Technical Note: Could benzalkonium chloride be a suitable alternative to mercuric chloride for preservation of seawater samples?

Instrumental equipment unsuitable or unavailable for fieldwork as well as lack of ship space can necessitate the preservation of seawater samples prior to analysis in a shore-based laboratory. Mercuric chloride (HgCl2) is routinely used for such preservation, but its handling and subsequent disposal incur environmental risks and significant expense. There is therefore a strong motivation to find less hazardous alternatives. Benzalkonium chloride (BAC) has been used previously as microbial inhibitor for freshwater samples. Here, we assess the use of BAC for marine samples prior to the measurement of oxygen-to-argon (O2 / Ar) ratios, as used for the determination of biological net community production. BAC at a concentration of 50 mg dm−3 inhibited microbial activity for at least 3 days in samples tested with chlorophyll a (Chl a) concentrations up to 1 mg m−3. BAC concentrations of 100 and 200 mg dm−3 were no more effective than 50 mg dm−3 . With fewer risks to human health and the environment, and no requirement for expensive waste disposal, BAC could be a viable alternative to HgCl2 for short-term preservation of seawater samples, but is not a replacement for HgCl2 in the case of oxygen triple isotope analysis, which requires storage over weeks to months. In any event, further tests on a case-by-case basis should be undertaken if use of BAC was considered, since its inhibitory activity may depend on concentration and composition of the microbial community

Narrow 87Rb and 133Cs hyperfine transitions in evacuated wall-coated cells

An extension of work on wall-coated cells was made to include observation by a triple resonance technique of the 0-0 hyperfine transitions in 87Rb and 133Cs. Conventional RF excited lamps were used. Interest in such cells is for possible application in atomic clocks. The Rb cell would appear to remain especially promising in this respect

Contemporary perspectives of the child in action: An investigation into children’s connectedness with, and contribution to, the world around them

Childcare within Australia has undergone significant reform as a result of the implementation of the nationally mandated Belonging, Being and Becoming: The Early Years Learning Framework [EYLF] (Department for Education, Employment and Workplace Relations [DEEWR]. 2009. Belonging, Being and Becoming. The Early Years Learning Framework for Australia. Canberra: Australian Government Department of Education, Employment and Workplace Relations). The EYLF articulates contemporary perspectives of the child through its principles, practices and learning outcomes. Educators are required to promote these principles, practices and learning outcomes with children aged from birth to 5 years. This paper reports the findings from a research project that sought to investigate how educators applied their understanding of learning outcome two of the EYLF (children are connected with and contribute to their world). The focus of this research was educators working with children aged two to three years within childcare centres operating on school sites, in metropolitan Western Australian. The research design was qualitative and situated within the interpretivist paradigm. Observations were used as the method for gathering data and these were analysed through a process of coding. This paper presents the observational findings of educators’ practices within learning outcome two. Composite vignettes from the voice of the child are included to present the observational findings. In centralising the voice of the child, contemporary perspectives are made explicit

A Bibliography of Explosives

University of Kansas --- Department of Chemistry

Dynamical Localization in Quasi-Periodic Driven Systems

We investigate how the time dependence of the Hamiltonian determines the occurrence of Dynamical Localization (DL) in driven quantum systems with two incommensurate frequencies. If both frequencies are associated to impulsive terms, DL is permanently destroyed. In this case, we show that the evolution is similar to a decoherent case. On the other hand, if both frequencies are associated to smooth driving functions, DL persists although on a time scale longer than in the periodic case. When the driving function consists of a series of pulses of duration $\sigma$, we show that the localization time increases as $\sigma^{-2}$ as the impulsive limit, $\sigma\to 0$, is approached. In the intermediate case, in which only one of the frequencies is associated to an impulsive term in the Hamiltonian, a transition from a localized to a delocalized dynamics takes place at a certain critical value of the strength parameter. We provide an estimate for this critical value, based on analytical considerations. We show how, in all cases, the frequency spectrum of the dynamical response can be used to understand the global features of the motion. All results are numerically checked.Comment: 7 pages, 5 figures included. In this version is that Subsection III.B and Appendix A on the quasiperiodic Fermi Accelerator has been replaced by a reference to published wor

Multi-Material Ultrasonic Consolidation

Ultrasonic consolidation (UC) is a recently developed direct metal solid freeform fabrication process. While the process has been well-demonstrated for part fabrication in Al alloy 3003 H18, including with intricate cooling channels, some of the potential strengths of the process have not been fully exploited. One of them is its flexibility with build materials and the other is its suitability for fabrication of multi-material and functionally graded material parts with enhanced functional or mechanical properties. Capitalizing on these capabilities is critical for broadening the application range and commercial utilization of the process. In the current work, UC was used to investigate ultrasonic bonding of a broad range of engineering materials, which included stainless steels, Ni-base alloys, brass, Al alloys, and Al alloy composites. UC multimaterial part fabrication was examined using Al alloy 3003 as the bulk part material and the above mentioned materials as performance enhancement materials. Studies were focused on microstructural aspects to evaluate interface characteristics between dissimilar material layers. The results showed that most of these materials can be successfully bonded to Al alloy 3003 and vice versa using the ultrasonic consolidation process. Bond formation and interface characteristics between various material combinations are discussed based on oxide layer characteristics, material properties, and others.Mechanical Engineerin

Call centre management: responsibilities and performance

PURPOSE - To investigate call centre management from the perspective of the managers, particularly what the key management responsibilities are in managing call centres and the key performance indicators (KPIs) used in managing call centres. DESIGN/METHODOLOGY/APPROACH - A survey of call centre managers, followed by in-depth interviews. FINDINGS - There is confusion over the strategic intent of call centres. Centres are primarily used by organisations as a means of reducing costs, with customer service delivery a secondary consideration. Call centre managers, however, declared customer service as their main management responsibility. PRACTICAL IMPLICATION - The metrics employed in the call centres resulted in managers concentrating on the call itself rather than the outcome of the call from the perspective of the customer or the organisation. Some quantitative measures were used as proxies for customer service, but the achievement of the relevant KPI became a goal in its own right. There appears to be an insatiable appetite for quantitative performance measures, despite their limitations, almost to the exclusion of all other performance measures. ORIGINALITY/VALUE - The implication of the results for call centre managers, and their managers, is that call centres could be better managed if a wider range of means and measures were used

Some Physical Consequences of Abrupt Changes in the Multipole Moments of a Gravitating Body

The Barrab\`es-Israel theory of light-like shells in General Relativity is used to show explicitly that in general a light-like shell is accompanied by an impulsive gravitational wave. The gravitational wave is identified by its Petrov Type N contribution to a Dirac delta-function term in the Weyl conformal curvature tensor (with the delta-function singular on the null hypersurface history of the wave and shell). An example is described in which an asymptotically flat static vacuum Weyl space-time experiences a sudden change across a null hypersurface in the multipole moments of its isolated axially symmetric source. A light-like shell and an impulsive gravitational wave are identified, both having the null hypersurface as history. The stress-energy in the shell is dominated (at large distance from the source) by the jump in the monopole moment (the mass) of the source with the jump in the quadrupole moment mainly responsible for the stress being anisotropic. The gravitational wave owes its existence principally to the jump in the quadrupole moment of the source confirming what would be expected.Comment: 26 pages, tex, no figures, to appear in Phys.Rev.