit the trend toward narrower linewidths unless a way is found to overcome this problem     

Cytochemical analysis of polyamines in Ehrlich ascitic carcinoma cells during different phases of mitotic cycle under the effects of difluoromethylornithine

Mice bearing Ehrlich carcinoma cells received one 80 mg/kg dose of DFMO. After 20 hours the cells were extracted from the peritoneal cavity and separated by means of sedimentation of 1 g in saccharose gradient into 9 fractions depending on the mitotic cycle phase. The content of polyamines in the cells of each fraction was detected by the fluorescent method using fluorescamine. It was shown that the tumor cells during G1 phase mitotic cycle (13-15% cells blocked) and especially cells in the 1st half of S-phase (19-23% cells blocked) were most sensitive to inhibitory effect of DFMO.     

Early electromigration effects and early resistance changes

This paper reviews different known physical phenomena acting during electromigration, such as changes in the mechanical stress of the metal line, void growth and precipitation/dissolution of alloy elements (Cu, Si) and their effects on early resistance changes. The superposition of all these phenomena is also discussed to describe the typical early resistance changes detected in Al–Cu lines of the present technology.     

神经外科病人术后ICP增高与高碳酸血症的临床相关性研究

目的：探讨NICU术后持续ICP监测病人发生ICP升高的临床意义及其与术后高碳酸血症的相关性。方法：对428例行神经外科开颅手术并安装颅内皮层下颅内压探头的NICU患者,术后给予持续颅内压监测,进行血气分析,判断有无CO2潴留、高碳酸血症。结果：153例患者术后有ICP升高,其中32例患者血气分析结果提示CO2蓄积,占20．91％;改善患者通气情况,及时纠正高碳酸血症可有效降低ICP。结论：术后ICP水平与机体CO2潴留、高碳酸血症的严重程度呈正相关。     

信息安全企业的渠道战略(下篇)

在上篇文章中,从渠道在公司的战略重要性、提倡竞争等几个方面谈了信息安全企业的渠道战略。下篇将围绕渠道的复合化、本地化、增值服务、渠道与品牌的关系展开论述。复合渠道体系分销商经营多品牌的分销模式,被业内称为渠道复合化。渠道复合化无论是对供应商还是分销商以及下游代理商,都具有非常大的价值,它可以提升整个供应链的价值和内涵。神州数码高级副总裁兼通用信息产品事业部总经理毛向前认为,渠道复合化已成为新的趋势。2004年,中国信息安全产品市场竞争程度的日益激烈以及用户的逐渐成熟,厂商和分销商的合作似乎出现了前所未有的…     

The reconstruction of the relative phases and polarization of theelectromagnetic field based on amplitude measurements

The problem of determining the relative phases among the components of a monochromatic electromagnetic field at a single point based on amplitude measurements only is addressed. The following questions are answered: (1) How is the phase information reconstructed from amplitude measurements? (2) Do amplitude measurements contain enough information to reconstruct the phases uniquely? (3) How many amplitude measurements are required? and (4) In what directions must the amplitude measurements be taken to ensure that the reconstructed phases are unique? To answer these questions, a more general problem in n dimensions, the special case where n=3 being the solution to the above problem, is proposed and solved     

Estimation of energy consumption and execution time in early phases of design lifecycle: an application to biomedical systems

Nowadays, embedded systems are present in a great many areas of human activity. ATMs, mobile phones, clocks, refrigerators, microwaves, scopes and routers are a few examples of embedded systems. Furthermore, advances in microelectronics have allowed for the development of embedded systems with several complex features, thereby upholding the development of powerful mobile mechanisms such as military gadgets and medical devices. These devices generally rely on constrained energy sources (e.g. a battery), in such a way that if the energy source is depleted, the system stops functioning. Hence estimating energy consumption in an early design phase can provide significant insights for designers about energy source lifetime as well as optimising systems parts.     

The influence of addition elements on the early resistance changes observed during electromigration testing of Al metal lines

This paper provides a critical review on early resistance changes observed during electromigration testing of Al, AlSi and AlSiCu metal lines. At present, high resolution in situ electrical resistance measurements are widely accepted as a valuable tool for the study of electromigration. It will be shown however that the results of these measurements should be interpreted with care. It will indeed be shown that, particularly for Si and/or Cu alloyed metallizations, an early resistance change measurement (during electromigration) can contain information that has no link with the damage induced by the electromigration process. A number of disturbing factors will be identified, which are all induced by temperature driven processes. The first type of disturbance is well known: the immediate change of the measured resistance with temperature steps and fluctuations (thermometer effect). The second type of disturbance is not so widely recognised. It is induced by time dependent changes that are observed over an extended period of time, following a preceding temperature step. Two types of disturbing contributions to resistance changes of this second type are identified, which will be denoted as irreversible changes and reversible changes. The irreversible resistance changes are usually observed during the first annealing of the metal line. The reversible changes are typically detected at the start of an electromigration measurement, when the current stress is switched on. It is shown that both the reversible and irreversible changes are caused by precipitation/dissolution reactions of addition elements. It is also shown that the often observed parabolic initial resistance increase that is detected at the start of electromigration experiments should be attributed to the time dependent, reversible dissolution of the addition element(s). Comparable experiments, executed however at a much reduced current level so that no Joule heating takes place, and hence no reversible processes are initiated, show that the kinetics of the purely electron-wind induced resistance changes are completely different: instead of a parabolic initial increase, an incubation time can be observed during the first stage of the measurement.     

The effects of point defects on the electrical activation ofSi-implanted GaAs during rapid thermal annealing

The effects of point defects on the electrical activation of Si-implanted GaAs during rapid thermal annealing were investigated using slow positron beam, cross-sectional transmission electron microscopy, and Hall measurements. The increase of the Ga vacancy concentration in the GaAs substrate induced by the SiO₂ cap layer on the substrate during annealing was observed to decrease the activation efficiency and the number of extrinsic stacking faults via the recombination of interstitials with vacancies. It was found that the efficiency of the carrier creation is not dependent upon the Ga vacancy concentration during the rapid thermal annealing of Si-implanted GaAs. Hence, it is proposed that the electrical activation of Si-implanted GaAs is not due to implantation-induced vacancies but to the self-exchange of interstitial Si atoms with the host Ga substitutional atoms     

The Radiation Laboratory, fifty years later [telecom and remotesensing]

The author gives his impressions of the Radiation Laboratory of MIT as it existed from 1940 to 1945. He explores relationships of developments at the lab to present activity in radiowave propagation and remote sensing. His comments relate primarily to telecommunications and nonmilitary applications of remote sensing     

Interfacial effects during GaN growth on 6H-SiC

GaN growth on 6H-SiC was investigated for heterojunction device applications. Dopant diffusion and surface reactions were discovered at the GaN/SiC heterojunction. A systematic study was therefore conducted focusing on: 1) SiC substrate preparation, 2) SiC nitridation; the effect of flowing ammonia (NH₃) at 1050°C on the SiC, and 3) the conductivity type and carrier concentration of the SiC substrate. Atomic force microscopy measurements revealed that the SiC substrates became smoother after the nitridation process possibly due to nitrogen chemisorption and etching. Current-voltage and capacitance-voltage measurements on Cr-Schottky diodes made on SiC revealed evidence for an increased potential barrier in the nitrided samples that can be explained by an interfacial monolayer ofSiN_x. Furthermore, we compared GaN/SiC heterojunction n-n and n-p diodes made from direct and selective GaN growth. Capacitancevoltage measurements on GaN/SiC n-p heterojunctions indicate that the effective doping in the junction increases as the growth temperature increases. Secondary ion mass spectrometry measurements exposed a tail of Al in the GaN due to acceptor out-diffusion from the p-SiC.     

Reconstruction of out-of-plane cardiac displacement patterns asobserved on the chest wall during various phases of ECG by capacitancetransducer

The out-of-plane displacements due to cardiac action have been measured on the chest wall by an electronic distance measurement technique which is based on the variation of the capacitance between the probe and moving surface. The displacements were measured at 36 locations over the entire cardiac region along with ECG and were directly fed to an IBM PC/AT computer after A/D conversion. From these data, the displacement patterns for the whole region during the complete cardiac cycle could be reconstructed in a perspective view. The sequential analyses of the displacements shows the details of the cardiac events and the results obtained are in agreement with other techniques. The averaged displacements over various regions of the heart for normal subjects have also been presented.     

Formation of secondary phases during crystal growth of Pb5Ge3O11

Studies of secondary phases formed during the Czochralski growth of lead germanate crystals (Pb₅Ge₃O₁₁) show that these phases form inclusions in the crystal, thereby reducing its optical quality, and can also cause twinning and cracking. Results of differential thermal analysis, energy dispersive X-ray fluorescence analysis, and X-ray diffraction studies of secondary phases are presented. The narrow stability range for Pb₅Ge₃O₁₁ shown in the phase diagram, the thermal instability of this compound, and its pronounced supercooling during crystallization suggest that equilibrium conditions are difficult to sustain and that other compounds of the PbO-GeO₂ family may form, although Pb₅Ge3O₁₁ is melting congruently. It is shown that Pb₃GeO₅ and PbGeO₃, which are both reported to melt congruently, can crystallize during the growth of Pb₅Ge₃O₁₁ forming inclusions in the crystal. The successful synthesis of these three compounds is reported. The compound Pb₃Ge₂O₇, reported in the literature, is identified as a mixture of Pb₅Ge₃O₁₁ and PbGeO₃. Experimental conditions are presented for growing single phase Pb₅Ge₃O₁₁ crystals of uniform composition and high optical quality. This paper is based on a presentation at the Conference on Preparation and Properies of Electronic Materials, Princeton, N. J., August 1975.     

Temperature and duration effects on microstructure evolution during copper wafer bonding

Interfacial morphologies during Cu wafer bonding at bonding temperatures of 300–400°C for 30 min followed by an optional 30-min or 60-min nitrogen anneal were investigated by means of transmission electron microscopy (TEM). Results showed that increased bonding temperature or increased annealing duration improved the bonding quality. Wafers bonded at 400°C for 30 min followed by nitrogen annealing at 400°C for 30 min, and wafers bonded at 350°C for 30 min followed by nitrogen annealing at 350°C for 60 min achieve the same excellent bonding quality.     

Effects of DL-difluoromethylornithine on the cell surface charge of Ehrlich ascitic cancer during different phases of the mitotic cycle

Difluoromethylornithine (DFMO)-induced polyamide deficiency has been studied for its effect on the electrophoretic mobility of the Ehrlich ascitic cells in G1, S and G2 phases of the mitotic cycle. The DFMO treatment alters the pattern of the electrophoretic mobility distribution of Ehrlich ascite cells. The most profound changes of the electrophoretic mobility pattern are observed in G1-phase and at the S phase beginning. Exogenic polyamines decrease the electrophoretic mobility of cancer cells, which is accompanied by restoration of the initial pattern of the electrophoretic mobility distribution.     

Long-term intramuscular electrical activation of the phrenic nerve:safety and reliability

The safety and reliability of a system for long-term intramuscular electrical activation of the phrenic nerve was evaluated in seven dogs. In this system, electrodes are implanted bilaterally into the diaphragm without directly contacting the phrenic nerve using a laparoscope to direct placement. Five dogs underwent chronic bilateral intramuscular diaphragm stimulation (IDS) for 61 to 183 days at stimulus parameters selected to evoke at least 120% of the animal's basal ventilation. Two dogs maintained as controls did not undergo chronic stimulation. The safety and reliability of the system was evaluated in terms of tissue responses to the electrode, alterations in diaphragm muscle, pulmonary function, electrode reliability, and cardiac activation. No adverse responses to the electrode or stimulation were found. The histochemistry of chronically stimulated diaphragm suggested transformation towards type I (oxidative metabolism) muscle fibers. Two IDS electrodes dislodged out of a total of 32 IDS electrodes implanted. Both electrodes dislodged within seven days of implant. All IDS electrodes had stable and repeatable recruitment properties. No IDS electrode mechanical failures were found and no electrode corrosion was observed. It is concluded from these experiments that intramuscular activation of the phrenic nerve will present a minimal risk to human patients who are good candidates for clinical studies using this technique     

The effects of nonuniform and correlated noise on superresolutionalgorithms

The effects of nonuniform noise power and correlated noise in an antenna array on the performance of the recursive suppression, standard MUSIC, and reduced MUSIC superresolution algorithms are examined. It is shown that the speeds of resolution of all the algorithms are slowed, but their steady-state errors exhibit only a mild sensitivity to moderate noise-power variations if the signal-to-noise (SNR) is sufficiently large. The sensitivity of the standard MUSIC algorithm to correlated noise is shown to be much more than that of the other two algorithms, which can tolerate considerable correlated noise even when the SNR is relatively low     

The effects of limiting on angle- and amplitude-modulated signal

The AM compression, AM-PM and PM-AM conversion of a limiter is determined from its describing function.