Sperm storage in females of the smooth newt (Triturus v. vulgaris L.): I. Ultrastructure of the spermathecae during the breeding season

Sperm storage in cloacal spermathecae was studied in females of Triturus v. vulgaris collected early in the breeding season in southern England. Females collected in terrestrial situations, presumably unmated, were mated in the laboratory, and the ultrastructure of the transferred sperm and the spermathecae was observed at various intervals after mating. Sperm from a spermatophore cap lodged in a female's cloacal orifice can migrate into spermathecae within 1 hr after mating. Spherical structures on the axial fibers of some sperm in the cap could indicate immaturity. Disorderly clusters of sperm from the cap are still present in the cloacal chamber 12 hr after mating but are absent 24 hr after mating. During storage, sperm often are in tangled masses in the spermathecal tubules. The sperm are coated with spermathecal secretions, and some sperm nuclei were observed embedded in the spermathecal epithelium. Little evidence for spermiophagy early in the breeding season was found. During oviposition, mazes of sperm occur external to the spermathecal orifices, and sperm may be released in this condition onto eggs as they pass through the cloaca. The tangled clusters in which sperm are found from pick-up to oviposition are hypothesized as an adaptation to reduce the effectiveness of sperm competition from the ejaculates of rival males. Additional studies, using the same protocol and covering the entire cycle of sperm storage, are necessary to enable interspecific comparisons leading to phylogenetic hypotheses.     

α—Fe 中氢致软化同氢致硬化机制的研究

本文研究了工业纯 α-Fe 中晶内同晶界对氢致软化同氢致硬化效应的不同贡献,发现其中仍以晶内贡献为主,并提出了相应的新机制。     

C-Map: A High-level Language for Engineering Analysis and Design

C-MAP is a high level language for engineering computations. In addition to the conventional programming features, C-MAP has over 100 functions covering a broad spectrum of numerical methods for engineering computations ranging from elementary calculus to non-linear constrained optimization problems. These basic functions can be nested in innumerable ways that give C-MAP great flexibility and power. C-MAP comprises four integrated components: (i) a fullscreen text editor with multiple stacked windows for simultaneous editing of programs and output files; (ii) a simplified C-like programming language with control structures, recursive functions, math library, and built-in functions for advanced engineering computations including the processing of general matrix and complex expressions; (iii) an interactive expression processor; and (iv) a simple authoring system with automatic cross-referencing of keywords. The program's versatility helps to meet the different needs of users at different stages of learning. A beginner may use only the built-in functions for math and matrix operations to get immediate, useful results; the advanced users may write their own functions for more complex problems. This paper discusses the features of C-MAP and its applications in teaching structural engineering     

Pharmacokinetics of rocuronium during the three stages of liver transplantation

BACKGROUND: Little is known about the influence of liver transplantation on the pharmacokinetics of most anesthetic drugs. The authors determined the pharmacokinetics of rocuronium during liver transplantation and examined whether variability in pharmacokinetics could explain variability in recovery of neuromuscular function. METHODS: Twenty patients undergoing liver transplantation were given rocuronium, 600 microg/kg, after induction of anesthesia and again after perfusion of the transplanted liver. Plasma was sampled to determine rocuronium concentrations. Pharmacokinetic models were fit to rocuronium concentrations versus time data using a mixed-effects population approach. Various models permitted changes in clearance (Cl) or central compartment volume to account for changes in hepatic function and circulatory status during the paleohepatic, anhepatic, and neohepatic periods. Time to initial recovery of four twitches of the orbicularis oculi was determined. RESULTS: During the paleohepatic and anhepatic periods, the typical value of Cl was 2.47 ml x kg(-1) x min(-1) and was not influenced by the magnitude of preexisting liver disease (as evidenced by prothrombin time, bilirubin, serum albumin, alanine transaminase [ALT], and aspartate transaminase [AST]). During the neohepatic period, the typical value of Cl varied as a function of the duration of warm ischemia of the hepatic allograft and was 2.72 ml x kg(-1) x min(-1) for a patient with an average 60-min period of warm ischemia; time to neuromuscular recovery varied as a function of Cl. CONCLUSIONS: Despite prolonged hypothermic ischemia, the newly transplanted liver eliminates rocuronium as well as the diseased native liver (and comparably with historical control values). However, some patients had decreased rocuronium Cl during the neohepatic period, apparently a result of prolonged graft warm ischemia. The authors' finding of preservation of hepatic drug elimination in the hepatic allograft is consistent with limited data for other drugs evaluated during anesthesia.     

Temporal filter of the motion sensor in glaucoma

Glaucoma reportedly affects motion perception. As an initial step in characterizing glaucoma-induced changes in the motion system, we determined the range of temporal frequencies that the motion system could process. A noise-masking paradigm was used to measure contrast energy thresholds of 26 glaucoma patients at various stages of the disease and 16 age-similar subjects with normal vision. Using a sinusoidal stimulus, thresholds were measured for the discrimination of motion direction and for the stimulus embedded within a pattern of dynamic spatial noise. The noise was filtered to contain only low spatial frequencies, and the temporal-frequency spectrum of the noise was manipulated across conditions to derive the temporal filter shape of the most efficient motion sensor. The results show that the range of temporal frequencies processed by the motion system is diminished in the glaucoma group. The filters of the glaucoma subjects have reduced bandwidths compared with the normal-vision group. In addition, the upper cut-off frequency of the filters of the glaucoma subjects is correlated with stage of disease as indexed by the mean deviation of the Humphrey Visual Field Analyzer program 24-2, as well as the cup-to-disk ratio.     

Routine portable chest radiographs in the medical intensive care unit: effects and costs

OBJECTIVE: To determine the effects and net costs of routine chest radiographs in a medical intensive care unit (ICU). DESIGN: A prospective, cohort study. A survey of experts in critical care and pulmonary diseases was undertaken to assess the effect of routine radiographs on patient management. SETTING: Medical ICU of a university hospital. PATIENTS: Eighty randomly selected patients admitted to a medical ICU. Two hundred fourteen experts were surveyed; 118 (55%)/214 responded. MEASUREMENTS AND MAIN RESULTS: Daily interviews with medical ICU clinicians were conducted to assess the radiographic findings in the routine radiographs and actions taken based on these findings. Experts evaluated the findings, their importance, the actions taken, and the probability of complications if the actions had not been taken at that time. Experts also predicted increases in length of stay associated with these complications. Presence of radiographic findings, changes in management because of the findings, net costs of routine chest radiographs, cost per finding that prompted an action, and expected changes in length of stay resulting from the actions were also assessed. Seventy-two (33%) of 221 routine radiographs (95% confidence interval: 25% to 39%) had findings, of which 44 (61%) were judged important, and 18 (8%, 95% confidence interval: 5% to 12%) prompted actions. Experts predicted that each action averted, on average, 2.1 +/- 1.7 days (SD) in the medical ICU. Mean savings per routine radiograph was $98. Net savings from routine chest radiographs remained after sensitivity analysis for expected change in length of stay, percentage of patients with routine radiographs, and percentage of routine radiographs that produce changes in management. CONCLUSION: The policy of obtaining routine chest radiographs in the medical ICU is effective and results in net savings.     

Potential prognostic value of C-erbB-2 expression in medulloblastomas in very young children

PURPOSE: The expression of the c-erbB-2 oncogene was studied in childhood medulloblastoma to evaluate its prognostic value, which has been claimed previously. PATIENTS AND METHODS: Tumor material from 45 patients < 15 years old at diagnosis was studied using 3 monoclonal antibodies against the internal and external domains of the c-erbB-2 oncogene product. RESULTS: Six of the 45 (13%) tumor specimens were found to be positive. C-erbB-2 expression was found more often in patients < 3 years old at diagnosis (4 of 15 patients, 27%) than in older patients (2 of 30, 6.6%). During the follow-up period (5.8 +/- 2.8 years) all patients with c-erbB-2 expression died of disease (after 1.2 +/- 0.7 years). Kaplan-Meier estimation revealed a highly significant correlation of c-erbB-2 expression and survival (p = 0.002). A further study of the expression of synaptophysin and the glial fibrillary acidic protein (GFAP) in the 45 tumors revealed a negative correlation of the expression of c-erbB-2 and these proteins. CONCLUSION: C-erbB-2, which may be predominantly expressed by less differentiated tumors, was found to delineate a poorer prognostic subgroup, especially when diagnosed in patients < 3 years old.