用设计管理功能改变FPGA设计流程

在传统的FPGA系统设计中,不同的尝试必须按顺序依次进行,使得编译时间延长,而采用新的设计工具可并行编译多个实现,用一次编译时间比较两种实现的结果,可加快产品开发速度。     

AMOLED电视将继续面临成本困扰

尽管AMOLED电视在今年美国CES展上露面令人振奋,但由于制造困难和原材料成本高昂,未来几年这种电视的全球出货量将非常有限。     

在先进移动设备上应用MEMS传感器

MEMS传感器包括加速度计、陀螺仪、磁力计、压力传感器和麦克风,因其具有低成本、小尺寸、低功耗、高性能等特性,近几年来被大量集成到便携设备中。     

Effect of citric acid concentration on dentin demineralization, dehydration, and rehydration: atomic force microscopy study

Helper T cells (Th) are classified as type 1 (Th1) and type 2 (Th2) according to the cytokines they produce; interferon-gamma is produced by Th1, and interleukin-4 by Th2. We counted the circulating CD4-positive Th cells that produce interferon-gamma or interleukin-4 with an enzyme-linked immunospot assay. CD4-positive T cells isolated from patients with chronic hepatitis B (n = 10), chronic hepatitis C (n = 16), and healthy subjects (n = 10) were stimulated with anti-CD3 antibody in vitro. The number of interferon-gamma-producing Th cells was significantly lower in patients with chronic hepatitis C than in healthy subjects (P = 0.0024), whereas in patients with chronic hepatitis B, the number was similar to that in healthy subjects (P = 0.8530). The number of interleukin-4-producing Th cells was significantly higher in patients with chronic hepatitis C (P = 0.0010) and chronic hepatitis B (P = 0.0089) than in healthy subjects. In chronic hepatitis C, the number of interferon-gamma-producing Th cells was increased after incubation of the cells with interferon-alpha (P = 0.008) or with recombinant interferon-gammala (P = 0.024), but not with interferon-beta (P = 0.051). The number of interleukin-4-producing Th cells was decreased after incubation with interferon-alpha (P = 0.0004), with interferon-beta (P = 0.003), and with recombinant interferon-gammala (P = 0.0004). Changes in the numbers of interferon-gamma- or interleukin-4-producing Th cells in vitro were more evident in sustained responders to interferon therapy than in non-responders. These results suggest that Th2 cells are the predominant cell type in chronic hepatitis C, and that their activity may be suppressed by the administration of interferon.     

Symptoms of depression and changes in body weight from adolescence to mid-life

OBJECTIVE: To investigate the relationship of symptoms of depression to weight changes in healthy individuals of normal weight across a follow-up of over 20 y. PARTICIPANTS AND DESIGN: College students (3885 men and 841 women) were administered a self-report depression measure in the mid-1960s. Their baseline body mass index (BMI) was calculated from their college medical records. Participants were contacted by mail in the late 1980s and asked to report their current height and weight as well as their smoking and exercise habits. Another measure of depressive symptoms was obtained from 3560 individuals at follow-up. Multiple regression models were used to relate changes in weight to depression scores while controlling for background (gender, baseline BMI and the gender by BMI interaction) and behavioral (exercise and smoking) predictors. RESULTS: The relationship between depressive symptoms and body weight change took the form of an interaction with baseline BMI (P < 0.001). Those with high baseline depression scores gained less weight than their nondepressed counterparts if they were initially lean, but more if they were initially heavy. This trend was especially strong in those with high depression scores at both baseline and follow-up. CONCLUSIONS: The findings support the hypothesis that depression exaggerates pre-existing weight change tendencies. This pattern would not have been detected by an examination of main effects alone, illustrating the need to move toward more complicated interactive models in the study of psychological factors and weight.     

Transthoracic Doppler echocardiography of normally originating coronary arteries in children

Transthoracic Doppler color flow and spectral velocity patterns of normal coronary arteries in children have not been well studied. We designed this study to evaluate coronary artery flow velocity characteristics in normal and hypertrophied hearts. Sixty-eight children with optimal two-dimensional echocardiographic images of the left coronary artery (LCA) and right coronary artery (RCA) were prospectively studied. The heart was normal in 45 children, and 23 had left and/or right ventricular hypertrophy assessed by echocardiography (mean age 5.8 versus 5.2 years, p = NS). Color flow signals were detected in the LCA in 63(92%) of the 68 children studied, and pulsed Doppler spectral waveforms were recorded in 47 (69%). The latter were recorded in 26 (58%) of 45 normal children and in 21 (91%) of 23 children with left ventricular hypertrophy. Diastolic RCA flow signals were detected mostly in those with right ventricular hypertrophy (10 of 10). Higher levels of LCA maximum diastolic velocity (42 +/- 23 versus 24 +/- 6 cm/sec, p = 0.0004), increased diastolic flow (16 +/- 15 versus 6 +/- 4 ml/min, p = 0.01), and delayed time to peak diastolic velocity expressed as a percentage of diastolic spectral duration (38% +/- 14% versus 20% +/- 8%, p = 0.0001) were observed in children with left ventricular hypertrophy than in those in normal children. A strong correlation was present between Doppler-derived LCA flow and left ventricular mass/m2 (r = 0.7, p = 0.001). In normal hearts, LCA spectral velocity pattern did not change with increasing age, but the time velocity integral became progressively larger, resulting in a strong correlation with weight (p < 0.001, r = 0.78). This study demonstrates (1) LCA flow signals can be detected and quantitated in the majority of children with and those without left ventricular hypertrophy. (2) Left ventricular hypertrophy is associated with increased LCA flow, higher diastolic velocity, and delayed peak diastolic velocity. (3) RCA flow signals are mostly detected when there is right ventricular hypertrophy. Studies on larger groups of patients are needed to further confirm our observations and to enhance understanding of coronary artery flow reserve.     

Effect of surface properties on the antithrombogenicity of silk fibroin/S-carboxymethyl kerateine blend films

Polymeric blends of silk fibroin (SF) and S-carboxymethyl kerateine (SCMK) were prepared by the solvent casting method to study the effect of surface properties on the antithrombogenicity. The films of SF/SCMK showed better antithrombogenic properties than SF or SCMK alone. Among them, the film containing 50 wt% SCMK showed the best antithrombogenicity. When the SF/SCMK films were treated with methanol, the antithrombogenicity of the films was scarcely affected except the SF-rich ones. The enhanced antithrombogenic properties were explained in terms of polarity of the surface. The blend films showed an enhancement of polar contribution to surface free energy (gamma(P)S and polar stabilization energy (I(SW)). SF-rich films showed high gamma(P)S and I(SW) values when treated with methanol. This change of surface properties was considered to be due to the fact that the conformational transition from random coil structure to beta-structure of proteins may have affected the surface properties, especially the polar properties.     

Protective heterologous antiviral immunity and enhanced immunopathogenesis mediated by memory T cell populations

A basic principle of immunology is that prior immunity results in complete protection against a homologous agent. In this study, we show that memory T cells specific to unrelated viruses may alter the host's primary immune response to a second virus. Studies with a panel of heterologous viruses, including lymphocytic choriomeningitis (LCMV), Pichinde (PV), vaccinia (VV), and murine cytomegalo (MCMV) viruses showed that prior immunity with one of these viruses in many cases enhanced clearance of a second unrelated virus early in infection. Such protective immunity was common, but it depended on the virus sequence and was not necessarily reciprocal. Cell transfer studies showed that both CD4 and CD8 T cell populations from LCMV-immune mice were required to transfer protective immunity to naive hosts challenged with PV or VV. In the case of LCMV-immune versus naive mice challenged with VV, there was an enhanced early recruitment of memory phenotype interferon (IFN) gamma-secreting CD4(+) and CD8(+) cells into the peritoneal cavity and increased IFN-gamma levels in this initial site of virus replication. Studies with IFN-gamma receptor knockout mice confirmed a role for IFN-gamma in mediating the protective effect by LCMV-immune T cell populations when mice were challenged with VV but not PV. In some virus sequences memory cell populations, although clearing the challenge virus more rapidly, elicited enhanced IFN-gamma-dependent immunopathogenesis in the form of acute fatty necrosis. These results indicate that how a host responds to an infectious agent is a function of its history of previous infections and their influence on the memory T cell pool.     

Progesterone induces calcitonin gene expression in human endometrium within the putative window of implantation

The human endometrium acquires the ability to implant the developing embryo within a specific time window that is thought to open between days 19-24 of the secretory phase of the menstrual cycle. During this period the endometrium undergoes pronounced structural and functional changes induced by the ovarian steroids, estrogen and progesterone, that prepare it to be receptive to invasion by the embryo. The identification of reliable biochemical markers to assess this critical receptive phase in the context of the natural cycle remains one of the major challenges in the study of human reproduction. Our previous studies in a rat model system demonstrated that the expression of calcitonin, a peptide hormone involved in calcium homeostasis, is transiently induced by progesterone in the glandular epithelium at the onset of implantation. Attenuation of calcitonin synthesis in the uterus during the preimplantation phase by administration of calcitonin antisense oligodeoxynucleotides severely impairs implantation of rat embryos, suggesting that this peptide hormone plays a critical role in uterine receptivity. To investigate whether calcitonin is also expressed in the human endometrium during implantation, we monitored the spatio-temporal expression of calcitonin on various days of the menstrual cycle. Our studies employing RT-PCR showed that calcitonin messenger ribonucleic acid is expressed in human endometrium during the postovulatory midsecretory phase (days 17-25) of the menstrual cycle, with maximal expression occurring between days 19-21. Very little calcitonin expression was detected in the endometrium in either the preovulatory proliferative (days 5-14) or the late secretory (days 26-28) phase. In situ hybridization and immunocytochemical analyses localized the calcitonin expression predominantly in the glandular epithelial cells of the endometrium. Our studies further showed that calcitonin expression in the human endometrium is under progesterone regulation. Treatment of women with an antiprogestin, mifepristone (RU-486), drastically reduced calcitonin expression in the endometrium. Collectively, these findings reveal that progesterone-induced expression of calcitonin in the secretory endometrium temporally coincides with the putative window of implantation in the human.