Hybridization in Australian Freshwater Crayfish—Production of All-Male Progeny

Abstract.— In freshwater crayfish aquaculture high densities can result from uncontrolled reproduction. Hence some farmers manually sex yabbies Cherax albidus and stock only mate crayfish in farm dams or ponds. Although male-only yabby populations produce an estimated 70% increase in gross income, hand sexing is time consuming and prone to error. A hybridization experiment using freshwater crayfish from the yabby species complex, collected from geographically isolated regions throughout Australia, revealed a hybrid between Cherax rotundus females and C. albidus males which consistently produces only male progeny. This has been confirmed in nine crosses of the same two species. The reciprocal cross of C. albidus females × C. rotundus males produces both male and female progeny. The consistent production of only male progeny by hybridization has not been recorded previously for a crustacean.     

Effect of root water extraction on wetted regions from continuous irrigation sources

Analytical studies of flow from irrigation sources into regions of root water uptake typically require the root distribution and the local water extraction rate as data of the problem. In reality, these are strongly influenced by local soil water content and, hence, position relative to the source. This work introduces a model with moisture-dependent root water extraction rate, so that the spatial distribution of uptake is no longer a datum, but emerges as part of the solution. For a diversity of conditions we obtain simple steady solutions describing the interactions between continuous sources and regions of wetting and water extraction. It is shown that as the uptake rate increases, the region decreases markedly in size and becomes more symmetrical in the vertical; for sources at depths that are small relative to the sorptive length, interaction with the surface becomes important; surface evaporation losses significantly reduce the region and increase asymmetry; with non-evaporating surfaces, the region is larger and more symmetrical. The dimensionless coefficient β, proportional to the ratio of the local extraction rate to the Kirchhoff potential, determines behaviour. Estimating β under controlled and field conditions is discussed.     

Paranasal meningioma in a horse.

Paranasal meningioma was diagnosed in a 5-year-old Appaloosa gelding. The mass occupied the right maxillary, frontal, and sphenopalatine sinuses but did not invade the calvarium. The diagnosis was based on histologic evaluation, positive immunohistochemical staining for vimentin and cytokeratin, and ultrastructural features including the presence of interdigitating spindle cells with numerous desmosomes.     

Indications, management, and outcome of long-term positive-pressure ventilation in dogs and cats: 148 cases (1990-2001)

OBJECTIVE: To determine outcome of positive-pressure ventilation (PPV) for 24 hours or longer and identify factors associated with successful weaning from PPV and survival to hospital discharge in dogs and cats. DESIGN: Retrospective case series. ANIMALS: 124 dogs and 24 cats that received PPV for 24 hours or longer. PROCEDURES: Medical records were reviewed for signalment, primary diagnosis, reason for initiating PPV, measures of oxygenation and ventilation before and during PPV, ventilator settings, complications, duration of PPV, and outcome. Animals were categorized into 1 of 3 groups on the basis of the reason for PPV. RESULTS: Group 1 patients received PPV for inadequate oxygenation (67 dogs and 6 cats), group 2 for inadequate ventilation (46 dogs and 16 cats), and group 3 for inadequate oxygenation and ventilation (11 dogs and 2 cats). Of the group 1 animals, 36% (26/73) were weaned from PPV and 22% (16/73) survived to hospital discharge. In group 2, 50% (31/62) were weaned from PPV and 39% (24/62) survived to hospital discharge. In group 3, 3 of 13 were weaned from PPV and 1 of 13 survived to hospital discharge. Likelihood of successful weaning and survival to hospital discharge were significantly higher for group 2 animals, and cats had a significantly lower likelihood of successful weaning from PPV, compared with dogs. Median duration of PPV was 48 hours (range, 24 to 356 hours) and was not associated with outcome. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that long-term PPV is practical and successful in dogs and cats.     

Employment

The 1990s began with unprecedented market conditions for labour: unemployment rates were reaching their highest level in over 50 years, participation in the labour market had fallen to historically low levels and net emigration was widespread across all occupations. It seemed that things could only get better. While some did benefit from the limited growth that took place in the nineties, many did not. The greater inequality generated during the 1980s was fanned by the deregulation of the labour market and remained undiminished throughout the following decade. The marked reduction in manufacturing employment in the 1980s continued into the early 1990s negatively impacting Maori and Pacific Island men and women in particular. Increasingly post‐secondary school education became necessary to gain entry into regular work and those with little formal education and few work skills fell further down the queue. These changes are closely allied to the processes of globalisation which is already exercising considerable influence on the employment opportunities of New Zealanders.     

The Location Behavior of the Multinational Enterprise: Some Analytical Issues

ABSTRACT In the international business literature location behavior has traditionally been analyzed using Dunning's (1977 ) OLI framework, which focuses on the nature, role, and behavior of multinational enterprise (MNE). In this paper it is argued that this approach is now no longer appropriate for discussing the spatial behavior of MNEs, because of the fundamental changes which have taken place either in MNE organization or in the global and institutional environment for foreign direct investment (FDI). At the same time, the paper argues that current location theory from regional economics and economic geography is also largely unsuitable for discussing these issues, such that the spatial behavior of the MNE provides a set of difficult challenges to location analysts. There appears to have been some response to these issues from the international business and management literature, most notably the Porter literature on clusters. However, it is also argued here that this literature provides few, if any, real answers to the problems set by the geographical behavior of the MNE. It is concluded that a fusion of traditional economic geography approaches with a focus on the information and organizational aspects of the firm and the region under consideration may be a way forward for both theory and empirical analysis.     

Negotiating local livelihoods: Scales of conflict in the Se San River Basin

Abstract: The Se San is an important tributary river basin of the Mekong. In 1993, Vietnam began building the Yali Falls Dam 80 kilometres upstream of the point at which this westward flowing river enters Cambodia. Ninety indigenous communities along the Se San River in two provinces of north‐eastern Cambodia have been impacted severely by flooding, and a dramatically altered hydrological regime that affects fisheries and all other aspects of livelihood, such as river bank agriculture. Since 2000, when the first turbines were commissioned, the affected communities have been increasingly vocal regarding the impacts of Yali and the plans for several more dams on upper reaches of the river. A complex set of actors including non‐governmental organisations, village, district and provincial authorities, national committees in Cambodia and Vietnam, the Mekong River Commission and a range of international players have become involved in a two‐track process, which has nevertheless allowed little space for negotiation over the Se San River on the part of those most directly affected. This case has fundamental implications for governance and conflict management in the Mekong and more widely. The Australian Mekong Resource Centre has been working with local actors to document the Se San case as part of an international project on River Basin Management: a negotiated approach, in support of six cases that involve up‐scaling of grassroots river basin initiatives in Africa, Latin America and Asia. In this article, we illustrate the significance of and problematise negotiation as a socially and politically embedded conflict management principle, with reference to the Se San case.