Laparoscopic versus open appendectomy

BACKGROUND: Clinical manifestations and course of sickle-cell anemia are variable. Knowledge about the factors, possibly geographic, that influence prognosis are still scanty. POPULATION AND METHODS: Data of hospitalization and management of children with sickle-cell disease were studied during two years (1992-1993) in the Pediatric Unit of Libreville Hospital. They concerned 205 admissions of 171 children and 131 outpatients. RESULTS: The main causes of hospitalization were: acute anemia (36 cases before the age of 5 years); painful crisis whose frequency increased with age (23% before 5 years, 35% between 5 and 10, 42% after 10 years); infections, essentially pulmonary occurring early, and bone infections at any age. Eight children died (because a complication of their disease). Among the 131 outpatients, half were detected because pyrexia, anemia and/or more often "hand-foot syndrome". More than 60% had hepatomegaly, one third still had splenomegaly after five years of age and more than one third was icteric. More than half children older than ten years had growth disorders. Mean hemoglobin level was 7 g/dL. 21 of the 83 tested children for HBsAg were positive and only one out of 79 was positive for HIV. CONCLUSIONS: Clinical manifestations and course of sickle-cell anemia in our patients are similar to those reported in Congolese children. Genetic and environmental factors may be responsible for differences with children from other, in particular French, cohorts.     

Prophylactic efficacy of tilmicosin for bovine respiratory tract disease

The prophylactic administration of injectable tilmicosin for pneumonia in weaned beef calves was investigated in 1,806 animals. Comparisons were made among calves receiving an "on-arrival" injection of tilmicosin, calves receiving a single injection of long-acting oxytetracycline, and calves receiving no prophylaxis. Morbidity and mortality attributable to pneumonia, morbidity and mortality attributable to all causes, and case fatality were significantly lower in the group of calves that received tilmicosin, compared with calves that received long-acting oxytetracycline and calves that received no prophylactic antibiotic. Mean time to initial pneumonia treatment was significantly extended in calves that received prophylaxis, compared with those that received no antibiotic on arrival at the feedlot. Calves that received tilmicosin gained significantly more weight than calves that received oxytetracycline. Calves that were not treated for pneumonia during the trial period gained significantly more weight than did those calves that were treated for pneumonia regardless of experimental group. The majority of mortalities were attributable to fibrinous pneumonia (31/34). Important bacterial isolates (Pasteurella spp, Haemophilus somnus, Actinomyces pyogenes) obtained at necropsy did not have resistance to tilmicosin in association with administration of tilmicosin as prophylaxis for pneumonia. However, bacterial resistance to trimethoprim/sulfonamide and to oxytetracycline were commonly found in these postmortem isolates.     

The development of sibling relationships in infancy: a short-term longitudinal study

24 infants and their preschool-aged siblings were observed in a laboratory playroom in the presence of their parents. Observations took place when the infants were 12 months old and again 6 months later. Analysis of the social behavior revealed that, at both ages, the children assumed differentiable roles in their interactions: The infants "followed" by observing and imitating while the preschoolers "led" by drawing the infants' attention and by assertive dominance. Over time, infants became increasingly willing to direct social behaviors toward their siblings. There was remarkable behavioral stability across time, with the infants' early propensities seemingly causally related to later pre-schoolers' behavior. Older girls directed more social behaviors to siblings than boys did. The amount of parent-directed behavior was affected by the number of adults present, whereas the amount of sibling-directed behavior was unaffected.     

The turnover and distribution of labelled corticosterone during post-natal development of the duckling (Anas platyrhynchos)

During 6 months of post-natal development in the laboratory, the weight of the adrenal gland relative to body weight decreases exponentially. In the 3 day-old duckling a single intravenous dose of labelled corticosterone becomes distributed in a very large apparent volume and an "extracellular" pool that is greater than the extracellular fluid volume and the pattern of disappearance of labelled hormone from plasma is biphasic. Later during development the volumes of distribution decrease and the biphasic pattern of disappearance becomes less distinct until at 6 months only one phase of disappearance can be detected with confidence. No significant change in plasma corticosterone concentration occurs during this period of development in the laboratory. Estimations of the corticosterone secretory rates, however, indicate that whereas the adrenal weight-specific rate os secretion increases during the first 3 weeks and declines therafter, the bodyf weight-specific secretory rate continues to decline throughtout the period of increasing body weight.     

Periodic attachment in future mobile telecommunications

In mobile telecommunications the network needs to monitor the terminal status, i.e., switched on, switched off, busy, idle. Once a mobile terminal is switched on, it automatically informs the network accordingly (attachment action). Regarding the way that the network identifies that a terminal is switched off (detachment), a procedure called periodic attachment is proposed: the terminal (when switched on) periodically reports to the network its active status. If the network detects silence for more than an agreed time period it considers the terminal switched off. Paging signalling savings can be achieved if the network is informed early that a mobile terminal is switched off. However, periodic attachment requires access to the network database system, which might cause a bottleneck. In this paper the performance characteristics of periodic attachment and the induced signalling load are evaluated as influenced by the selection of the time-out period. A constant time-out period for the whole day can cause a large amount of database transactions especially during low traffic hours. A method for dynamic time-out period selection to fit the varying conditions during the day is proposed and evaluated     

弱碱三元复合驱与强碱三元复合驱的对比

三元复合驱即将成为大庆油田的主导开发技术,为了推荐出合适的三元复合驱类型,对比研究了弱碱三元复合驱与强碱三元复合驱。研究表明,弱碱三元复合驱可以比水驱提高采收率20%以上,与强碱三元复合驱相当;弱碱三元复合驱与强碱三元复合驱乳化液粘度都超过100 mPa.s,两种类型三元复合乳化能力相差不多,甚至弱碱三元复合驱乳化能力还略强一些;在注采能力、采油速度方面,弱碱三元复合驱甚至高于强碱三元复合驱;特别是在结垢程度上,弱碱三元复合驱比强碱三元复合驱弱,对生产井的影响较小。因此,在三元复合驱推广应用时应当选用弱碱三元复合驱。     

基矛电磁波的低流速测量中干扰因素分析研究

介绍了电磁渡测量流速的基本原理一多普勒效应．分析了影响低流速测量的主要干扰因素一发射泄漏干扰和旁瓣干扰。根据接收信号中发射泄漏干扰不变的特性,提出了去均值滤波的方法来消除干扰,对数据进行预处理;根据旁瓣干扰的信号特性,提出了通过频谱加窗和二次加权平均法构造频域带通滤波器来抑制干扰的方法,在仿真比较完各个窗函数的性能之后...     

Optimal component configuration and component routing

Code mobility and mobile agents have received a lot of attention as a paradigm based on which distributed applications can be built. There has been little work however on the mathematical modeling of component mobility. In this direction, we present and analyze three optimization models for component mobility. We are seeking the optimal allocation of components to network nodes and the optimal component routes that will minimize the network traffic that is incurred in the course of component communication. Optimal solutions are found either through a mixed binary integer programming formulation or by employing max flow computations. Complexity results are also reported.     

O6-alkylguanine-DNA alkyltransferase inactivation by ester prodrugs of O6-benzylguanine derivatives and their rate of hydrolysis by cellular esterases

To modulate the bioavailability and perhaps improve the tumor cell selectivity of O6-alkylguanine-DNA alkyltransferase (AGT) inactivators, pivaloyloxymethyl ester derivatives of O6-benzylguanine (BG) were synthesized and tested as AGT inactivators and as substrates for cellular esterases. The potential prodrugs examined were the 7- and 9-pivaloyloxymethyl derivatives of O6-benzylguanine (7- and 9-esterBG), and of 8-aza-O6-benzylguanine (8-aza-7-esterBG and 8-aza-9-esterBG) and the 9-pivaloyloxymethyl derivative of 8-bromo-O6-benzylguanine (8-bromo-9-esterBG). The benzylated purines were all potent inactivators of the pure AGT and of the AGT activity in HT29 cells and cell extracts. Each ester was at least 75 times less potent than the corresponding benzylated purine against the pure human AGT. In contrast, the activities of esters and their respective benzylated purine were similar in crude cell extracts and in intact cells. The increase in potency of esters in cellular extracts could be explained by a conversion of the respective prodrug to the more potent benzylated purine in the presence of cellular esterases. The apparent catalytic activity (Vmax/Km) of liver microsomal esterase for 8-azaBG ester prodrugs was 70-130 times greater than for BG prodrugs and 10-20 times greater than for 8-bromo-9-esterBG. Tumor cell hydrolysis of the esters varied considerably as a function of cell type and prodrug structure. These data suggest that these or related prodrugs may be advantageous for selective AGT inactivation in certain tumor types.