典型作战剖面下的紫外告警对抗有效性分析

简要叙述了红外制导导弹对作战飞机构成的威胁,介绍了紫外告警系统的作用及发展状况,研究了空空红外制导导弹在迎头前向、尾追攻击及地空导弹攻击时,对作战飞机的威胁特征,计算分析了攻击所需时间和投放红外干扰弹的作用效果．阐述了紫外告警系统在作战飞机上实现全方位探测的必要性和重要性．     

A comparison of the carcase characteristics of pigs immunized with a ‘gonadotrophin-releasing factor (GnRF)’ vaccine against boar taint with physically castrated pigs

Evaluating the effect of using a GnRF vaccine against boar taint on the carcase characteristics of boars, vaccinated pigs were compared with physically castrated. In total, 554 male pigs were randomly assigned to treatment groups. T01 comprised physically castrated pigs in the first week of life, T02 comprised pigs vaccinated twice before slaughtering. There was neither significant difference between the groups in terms of average liveweight nor in the hot carcase weight. The mean dressing percentage was 1.5% higher for T01 than for T02 (P < 0.0001). The lean meat percentage was significantly higher in T02 (P < 0.0001). Backfat and backmuscle thickness were significantly higher in T01 (P < 0.0001 and P = 0.0099, respectively). Within the EUROP grading vaccinated pigs were in favour (P = 0.0034). There were no significant differences using the AutoFOM system: weights of the boned ham, boned shoulder and loin (P = 0.5102, P = 0.8881 and P = 0.1919, respectively). The weight of the belly was significantly higher (P = 0.0042) in T01 while the lean meat percentage of belly was significantly higher (P < 0.0001) in T02.     

Model experiments mimicking the human intestinal transit and metabolism of D-galacturonic acid and amidated pectin

In order to study the human intestinal transit and metabolism of D-galacturonic acid and amidated pectin a number of model experiments were carried out. Both substrates were incubated under aerobic conditions at 37 degrees C using saliva (2 min) and simulated gastric juice (4 h). Under anaerobic conditions the substrates were incubated at 37 degrees C using human ileostomy and colostomy fluids, each obtained from three different donors, for 10 and for 24 h, respectively. D-Galacturonic acid, SCFA (acetic acid, propionic acid, and butyric acid), as well as methanol were analyzed photometrically after carbazole reaction, GC-flame ionization detection (GC-FID), and headspace solid-phase microextraction GC/MS (HS-SPME-GC/MS), respectively. D-Galacturonic acid and amidated pectin were found to be stable during incubations with saliva and simulated gastric juice, whereas both substrates underwent degradation in the course of human ileostomy and colostomy fluid incubations. D-Galacturonic acid was practically completely decomposed within 10 h and SCFA, with acetic acid as the major representative, were formed up to 98% of the incubated substrate in colostomy effluent. The amidated pectin was only degraded in part, revealing stable amounts of 22-35% and 3-17% in ileostomy (after 10 h) and colostomy fluid (after 24 h), respectively. SCFA were generated up to 59% of the applied amidated pectin. In parallel, 19-60% and 52-67% of the available methyl ester groups were cleaved in the course of incubations with ileostomy and colostomy fluids, respectively. The results demonstrate for the first time that D-galacturonic acid and amidated pectin are stable in human saliva and simulated gastric juice. The degradation of both compounds during incubation with ileostomy effluent is highlighted, providing evidence for a considerable metabolic potential of the small intestine.     

Mapping the inside of the ribosome with an RNA helical ruler

The structure of ribosomal RNA (rRNA) in the ribosome was probed with hydroxyl radicals generated locally from iron(II) tethered to the 5' ends of anticodon stem-loop analogs (ASLs) of transfer RNA. The ASLs, ranging in length from 4 to 33 base pairs, bound to the ribosome in a messenger RNA-dependent manner and directed cleavage to specific regions of the 16S, 23S, and 5S rRNA chains. The positions and intensities of cleavage depended on whether the ASLs were bound to the ribosomal A or P site, and on the lengths of their stems. These data predict the three-dimensional locations of the rRNA targets relative to the positions of A- and P- site transfer RNAs inside the ribosome.     

Quantification by flow cytometry of chromosome-17 deletions in Smith-Magenis syndrome patients

BACKGROUND: Previous studies have suggested varying molecular weights for mast cell derived tumour necrosis factor alpha (TNF alpha ) and little data exist upon the factors which may regulate the control of this cytokine in these cells. OBJECTIVE: To determine the molecular weight of canine mastocytoma-derived TNF alpha, to determine whether it is pre-formed within the granule and whether is expression could be up-regulated by stem cell factor (SCF). METHODS: Molecular sizing was assessed by immunoblot. The cellular localization of the TNF alpha was determined by immunocytochemistry before and after stimulation by A23187 and passive sensitization. Subcellular localization was performed by immunogold immunocytochemistry. Changes in the level of mastocytoma mRNA for TNF alpha in response to stimulation with SCF or fibroblast conditioned media for up to 12 weeks were studied using Northern analysis and changes in the level of TNF alpha protein expression on immunoblot and immunocytochemistry. RESULTS: Mast cells contained authentic 17 kDa TNF alpha as identified by immunoblotting. Immunocytochemical studies demonstrated preformed TNF alpha which was released by stimulation with antigen after passive sensitization, or by the calcium ionophore A23187. Further confirmation of the preformed nature of this TNF alpha was provided by immunogold electron microscopy which localized this cytokine to the granule of the inactive mast cell. Northern blotting revealed a constitutive message for TNF alpha, which increased in response to fibroblast conditioned media (FCM) and to recombinant human SCF. Immunocytochemical studies of mast cells cultured long-term with FCM or with recombinant SCF showed increased expression of TNF alpha over the course of 12 weeks incubation with these stimuli. CONCLUSION: Mastocytoma derived-TNF alpha is a preformed, granule-associated 17 kDa cytokine which is released on stimulation with A23187 or passive sensitization. It is up-regulated by stem cell factor and by FCM over the course of 12 weeks.     

Multilevel signals and trellis coding for data communication modems

The special bandwidth efficiency features of coded single carrier multilevel data communication signals pave the way for implementation of high speed data transmission via public analogue telephone networks. The minimum distance of nonredundant coded signals and the minimum free-distance of redundant coded signals are discussed and their influence on error rates is analysed. Security of data on public networks, where it is subject to noise and interference, is improved by advanced trellis coding. Combining the trellis with multilevel signalling provides high speed data modems with security against nearly all spurious signals, transient noise and circuit impairments. The signal structure and coding algorithm of CCITT's recent recommendations on 9600 bit/s and 14 400 bit/s modems for PSTN and leased lines are also discussed.     

Sensitivity of Electrical Appliances to Harmonics and Fractional Harmonics of the Power SYSTEM's Voltage. Part I: Transformers and Induction Machines

The work described in Part I deals with analytical as well as experimental investigations of the effects of harmonics on singleand three-phase transformers including singleand three-phase induction machines as they occur in electrical appliances. The systematic treatment shows that single-phase and three-phase induction machines are more prone to temperature rises due to voltage harmonics than transformers. The work described has been supported by the U.S. Department of Energy.     

Studies and comparison of pterin patterns in the plasma of dogs and cats and their alteration in various neoplasias and virus infections

Studies using in vitro systems have indicated that Tamm-Horsfall protein (THP) can interact with calcium oxalate (CaOx) crystals during kidney stone formation. However, information regarding the nature of its participation in this process remains controversial and unclear. In order to better understand the putative interaction of THP and crystals in vivo, we compared the localization of THP in normal rats and in chronic and semi-acute rat models of nephrolithiasis. In these rats, CaOx crystal deposits were induced in the kidneys by administering ethylene glycol (EG) in drinking water. The formation of CaOx mono- and dihydrate aggregates in the urine was confirmed by scanning electron microscopy. Immunohistochemical localization, as well as protein A-gold labeling at the ultrastructural level, demonstrated that in addition to its normal distribution, THP specifically associated with the renal crystal deposits. The THP-containing, organic matrix-like material consisted of a fine, fibrillar meshwork surrounding individual crystals and their aggregates. In addition, THP also appeared in the papilla, where it is normally absent, concurrent with the appearance of crystal deposits in the kidneys. These observations indicate that in nephrolithic rats the normal localization of THP is altered. Such an alteration may indicate an important physiological event related to crystal aggregation and kidney stone formation.     

A family of homogeneous analysis models for the design of scalable structures

Research in optimum structural design has shown that mathematical programming techniques can be employed efficiently only in conjunction with explicit approximate constraints. In the course of time a well-established approximation for homogeneous functions (scalable structures) has emerged based on the linear Taylor expansion of the displacement functions in the compliance design space (Reciprocal approximation). It has been shown that the quality of this approximation is based on the property that homogeneity of the constraints is maintained and consequently the approximation is exact along the scaling line.The present paper presents a new family of approximations of homogenous functions which have the same properties as the Reciprocal approximation and which produce more accurate models in most of the tested cases. The approximations are obtained by mapping the direct linear Taylor expansion of the constraints unto a space spanned by intervening variables (original design variables to a powerm). Taking the envelope of these constraints along the scaling line yields a new family of approximations governed by the parameterm. It is shown that the Reciprocal approximation is a particular member of this family of approximations (m = –1).The new technique is illustrated with classical examples of truss optimization. An optimal plate design is also reported. A parametric study of the results for various values of the exponentm is presented. It is shown that for special values of the exponentm the new approximations usually yield better models than those based on the Reciprocal approximation.