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The influence of Ar+ ion irradiation on structural and nanomechanical properties of Yttria Stabilized Zirconia (YSZ) single crystals were studied. Specimens grown in three crystallographic orientations 〈1 0 0〉, 〈1 0 0〉 and 〈1 1 1〉 were irradiated at room temperature with 160 keV Ar-ions up to 3 fluences: 1 × 1014, 1 × 1015 and 1 × 1016 cm−2. Structural properties of the modified layers were measured by means of Grazing Incidence X-ray Diffraction (GI XRD) and Raman Spectroscopy techniques, whereas nanomechanical properties were asessed by using nanoindentation technique. Obtained results revealed shifts of the characteristic peaks and hardening effect in the function of Ar-ion fluence. Reported changes originate from at least two phenomena: (i) creation of radiation defects and (ii) local increase of stress induced by damage created by incoming ions – which magnitude may depend on crystallographic orientation.

Purpose This study investigated the disclosure practices of people who stutter, and the relationship between disclosure of stuttering and quality of life. Method Participants were 322 adults who stutter recruited from speech-language pathologists and support group leaders. Participants completed a survey that contained items measuring level of disclosure of stuttering, as well as a global measure of self-rated quality of life. Participants were grouped into low, average, and high quality of life subgroups. Analysis of variance tests compared disclosure levels among these subgroups. Results The low quality of life subgroup reported significantly lower levels of disclosure compared to both the average and high quality of life subgroups. Participants with self-help/support group experience for stuttering demonstrated significantly higher levels of disclosure of stuttering compared to individuals without such experience. In addition, a substantial number of participants in the overall sample reported that they more than rarely feel the need to conceal stuttering from others (40%), and that no one knows that they stutter in many areas of life (37%). Conclusions Attempts to conceal stuttering in at least some life situations are not uncommon among adults who stutter. However, being involved in self-help support groups may be a helpful way of increasing disclosure of stuttering. Speech-language pathologists should become aware of the positive relationship between disclosure of stuttering and quality of life and its relevance in assessment and treatment when working with people who stutter.

It has been observed that tall structures are sometimes struck by lightning below their tops. This phenomenon necessitates the use of special procedures for the protection of tall structures from lightning hazards. This paper focuses on the analysis of lightning flashes that struck the CN Tower below its tip over an extended period of time (1991–2005). Through the use of video images recorded during the reporting period, it was found that out of 404 flashes to the tower, only 16 hit the tower below its tip (3.96%). The distance between the tower's tip and the strike location varied from 5.4 to 70 m. Statistical analysis of flash characteristics of strikes below the tower's tip generally shows that the flash duration and the number of strokes per flash are considerably lower than those for the majority of cases, when the tower is struck at its tip. Furthermore, a trend of decrease in flash duration is found as the distance between the tower's tip and the strike location increases. Therefore, based on the analysis of the available data, lightning strikes below the top of a tall structure do not seem to pose greater danger than strikes to the structure's top, assuming that the structure is also protected along its sides. It is hoped that the presented observations and statistical analyses will be of value in the development of sophisticated measures against lightning hazards at elevated objects.

Lightning strikes to the Toronto Canadian National (CN) Tower have been observed since 1978. In this paper, a brief description of the lightning measurement systems is provided, with emphasis on the current measurement system. Current and field measurement systems with broad bandwidths and high resolutions have been operational since 1991. Typical current derivative and current waveforms of a CN Tower lightning return stroke are also presented. Extensive cumulative statistics of waveform parameters (maximum steepness, risetime to maximum steepness, wavefront peak, risetime to wavefront peak, and absolute peak) of lightning return-stroke current signals measured at the CN Tower during a 10-year period have been derived. The statistical analysis shows that in 50% of the current records: the current wavefront maximum steepness exceeds 18.8 kA/μs, the risetime to maximum steepness exceeds 138 ns, the current wavefront peak exceeds 5 kA, the risetime to wavefront peak exceeds 636 ns and the current absolute peak exceeds 7.2 kA. The statistical analysis also shows that first return strokes feature lower current steepness and higher current peak when compared with subsequent return strokes. Recommendations concerning instrumentation and techniques for the proper measurement of lightning return-stroke currents are discussed. The presented statistical results will be of assistance in the establishment of more sophisticated protective measures against lightning hazards, especially at elevated objects.

Zebra finches communicate via several distinct vocalizations, of which song is the most studied. Behavioral observations indicate that adults are able to discriminate among the songs of different conspecific individuals. In the wild, zebra finches live in structured but mobile colonies, and encounter new individuals on a frequent basis. Thus it seems plausible that adult finches might have the capacity to recognize and remember new songs they encounter on a single day, but this has never been directly tested. Here we devised a simple observational assay to determine whether adult male zebra finches show recognition of a song they have heard repeatedly from taped playbacks, over a single three hour period the day before. We quantified the rate of production of six discrete behaviors (short calls, contact calls, singing, short hops, long hops, and beak swipes) made by adult male zebra finches as they listened to the playbacks. At the onset of song playback, all birds suspended these behaviors and sat silently-occasionally moving their heads. Then, after a measurable period ("response latency"), the birds resumed these activities. We observed that the response latency was long (approximately 10 min) when birds were hearing a particular song for the first time. The response latency was much shorter (approximately 1-2 min) when the birds had heard the same song the day before. Thus, functional song memories must result from as little as 3 h of passive song-exposure. These results suggest that ongoing song learning may play a natural role in the daily life of adult zebra finches, and provide a behavioral reference point for studies of molecular and physiological plasticity in the adult auditory system.

Insulin-like growth factor I (IGF-I) is required for normal embryonic development and postnatal growth. Like most hormones and growth factors, IGF-I is synthesized as a proprotein that is converted to the mature form by endoproteolysis. Processing of pro-IGF-I to mature IGF-I occurs by cleavage within the unique pentabasic processing motif Lys-X-X-Lys-X-X-Arg71-X-X-Arg-X-X-Arg77. We have previously shown that human embryonic kidney 293 cells process pro-IGF-IA at Arg71 to generate IGF-I-(1-70) and at Arg77 to produce IGF-I-(1-76). Cleavage at each of these sites requires upstream basic residues, indicating that subtilisin-related proprotein convertases (SPCs) may be involved. In order to investigate the identity of the endogenous enzymes involved in maturation of pro-IGF-IA, we have expressed wild-type and mutant pro-IGF-IA in 293 cells and in the furin-deficient Chinese hamster ovary cell line, RPE.40. We have also co-expressed these constructs with SPCs that are thought to play a role in processing precursor proteins in the constitutive pathway: furin, PACE4, PC6A, PC6B, and LPC. The results show that furin is most active at cleaving wild-type and mutant pro-IGF-IA and can cleave these precursors at multiple sites within the pentabasic motif. PC6A and LPC are less active than furin but cleave only at Arg71. PACE4 and PC6B have very little activity on pro-IGF-IA precursors. Wild-type pro-IGF-IA was correctly processed to mature IGF-I in 10 of 10 cell lines that were tested. Since furin, PC6A, and LPC are known to have a broad pattern of tissue distribution and we have demonstrated expression of LPC in RPE.40 cells, our results suggest that these SPCs may be responsible for the endogenous pro-IGF-IA processing activity observed in a wide variety of cell lines.

N-Glycolylneuraminic acid (Neu5Gc) is an oncofetal antigen in humans and is developmentally regulated in rodents. We have explored the biology of N-acetylneuraminic acid hydroxylase, the enzyme responsible for conversion of the parent sialic acid, N-acetylneuraminic acid (Neu5Ac) to Neu5Gc. We show that the major sialic acid in all compartments of murine myeloma cell lines is Neu5Gc. Pulse-chase analysis in these cells with the sialic acid precursor [6-3H]N-acetylmannosamine demonstrates that most of the newly synthesized Neu5Gc appears initially in the cytosolic low-molecular weight pool bound to CMP. The percentage of Neu5Gc on membrane-bound sialic acids closely parallels that in the CMP-bound pool at various times of chase, whereas that in the free sialic acid pool is very low initially, and rises only later during the chase. This implies that conversion from Neu5Ac to Neu5Gc occurs primarily while Neu5Ac is in its sugar nucleotide form. In support of this, the hydroxylase enzyme from a variety of tissues and cells converted CMP-Neu5Ac to CMP-Neu5Gc, but showed no activity towards free or alpha-glycosidically bound Neu5Ac. Furthermore, the majority of the enzyme activity is found in the cytosol. Studies with isolated intact Golgi vesicles indicate that CMP-Neu5Gc can be transported and utilized for transfer of Neu5Gc to glycoconjugates. The general properties of the enzyme have also been investigated. The Km for CMP-Neu5Ac is in the range of 0.6-2.5 microM. No activity can be detected against the beta-methylglycoside of Neu5Ac. On the other hand, inhibition studies suggest that the enzyme recognizes both the 5'-phosphate group and the pyrimidine base of the substrate. Taken together, the data allow us to propose pathways for the biosynthesis and reutilization of Neu5Gc, with initial conversion from Neu5Ac occurring primarily at the level of the sugar nucleotide. Subsequent release and reutilization of Neu5Gc could then account for the higher steady-state level of Neu5Gc found in all of the sialic acid pools of the cell.