Performance improvement and sustainability of irrigation systems under the Irrigation System Management Project: Report on the Workshop for Technical Assistants (Department of Irrigation), Colombo, 2-8 September 1992

Irrigation managementPerformance evaluationTrainingSustainabilityInstitution building

Irrigation management training for institutional development: A case study from Malaysia

Irrigation managementTrainingStrategy planningResearchHuman resourcesInstitution building

Training needs assessment in Malaysia: Exercise held at Kuala Lampur and Kota Bharu from 13th October 1989

Training / Irrigation / Evaluation / Malaysia

Prescription of rhythmic patterns for legged locomotion

As the engine behind many life phenomena, motor information generated by the central nervous system (CNS) plays a critical role in the activities of all animals. In this work, a novel, macroscopic and model-independent approach is presented for creating different patterns of coupled neural oscillations observed in biological central pattern generators (CPG) during the control of legged locomotion. Based on a simple distributed state machine, which consists of two nodes sharing pre-defined number of resources, the concept of oscillatory building blocks (OBBs) is summarised for the production of elaborated rhythmic patterns. Various types of OBBs can be designed to construct a motion joint of one degree-of-freedom (DOF) with adjustable oscillatory frequencies and duty cycles. An OBBs network can thus be potentially built to generate a full range of locomotion patterns of a legged animal with controlled transitions between different rhythmic patterns. It is shown that gait pattern transition can be achieved by simply changing a single parameter of an OBB module. Essentially this simple mechanism allows for the consolidation of a methodology for the construction of artificial CPG architectures behaving as an asymmetric Hopfield neural network. Moreover, the proposed CPG model introduced here is amenable to analogue and/or digital circuit integration

Cosmology with Interaction between Phantom Dark Energy and Dark Matter and the Coincidence Problem

We study a cosmological model in which phantom dark energy is coupled to dark matter by phenomenologically introducing a coupled term to the equations of motion of dark energy and dark matter. This term is parameterized by a dimensionless coupling function $\delta$, Hubble parameter and the energy density of dark matter, and it describes an energy flow between the dark energy and dark matter. We discuss two cases: one is the case where the equation-of-state $\omega_e$ of the dark energy is a constant; the other is that the dimensionless coupling function $\delta$ is a constant. We investigate the effect of the interaction on the evolution of the universe, the total lifetime of the universe, and the ratio of the period when the universe is in the coincidence state to its total lifetime. It turns out that the interaction will produce significant deviation from the case without the interaction.Comment: Latex, 17 pages including 14 figures, minor change

Joint Cosmological Formation of QSOs and Bulge-dominated Galaxies

Older and more recent pieces of observational evidence suggest a strong connection between QSOs and galaxies; in particular, the recently discovered correlation between black hole and galactic bulge masses suggests that QSO activity is directly connected to the formation of galactic bulges. The cosmological problem of QSO formation is analyzed in the framework of an analytical model for galaxy formation; for the first time a joint comparison with galaxy and QSO observables is performed. In this model it is assumed that the same physical variable which determines galaxy morphology is able to modulate the mass of the black hole responsible for QSO activity. Both halo spin and the occurence of a major merger are considered as candidates to this role. The predictions of the model are compared to available data for the type-dependent galaxy mass functions, the star-formation history of elliptical galaxies, the QSO luminosity function and its evolution (including the obscured objects contributing to the hard-X-ray background), the mass function of dormant black holes and the distribution of black-hole -- bulge mass ratios. A good agreement with observations is obtained if the halo spin modulates the efficiency of black-hole formation, and if the galactic halos at $z=0$ have shone in an inverted order with respect to the hierarchical one (i.e., stars and black holes in bigger galactic halos have formed before those in smaller ones). This inversion of hierarchical order for galaxy formation, which reconciles galaxy formation with QSO evolution, is consistent with many pieces of observational evidence.Comment: 20 pages, figures included, mn.sty, in press on MNRAS, fig 6 changed (new data added at z=4.4

Reordering Hierarchical Tree Based on Bilateral Symmetric Distance

BACKGROUND: In microarray data analysis, hierarchical clustering (HC) is often used to group samples or genes according to their gene expression profiles to study their associations. In a typical HC, nested clustering structures can be quickly identified in a tree. The relationship between objects is lost, however, because clusters rather than individual objects are compared. This results in a tree that is hard to interpret. METHODOLOGY/PRINCIPAL FINDINGS: This study proposes an ordering method, HC-SYM, which minimizes bilateral symmetric distance of two adjacent clusters in a tree so that similar objects in the clusters are located in the cluster boundaries. The performance of HC-SYM was evaluated by both supervised and unsupervised approaches and compared favourably with other ordering methods. CONCLUSIONS/SIGNIFICANCE: The intuitive relationship between objects and flexibility of the HC-SYM method can be very helpful in the exploratory analysis of not only microarray data but also similar high-dimensional data

The Nature of Optically Dull Active Galactic Nuclei in COSMOS

We present infrared, optical, and X-ray data of 48 X-ray bright, optically dull AGNs in the COSMOS field. These objects exhibit the X-ray luminosity of an active galactic nucleus (AGN) but lack broad and narrow emission lines in their optical spectrum. We show that despite the lack of optical emission lines, most of these optically dull AGNs are not well-described by a typical passive red galaxy spectrum: instead they exhibit weak but significant blue emission like an unobscured AGN. Photometric observations over several years additionally show significant variability in the blue emission of four optically dull AGNs. The nature of the blue and infrared emission suggest that the optically inactive appearance of these AGNs cannot be caused by obscuration intrinsic to the AGNs. Instead, up to ~70% of optically dull AGNs are diluted by their hosts, with bright or simply edge-on hosts lying preferentially within the spectroscopic aperture. The remaining ~30% of optically dull AGNs have anomalously high f_x/f_o ratios and are intrinsically weak, not obscured, in the optical. These optically dull AGNs are best described as a weakly accreting AGN with a truncated accretion disk from a radiatively inefficient accretion flow.Comment: 12 pages, 10 figures. Accepted for publication in the Ap

QAPgrid: A Two Level QAP-Based Approach for Large-Scale Data Analysis and Visualization

Background: The visualization of large volumes of data is a computationally challenging task that often promises rewarding new insights. There is great potential in the application of new algorithms and models from combinatorial optimisation. Datasets often contain “hidden regularities” and a combined identification and visualization method should reveal these structures and present them in a way that helps analysis. While several methodologies exist, including those that use non-linear optimization algorithms, severe limitations exist even when working with only a few hundred objects. Methodology/Principal Findings: We present a new data visualization approach (QAPgrid) that reveals patterns of similarities and differences in large datasets of objects for which a similarity measure can be computed. Objects are assigned to positions on an underlying square grid in a two-dimensional space. We use the Quadratic Assignment Problem (QAP) as a mathematical model to provide an objective function for assignment of objects to positions on the grid. We employ a Memetic Algorithm (a powerful metaheuristic) to tackle the large instances of this NP-hard combinatorial optimization problem, and we show its performance on the visualization of real data sets. Conclusions/Significance: Overall, the results show that QAPgrid algorithm is able to produce a layout that represents the relationships between objects in the data set. Furthermore, it also represents the relationships between clusters that are feed into the algorithm. We apply the QAPgrid on the 84 Indo-European languages instance, producing a near-optimal layout. Next, we produce a layout of 470 world universities with an observed high degree of correlation with the score used by the Academic Ranking of World Universities compiled in the The Shanghai Jiao Tong University Academic Ranking of World Universities without the need of an ad hoc weighting of attributes. Finally, our Gene Ontology-based study on Saccharomyces cerevisiae fully demonstrates the scalability and precision of our method as a novel alternative tool for functional genomics

The COSMOS AGN Spectroscopic Survey I: XMM Counterparts

We present optical spectroscopy for an X-ray and optical flux-limited sample of 677 XMM-Newton selected targets covering the 2 deg^2 COSMOS field, with a yield of 485 high-confidence redshifts. The majority of the spectra were obtained over three seasons (2005-2007) with the IMACS instrument on the Magellan (Baade) telescope. We also include in the sample previously published Sloan Digital Sky Survey spectra and supplemental observations with MMT/Hectospec. We detail the observations and classification analyses. The survey is 90% complete to flux limits of f_{0.5-10 keV}>8 x 10^-16 erg cm^-2 s^-1 and i_AB+<22, where over 90% of targets have high-confidence redshifts. Making simple corrections for incompleteness due to redshift and spectral type allows for a description of the complete population to $i_AB+<23. The corrected sample includes 57% broad emission line (Type 1, unobscured) AGN at 0.13<z<4.26, 25% narrow emission line (Type 2, obscured) AGN at 0.07<z<1.29, and 18% absorption line (host-dominated, obscured) AGN at 0<z<1.22 (excluding the stars that made up 4% of the X-ray targets). We show that the survey's limits in X-ray and optical flux include nearly all X-ray AGN (defined by L_{0.5-10 keV}>3 x 10^42 erg s^-1) to z<1, of both optically obscured and unobscured types. We find statistically significant evidence that the obscured to unobscured AGN ratio at z<1 increases with redshift and decreases with luminosity.Comment: Accepted for publication in the ApJ. 31 pages, 17 figures. Table 2 is available on reques