New data on biogeography, classification and phylogeny of Рhysidae (Gastropoda: Hygrophila) = Новые данные биогеографии, классификации и филогении Рhysidae (Gastropoda: Hygrophila)

Physidae are a family of freshwater pulmonate gastropods with about 90-100 named species, newly divided among 23 genera in seven tribes and four clades. Morphological studies resulted in discovery of many new characters, some of them progressive, yielding criteria for primitive versus advanced states. Thus it is possible to assert that primitive groups are concentrated on the Pacific coast from Mexico to Costa Rica, and to trace the spread of lineages from this region to other parts of the world

Linearized supergravity from Matrix theory

We show that the linearized supergravity potential between two objects arising from the exchange of quanta with zero longitudinal momentum is reproduced to all orders in 1/r by terms in the one-loop Matrix theory potential. The essential ingredient in the proof is the identification of the Matrix theory quantities corresponding to moments of the stress tensor and membrane current. We also point out that finite-N Matrix theory violates the equivalence principle.Comment: 13 pages, LaTex, v2: additional comments mostly in section

Mathematics Professional Development Workshop for Middle School Teachers: Concept Versus Memorization

This article includes professional development topics for middle school mathematics and science teachers from two week-long Urban Teacher Institutes. These Institutes were held at J. Sargeant Reynolds Community College (JSRCC) and its partner institution, Virginia Commonwealth University (VCU), during the summers of 2007 and 2008, and were supported by a grant obtained by Dr. Harriet Morrison (JSRCC). Co-author Dr. Dewey Taylor directed the 2007 workshop, and both authors served as faculty leaders in both workshops. The workshops focused on teaching in an urban environment and community mapping (understanding the details of a certain locale to make the teacher more knowledgeable about the environments of both the students and the schools). The community mapping aspect of the workshops was led by Dr. Shirley Key of the University of Memphis. They featured content teaching and applications led by VCU faculty in mathematics, physics, forensics, engineering, mathematics education, and science education. This article focuses on the mathematics professional development strand in the workshop which featured conceptual learning with graphing calculator support as an alternative to the memorization of formulas

A curvilinear snake arm robot with gripper-axis fibre-optic image processor feedback

The official version of this article can be found at the link below.A curvilinear robot constructed from a number of modular flexible sections of fixed length and diameter but independently controlled radius and direction of curvature has been equipped with an optical fibre image guide transmitting images from between the gripper jaws to the remote TV camera of Microvision-100, a microcomputer controlled real-time DMA-based vision System that is easily trained to recognise the shape, position and orientation of components. The gripper position and orientation is controlled by feedback from the vision System, the action taken depending on component recognition and inspection for defects. Redundant degrees of freedom enable the curvilinear robot to avoid obstacles and work in confined spaces.The research programme described in this paper is supported by the U.K. Science and Engineering Research Council

An associated solvent theory of polymer solutions

Association model theory for thermodynamic properties of nonpolar polymer mixtures with polar solven

Teleprinter uses thermal printing technique

Alphameric/facsimile printer receives serial digital data in the form of a specified number of bits per group and prints it on thermally sensitive paper. A solid state shift-register memorizes the incoming serial digital data

Evaluation of the Doraiswamy-Thompson winter wheat crop calendar model incorporating a modified spring restart sequence

The Robertson phenology was used to provide growth stage information to a wheat stress indicator mode. A stress indicator model demands two acurate predictions from a crop calendar: date of spring growth initiation; and crop calendar stage at growth initiation. Several approaches for restarting the Robertson phenology model at spring growth initiation were studied. Although best results were obtained with a solar thermal unit method, an alternate approach which indicates soil temperature as the controlling parameter for spring growth initiation was selected and tested. The modified model (Doraiswamy-Thompson) is compared to LACIE-Robertson model predictions

An Economic Analysis of Corn-based Ethanol Production

A global multi-commodity simulation model was developed to estimate the impact of changes in ethanol production on the U.S. corn industry. Increased ethanol production under the Energy Acts of 2005 and 2007 resulted in a significant increase in the price of corn. However, for corn-based ethanol production, the break-even price of corn is approximately $4.52 per bushel with a federal subsidy of$0.51 per gallon of pure ethanol and $2.50 gasoline. With a corn price of$4.52, the economically desirable ethanol production is approximately 11 billion gallons. In order to produce 15 billion gallons of corn-based ethanol and to maintain the price of corn at $4.52 per bushel, supply of corn in the U.S. should be increased substantially through increases in corn yield rather than increases in corn acres. The increased price of corn leads to major structural changes in the corn industry in the United States as well as other corn producing and consuming countries. Corn production would increase in response to higher price levels, corn used for livestock feed may decrease, and U.S. exports decrease due mainly to a surge in corn used for ethanol production. This decrease in U.S. exports should be met by additional production in other countries. The increased price of corn also leads to increases in the prices of soybeans, wheat, high fructose corn syrup (HFCS), and agricultural inputs, such as land value and cash rent, fertilizer and chemicals, and farm equipment. In addition, the current price of corn has resulted in an increase in the production cost of livestock. The increase in prices of agricultural commodities and inputs would cause increases in retail prices of food in the U.S.ethanol, price impacts, supply, demand, econometric simulation, HFCS, Resource /Energy Economics and Policy,