The culture-based fisheries in small, farmer-managed reservoirs in two provinces of northern Vietnam: an evaluation based on three production cycles

In this paper the results of a study conducted on the culture-based fisheries in small (ranging from 2 to 160 ha), farmer-managed reservoirs in YenBai and ThaiNguyen Provinces in the northern highland region of Vietnam, for the production cycles of 1997/98, 98/99 and 99/00 are presented. The small reservoirs are leased to small farmers by the provincial authorities for fishery activities, and all lessees adopt culture-based fisheries when fingerlings of grass carp (Ctenopharyngodon idella), silver carp (Hypophthalmichthys molitrix), bighead carp (Aristichthys nobilis), common carp (Cyprinus carpio) and mrigal (Cirrihinus mrigala) are stocked between March and mid-April each year and harvested, using large seine nets, after approximately 11-12 months. The mean yields from reservoirs in YenBai and ThaiNguyen Provinces in 97/98, 98/99 and 99/00 production cycles were 251, 332 and 253, and 331, 372 and 210 kg ha⁻¹ respectively. There were major differences in the fish productivity in the reservoirs in the two Provinces, and in a reservoir between culture cycles. The stocking strategies appeared to be rather ad hoc, being determined by the availability of seed stock and the financial status of the lessees. Accordingly, there was no apparent consistent trend in the improvement of yields from the culture-based fishery practice throughout the growth cycles. The fish yields in reservoirs in each Province were significantly related to reservoir area (exponentially) and to mean weight of stocked fish and conductivity (logarithmically). Of the stocked fish, the highest returns were obtained with mrigal and bighead carp, which collectively contributed > 50% to the harvest. The return from common carp was the lowest. The mean growth rate of grass carp (2.7 g day⁻¹), followed by bighead carp (2.0 g day⁻¹) was the highest in reservoirs in YenBai Province, bighead carp (4.0 g day⁻¹) followed by grass carp (3.2 g day⁻¹) was the highest in ThaiNguyen Province. The seed stocked on average accounted for 65% and 48% of the total operating costs in YenBai and ThaiNguyen Provinces, and the mean cost:benefit ratio of the culture-based fishery in the two Provinces was 0.35 and 0.37 respectively. The culture-based fishery on average contributed about 28% to the gross income of a farmer lessee.

Expectations and liquidity in Yen bond markets

The relationship between daily yields on Japanese government bonds (JGBs), and high grade (AA and AAA) yen eurobonds is investigated. We find the cointegration vector differs slightly from the expected order predicted by the expectations hypothesis and attribute this to differing degrees of liquidity in the eurobond and JGB markets. We conclude that the concentration of new Japanese government issues in maturities of five to ten years, combined with the practice by the authorities of holding a significant amount of outstanding bonds, has distorted the transmission process between different risk classes of bonds. An example of the dynamics of the credit spread on the ten-year AA eurobond is provided.

Elucidation of bucephalid parasite life-cycles using mutation scanning analysis

Nucleotide variation in a portion of the mitochondrial cytochrome c oxidase subunit1 (cox1) gene from asexual stages of bucephalids of southern Australian scallops (Chlamys asperrima, Chlamys bifrons and Pecten fumatus) was investigated using a mutation scanning–sequencing approach. Single-strand conformation polymorphism (SSCP) analysis revealed three main profile types (A, B and C) for parasites isolated from scallops. Sequence analysis revealed that samples represented by profiles B and C had a high degree (97.3%) of sequence similarity, whereas they were ~21% different in sequence from those represented by profile A. These findings suggested that at least two types or species (represented by profile A, or profile B or C) of bucephalid infect scallops, of which both were detected in South Australia, while only one was found in Victoria. The prevalence of bucephalids (and their SSCP haplotypes) appeared to differ among the three species of scallop in South Australia as well as between the two scallop species in Victoria, indicating a degree of host specificity. Adult bucephalids were collected from Eastern Australian Salmon (Arripis trutta), in an attempt to match them with the asexual stages from the scallop hosts. Neither of the two taxa of adult bucephalid (Telorhynchus arripidis and an un-named Telorhynchus species) shared SSCP profiles with the bucephalids from scallops, but were genetically similar, suggesting that the asexual stages from scallops may represent the genus Telorhynchus. This study, which assessed nucleotide sequence variation in a portion of the mitochondrial cox1 gene for bucephalids found in scallops and arripid fish, illustrates the usefulness of the mutation scanning approach to elucidate complex life-cycles of marine parasites.

Intraday periodicity and long memory volatility processes in the Korean bond futures market

This article examines long memory volatility processes in the 5 minute Korean Treasury bond futures data using two different techniques: the GPH test and the EML test. Two proxies of volatility returns are used: absolute returns and square returns. We found intraday periodicity and autocorrelation persistence in the volatility for the 5 minute returns. The empirical results from both techniques indicate that there is little evidence of long memory in the level of returns, but there is significant evidence of long memory in the absolute returns and the square returns. This implies that volatility is best characterised by long memory processes. Additionally, we found that the absolute returns are the most appropriate indicator to represent the long memory volatility processes.

The equilibrium relations between stock index and bond index: evidence from Bursa Malaysia

This paper aims at examining the correlation structure, co-integration relationship and volatility linkage between stock and bond market indices over a period from January 1994 to June 2004. This study uses Johansen Cointegratoin test, VECM-X model and GARCH (1,1) with MDH model to examine the existence of long-term relation and volatility linkage between stock and bond market. The findings shed some light on the existence of mean-reverting pattern of correlation across different economic environments.  Findings on co-movement of stock and bond indices suggest an equilibrium relationship with short-term error correction. While evidence from volatility linkage also suggests that bond market cannot provide a meaningful explanation for conditional volatility in stock market, therefore, rejecting the mixture of distribution hypothesis.

The credit spread dynamics of Latin American euro issues in international bond markets

This paper investigates two important relationships using the sovereign issues made by major Latin American economies in the international bond market: the determinants of credit spread changes using variables derived from structural and macroeconomic theory and the impact of a default episode on the underlying equilibrium dynamics. We find four significant determinants of credit spread changes: an asset and interest rate factor—consistent with structural models of credit spread pricing; the exchange rate—consistent with macroeconomic determinants and the slope of the yield curve—consistent with a business cycle effect. Also, an intra-regional analysis of sovereign yields reveals a shift in the long-run equilibrium dynamics around the Argentine default on the 23 December 2001.

Common trends and common cycles in per capita GDP : the case of the G7 Countries, 1870-2001

In this paper we analyze per capita incomes of the G7 countries using the common cycles test developed by Vahid and Engle (Journal of Applied Econometrics, 8:341–360, 1993) and extended by Hecq et al. (Oxford Bulletin of Economics and Statistics, 62:511–532, 2000; Econometric Reviews, 21:273–307, 2002) and the common trend test developed by Johansen (Journal of Economic Dynamics and Control, 12:231–254, 1988). Our main contribution is that we impose the common cycle and common trend restrictions in decomposing the innovations into permanent and transitory components. Our main finding is permanent shocks explain the bulk of the variations in incomes for the G7 countries over short time horizons, and is in sharp contrast to the bulk of the recent literature. We attribute this to the greater forecasting accuracy achieved, which we later confirm through performing a post sample forecasting exercise, from the variance decomposition analysis.

Effect of heat-treatment atmosphere on the bond strength of apatite layer on Ti substrate

Objectives
The purpose of this study was to investigate the bond strength of apatite layer on titanium (Ti) substrate coated by biomimetic method and to improve the bonding of apatite layer to Ti substrate by optimizing the alkali heat-treatment process.

Methods
Ti plates pre-treated with an alkali solution of 10 M sodium hydroxide (NaOH) were heat-treated at 600 °C for 1 h at different atmospheres: in air and in vacuum. A dense apatite layer formed on top of the sodium titanate layer after soaking the alkali and heat-treated Ti samples in simulated body fluid (SBF) for up to 3 weeks. The bond strengths of the sodium titanate layer on Ti substrate, and apatite layer on the sodium titanate layer, were measured, respectively, by applying a tensile load. The fracture sites were observed with a scanning electron microscope (SEM).

Results
The apatite layer on the substrate after alkali heat-treatment in air achieved higher bond strength than that on the substrate after alkali heat-treatment in vacuum. It was found that the interfacial structure between the sodium titanate and Ti substrate has a significant influence on the bond strength of the apatite layer.

Significance
It is advised that titanium implants can achieve better osseointegration under load-bearing conditions by depositing an apatite layer in vivo on a Ti surface subjected to alkali and heat-treated in air.

Economic transition and commercial property cycles in China

Drawn from a recently completed study, this paper aims at a better understanding of commercial property cycles in the transitional economy of China. It examines the behaviour of the property submarket system in China and considers structural changes in the socio-economic system as a primary factor in addressing the research problem. The study suggests that the underlying social and economic structure has greatly determined market behaviour. It finds that radical changes can alter the formal structure (the designed structure) of the market system, including the property market structure, but cannot alter the informal structure (i.e. the emergent structure) at the similar rate. As the study shows, cycles in the commercial property market in the economic transition is largely a key resulting feature of the continuous structural change both at formal and informal levels in a way that is often imbalanced and not always consistently changing together. The same situation also applies to the transformation of inner-city built form, which is featured by a delayed change of physical building stock against the space demand trend that is underpinned by the socio-economic transition. Put simply, there is a supply lag, mainly in the form of changing land use and building stock replacement, against economic change (the business cycle). This affects the level of effective demand for office space and hence becomes a major force in shaping current office cycles.