Publications, Personnel and Government Organizations Related to the Limnology, Aquatic Biology and Ichthyology of the Inland Waters of Texas

This report is the result of a growing concern about the rate at which development of the water resources of Texas is outstripping biological and ecological knowledge of the aquatic environments concerned. Most Texas streams are already much modified by present impoundments, diversions, and pollution. The magnitude of proposed future development is evidenced by planning proposals published in 1961 by the Texas Board of Water Engineers (1) and in 1966 by its successor agency, the Texas Water Development Board (2). Although municipal, industrial, and agricultural water requirements currently have a preeminent role in planning water development, recreational considerations are becoming increasingly important. Factors which influence the quality and quantity of the aquatic biota have a profound effect on recreational potential, as well as on water quality aspects of other water uses. Thus far water resource development in Texas has proceeded with little information available on possible biological effects, and only general predictions can be made based on experience elsewhere. If data are going to be available which will enable effective consideration of biological problems to be made in the planning stages of water development projects, there must be sizable increases in the quantity and quality of aquatic research. The taxonomy and distribution of fresh water fishes in Texas are well known, but ecological data are scarce. Our knowledge of the taxonomy, distribution and ecology of other aquatic organisms in Texas is rudimentary. Baseline information giving data on stream populations prior to development modification is meager, in contrast to the abundant physical and chemical data provided by the United States Geological Survey, the Texas Water Development Board and other agencies. Additional research is still needed on many physical and chemical problems, however. The compilation contained herein has two objectives: (1) to be of assistance to those already working in the fields covered and (2) to provide a status report which may encourage and perhaps make easier the entry of new researchers into these fields. Primary emphasis has been placed on compiling the bibliographic material and on the personnel roster. The data on state and federal agencies and on courses offered at colleges and universities became available in the course of the investigation and has been included primarily to assist those new to the field in becoming oriented

The Composition and Distribution of the Fish Fauna of the Navasota River

Twenty-one thousand fish representing 9 orders, 14 families and 56 species were collected from various habitats of the Navasota River drainage. Some species such as Notropis lutrensis, Gambusia affinis and Lepomis macrocllirlls were taken throughout the drainage from widely varying habitats. Others, such as Notropis atrocaudalis, N. venustus and Campostoma anomalum, were found only a few times in more specialized habitats. Some Austroriparian species, such as Fundulus notti, F. olivaceous and Lepomis marginatus, apparently reach their western range limits at or near the Navasota drainage. Other east Texas and coastal plains fishes such as Amia calva and Lepomis symmetricus reach their western inland limits at near the Navasota drainage. Some species, such as Dionda episcopa, Hybognathus plactius, and Etheostoma spectabile, are found in more western drainages but are absent from teh Navasota drainage. It is suggested that some of these fish distributions are the result of immigration or stream piracy. Proposed water development projects for the Navasota River include the construction of dams. If these dams are constructed, changes in the fish populations are sure to occur. This study should contribute basic information from which the effects of future water development can be evaluated

A research pathway for experimental psychopathology: the role of external validity criteria

This paper outlines a putative pathway for experimental psychopathology research developing psychological models of clinical disorders. The pathway uses established external validity criteria to define the pathway and clarifies the important role that research conducted on healthy participants can play in our understanding of clinical disorders. Defining a research pathway for experimental psychopathology in this way has a number of benefits It would (1) make explicit the need to address the external validity of developed models, (2) provide a clear set of criteria that would be required to extend research on healthy individuals to diagnostic populations, and (3) recommend using general psychological knowledge when developing models of psychopathology

Task-Oriented Conversational Behavior of Agents for Collaboration in Human-Agent Teamwork

International audienceCoordination is an essential ingredient for human-agent teamwork. It requires team members to share knowledge to establish common grounding and mutual awareness among them. This paper proposes a be-havioral architecture C 2 BDI that enhances the knowledge sharing using natural language communication between team members. Collaborative conversation protocols and resource allocation mechanism have been defined that provide proactive behavior to agents for coordination. This architecture has been applied to a real scenario in a collaborative virtual environment for learning. The solution enables users to coordinate with other team members

An integral method for solving nonlinear eigenvalue problems

We propose a numerical method for computing all eigenvalues (and the corresponding eigenvectors) of a nonlinear holomorphic eigenvalue problem that lie within a given contour in the complex plane. The method uses complex integrals of the resolvent operator, applied to at least $k$ column vectors, where $k$ is the number of eigenvalues inside the contour. The theorem of Keldysh is employed to show that the original nonlinear eigenvalue problem reduces to a linear eigenvalue problem of dimension $k$. No initial approximations of eigenvalues and eigenvectors are needed. The method is particularly suitable for moderately large eigenvalue problems where $k$ is much smaller than the matrix dimension. We also give an extension of the method to the case where $k$ is larger than the matrix dimension. The quadrature errors caused by the trapezoid sum are discussed for the case of analytic closed contours. Using well known techniques it is shown that the error decays exponentially with an exponent given by the product of the number of quadrature points and the minimal distance of the eigenvalues to the contour

Study of solid 4He in two dimensions. The issue of zero-point defects and study of confined crystal

Defects are believed to play a fundamental role in the supersolid state of 4He. We report on studies by exact Quantum Monte Carlo (QMC) simulations at zero temperature of the properties of solid 4He in presence of many vacancies, up to 30 in two dimensions (2D). In all studied cases the crystalline order is stable at least as long as the concentration of vacancies is below 2.5%. In the 2D system for a small number, n_v, of vacancies such defects can be identified in the crystalline lattice and are strongly correlated with an attractive interaction. On the contrary when n_v~10 vacancies in the relaxed system disappear and in their place one finds dislocations and a revival of the Bose-Einstein condensation. Thus, should zero-point motion defects be present in solid 4He, such defects would be dislocations and not vacancies, at least in 2D. In order to avoid using periodic boundary conditions we have studied the exact ground state of solid 4He confined in a circular region by an external potential. We find that defects tend to be localized in an interfacial region of width of about 15 A. Our computation allows to put as upper bound limit to zero--point defects the concentration 0.003 in the 2D system close to melting density.Comment: 17 pages, accepted for publication in J. Low Temp. Phys., Special Issue on Supersolid

Single Spin Measurement using Single Electron Transistors to Probe Two Electron Systems

We present a method for measuring single spins embedded in a solid by probing two electron systems with a single electron transistor (SET). Restrictions imposed by the Pauli Principle on allowed two electron states mean that the spin state of such systems has a profound impact on the orbital states (positions) of the electrons, a parameter which SET's are extremely well suited to measure. We focus on a particular system capable of being fabricated with current technology: a Te double donor in Si adjacent to a Si/SiO2 interface and lying directly beneath the SET island electrode, and we outline a measurement strategy capable of resolving single electron and nuclear spins in this system. We discuss the limitations of the measurement imposed by spin scattering arising from fluctuations emanating from the SET and from lattice phonons. We conclude that measurement of single spins, a necessary requirement for several proposed quantum computer architectures, is feasible in Si using this strategy.Comment: 22 Pages, 8 Figures; revised version contains updated references and small textual changes. Submitted to Phys. Rev.

Dark soliton states of Bose-Einstein condensates in anisotropic traps

Dark soliton states of Bose-Einstein condensates in harmonic traps are studied both analytically and computationally by the direct solution of the Gross-Pitaevskii equation in three dimensions. The ground and self-consistent excited states are found numerically by relaxation in imaginary time. The energy of a stationary soliton in a harmonic trap is shown to be independent of density and geometry for large numbers of atoms. Large amplitude field modulation at a frequency resonant with the energy of a dark soliton is found to give rise to a state with multiple vortices. The Bogoliubov excitation spectrum of the soliton state contains complex frequencies, which disappear for sufficiently small numbers of atoms or large transverse confinement. The relationship between these complex modes and the snake instability is investigated numerically by propagation in real time.Comment: 11 pages, 8 embedded figures (two in color

Creating university spin-offs: A science-based design perspective

Academic entrepreneurship by means of university spin-offs commercializes technological breakthroughs, which may otherwise remain unexploited. However, many universities face difficulties in creating spin-offs. This article adopts a science-based design approach to connect scholarly research with the pragmatics of effectively creating university spin-offs. This approach serves to link the practice of university spin-off creation, via design principles, to the scholarly knowledge in this area. As such, science-based design promotes the interplay between emergent and deliberate design processes. This framework is used to develop a set of design principles that are practice based as well as grounded in the existing body of research on university spin-offs. A case-study of spin-off creation at a Dutch university illustrates the interplay between initial processes characterized by emergent design and the subsequent process that was more deliberate in nature. This case study also suggests there are two fundamentally different phases in building capacity for university spin-off creation. First, an infrastructure for spin-off creation (including a collaborative network of investors, managers and advisors) is developed that then enables support activities to individual spin-off ventures. This study concludes that to build and increase capacity for creating spin-offs, universities should do the following: (1) create university-wide awareness of entrepreneurship opportunities, stimulate the development of entrepreneurial ideas, and subsequently screen entrepreneurs and ideas by programs targeted at students and academic staff; (2) support start-up teams in composing and learning the right mix of venturing skills and knowledge by providing access to advice, coaching, and training; (3) help starters in obtaining access to resources and developing their social capital by creating a collaborative network organization of investors, managers, and advisors; (4) set clear and supportive rules and procedures that regulate the university spin-off process, enhance fair treatment of involved parties, and separate spin-off processes from academic research and teaching; and (5) shape a university culture that reinforces academic entrepreneurship by creating norms and exemplars that motivate entrepreneurial behavior. These and other results of this study illustrate how science-based design can connect scholarly research to the pragmatics of actually creating spin-offs in academic institutions