Low-temperature (⩽550°C) fabrication of poly-Si thin-filmtransistors

High performance n- and p-channel thin-film transistors (TFTs) have been fabricated in polycrystalline silicon films using a self-aligned-gate process without exceeding 550°C. This process features the use of polycrystalline Si_0.5Ge_0.5 for the gate material and high-dose H⁺ implantation for grain-boundary passivation so that shorter process times can be used. Low threshold voltages of 2.8 and -0.2 V, and high field-effect mobilities of 35 and 28 cm²/V-s, where achieved by the NMOS and PMOS devices, respectively. The performance of these devices is comparable to that of previously reported devices fabricated using process temperatures up to 600°C, and is adequate for large-area-display peripheral driver circuits. The significant reduction in maximum process temperature makes this process advantageous for the fabrication of CMOS circuits on large-area glass substrates     

The efficacy of live attenuated, cold-adapted, trivalent, intranasal influenzavirus vaccine in children

BACKGROUND: Influenzavirus vaccine is used infrequently in healthy children, even though the rates of influenza in this group are high. We conducted a multicenter, double-blind, placebo-controlled trial of a live attenuated, cold-adapted, trivalent influenzavirus vaccine in children 15 to 71 months old. METHODS: Two hundred eighty-eight children were assigned to receive one dose of vaccine or placebo given by intranasal spray, and 1314 were assigned to receive two doses approximately 60 days apart. The strains included in the vaccine were antigenically equivalent to those in the inactivated influenzavirus vaccine in use at the time. The subjects were monitored with viral cultures for influenza during the subsequent influenza season. A case of influenza was defined as an illness associated with the isolation of wild-type influenzavirus from respiratory secretions. RESULTS: The intranasal vaccine was accepted and well tolerated. Among children who were initially seronegative, antibody titers increased by a factor of four in 61 to 96 percent, depending on the influenza strain. Culture-positive influenza was significantly less common in the vaccine group (14 cases among 1070 subjects) than the placebo group (95 cases among 532 subjects). The vaccine efficacy was 93 percent (95 percent confidence interval, 88 to 96 percent) against culture-confirmed influenza. Both the one-dose regimen (89 percent efficacy) and the two-dose regimen (94 percent efficacy) were efficacious, and the vaccine was efficacious against both strains of influenza circulating in 1996-1997, A(H3N2) and B. The vaccinated children had significantly fewer febrile illnesses, including 30 percent fewer episodes of febrile otitis media (95 percent confidence interval, 18 to 45 percent; P<0.001). CONCLUSIONS: A live attenuated, cold-adapted influenzavirus vaccine was safe, immunogenic, and effective against influenza A(H3N2) and B in healthy children.     

Evidence that histamine is the principal pharmacological component of venom from an Australian wolf spider (Lycosa godeffroyi)

Wolf spiders are common throughout Australia and have been known to cause severe reactions in both animals and humans. However, little work has been done on the pharmacological activity of Australian lycosids. The purpose of this study was to obtain a preliminary pharmacological profile of the venom from an Australian wolf spider (Lycosa godeffroyi). The venom caused dose-dependent contractions of guinea-pig isolated ileum (1-4 microg/ml), endothelium-dependent relaxation in rat isolated aortae (10 microg/ml), a decrease in mean arterial blood pressure in the anaesthetised rat (100 microg/kg, i.v.) and an increase in insufflation pressure in the anaesthetised guinea-pig (50 microg/kg, i.v.). All of these responses were significantly inhibited by the H1-receptor antagonist mepyramine at concentrations that selectively inhibited responses to histamine. Venom (5 microg/ml) caused a decrease in twitch height of the rat stimulated (0.3 msec, 0.2 Hz, 100 V) vas deferens (prostatic segment). A fluorometric assay for histamine detected a concentration of 44.5 ng/microg venom protein. It appears that the in vitro and in vivo activity of L. godeffroyi venom observed in the present study is due to the presence of histamine.     

Copulation releaser pheromone in body scales of female whitemarked tussock moth,Orgyia leucostigma (Lepidoptera: Lymantriidae): Identification and behavioral role

The copulatory behavior of the male whitemarked tussock moth,Orgyia leucostigma, was released by extracts of female body scales applied to rubber septum models baited with a female sex pheromone gland. The major compounds in the scale extracts were identified by GC-MS as a series ofn-alkanes from C-21 to C-29. Of these,n-tricosane,n-tetracosane,n-pentacosane, andn-heptacosane, applied at 10 ng/septum, caused significantly more males to attempt copulation than hexane-treated controls. Mixtures of then-alkanes, resembling the composition in the scale extracts, were no better than the two most active alkanes,n-tetracosane andn-pentacosane, alone. The releaser effect of then-alkanes was dose dependent. EAG responses to the identifiedn-alkanes were small suggesting, along with the behavioral observations, that their perception occurred at very close range. Other factors releasing male copulatory behavior are discussed.     

Two pleiotropic classes of daf-2 mutation affect larval arrest, adult behavior, reproduction and longevity in Caenorhabditis elegans

The nematode Caenorhabditis elegans responds to overcrowding and scarcity of food by arresting development as a dauer larva, a nonfeeding, long-lived, stress-resistant, alternative third-larval stage. Previous work has shown that mutations in the genes daf-2 (encoding a member of the insulin receptor family) and age-1 (encoding a PI 3-kinase) result in constitutive formation of dauer larvae (Daf-c), increased adult longevity (Age), and increased intrinsic thermotolerance (Itt). Some daf-2 mutants have additional developmental, behavioral, and reproductive defects. We have characterized in detail 15 temperature-sensitive and 1 nonconditional daf-2 allele to investigate the extent of daf-2 mutant defects and to examine whether specific mutant traits correlate with each other. The greatest longevity seen in daf-2 mutant adults was approximately three times that of wild type. The temperature-sensitive daf-2 mutants fell into two overlapping classes, including eight class 1 mutants, which are Daf-c, Age, and Itt, and exhibit low levels of L1 arrest at 25.5 degrees. Seven class 2 mutants also exhibit the class 1 defects as well as some or all of the following: reduced adult motility, abnormal adult body and gonad morphology, high levels of embryonic and L1 arrest, production of progeny late in life, and reduced brood size. The strengths of the Daf-c, Age, and Itt phenotypes largely correlated with each other but not with the strength of class 2-specific defects. This suggests that the DAF-2 receptor is bifunctional. Examination of the null phenotype revealed a maternally rescued egg, L1 lethal component, and a nonconditional Daf-c component. With respect to the Daf-c phenotype, the dauer-defective (Daf-d) mutation daf-12(m20) was epistatic to daf-2 class 1 alleles but not the severe class 2 alleles tested. All daf-2 mutant defects were suppressed by the daf-d mutation daf-16(m26). Our findings suggest a new model for daf-2, age-1, daf-12, and daf-16 interactions.     

Effects of limited proteolysis on broad bean polyphenoloxidase

Partially purified broad bean polyphenoloxidase was treated with a variety of proteases. Enzyme activity increased after treatment with chymotrypsin, pepsin, subtilisin, thermolysin, trypsin, and Staphylococcus aureus V₈ protease but this activation was masked when assayed in the presence of sodium dodecylsulfate. The enzyme was resistant to proteolysis when treated with chymotrypsin, elastase, pepsin, thermolysin, and V₈ protease. Proteinase K, subtilisin and trypsin treatment resulted in partial degradation of the enzyme but only trypsin generated an active enzyme form with a slightly smaller molecular weight. Electrophoresis, followed by enzyme staining and or Western blotting, showed that trypsin treatment converted the active 45 kd enzyme into a 43 kd enzyme within 20 min. Treatment with proteinase K, subtilisin and trypsin also produced inactive higher molecular weight forms of purified polyphenoloxidase that were identified by Western blotting. The use of antibodies coupled with Western blotting also identified inactive, active, and latent polyphenoloxidase after protease treatment, and suggests that immunological methods can be used to establish the types and amounts of polyphenoloxidase present in a given tissue.     

Differences in airway closure between normal and asthmatic subjects measured with single-photon emission computed tomography and technegas

The absence of a maximal dose-response plateau as well as gas trapping and increases in closing capacity (CC) suggest that increased airway closure is an important mechanical abnormality of asthmatic airways. We compared the extent and distribution of airway closure in 13 normal and in 23 asthmatic subjects. Airway closure (LVclosed) was measured with single-photon emission computed tomography (SPECT) and an inhaled Technegas bolus as the percentage of lung volume without Technegas (LVtrans), and with CC, using nitrogen washout. LVclosed was compared in the apical, middle and lower zones, each being of equal vertical height. Values of mean LVclosed +/- 95% confidence interval (CI) were similar in normal (30 +/- 6.0% LVtrans) and asthmatic subjects (30 +/- 7.8% LVtrans). In normal subjects, LVclosed correlated with both age (r = 0.89, p < 0. 01) and CC (r = 0.86, p < 0.01), was more extensive in the lower zone (58 +/- 18.8% LVtrans, p < 0.01) than in the middle and upper zones (17 +/- 8.7% and 26 +/- 8.2 LVtrans, respectively), and increased with age in both the middle and lower zones (r = 0.94 and r = 0.90, respectively, p < 0.01). In asthmatic subjects, LVclosed did not correlate with age; was greatest in the lower zone, intermediate in the middle zone, and lowest in the apical zone (59 +/- 13.2%, 22 +/- 5.8%, and 12 +/- 4.4% LVtrans, respectively, p < 0. 01); and correlated weakly with age in the middle zone only (r = 0. 46, p < 0.05). We conclude that there is a predictable pattern of airway closure in normal subjects and that it is primarily influenced by pulmonary elastic recoil. This pattern is lost in asthmatic subjects. This may be explained by an increased range of closing pressures and a patchy distribution of airway closure, probably secondary to allergic inflammation.