Salmonid observations at a Klamath River thermal refuge under various hydrological and meteorological conditions

The Beaver Creek confluence with the main‐stem Klamath River was studied to assess salmonid use in a thermal mixing zone under various summer hydrological and meteorological conditions. Main‐stem flow releases from Iron Gate Dam ranged from 17 cms (615 cfs) to 37 cms (1320 cfs) during the study period and main‐stem water temperatures ranged from 19.5 to 26°C. A grid was constructed to define the thermal refuge as a system of cells. Temperatures were monitored using remote temperature loggers and fish counts were conducted using daytime snorkelling. Most juvenile salmonids were observed moving into the refuge when main‐stem temperatures exceeded 22–23°C. Salmonids in the thermal refuge did not necessarily seek the coolest water, but were generally located in habitats commensurate with species‐specific behavioural needs within their thermal tolerance range. Such ranges largely occurred within refuge areas. Variable meteorological conditions confounded observable biological thermal benefit to fish resulting from higher or lower main‐stem flows. Thermal regime dynamics indicated that under the hydrological and meteorological conditions observed, higher flows from Iron Gate Dam showed some ability to change the structure of the refuge area. It appeared that without the thermal refuge, main‐stem flows alone could not sustain the salmonid population because high water temperatures usually exceeded their published thermal tolerance limits. Copyright © 2007 John Wiley & Sons, Ltd.     

Comments, with reply, on `Synchronization and relativity' by G.M.R.Winkler

The commenter asserts that the above-titled paper by G.M.R. Winkler (see ibid., vol.79, no.7, p.1029-39, July 1991) perpetuates a fairly widespread fundamental error by using a semipopular explanation for the dissemination of time in rotating frames of reference. The misconception that one must employ general relativity to describe kinematic phenomena (synchronization, Sagnac effect, etc.) in accelerated systems, even in flat space-time, is exposed by the commenter, who proposes a way to resolve the problem. Winkler replies that he shares the commenter's concerns but does not necessarily agree with the way he proposes to resolve the issues, and he presents arguments to support his position. In a further comment, the commenter disagrees and offers further discussion     

Characterization of copper voids in damascene processes

The introduction of copper Damascene processing into integrated circuits has brought about a host of new defectivity issues, especially those related to pitting and voiding. These defects must be understood and eliminated to achieve competitive manufacturing yields and assure device reliability. This paper reviews various defect inspection methodologies that are useful for characterizing copper voids and their electrical effects.     

Characterization of DNA sequences encoding a novel isoform of the 55 kDa B regulatory subunit of the type 2A protein serine/threonine phosphatase of Arabidopsis thaliana

We have identified a novel gene (AtB beta) encoding a previously uncharacterized isoform of the B regulatory subunit of the type 2A serine/threonine protein phosphatase (PP2A) of Arabidopsis, and show that mRNA derived from the AtB beta gene accumulates in all Arabidopsis organs. In addition, we examined the expression of the three genes encoding the A regulatory subunit of Arabidopsis PP2A and show these genes are expressed in all organs as well. Taken together, our results suggest a myriad of PP2A subunit combinations, possibly with distinct substrate specificities, may occur within each Arabidopsis cell.     

Green power in LA: Overcoming institutional barriers

Los Angeles, USA-based Utility company LADWP has embarked on an ambitious programme to fundamentally shift the utility's power sources away from fossil fuels such as coal and nuclear power towards cleaner generation. Lyn Corum, Refocus correspondent describes the ups and downs and current status of the Utility's project.     

Damage mechanisms in a cast ductile iron and a Al2O3p /Al composite

Mechanical behavior and damage mechanisms of an Al₂O₃ particulate-reinforced Al matrix composite (Al₂O_3p /Al) prepared by pressure infiltration are investigated and compared with those of a cast ductile iron. In addition to low cost and reduced weight, the composite has a Young’s modulus comparable to the ductile iron. However, its fracture toughness is lower than that of the ductile iron. Interface debonding between the graphite and ferrite is responsible for the crack initiation behavior of the ductile iron. The crack in the ductile iron is arrested by the ductile ferrite phase surrounding the graphite, leading to high fracture toughness. For the Al₂O_3p /Al composite, the dominating crack initiation mode is particulate cracking. Interface debonding and zigzag cracking of particulates are additional fracture modes. The high content of Al₂O₃ particulates and the high thermal and elastic incompatibilities between the Al matrix and Al₂O₃ particulates result in brittle fracture and low fracture toughness for the composite. Possible ways to increase the fracture toughness of the Al₂O_3p /Al composite material are also outlined.     

High-temperature mechanical behavior of Ti-6Al-4V alloy and TiC p /Ti-6Al-4V composite

Mechanical behaviors at 538 °C, including tensile and creep properties, were investigated for both the Ti-6Al-4V alloy and the Ti-6Al-4V composite reinforced with 10 wt pct TiC particulates fabricated by cold and hot isostatic pressing (CHIP). It was shown that the yield strength (YS) and ultimate tensile strength (UTS) of the composite were greater than those of the matrix alloy at the strain rates ranging from approximately 10⁻⁵ to 10⁻³ s⁻¹. However, the elongation of the composite material was substantially lower than that of the matrix alloy. The creep resistance of the composite was superior to that of the matrix alloy. The data of minimum creep strain rate vs applied stress for the composite can be fit to a power-law equation, and the stress exponent values of 5 and 8 were obtained for applied stress ranges of 103 to 232 MPa and 232 to 379 MPa, respectively. The damage mechanisms were different for the matrix alloy and the composite, as demonstrated by the scanning electron microscopy (SEM) observation of fracture surfaces and the optical microscopy examination of the regions adjacent to the fracture surface. The tensile-tested matrix alloy showed dimpled fracture, while the creep-tested matrix alloy exhibited preferentially interlath and intercolony cracking. The failure of the tensile-tested and creep-tested composite material was controlled by the cleavage failure of the particulates, which was followed by the ductile fracture of the matrix.