bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy-dependent variability and the origin of the soft X-ray excess in active galactic nuclei
Authors: Gierliński Marek , Done Chris
Published: July 2006

The origin of the soft excess seen in many active galactic nuclei (AGN) below ∼1 keV is still an unsolved problem. It is unlikely to represent a true continuum component as its characteristic ‘temperature’ shows a remarkable constancy over a wide range of AGN luminosity and black hole mass. This instead favours an association with atomic processes, in particular with the increase in opacity between 0.7 and 2 keV associated with partially ionized O and Fe. The opacity jump can give rise to a soft excess through either reflection or transmission, and both scenarios can fit the spectra equally well as long as there is strong velocity shear to smear out the characteristic narrow atomic features. Here we use orthogonal constraints from the energy-dependent variability. The rms spectra seen in XMM—Newton AGN data often show a broad peak between 0.7 and 2 keV. We show that the absorption model can explain the data well if the ionization state of the smeared absorption responds to luminosity changes in the continuum.
Hydraulic Gravel Packing for Deep Water Wells
Authors: Fawcett A. E.
Published: July 2006

The practice of placing gravel by the hydraulic method of pumping gravel into the well bore or underreamed section of the hole and into the annular space around the screen sections and blank liner is discussed.
Subterranean Natural Brines Produce Sodium Sulphate in West Texas
Authors: Reeves C. C.
Published: July 2006

Profitable production of sodium sulphate from natural brine occurs only in California and Texas. Although the Ozark‐Mahoning Company developed sodium sulphate production from natural brine in the Monahans, Texas, area during the early 1930's, Pleistocene deposits in the “Rich Lake” and Brownfield depression areas of Terry County have recently been developed. The unusual geology of these deposits and production methods utilized are briefly described.
Temperature and Phosphates as Ground‐Water Tracers
Authors: Sampayo F. F. , Wilke H. R.
Published: July 2006

This study was undertaken to determine the effect of recharging warm air conditioning and storm waters on ground‐water temperatures in the West Lafayette, Indiana area and to establish the direction of flow of the recharged water out of the recharge pit.

During 1961–62 Purdue University has discharged approximately 4.0 MGD (million gallons per day) of water at an abandoned gravel pit south of the campus. This water had a temperature averaging 77° F and a phosphate content of about 4 ppm. In order to obtain the proposed objective, weekly temperature measurements were taken at selected points throughout the area involved in the study. Water samples were collected at some of these locations every two weeks. The samples were analyzed for phosphate content. The research program extended over a period of twelve months.

The results obtained indicated that the influence of ground‐water recharge on ground‐water temperatures appeared to be localized to a small area surrounding the pit. No evidence was found to indicate that recharge at the pit was causing any increases of ground‐water temperatures for more than about 1,000 feet from the pit.

Although the results of phosphate testing were not conclusive, they seemed to be in close agreement with the temperature measurements in indicating the direction and velocity of ground‐water flow. The direction of flow of the recharged water was found to be south toward the Wabash River, but could only be established for a short distance (approximately 1,000 feet). Ground‐water velocity was calculated to be about 1.7 feet per day using ground‐water temperatures as the tracer, and 2.3 feet per day when phosphate concentration was the tracer used.
The Hele‐Shaw Model – A Research Device in Ground‐Water Studies
Authors: Sternberg Y. M. , Scott V. H.
Published: July 2006

The Hele‐Shaw viscous flow model has been found to be a useful device in analyzing and studying certain types of ground‐water flow problems. The discussion includes the theory of the Hele‐Shaw model, scaling considerations, construction techniques, and examples of problems adaptable to this model such as recharge pits, seepage of saline water, tidal fluctuations and others.
Natural Controls Involved in Shallow Aquifer Contaminationa
Authors: Deutsch M.
Published: July 2006

Shallow aquifers, commonly the most important sources of ground water, are also those most susceptible to contamination. The mode of entry of contaminants to shallow aquifers is (1) directly, via wells or secondary openings in consolidated rocks, (2) percolation through the zone of aeration, (3) induced infiltration through the zone of saturation, and (4) interaquifer leakage or flow through open holes.

Natural removal or degradation of contaminants is by filtration, dispersion, sorption, ion exchange, oxidation, and various biochemical processes. These phenomena are controlled by the physical environment, structure; mineralogy, and hydraulic characteristics of the earth materials contacted by the liquid wastes.

When liquid wastes enter an aquifer directly, there is little or no natural treatment by filtration, sorption, or oxidation. Purification is only by those processes that operate within the aquifer under anaerobic conditions. Contaminants from natural sources that enter aquifers under saturated‐flow conditions are degraded primarily by dilution. The natural processes effective in reducing contamination from surface‐water sources depend on the hydraulic regimen involved, which vary with individual cases.

Liquid wastes percolating through the zone of aeration are those most likely to be purified by natural environment processes. Natural processes, however, do not effectively remove or degrade all contaminants, especially some of the many highly stable compounds that have gained widespread use in recent years, such as synthetic detergents. Comprehensive interdisciplinary research into the ability of various earth materials to remove many types of contaminants under varying hydrologic conditions is needed.
Waste Injection into a Deep Limestone in Northwestern Floridaa
Authors: Barraclough J. T.
Published: July 2006

During a three‐month trial period, 70 million gallons of industrial wastes were successfully injected at moderate pressures into a deep limestone in the westernmost part of Florida. The movement of these wastes is expected to be predominantly southward toward the natural discharge area which is presumed to be far out in the Gulf of Mexico. The limestone lies between two thick beds of clay (aquicludes) and contains 13,000 parts per million salty water. A series of aquifers and aquicludes appear capable of preventing contamination of the overlying fresh‐water aquifers.
The Design and Construction of Hele‐Shaw Models
Authors: Columbus Nathan
Published: July 2006

Criteria and factors are considered which affect the design of a Hele‐Shaw viscous flow model for use in ground‐ water studies. Procedures and construction techniques for assembling such a model are outlined. Some of the advantages and drawbacks in using a viscous flow model are discussed, Three examples are used to demonstrate the use of the model
Some Technical Aspects of Ground‐Water Administrationa
Authors: Nuzman C. E.
Published: July 2006

This paper is concerned with the development of the application of theoretical aquifer concepts to the administration of water rights from ground‐water sources, and exam‐ ples of the application are given. Kansas operating under the Appropriation Doctrine is applying the rule of priority of right, the first in time is the first in right, to the administra‐ tion of water rights from ground‐water sources. The application is not absolute in that some mutual interference pre‐scribed by the reasonable raising and lowering of the water level must be allowed as specified in the law.

The application of hydrologic considerations in the administration of problems between individual wells is first given. The scope is then expanded and data presented for the application to large basin development where pumpage is largely from storage, using the current situation in the high plains area of western Kansas for the example.

An addition to the normal ground‐water basic data collection program called a “Key Well” program is proposed where the key well is a production well. This well is to be fully instrumented to give information on diversion costs and evaluate methods of construction, as well as identify any changes in aquifer characteristics with respect to time.
Steady‐State Discharge to a Partially Penetrating Artesian Well: An Electrolyte‐Tank Model Studya
Authors: Franke O. L.
Published: July 2006

A systematic investigation of the steady‐state discharge to wells that partially penetrate a homogeneous and isotropic non‐leaky artesian aquifer was made using an electrolyte‐tank model. The experimental results were compared with the discharge calculated by methods developed by several previous writers. This comparison showed that the formula of Li, Bock, and Benton (1954) gave the most reliable results over the widest range of the appropriate geometric variables.
Arizona v. California Landmark on the Colorado Rivera
Authors: Taylor E. F.
Published: July 2006

The outlook for Congressional legislation resolving iong‐time controversies over waters of the Colorado River, optimistic in 1966, has been dimmed by political misunderstanding. The essential ingredient of progress ‐harmony between Arizona and California water leaders ‐has been lost. They worked together on a bill to bring peace to the river and economic advantage to themselves and all Lower Colorado River Basin States. They got to the threshold, but not across it.

Unless falling short of complete success has irreparably upset the delicate balance of Arizona‐California interests, they must inevitably rejoin forces to reach their mutual goals. When and if they do, we believe the background for action and the proposed legislation outlined here will continue to be their best means of compromise.
A Non‐Graphical Method of Determining u and W(u)
Authors: Sheahan N. T.
Published: July 2006

A method is presented for determining values of u and W(u) for u greater than 0.01 from time‐drawdown data without the use of graphical approximations or type‐curves. The method utilizes the function Z(u) which is defined in the paper and makes possible the application of statistical analyses of test data for bounded aquifers and other types of complex field problems. If the field data are taken so that t is a consecutive multiple of two, the method can be applied directly to the drawdown observations. An example of this method used to analyze test data for a bounded aquifer and a table of values of W(u) and Z(u) for selected values of u between 0.01 and 4.6 are also presented.
Ground‐Water Economics as Viewed by the Private Consultant
Authors: Klaer F. H.
Published: July 2006

Water as a natural resource has little value until somebody wants to use it and the dollars and cents value has normally been established by the costs of moving water from its source to the point of beneficial use. The value of water ranges within wide limits from perhaps $2 per million gallons to $70 to $100 per million gallons and an average value might be $20 to $30 per million gallons. Water is no longer free and the costs of providing water in adequate quantity and of suitable quality will increase in the future as the sources of water are more fully utilized and the needs for more extensive treatment increase. The decision to use surface water or ground water is usually based on availability and the costs of providing the water at the point of use for the lowest possible cost. In estimating such costs, however, all costs of development, construction, treatment, operation and maintenance must be included. The principal advantages of ground water include availability close to the point of use, usually lower treatment costs, lower capital outlay, ability to increase the supply by small increments and smaller property requirements for storage. Ground water is often preferred because of its constant chemical quality and temperature. It is the opinion of the author that the effects of the impending water shortage can be minimized by elimination of pollution of our available water supplies and greater use and better management of our ground‐water supplies including natural and induced recharge.
Research in Ground‐Water Economics in the High Plains Area of Colorado
Authors: Barkley P. W.
Published: July 2006

The ground‐water aquifer underlying the northeastern corner of Colorado presently is estimated at 80,000,000 acre feet — enough to last several decades at present rates of use. The rate of use has, however, been increasing substantially in recent years and the possibility of depleting this resource is very real. While depletion of stock resources is a common theme in conservation and natural resources literature, only a few empirical studies are available to show the economic consequences of alternative rates of use. As a result, ground‐water policy has often lagged behind the needs of developing areas.

The Economics Department at Colorado State University, under the auspices of the Office of Water Resources Research is currently engaged in an empirical study of ground‐water development problems in Colorado's High Plains area. Research is just beginning, but the following themes will be examined:

The economics of common property resources and the different management problems associated with them.

Problems faced by individual farm operators as they make the switch from dry‐land to irrigated farming. Problems of externalities among farm firms will be approached.

Problems likely to be faced by inhabitants of communities in the developing area. The integration of the agricultural with the non‐agricultural sectors will be stressed.

Policy recommendations appropriate to areas of rapid ground‐water development.

While the activities at Colorado State University are confined to a relatively small geographic area, it is assumed that applications will be made broader in scope and will prove useful in other parts of the nation.
“Exploration for Hidden Water” by Mohammad Karaji—The Oldest Textbook on Hydrology?
Authors: Nadji Mehdi , Voigt Rudolf
Published: July 2006

Reviewing a classical Persian book on ground‐water problems of the 11th century, it is shown that

Ground‐water hydrology developed absolutely independently of geology.

The Arabic‐Persian scientists of that time knew about the hydrologic cycle and the existence of different types of water underground; and they knew that the quality of water depends on the character of the rocks through which ground water flows.

Techniques of developing ground‐water resources in the Middle East, i.e., the digging of wells and qanats, were of such a high standard that they are still in use today.

Generally, it can be stated that the oriental scientists of the Middle Ages knew of the basic principles of hydrology. Thus they were far ahead of their contemporaries in Europe.
Evaluation of Nitrate Content of Ground Water in Hall County, Nebraskaa
Authors: Piskin Rauf
Published: July 2006

Nitrate concentrations in ground water are low, less than 10 mg/l, in most parts of Hall County. Water from 46 percent of the sampled wells had nitrate concentrations greater than 10 mg/l, and 13 percent had greater than 45 mg/l. Sharp contrasts in concentrations occurring within short distances are common. Seasonal changes and a progressive increase of nitrate concentrations have occurred in some observed wells. Concentrations decrease with increasing well depth and well penetration below the water table. Nitrate in ground water is stratified where the concentration is high. Highest concentrations are found at or near the water table in the vicinity of sampled wells located close to a potential nitrate source. Potential sources of nitrate in the ground water of Hall County are fertilizers, feedlots, septic‐tank effluents, seepage from the Wood River, precipitation, and soil fertility. Whereas seepage from the Wood River contributes nitrate to ground water adjacent to the stream, seepage from the Platte River dilutes the nitrate content of ground water. The hydraulic conductivity of the unsaturated zone is an important factor in controlling nitrate content of ground water.
Digital Model Studies of Steady‐State Radial Flow to Partially Penetrating Wells in Alluvial Plains
Authors: Lakshminarayana V. , Rajagopalan S. P.
Published: July 2006

A digital simulation model for the steady‐state radial flow towards partially penetrating wells in the alluvial plains is presented. As the deposits in these plains are heterogenous with several good water‐bearing formations crisscrossed with silty layers, the deposits are treated as a single anisotropic aquifer with water‐table conditions prevailing. The iterative alternate direction implicit technique is used for the solution of the steady‐state flow. The digital simulation model is used to study the effects of anisotropy, screen setting, and screen length on the discharge per unit length of screen; and in evaluating the errors involved in determining lateral permeability from distance‐drawdown data. The digital simulation model is applied to field pump‐test data for purposes of identification of aquifer anisotropy and radius of influence of well, and in evaluation of errors in determining lateral permeability from distance‐drawdown data.
Migration of Landfill Leachate Through Glacial Tills
Authors: Cartwright Keros , Griffin Robert A. , Gilkeson Robert H.
Published: July 2006

To evaluate the potential of natural clay minerals for attenuating and preventing the pollution of water resources by landfill leachates, leachate was collected by anaerobic techniques from the 15‐year old Du Page County sanitary landfill near Chicago, Illinois, and was passed through 44 laboratory columns that contained various mixtures of calcium‐saturated clays and washed quartz sand. The columns were constructed to simulate slow, saturated, anaerobic flow, and manometers were placed at five locations in each column to measure any changes in hydraulic conductivity. Leachate was run through the columns for periods ranging from 6 to 10 months, during which time effluents were collected periodically and analyzed for 21 chemical constituents. The columns were then sectioned and the clays analyzed to determine the vertical distribution of the chemical constituents in each column. Sterilized landfill leachate was used in a duplicate set of columns to determine the effects of gross biological activity.

Chloride and certain organic compounds were relatively unattenuated by passage through the clay columns; monovalent cations, such as Na, K, and NH4, were moderately attenuated; and heavy metals, such as Pb, Cd, and Zn, were attenuated by even small amounts of clay. Concentrations of Ca and Fe were much higher in the column effluents than they were in the original leachate. The increase in Ca in the column effluents was due to cation exchange with ions in the refuse leachate. The Fe increase probably resulted from reduction of the oxidized Fe on clay surfaces by anaerobic refuse leachate to more soluble reduced Fe.

Both biologically active and sterilized leachate reduced the hydraulic conductivity of the clay‐mixture columns during the experiment. The active leachate reduced the hydraulic conductivity to a much greater degree than the sterile leachate.

Results of the laboratory data were compared with field data from the Du Page County sanitary landfill and from other existing landfills where detailed data are available. The field data show a “hardness halo” corresponding to the Ca release in the columns. The relative attenuation rates of some of the ions were also confirmed by the field data. The change in hydraulic conductivity was not as clearly shown.

Ion exchange capacity, hydraulic conductivity, and buffering capacity of the earth materials were all shown to be important in assessing the potential of landfills for water pollution.
THE RELATIONSHIP BETWEEN INTERNATIONAL EQUITY MARKET BEHAVIOUR AND THE JSE
Authors: Samouilhan Nl
Published: July 2006

This paper investigates empirically the relationship between domestic and international market returns and volatilities, using the London Stock Exchange as the international market proxy. In order to address problems of widely differing bourse composition, the relationships are tested at both the broad bourse index level and the sectoral sub‐indices level. The paper finds significant evidence of a positive relationship between foreign returns and domestic returns and, in addition, between foreign volatility and domestic volatility. It is found that, for most sectors, the main association period is during the same concurrent trading day, although there are additional significant lags present in most of the series. Strong evidence is also found that the magnitude of volatility on the JSE and most of its sub‐indices reacts far more to negative shocks than it does to positive shocks.
THE FOOD SECURITY PROBLEM IN ETHIOPIA – A SUPPLY SIDE ANALYSIS
Authors: Nichola Tennassie
Published: July 2006

Since 1961 Ethiopia has been ruled by a Monarchy, a Marxist military dictatorship, and presently by a coalition of political parties that came to power in 1991after a protracted civil war. These three governments have pursued different ideologies in formulating policies to guide agricultural development. However, to date Ethiopia remains food insecure. Ethiopian agriculture is dominated by peasant farmers and 85 per cent of the population is rural. Rural poverty and, hence, food insecurity is intricately related to insufficient land and a lack of long‐term tenure security. The aggregate country level food security was assessed using various indicators for the periods of the three governments. The growth rates and the variability in the indicators suggest that Ethiopia is suffering from both chronic and transitory food insecurity.
Laser Forming of Varying Thickness Plate—Part II: Process Synthesis
Authors: Cheng Peng , Fan Yajun , Zhang Jie , Yao Y. Lawrence , Mika David P. , Zhang Wenwu , Graham Michael , Marte Jud , Jones Marshall
Published: July 2006

Laser forming (LF) is a non-traditional forming process that does not require hard tooling or external forces and, hence, may dramatically increase process flexibility and reduce the cost of forming. While extensive progress has been made in analyzing and predicting the deformation given a set of process parameters, few attempts have been made to determine the laser scanning paths and laser heat conditions given a desired shape. This paper presents a strain-based strategy for laser forming process design for thin plates with varying thickness, which is utilized in determining the scanning paths and the proper heating conditions. For varying thickness plates, both the in-plane membrane strain and the bending strain need to be accounted for in process design. Compared with uniform thickness plate, the required bending strain varies with not only the shape curvature but also with the plate thickness. The scanning paths are determined by considering the different weight of bending strain and in-plane strain. A thickness-dependent database is established by LF finite element analysis simulation, and the heating conditions are determined by matching the ratio of bending strain to in-plane strain between the required values and the laser forming values found in the database. The approach is validated by numerical simulation and experiments using several typical shapes.
Polymer Flow in a Melt Pressure Regulator
Authors: Fan Bingfeng , Munavalli Mahesh , Kazmer David O.
Published: July 2006

A non-Newtonian, non-isothermal flow analysis has been developed to assist the design of a self-compensating polymer melt regulator, which is a device capable of regulating the melt pressure in polymer processing via an open loop control architecture. The governing mass and momentum equations for the two-dimensional, axisymmetric flow field are solved by a mixed finite element method, in which the velocity components are interpolated by quadratic functions, and the pressure is interpolated by a linear function. The temperature field is solved by the finite difference method. Results of the outlet pressure, valve pin position, bulk temperature rise, and flow rate as functions of the control force for Newtonian isothermal analyses and non-Newtonian non-isothermal analyses are provided. The simulation demonstrates the behavior of candidate regulator designs and provides the performance attributes such as outlet pressure, flow rate, temperature rise, etc., given the decision variables, such as valve parameters, process conditions, and polymer melt rheology. The results indicate that for a regulator design on the order of 20mm diameter, the regulator operates in a mostly closed condition with an aperture opening varying between 0.1 and 1mm. The results suggest that the bulk temperature increases with control force and flow rate and is largely attributable to the increases in viscous heating of the melt through the flow channels, rather than the pinch off between the valve pin and the valve body.
Finite Element Modeling and Analysis of Warm Forming of Aluminum Alloys—Validation Through Comparisons With Experiments and Determination of a Failure Criterion
Authors: Kim Hong Seok , Koç Muammer , Ni Jun , Ghosh Amit
Published: July 2006

In this study, thermomechanically coupled finite element analysis (FEA) was performed for forming aluminum rectangular cups at elevated temperatures. In order to identify the onset of a failure during FEA, applicability, accuracy, and repeatability of three different failure criteria (maximum load, minimum thickness, and thickness ratio) were investigated. The thickness ratio criterion was selected since it resulted in accurate prediction of necking-type failure when compared with experimental measurements obtained under a variety of warm forming conditions. Predicted part depth values from FEA at various die-punch temperature combinations and blank holder pressures conditions were also compared with experiments, and showed good agreement. Forming limit diagrams were established at three different warm forming temperature levels (250°C, 300°C, and 350°C). An increasing limiting strain was observed with increasing forming temperature both in FEA and experiments. In addition, strain distributions on the formed part obtained under different die-punch temperature combinations were also compared to further validate the accuracy of FEA. A high temperature gradient between die and punch (Tdie>Tpunch) was found to result in increased formability; i.e., high part depths.
Probing the Solvent-Assisted Nucleation Pathway in Chemical Self-Assembly
Authors: Jonkheijm Pascal , van der Schoot Paul , Schenning Albertus P. H. J. , Meijer E. W.
Published: July 2006

Hierarchical self-assembly offers a powerful strategy for producing molecular nanostructures. Although widely used, the mechanistic details of self-assembly processes are poorly understood. We spectroscopically monitored a nucleation process in the self-assembly of p-conjugated molecules into helical supramolecular fibrillar structures. The data support a nucleation-growth pathway that gives rise to a remarkably high degree of cooperativity. Furthermore, we characterize a helical transition in the nucleating species before growth. The self-assembly process depends strongly on solvent structure, suggesting that an organized shell of solvent molecules plays an explicit role in rigidifying the aggregates and guiding them toward further assembly into bundles and/or gels.
Galileo, Scientific Entrepreneur
Authors: Findlen Paula E.
Published: July 2006

Galileo's Instruments of Credit
. Telescopes, Images, Secrecy.
By Mario Biagioli
. University of Chicago Press, Chicago, 2006. 312 pp. $35, £22.50. ISBN 0-226-04561-7.

The author explores how Galileo shifted his tactics as his circumstances changed through such episodes as his early discoveries using the telescope, the dispute over sunspots, and the controversy over the relation between Copernicus's theories and Scripture.
Shuttling of HDAC5 in H9C2 cells regulates YY1 function through CaMKIV/PKD and PP2A
Authors: Sucharov Carmen C. , Langer Stephen , Bristow Michael , Leinwand Leslie
Published: July 2006

YY1 is a transcription factor that can activate or repress transcription of a variety of genes and is involved in several developmental processes. YY1 is a repressor of transcription in differentiated H9C2 cells and in neonatal cardiac myocytes but an activator of transcription in undifferentiated H9C2 cells. We now present a detailed analysis of the functional domains of YY1 when it is acting as a repressor or an activator and identify the mechanism whereby its function is regulated in the differentiation of H9C2 cells. We show that histone deacetylase 5 (HDAC5) is localized to the cytoplasm in undifferentiated H9C2 cells and that this localization is dependent on Ca2+/calmodulin-dependent kinase IV (CaMKIV) and/or protein kinase D (PKD). In differentiated cells, HDAC5 is nuclear and interacts with YY1. Finally, we show that HDAC5 localization in differentiated cells is dependent on phosphatase 2A (PP2A). Our results suggest that a signaling mechanism that involves CaMKIV/PKD and PP2A controls YY1 function through regulation of HDAC5 and is important in the maintenance of muscle differentiation.
Ribosomal S6 kinase-1 modulates interleukin-1β-induced persistent activation of NF-κB through phosphorylation of IκBβ
Authors: Xu Shanqin , Bayat Hossein , Hou Xiuyun , Jiang Bingbing
Published: July 2006

Activation of NF-κB requires the phosphorylation and degradation of its associated inhibitory proteins, IκB. Previously, we reported that the extracellular signal-regulated kinase (ERK) is required for IL-1β to induce persistent activation of NF-κB in cultured rat vascular smooth muscle cells (VSMCs). The present study examined the mechanism by which the ERK signaling cascade modulates the duration of NF-κB activation. In cultured rat VSMCs, IL-1β activated ERK and induced degradation of both IκBα and IκBβ, which was associated with nuclear translocation of both ribosomal S6 kinase (RSK)1 and NF-κB p65. RSK1, a downstream kinase of ERK, was associated with an IκBβ/NF-κB complex, which was independent of the phosphorylation status of RSK1. Treatment of VSMCs with IL-1β decreased IκBβ in the RSK1/IκBβ/NF-κB complex, an effect that was attenuated by inhibition of ERK activation. Knockdown of RSK1 by small interference RNA attenuated the IL-1β-induced IκBβ decrease without influencing ether ERK phosphorylation or the earlier IκBα degradation. By using recombinant wild-type and mutant IκBβ proteins, both active ERK2 and RSK1 were found to directly phosphorylate IκBβ, but only active RSK1 phosphorylated IκBβ on Ser19 and Ser23, two sites known to mediate the subsequent ubiquitination and degradation. In conclusion, in the ERK signaling cascade, RSK1 is a key component that directly phosphorylates IκBβ and contributes to the persistent activation of NF-κB by IL-1β.
Early Postnatal Plasticity in Neocortex of Fmr1 Knockout Mice
Authors: Desai Niraj S. , Casimiro Tanya M. , Gruber Stephen M. , Vanderklish Peter W.
Published: July 2006

Fragile X syndrome is produced by a defect in a single X-linked gene, called Fmr1, and is characterized by abnormal dendritic spine morphologies with spines that are longer and thinner in neocortex than those from age-matched controls. Studies using Fmr1 knockout mice indicate that spine abnormalities are especially pronounced in the first month of life, suggesting that altered developmental plasticity underlies some of the behavioral phenotypes associated with the syndrome. To address this issue, we used intracellular recordings in neocortical slices from early postnatal mice to examine the effects of Fmr1 disruption on two forms of plasticity active during development. One of these, long-term potentiation of intrinsic excitability, is intrinsic in expression and requires mGluR5 activation. The other, spike timing-dependent plasticity, is synaptic in expression and requires N-methyl-d-aspartate receptor activation. While intrinsic plasticity was normal in the knockout mice, synaptic plasticity was altered in an unusual and striking way: long-term depression was robust but long-term potentiation was entirely absent. These findings underscore the ideas that Fmr1 has highly selective effects on plasticity and that abnormal postnatal development is an important component of the disorder.
Plasticity of Spinal Cord Reflexes After a Complete Transection in Adult Rats: Relationship to Stepping Ability
Authors: Lavrov Igor , Gerasimenko Yury P. , Ichiyama Ronaldo M. , Courtine Gregoire , Zhong Hui , Roy Roland R. , Edgerton V. Reggie
Published: July 2006

Changes in epidurally induced (S1) spinal cord reflexes were studied as a function of the level of restoration of stepping ability after spinal cord transection (ST). Three types of responses were observed. The early response (ER) had a latency of 2.5 to 3 ms and resulted from direct stimulation of motor fibers or motoneurons. The middle response (MR) had a latency of 5 to 7 ms and was monosynaptic. The late response (LR) had a latency of 9 to 11 ms and was polysynaptic. After a complete midthoracic ST, the LR was abolished, whereas the MR was facilitated and progressively increased. The LR reappeared about 3 wk after ST and increased during the following weeks. Restoration of stepping induced by epidural stimulation at 40 Hz coincided with changes in the LR. During the first 2 wk post-ST, rats were unable to step and electrophysiological assessment failed to show any LR. Three weeks post-ST, epidural stimulation resulted in a few steps and these coincided with reappearance of the LR. The ability of rats to step progressively improved from wk 3 to wk 6 post-ST. There was a continuously improved modulation of rhythmic EMG bursts that was correlated with restoration of the LR. These results suggest that restoration of polysynaptic spinal cord reflexes after complete ST coincides with restoration of stepping function when facilitated by epidural stimulation. Combined, these findings support the view that restoration of polysynaptic spinal cord reflexes induced epidurally may provide a measure of functional restoration of spinal cord locomotor networks after ST.
Control of Frontal Plane Motion of the Hindlimbs in the Unrestrained Walking Cat
Authors: Misiaszek John E.
Published: July 2006

This study describes the patterns of activity of hip abductor and adductor muscles and relates their activity to the frontal plane motions of the hindlimbs during unrestrained walking in the cat to provide insight into the function of these muscles in maintaining stability during walking. Electromyographic activity was recorded from hindlimb muscles while cats walked across a walkway. Four video cameras were used to record the movement of the animal in three dimensions. To further delineate the role of the hip abductors and adductors in regulating frontal plane movements of the legs, medial-lateral translations of the walking surface were periodically introduced. During walking, the hip abducts throughout much of the stance phase and adducts during swing. Normally, the abductors and adductors are co-active during much of the stance phase and are quiescent during swing. Consequently, the adduction observed during swing is likely the result of passive events. It is argued that the activity of the hip abductors during stance phase plays a prominent role in regulating frontal plane motion of the legs during walking. However, when medial-lateral stability is disturbed, both the hip abductors and adductors respond to stabilize the frontal plane motion of the body mass while also adjusting the frontal plane swing trajectory and subsequent paw placement. The balance corrective reactions observed in the cat after medial-lateral perturbations of the support surface reasonably approximate the reactions observed previously in humans, indicating that the cat is a reasonable model to explore the neural mechanisms of lateral stability during walking.
Chronic Bile Duct Injury Associated with Fibrotic Matrix Microenvironment Provokes Cholangiocarcinoma in p53-Deficient Mice
Authors: Farazi Paraskevi A. , Zeisberg Michael , Glickman Jonathan , Zhang Yan , Kalluri Raghu , DePinho Ronald A.
Published: July 2006

Intrahepatic cholangiocarcinoma (CCA) is a lethal malignancy of the biliary epithelium associated with p53 mutations, bile duct injury, inflammation, and fibrosis. Here, to validate these processes in CCA, we developed a liver cirrhosis model driven by chronic intermittent toxin exposure, which provokes bile duct injury/necrosis and proliferation, fibroblast recruitment, and progressive extracellular matrix (ECM) changes. Fibrotic changes in the matrix microenvironment, typified by increased type I and III collagens and fibroblast recruitment, were shown to stimulate biliary epithelium hyperplasia with subsequent progression to malignant intrahepatic CCA only in mice harboring a p53 mutant allele. These murine CCAs bear histologic and genetic features of human intrahepatic CCA, including dense peritumoral fibrosis, increased inducible nitric oxide synthase, nitrotyrosine, and cyclooxygenase-2 expression, c-Met activation, cErbB2 overexpression, down-regulation of membrane-associated E-cadherin, and p53 codon 248 mutation. Thus, p53 deficiency, chronic bile duct injury/proliferation, and the fibrotic matrix microenvironment cooperate to induce intrahepatic CCA, highlighting the key role of the ECM microenvironment in this common liver cancer. (Cancer Res 2006; 66(13): 6622-7) (Cancer Res 2006; 66(13): 6622-7)
Clay mineralogy of onshore UK Carboniferous mudrocks
Authors: Spears D. A.
Published: July 2006

The Carboniferous in Britain is diverse and this is reflected in the clay mineral assemblages. Several factors affecting the assemblages are identified including climate, rates of weathering and erosion, source rocks in the hinterland, preservation of palaeosols, whether the source rocks are nearby or distant, sorting during transportation, the presence of altered volcanic ash-falls in the depositional environment and the extent of burial diagenesis. There are temporal and geographic variations in the clay mineral assemblages in the mudrocks as a result of these controls. There are also clay-rich rocks that differ from the normal mudrocks and a knowledge of the clay mineralogy of these is a necessary prerequisite to a full understanding of their origins. Mudrocks falling in this category, and described below, include bauxitic clays, flint clays, fragmental clay rocks, tonsteins and K-bentonites and various palaeosols.
Anti-CD20 monoclonal antibody with enhanced affinity for CD16 activates NK cells at lower concentrations and more effectively than rituximab
Authors: Bowles Julie A. , Wang Siao-Yi , Link Brian K. , Allan Barrett , Beuerlein Gregory , Campbell Mary-Ann , Marquis David , Ondek Brian , Wooldridge James E. , Smith Brian J. , Breitmeyer James B. , Weiner George J.
Published: July 2006

Growing evidence indicates that the affinity of monoclonal antibodies (mAbs) for CD16 (FcγRIII) plays a central role in the ability of the mAb to mediate antitumor activity. We evaluated how CD16 polymorphisms, and mAb with modified affinity for target antigen and CD16, affect natural killer (NK) cell phenotype when CD20+ malignant B cells were also present. The mAb consisted of rituximab (R), anti-CD20 with enhanced affinity for CD20 (AME-B), and anti-CD20 with enhanced affinity for both CD20 and CD16 (AME-D). Higher concentrations of mAb were needed to induce CD16 modulation, CD54 up-regulation, and antibody-dependent cellular cytotoxicity (ADCC) on NK cells from subjects with the lower affinity CD16 polymorphism. The dose of mAb needed to induce NK activation was lower with AME-D irrespective of CD16 polymorphism. At saturating mAb concentrations, peak NK activation was greater for AME-D. Similar results were found with measurement of CD16 modulation, CD54 up-regulation, and ADCC. These data demonstrate that cells coated with mAb with enhanced affinity for CD16 are more effective at activating NK cells at both low and saturating mAb concentrations irrespective of CD16 polymorphism, and they provide further evidence for the clinical development of such mAbs with the goal of improving clinical response to mAb.
STAT3 positively regulates an early step in B-cell development
Authors: Chou Wei-Chun , Levy David E. , Lee Chien-Kuo
Published: July 2006

Transcription factors are critical for instructing the development of B lymphocytes from multipotential progenitor cells in the bone marrow (BM). Here, we show that the absence of STAT3 impaired B-cell development. Mice selectively lacking STAT3 in BM progenitor cells displayed reduced numbers of mature B cells, both in the BM and in the periphery. The reduction in the B-cell compartment included reduced percentages and numbers of pro-B, pre-B, and immature B cells in the absence of STAT3, whereas the number of pre–pro-B cells was increased. We found that pro-B and pre-B–cell populations lacking STAT3 were hyporesponsive to IL-7 because of a decreased number of IL-7–responsive cells rather than decreased expression or signaling of IL-7Rα. Moreover, STAT3-deficient mice displayed enhanced apoptosis in the pro-B population when deprived of survival factors, suggesting that at least 2 mechanisms (impaired differentiation and enhanced apoptosis) are involved in the mutant phenotype. Last, BM transplantation confirmed that impaired B lymphopoiesis in the absence of STAT3 was caused by a cell autonomous defect. In sum, these studies defined a specific role for STAT3 in early B-cell development, probably acting at the pre–pro-B transition by contributing to the survival of IL-7–responsive progenitors.
No evidence for learned mating discrimination in male Drosophila pseudoobscura
Authors: Kandul Nikolai P , Wright Kevin M , Kandul Ekaterina V , Noor Mohamed AF
Published: July 2006

Background

Since females often pay a higher cost for heterospecific matings, mate discrimination and species recognition are driven primarily by female choice. In contrast, frequent indiscriminate matings are hypothesized to maximize male fitness. However, recent studies show that previously indiscriminate males (e.g., Drosophila melanogaster and Poecilia reticulata) can learn to avoid heterospecific courtship. This ability of males to discriminate against heterospecific courtship may be advantageous in populations where two species co-occur if courtship or mating is costly.

Results

Here, we tested whether Drosophila pseudoobscura males learn to discriminate against heterospecific females after being exposed to and rejected by D. persimilis females. In most of our assays, we failed to observe differences in D. pseudoobscura courtship intensity of heterospecific females by males that had previously courted heterospecific females vs. males that had been maintained in isolation.

Conclusion

We conclude that learning to avoid heterospecific courtship may not be universal, even within the genus Drosophila, and may possibly be dependent on the natural history of the species.
Intra-professional and inter-professional referral patterns of chiropractors
Authors: Smith Monica , Greene Barry R , Haas Mitchell , Allareddy Veerasathpurush
Published: July 2006

Background

With the increasing popularity of chiropractic care in the United States, inter-professional relationships between conventional trained physicians (MDs and DOs) and chiropractors (DCs) will have an expanding impact on patient care. The objectives of this study are to describe the intra-professional referral patterns amongst DCs, describe the inter-professional referral patterns between DCs and conventional trained medical primary care physicians (MDPCPs), and to identify provider characteristics that may affect these referral behaviors.

Methods

A survey instrument to assess the attitudes and patterns of referral and consultation between MD primary care physicians (MDPCPs) and DCs was developed and sent to all DCs in the state of Iowa. Multivariable logistic regression models were built to assess the impact of provider characteristics on intra-professional and inter-professional referral patterns.

Results

Of all DCs contacted, 452 (40.7%) participated in the study. Close to 8% of DCs reported that they never send a case report when referring a patient to another DC, while 13% never send a case report to a MDPCP. About 10% of DCs never send follow-up clinical information to referring doctors. DCs that perform differential diagnosis were significantly more likely to have engaged in inter-professional referral than DCs who did not perform differential diagnosis.

Conclusion

The tendency toward informality, in both referral practices and sharing of clinical documentation for referred patients between MDPCPs and DCs, is an explicit marker of concerns that need to be addressed in order to improve coordination and continuity of care for patients shared between these provider types.
Nitric oxide and mitochondrial biogenesis
Authors: Nisoli Enzo , Carruba Michele O.
Published: July 2006

The characteristic structural organization of mitochondria is the product of synthesis of macromolecules within the mitochondria together with the import of proteins and lipids synthesized outside the organelle. Synthetic and import processes are required for mitochondrial proliferation and might also facilitate the growth of pre-existing mitochondria. Recent evidence indicates that these events are regulated in a complex way by several agonists and environmental conditions, through activation of specific signaling pathways and transcription factors. A newly discovered role of this organelle in retrograde intracellular signaling back to the nucleus has also emerged. This is likely to have far-reaching implications in development, aging, disease and environmental adaptation. Generation of nitric oxide (NO) appears to be an important player in these processes, possibly acting as a unifying molecular switch to trigger the whole mitochondrial biogenesis process. High levels of NO acutely inhibit cell respiration by binding to cytochrome c oxidase. Conversely, chronic, smaller increases in NO levels stimulate mitochondrial biogenesis in diverse cell types. NO-induced mitochondrial biogenesis seems to be linked to proliferation and differentiation of normal and tumor cells, as well as in aging.
Time-Resolved ESR Investigation of Several Ketyl–Phenoxyl Radical Pairs in a Sodium Dodecyl Sulfate Micelle
Authors: Ishiwata Natsuo , Murai Hisao , Kuwata Keiji
Published: July 2006

The CIDEP (chemically induced dynamic electron polarization) spectra of quasi-stable radical pairs formed in the laser flash photolysis of xanthone and several phenol derivatives in SDS (sodium dodecyl sulfate) micellar solutions were studied. In consideration of the spectral patterns of CIDEP and the results of the magnetic-field effects on the reaction, it is concluded that the steric bulkiness of phenol derivatives obstructs the free diffusion of the reactants and the intermediate radical pairs in the micelle. The dependence of the number and position of the t-butyl substituents upon the kinetic parameters and the interaction as the radical pairs in the micellar environment are presented.