VIETNAMESE FOREIGN POLICY: MEMORY AND LEARNING IN THE DOI MOI ERA

Ever since 1988, Vietnam has successfully diversified and multilateralised its relationships, whilst placing a strong degree of focus on integration into the international political economy. This multidirectional foreign policy is designed to contribute to a peaceful international environment and a stable domestic one in order to promote economic growth and build up the aggregate strength of the country. At the same time, it is designed to boost the country’s autonomy, protect its sovereignty and territorial integrity, as well as hedge against potential threats. This multidirectional foreign policy has contributed significantly to the economic reformist agenda, formally initiated at the 1986 Sixth Party Congress, otherwise known as Doi Moi. Additionally, it has boosted Vietnam’s international profile and reversed the diplomatic isolation it faced as the Cold War came to a close. As such, multidirectionalism has become a fundamental aspect of the Doi Moi process. This thesis traces the learning process since multidirectionalism’s inception and argues that this learning process, along with the economic benefits reaped, have evolved into positive memories for the Vietnamese Communist Party. This means multidirectionalism continues to be reinforced and as a result, these memories shape Vietnam’s continued expansion of that policy. Additionally, this thesis also offers a conceptual definition to the term multidirectionalism as well as explores the mechanisms through which Vietnam implements this policy

Pseudo-nonstationarity in the scaling exponents of finite-interval time series

The accurate estimation of scaling exponents is central in the observational study of scale-invariant phenomena. Natural systems unavoidably provide observations over restricted intervals; consequently, a stationary stochastic process (time series) can yield anomalous time variation in the scaling exponents, suggestive of nonstationarity. The variance in the estimates of scaling exponents computed from an interval of N observations is known for finite variance processes to vary as ~1/N as N for certain statistical estimators; however, the convergence to this behavior will depend on the details of the process, and may be slow. We study the variation in the scaling of second-order moments of the time-series increments with N for a variety of synthetic and “real world” time series, and we find that in particular for heavy tailed processes, for realizable N, one is far from this ~1/N limiting behavior. We propose a semiempirical estimate for the minimum N needed to make a meaningful estimate of the scaling exponents for model stochastic processes and compare these with some “real world” time series

Short Communication: Effects of temperature and chemical formulation on the acute toxicity of pentachlorophenol to Simocephalus vetulus (Schoedler, 1858) (Crustacea: Cladocera)

The influence of temperature on the acute toxicity of a technical formulation (86%) and pure formulation (99%) of pentachlorophenol (PCP) to less than 24-h-old Simocephalus vetulus neonates was determined with 48-h static toxicity tests. The technical grade PCP was significantly more toxic to S. vetulus than the pure PCP (P < 0.05). Sensitivity of S. vetulus to technical PCP also significantly increased with temperature (P < 0.05), but a significant temperature effect was not found with the pure PCP. The mean 48-h LC50 values for neonates exposed to technical PCP were 140 and 199 ug l⁻¹ at 22deg.C and 16deg.C, respectively, and for those exposed to pure PCP were 262 and 304 ug l⁻¹, respectively

Root developmental responses to heterogeneous water and nitrogen supply

Better understanding of the interaction between the soil physical properties determining water and nitrate availability and the root proliferation and gene expression components of nutrient acquisition could contribute to food security, but may have been limited by experimental systems. A sand rhizotron system was developed to investigate Arabidopsis (Arabidopsis thaliana) root responses to altered water and nitrate supply as manipulated by soil physical properties. When this system was compared to agar, root disparities were explained by differences in hydraulic properties, highlighting the importance of the soil physical component. The sand rhizotron system was adopted to quantify root proliferation and gene expression responses to altered water and nitrate availability in wild-type and selected mutant seedlings. In the sand rhizotron system, primary root length and lateral root density were oppositely regulated by water availability, but similarly independent of nitrate supply. The expression of the nitrate transporter AtNRT2.1 and the aquaporin AtPIP2.2 was coordinated across all treatments. Their concentration-dependent hydraulic regulation was confirmed for AtNRT2.1 by in situ imaging of a Green Fluorescent Protein reporter line. AtNAR2.1 and AtNRT2.1 expression demonstrated independent responses to water and nitrate availability despite the requirement of AtNAR2.1 for AtNRT2.1 uptake function. Root proliferation responses to water availability under high (10.0 mM) nitrate were lost in the atnar2.1 mutant and coincided with altered hormone-associated gene (AtEIN2, AtABI4 and AtIPT5) expression. Root proliferation and AtNAR2.1 responses to water availability under high (10.0 mM) nitrate required AtPIP2.2. The coordination of root proliferation and gene expression responses to altered water and nitrate availability is proposed, that includes novel roles for AtNRT2.1, AtNAR2.1 and AtPIP2.2

Signatures of dual scaling regimes in a simple avalanche model for magnetospheric activity

Recently, the paradigm that the dynamic magnetosphere displays sandpile-type phenomenology has been advanced, in which energy dissipation is by means of avalanches which do not have an intrinsic scale. This may in turn imply that the system is in a self-organised critical (SOC) state. Indicators of internal processes are consistent with this, examples are the power-law dependence of the power spectrum of auroral indices, and in situ magnetic field observations in the earth's geotail. However substorm statistics exhibit probability distributions with characteristic scales. In this paper we discuss a simple sandpile model which yields for energy discharges due to internal reorganisation a probability distribution that is a power-law, whereas systemwide discharges (flow of “sand” out of the system) form a distinct group whose probability distribution has a well defined mean. When the model is analysed over its full dynamic range, two regimes having different inverse power-law statistics emerge. These correspond to reconfigurations on two distinct length scales: short length scales sensitive to the discrete nature of the sandpile model, and long length scales up to the system size which correspond to the continuous limit of the model. The latter are anticipated to correspond to large-scale systems such as the magnetosphere. Since the energy inflow may be highly variable, the response of the sandpile model is examined under strong or variable loading and it is established that the power-law signature of the large-scale internal events persists. The interval distribution of these events is also discussed

Mechanisms of Vietnam's multidirectional foreign policy

It has been nearly 30 years since Vietnam shifted to a multidirectional foreign policy that places greater emphasis on cultivating friends and engaging with the international community. Vietnam has moved from being an isolated country, largely dependent on Soviet aid, to a country that bolsters its standing in bilateral and multilateral forums whilst reaping the economic benefits of greater integration into the global economy. Since the start of the 21st century, China’s more assertive posture, along with an increasingly complex, interdependent and multipolar world, has provided Vietnam with a host of problems. This article formulates a definition for a multidirectional foreign policy using Vietnam as a case study and argues that multidirectionalism allows Vietnam to reap economic benefits whilst safeguarding against uncertainty. Furthermore, the article tracks the three principal mechanisms through which Vietnam implements its multidirectional foreign policy: strategic and comprehensive partnerships, trade agreements, and multilateralism

Knapsack based Optimal Policies for Budget-Limited Multi-Armed Bandits

In budget-limited multi-armed bandit (MAB) problems, the learner's actions are costly and constrained by a fixed budget. Consequently, an optimal exploitation policy may not be to pull the optimal arm repeatedly, as is the case in other variants of MAB, but rather to pull the sequence of different arms that maximises the agent's total reward within the budget. This difference from existing MABs means that new approaches to maximising the total reward are required. Given this, we develop two pulling policies, namely: (i) KUBE; and (ii) fractional KUBE. Whereas the former provides better performance up to 40% in our experimental settings, the latter is computationally less expensive. We also prove logarithmic upper bounds for the regret of both policies, and show that these bounds are asymptotically optimal (i.e. they only differ from the best possible regret by a constant factor)

Extremum statistics: a framework for data analysis

Recent work has suggested that in highly correlated systems, such as sandpiles, turbulent fluids, ignited trees in forest fires and magnetization in a ferromagnet close to a critical point, the probability distribution of a global quantity (i.e. total energy dissipation, magnetization and so forth) that has been normalized to the first two moments follows a specific non-Gaussian curve. This curve follows a form suggested by extremum statistics, which is specified by a single parameter a (a = 1 corresponds to the Fisher-Tippett Type I (“Gumbel”) distribution). Here we present a framework for testing for extremal statistics in a global observable. In any given system, we wish to obtain a, in order to distinguish between the different Fisher-Tippett asymptotes, and to compare with the above work. The normalizations of the extremal curves are obtained as a function of a. We find that for realistic ranges of data, the various extremal distributions, when normalized to the first two moments, are difficult to distinguish. In addition, the convergence to the limiting extremal distributions for finite data sets is both slow and varies with the asymptote. However, when the third moment is expressed as a function of a, this is found to be a more sensitive method

Scaling collapse and structure functions: identifying self-affinity in finite length time series

Empirical determination of the scaling properties and exponents of time series presents a formidable challenge in testing, and developing, a theoretical understanding of turbulence and other out-of-equilibrium phenomena. We discuss the special case of self affine time series in the context of a stochastic process. We highlight two complementary approaches to the differenced variable of the data: i) attempting a scaling collapse of the Probability Density Functions which should then be well described by the solution of the corresponding Fokker-Planck equation and ii) using structure functions to determine the scaling properties of the higher order moments. We consider a method of conditioning that recovers the underlying self affine scaling in a finite length time series, and illustrate it using a Lévy flight