A statistical approach to estimate the experimental uncertainty of viscosity data obtained by the oscillating cup technique

The determination of the dynamic viscosity of metallic alloys at elevated temperatures is a key experiment for materials design and characterisation. To do so, the oscillating cup method is the most suited and commonly applied one. However, critical estimations of the experimental uncertainties are scarce, complicating the comparison of results obtained by different authors as well as with models set up in order to describe the changes of the dynamic viscosity with temperature and the alloy's composition. We present a statistical approach, first to estimate the uncertainties of the actual measured parameters of a torsional oscillation, and second to analyse the propagation of these errors when calculating the dynamic viscosity. Overall relative uncertainties in the range of 5–10% are obtained for selected experiments carried out on pure liquid Al, Sn and Cu. This figure is in good agreement with previous error estimations. However, method is ready to be involved in the usual numeric calculation procedure of the dynamic viscosity in the actual experiment and is thus able to take the individual conditions with a given sample into account.     

The initial stages of palladium deposition onto Pt(1 1 1)

The electrodeposition of Pd onto Pt(1 1 1) from PdCl₂ and PdSO₄ containing solutions was studied by cyclic voltammetry and in situ scanning tunnelling microscopy. Pd deposition starts by forming a pseudomorphic monolayer in both cases. While in the presence of chloride this monolayer is deposited at underpotentials, its formation in chloride-free solution is kinetically hindered to such an extent that the deposition peak is shifted negative of the equilibrium potential. Detailed structure information has been obtained from STM data about the Pd layer as well as the co-adsorbed anions. Bulk deposition from the chloride-containing solution proceeds via a quasi layer-by-layer fashion. However, the particular electrochemical properties of the first Pd monolayer disappear only after deposition of the equivalent of four more Pd layers. The electrochemical behaviour of such films is similar to that of a rough Pd(1 1 1) surface. Pd bulk deposition from chloride-free solution leads to the formation of three-dimensional clusters from the very beginning. About 10 ML equivalents are needed in that case to completely cover the first Pd monolayer.     

Intracerebroventricular administration of streptozotocin causes long-term diminutions in learning and memory abilities and in cerebral energy metabolism in adult rats.

Drastic abnormalities have been demonstrated to occur in cerebral glucose and energy metabolism in sporadic Alzheimer's disease, pointing to a primary disturbance in neuronal insulin and insulin receptor signal transduction and contributing to the causation of dementia. The compound streptozotocin (STZ) is known to inhibit insulin receptor function. This study was designed to investigate whether intracerebroventricularly (icv) applied STZ would inhibit neuronal insulin receptor function and would induce changes in both behavior and neuronal energy metabolism. Adult rats with icv-injected STZ developed long-term and progressive deficits in learning, memory, and cognitive behavior, indicated by decreases in working and reference memory in the holeboard task and the passive avoidance paradigm, along with a permanent and ongoing cerebral energy deficit. This animal model may be appropriate for investigations related to sporadic Alzheimer's dementia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tele-immobilization of (gone) wild animals in Dutch veterinary practice. 2: Anesthetics used in the immobilization of wild animals

In this article a review will be given of the groups of anaesthetics used for animal capture, their developmental history, mode of action and indication for use. A table with dosages of locally--in the Netherlands--available drugs will be presented for a number of animal species.     

Long-term ovarian and gonadotropin changes in mice exposed to 4-vinylcyclohexene

This study investigated the relationships between 4-vinylcyclohexene-induced follicular destruction, plasma FSH levels, and the development of ovarian preneoplastic changes. Female, 28-day-old, B6C3F1 mice were administered VCH (800 mg/kg/day, ip) or sesame seed oil, ip daily for 30 days. At 30, 60, 120, 240, and 360 days following the beginning of treatment, groups were killed, their ovaries were harvested, and plasma was collected for measurement of FSH. Ovarian weight was less and oocytes contained in preantral follicles were significantly fewer than controls at all time points. Plasma FSH concentrations in VCH-treated animals were increased significantly above controls at 240 d and 360 d. Histologically, there was oocyte loss at all times, whereas at 240 and 360 days, small to medium, irregularly shaped foci of hypertrophic cells were present. In addition, at 360 days 80% of the VCH-treated mice had a 1- to 2-mm, blood-filled cystic structure present in one or both ovaries. These studies indicate that VCH-induced oocyte destruction and follicle loss are associated with increases in plasma FSH, are associated with ovarian failure at 360 days, and are temporally related to ovarian cellular hypertrophy and the formation of blood-filled cystic ovarian structures. These events are possibly related to ovarian neoplasms produced by long-term exposure to VCH.     

Age and the selectivity of visual information processing.

Two experiments assessed age differences in the selectivity of visual information processing. Selectivity was measured by the amount of interference caused by nontarget letters when Ss detected a target letter in a visual display. In both experiments, young and elderly groups participated in search and nonsearch conditions; in the search condition, targets appeared anywhere in the display, whereas in the nonsearch condition targets were confined to the center position of the display. In Exp I, 20 19–27 yr olds and 20 65–90 yr olds were assigned to either condition for 2 sessions of testing. In Exp II, 16 young (mean age 19.8 yrs) and 16 elderly (mean age 71.8 yrs) Ss participated in both conditions. In both experiments, nontargets produced larger interference effects for old compared to young Ss in the search condition but not in the nonsearch condition. The obtained pattern of age effects could not be explained by age-related reductions in parafoveal acuity. Findings indicate that the magnitude of divided-attention deficit increases with age, whereas focused-attention deficits are unaffected by aging. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adult age differences in implicit and explicit memory: Time course and encoding effects.

Young and older adults were tested at three delays on word-stem completion or cued recall following semantic or structural word judgments. Identical three-letter stems were present at retrieval for both implicit (completion) and explicit (cued recall) tasks; only the intention to recall list words differed. The young adults outperformed the older adults on both implicit and explicit task at all test delays. Under some conditions, the older but not the young adults performed more poorly on cued recall than on stem completion, suggesting a possible failure to use implicitly available information to support explicit remembering. These results suggest that some forms of implicit memory decline with normal aging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)