bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel nonsense mutation in PAX9 is associated with marked variability in number of missing teeth
Authors: Hansen Lars , Kreiborg Sven , Jarlov Henrik , Niebuhr Erik , Eiberg Hans
Published: August 2007

Tooth development is under strict genetic control. During the last decade, studies in molecular genetics have led to the identification of gene defects causing the congenital absence of permanent teeth. Analyses of PAX9 and MSX1 in nine families with hypodontia and oligodontia revealed one new PAX9 mutation. A LOD score of Z = 1.8 (θ = 0.0) was obtained for D14S75 close to PAX9 in one three‐generation family, and sequencing of the gene identified the nonsense mutation c.433C>T. The mutation results in a truncated PAX9 protein containing the paired domain region as a result of the Q145X stop mutation. The family showed a marked phenotypic variability in the number of missing teeth, ranging from 2 to 15 missing teeth. The highest frequency of missing teeth was found for second molars followed by second premolars.
Chewing problems and dissatisfaction with chewing ability: a survey of older Tanzanians
Authors: Kida Irene A. , Åstrøm Anne N. , Strand Gunhild V. , Masalu Joyce R.
Published: August 2007

This study assessed the prevalence and correlates of reported chewing problems and dissatisfaction with chewing ability. Discrepancy between reported chewing problems and satisfaction/dissatisfaction with chewing ability was examined. A household survey was conducted in Tanzania in 2004/2005. A total of 1,031 adults (mean age 62.9 yr) underwent clinical examination and a personal interview. Forty per cent [95% confidence interval (CI): 37–43] reported problems with chewing at least one food item, and 25% (95% CI: 22–28) were dissatisfied with their chewing ability. Adjusted odds ratios (OR) for reporting problems with chewing any food were 1.6, 1.2, and 4.2 if having intact anterior/reduced posterior, reduced anterior/intact posterior, and reduced anterior/posterior occluding units, respectively. Subjects dissatisfied with their chewing ability were less likely to be female (OR = 0.6) and more likely to have reduced anterior/posterior occluding units (OR = 3.4), to report dental pain (OR =2.5), chewing problems (OR = 4.7), and oral impacts on daily performances (OIDP) (OR = 3.2). The OIDP scores discriminated between satisfied and dissatisfied groups, irrespective of confirmed chewing problems. Chewing problems and dissatisfaction with chewing ability was prevalent among older Tanzanians. Clinical measures of dentition status, together with reported functional and psychosocial impact scores, determined the subjects' evaluation of their chewing ability and should be taken into account when estimating treatment needs.
Interleukin‐17 plays a role in exacerbation of inflammation within chronic periapical lesions
Authors: Čolić Miodrag , Vasilijić Saša , Gazivoda Dragan , Vučević Dragana , Marjanović Marjan , Lukić Aleksandra
Published: August 2007

Interleukin (IL)‐17 plays an important role in inflammation and certain autoimmune diseases. However, its role in the pathogenesis of chronic dental periapical lesions has not been studied. Periapical lesion mononuclear cells (PL‐MNC) were isolated from inflammatory cells and phenotypically analyzed by immunocytochemistry. The cells were cultured in vitro and IL‐17 and IL‐8 were measured in the culture supernatants. Controls were peripheral blood (PB) MNC. The level of IL‐17 and the proportion of neutrophils were significantly higher in symptomatic lesions. In addition, the production of IL‐17 was higher in culture supernatants of PL‐MNC isolated from lesions with a predominance of T cells, and the IL‐17 concentration correlated with the proportion of CD3+ and CD4+ cells. There was a positive correlation between the levels of IL‐17 and IL‐8 in the group of symptomatic lesions. The relationship between these cytokines was additionally confirmed on the basis of augmented production of IL‐8 by both PL‐MNC and PB‐MNC treated with IL‐17. Our results suggest that IL‐17, by stimulating the production of IL‐8, may play a role in exacerbating inflammation within chronic periapical lesions.
Activity of superior head of human lateral pterygoid increases with increases in contralateral and protrusive jaw displacement
Authors: Bhutada Manish K. , Phanachet Intira , Whittle Terry , Peck Chris C. , Murray Greg M.
Published: August 2007

The hypothesis was that the superior head of human lateral pterygoid muscle (SHLP) plays a similar role in jaw movement as the inferior head of human lateral pterygoid muscle (IHLP). The aims were to determine the functional properties of SHLP single motor units (SMUs) and root mean square activity (RMS) of the SHLP during contralateral and protrusive jaw movement tasks and to compare these features with those identified previously for the IHLP. In 22 human subjects, SMUs were recorded intramuscularly from computer tomography‐verified sites within the SHLP during standardized contralateral and protrusive jaw movement tasks recorded by a jaw‐tracking device. Of the 50 SMUs discriminated, 39 were active during contralateral and 29 during protrusive jaw movements. The firing rates and RMS of the SHLP motor units increased with an increase in jaw displacement. The RMS activity across the entire trial during contralateral jaw movement was significantly greater than that during protrusion. Similarly to conclusions previously identified for the IHLP, the data are consistent with an important role for the SHLP in the control of contralateral and protrusive jaw movements. The similarities in SHLP and IHLP functional properties support the proposal that both heads should be regarded as a system of fibers acting as one muscle.
Early development of the lower deciduous dentition and oral vestibule in human embryos
Authors: Hovorakova Maria , Lesot Herve , Vonesch Jean‐Luc , Peterka Miroslav , Peterkova Renata
Published: August 2007

The aim of this work was to investigate the early development of the deciduous dentition and oral vestibule in the human embryonic lower jaw. Histological sections and three‐dimensional reconstructions from prenatal weeks 6–9 were used. A continuous anlage for the oral vestibule did not exist in the mandible. In contrast to the upper jaw, where we previously observed that the dental and vestibular epithelia developed separately, two dento‐vestibular bulges differentiated in the incisor region of the mandible. The lingual parts of each bulge were found to give rise to the respective central and lateral incisors, whereas the labial parts differentiated into the vestibular epithelium. In the canine and molar areas, the dental and vestibular epithelia originated separately. Later, the segments of the vestibular epithelium fused into the labial vestibular ridge, giving rise to the lower oral vestibule in the lip region. In the cheek region, the oral vestibule was found to originate in the mucosal inflection between the developing jaw and the cheek. A similar heterogenous developmental base for the oral vestibule was also observed in the upper jaw. There is thus no general scheme for the early development of the dental and vestibular epithelia that applies to both the upper and lower jaws, and to both their anterior and posterior regions.
Regenerative approaches in the craniofacial region: manipulating cellular progenitors for oro‐facial repair
Authors: Buxton PG , Cobourne MT
Published: August 2007

This review aims to highlight the potential for regeneration that resides within the bony tissues of the craniofacial region. We examine the five main cues which determine osteogenic differentiation: heritage of the cell, mechanical cues, the influence of the matrix, growth factor stimulation and cell‐to‐cell contact. We review how successful clinical procedures, such as guided tissue regeneration and distraction osteogenesis exploit this resident ability. We explore the developmental origins of the flat bones of the skull to see how such programmes of differentiation may inform new therapies or regenerative techniques. Finally we compare and contrast existing approaches of hard tissue reconstruction with future approaches inspired by the regenerative medicine philosophy, with particular emphasis on the potential for using chondrocyte‐inspired factors and replaceable scaffolds.
Significant alterations in peripheral blood lymphocyte subsets in patients with somatoform disorder
Authors: Pedrosa Gil Francisco , Schwarz Markus J , Müller Norbert , Nickel Marius , Ridout Nathan , Schmidmaier Ralf
Published: August 2007

Objective:

Previous studies have suggested that somatoform disorders (SFD) might be associated with changes in the function of the central and autonomic nervous systems. The aim of this study was to examine the possible immunological differences between SFD and healthy controls.

Methods:

Twenty-four patients with SFD and 13 healthy individuals completed the psychological questionnaires to assess symptom reporting [Symptom Checklist-90 Revised (SCL-90-R)] and to diagnose for SFD [Screening for Somatoform Symptoms scale (SOMS-scale)]. Participants also provided a blood sample taken in the morning, which was analysed with an automated cell counter to determine the number of leucocytes per μl and with flow cytometry to determine lymphocyte subsets.

Results:

With the exception of a higher T4/T8 ratio in the patient group, which was mainly because of lower CD8 counts, there were no significant differences in the absolute number of lymphocytes (subsets) between patients with SFD and healthy subjects. A positive correlation between B-lymphocyte subsets (CD19+CD22+, CD19+CD5+, CD19+CD3−) to all scales of the SCL-90-R, except somatisation, were found in SFD. Additionally, a positive correlation was found in SFD between CD14+CD16+ monocytes and somatisation (0.573) on the SCL-90-R scale.

Conclusion:

These data indicate that patients with SFD have an enhanced humoral immunity as shown by increased B-cell numbers and furthermore an elevated T4/T8 ratio because of lower CD8 suppressor cells. Further studies will be required to determine whether these alterations in lymphocyte subsets are directly involved in the pathophysiology of SFD.
Concentration Rebound Following In Situ Chemical Oxidation in Fractured Clay
Authors: Mundle Keely , Reynolds David A. , West Michael R. , Kueper Bernard H.
Published: August 2007

A two‐dimensional, transient‐flow, and transport numerical model was developed to simulate in situ chemical oxidation (ISCO) of trichloroethylene and tetrachloroethylene by potassium permanganate in fractured clay. This computer model incorporates dense, nonaqueous phase liquid dissolution, reactive aquifer material, multispecies matrix diffusion, and kinetic formulations for the oxidation reactions. A sensitivity analysis for two types of parameters, hydrogeological and engineering, including matrix porosity, matrix organic carbon, fracture aperture, potassium permanganate dosage, and hydraulic gradient, was conducted. Remediation metrics investigated were the relative rebound concentrations arising from back diffusion and percent mass destroyed. No well‐defined correlation was found between the magnitude of rebound concentrations during postremedy monitoring and the amount of contaminant mass destroyed during the application. Results indicate that all investigated parameters affect ISCO remediation in some form. Results indicate that when advective transport through the fracture is dominant relative to diffusive transport into the clay matrix (large System Peclet Number), permanganate is more likely to be flushed out of the system and treatment is not optimal. If the System Peclet Number is too small, indicating that diffusion into the matrix is dominant relative to advection through the fracture, permanganate does not traverse the entire fracture, leading to postremediation concentration rebound. Optimal application of ISCO requires balancing advective transport through the fracture with diffusive transport into the clay matrix.
Plant Response to Metal Contamination at an Oil Shale Tailing Site in Maoming, South China
Authors: Ding Aizhong , Cheng Lirong , Liu Puxin , Carpenter Philip J. , Teng Yanguo
Published: August 2007

The performance of phytoextraction is evaluated at an oil shale tailing site in South China, where the soil is moderately contaminated with heavy metals. Soil, wastes, and plant tissues (leaf, stem, and root) were collected from the site and analyzed for metals. The analytical results show that the plants can extract more metal from the surrounding soil than their nutrient requirements. Though the plants sampled are not hyperaccumulators for heavy metals as defined by other researchers, they can translocate heavy metals to their leaves and tolerate acidic soil with pH as low as 3.4. This makes them candidates for contaminated site remediation. Abelmoschus moschatus, Eleocharis quisetina J. et C.Presl, Acacia confusa wild., and Eucalyptus saligna were particularly effective in translocating heavy metals to easily harvestable leaves and shoots.
Influence of Dissolved Oxygen Convection on Well Sampling
Authors: Vroblesky Don A. , Casey Clifton C. , Lowery Mark A.
Published: August 2007

Convective transport of dissolved oxygen (D.O.) from shallow to deeper parts of wells was observed as the shallow water in wells in South Carolina became cooler than the deeper water in the wells due to seasonal changes. Wells having a relatively small depth to water were more susceptible to thermally induced convection than wells where the depth to water was greater because the shallower water levels were more influenced by air temperature. The potential for convective transport of D.O. to maintain oxygenated conditions in a well screened in an anaerobic aquifer was diminished as ground water exchange through the well screen increased and as oxygen demand increased. Transport of D.O. to the screened interval can adversely affect the ability of passive samplers to produce accurate concentrations of oxygen‐sensitive solutes such as iron, other redox indicators, and microbiological data. A comparison of passive sampling to low‐flow sampling in a well undergoing convection, however, showed general agreement of volatile organic compound concentrations. During low‐flow sampling, the pumped water may be a mixture of convecting water from within the well casing and aquifer water moving inward through the screen. This mixing of water during low‐flow sampling can substantially increase equilibration times, can cause false stabilization of indicator parameters, can give false indications of the redox state, and can provide microbiological data that are not representative of the aquifer conditions. Data from this investigation show that simple in‐well devices can effectively mitigate convective transport of oxygen. The devices can range from inflatable packers to simple, inexpensive baffle systems.
WATER ALLOCATION POLICY MODELING FOR THE DONG NAI RIVER BASIN: AN INTEGRATED PERSPECTIVE1
Authors: Ringler Claudia , Huy Nguyen Vu , Msangi Siwa
Published: August 2007

Abstract: Recent water sector reforms and increased scarcity and vulnerability of water resources, combined with declining public funding available for large scale infrastructure investment in the sector, have led to a greater awareness by the Government of Vietnam for the need to analyze water resource allocation and use in an integrated fashion, at the basin scale, and from a perspective of economic efficiency. In this study we focus on the development, application, and selected policy analyses using an integrated economic hydrologic river basin model for the Dong Nai River Basin in southern Vietnam. The model framework depicts the sectoral structure and location of water users (agriculture, industry, hydropower, domestic, and the environment) and the institutions for water allocation in the basin. Water benefit functions are developed for the major water uses subject to physical limitations and to constraints of system control and policy. Based on this modeling framework, we will analyze policies that can affect water allocation and use at the basin level, including both basin‐specific and general macroeconomic policies.
THE IMPORTANCE OF INSTITUTIONAL STRUCTURE IN CONTROLLING AGRICULTURAL RUNOFF1
Authors: Schuck Eric C. , Green Gareth P. , Clements Janet , Frasier W. Marshall
Published: August 2007

Abstract: Agricultural runoff, such as dissolved mineral salts and selenium, creates pronounced downstream impacts to agricultural producers and to wildlife. The ability to manage these problems efficiently depends critically on the institutional pricing structure of irrigation water delivery agencies. An important characteristic of irrigation water delivery is whether irrigators pay per unit of water received or make one payment regardless of the quantity of water received. In this study we compare the effectiveness of agricultural runoff reduction policies in two regions that employ these different water pricing structures. We find that reduction policy is more effective and can be achieved at a lower cost when water is priced on a per unit basis and that growers have greater incentive to act on their own to reduce runoff problems. Operating under a per unit pricing system encourages water conservation and runoff reduction, which creates public benefits that are not achieved under the single‐payment, fixed allotment method of irrigation water delivery.
EFFECTS OF CROPPING SYSTEMS ON NO3‐N LOSSES TO TILE DRAIN1
Authors: Kanwar Rameshwar S.
Published: August 2007

Abstract: Diverse cropping systems can have significant impacts on nutrient losses through tile drain systems and to surface water bodies (rivers and streams). Increased transport of nitrogen to water bodies can reduce dissolved oxygen and enrich the supply of nutrients, resulting in hypoxic zones. With the objective of reducing the transport of nutrients from agricultural watersheds, long term studies (1990 to 1998) were conducted in Iowa to investigate the impact of tillage, crop rotation, and N‐management practices on NO3‐N leaching losses to tile drain water. Results of these studies indicated that continuous corn production systems required higher input of nitrogen fertilizers and resulted in significantly higher NO3‐N leaching losses compared to rotated corn in plots either fertilized with manure or urea ammonium nitrate. Also, rotated corn gave higher corn yields, 8 megagrams per hectare (Mg/ha) versus 6 Mg/ha, than continuous corn. The higher N application rates resulted in increased NO3‐N concentrations in tile water. A strip cropping system with alfalfa lowered NO3‐N concentrations in tile water to less than 10 mg/l. These studies indicated that better land use practices can reduce NO3‐N leaching losses to surface and ground water systems and will help in mitigating environmental concerns of the production agriculture.
DEVELOPMENT OF NUTRIENT SUBMODULES FOR USE IN THE GRIDDED SURFACE SUBSURFACE HYDROLOGIC ANALYSIS (GSSHA) DISTRIBUTED WATERSHED MODEL1
Authors: Johnson Billy E. , Gerald Terry K.
Published: August 2007

Abstract: A primary water quality problem caused by non‐point source pollution (NPSP) is eutrophication, from excess nutrients in receiving water bodies. The control of nutrients arising from NPSP is difficult because the source areas can be hard to identify and typical treatment methods are infeasible due to the distributed nature of the pollutants. It may be possible to reduce nutrient related water quality problems through the restoration of highly disturbed watersheds with best management practices (BMPs). While restoration attempts may provide significant returns, they can be costly to implement and often are met with resistance in agricultural communities. Extending model results beyond the range of calibration to model future conditions such as for restoration scenarios requires the use of physically‐based models that include the important processes that generate streamflow and material transport, uptake, loss, transformation, and recycling of nutrients and other material. The research and development objectives of the US. Army Engineer Research and Development Center (ERDC) in Vicksburg, Mississippi, are to develop a watershed assessment and management model to simulate transport, uptake, loss, transformation, and recycling of nutrients such as nitrogen and phosphorus and associated material such as sediment and organic matter. In this study we will discuss current efforts at the ERDC's Environmental Laboratory to develop a state‐of‐the‐art watershed water quality model.
WATERSHED LEVEL BEST MANAGEMENT PRACTICE SELECTION AND PLACEMENT IN THE TOWN BROOK WATERSHED, NEW YORK1
Authors: Gitau Margaret W. , Veith Tamie L. , Gburek William J. , Jarrett Albert R.
Published: August 2007

Abstract: For a number of years, best management practices (BMPs) have been implemented within the Town Brook watershed as part of a watershed wide effort to reduce phosphorus losses to the New York City water supply reservoirs. Currently, there are no quantitative indications of the effectiveness of these practices at the watershed scale. Additionally, work is needed to evaluate management practice solutions for costs in relation to effectiveness. In this study we develop a methodology for evaluating management solutions to determine the best way(s) to select and place management practices so that pollutant removal targets are met at minimum cost. The study combines phosphorus losses as simulated by the Soil and Water Assessment Tool (SWAT), management practice effectiveness estimates from a predeveloped characterization tool, and practice costs in optimizations using a genetic algorithm. For a user defined target phosphorus removal (60 percent for this study), optimization favors nutrient management plans, crop rotations, contour strip cropping, and riparian forest buffers; the most cost effective scenario achieves a cost effectiveness of 24/kg phosphorus removal per year compared to the 34/kg phosphorus removal per year associated with the current basic implementation scheme. The study suggests that there is a need to evaluate potential solutions prior to implementation and offers a means of generating and evaluating the solutions.
ECONOMIC VALUATION OF RIPARIAN BUFFER AND OPEN SPACE IN A SUBURBAN WATERSHED1
Authors: Qiu Zeyuan , Prato Tony , Boehrn Gerry
Published: August 2007

Abstract: This study evaluates the economic value of riparian buffers and open space in a suburban watershed through two nonmarket valuation methods. A contingent valuation survey was implemented in the Dardenne Creek watershed, a suburban watershed of the St. Louis metropolitan area in Missouri, to evaluate the residents' perceptions of and willingness to pay (WTP) for adopting riparian buffers and preserving farmland in a hypothetical real estate market. A hedonic pricing model based on actual sale prices of homes in the watershed was applied to estimate the market value of open space and other environmental conditions such as flood zone and stream proximity in the study area. The results showed that residents' WTP was consistent with the economic values of open space and proximity to streams embedded in existing home prices. Through a better understanding of residents' perceptions and values, riparian buffer and open space programs can be designed and promoted to achieve greater implementation success and environmental benefit.
TURBULENCE IN MIRAMICHI BAY: THE BURNT CHURCH CONFLICT OVER NATIVE FISHING RIGHTS1
Authors: Obeidi Amer , Hipel Keith W. , Kilgour D. Marc
Published: August 2007

Abstract: A systematic technique is proposed for assisting in the design and implementation of policy and addressing the need to minimize or resolve disputes that may arise in the enforcement of regulations. The Graph Model for Conflict Resolution is a methodology that facilitates the modeling and analysis of interactive multiple participant‐multiple objective decision problems. In the problems considered here, decision makers and policy planners engaged in capacity building typically have different viewpoints over appropriate ways of developing options and enforcing policy choices. Incompatible understandings of resource potentials and limits, and disparities in utilization of these resources, exasperate stakeholders and make the capacity building process counterproductive and even conducive to conflict. A systematic conflict resolution technique is invaluable to policy makers and practitioners in defusing confrontations and reaching out for consensus among participants. In support of current approaches to policy planning and regulation, the Graph Model provides accurate predictions and strategic insights into shortand long‐term opportunities in multiple participant‐multiple objective decision situations. A conflict among the government of Canada, the Mi'kmaq First Nation, and commercial fishermen over the sharing of a natural resource in New Brunswick, Canada, is used to illustrate the advantages of this technique in practical problems.
LAKE WATER QUALITY ASSESSMENT FROM LANDSAT THEMATIC MAPPER DATA USING NEURAL NETWORK: AN APPROACH TO OPTIMAL BAND COMBINATION SELECTION1
Authors: Sudheer K.P. , Chaubey Indrajeet , Garg Vijay
Published: August 2007

Abstract: The concern about water quality in inland water bodies such as lakes and reservoirs has been increasing. Owing to the complexity associated with field collection of water quality samples and subsequent laboratory analyses, scientists and researchers have employed remote sensing techniques for water quality information retrieval. Due to the limitations of linear regression methods, many researchers have employed the artificial neural network (ANN) technique to decorrelate satellite data in order to assess water quality. In this paper, we propose a method that establishes the output sensitivity toward changes in the individual input reflectance channels while modeling water quality from remote sensing data collected by Landsat thematic mapper (TM). From the sensitivity, a hypothesis about the importance of each band can be made and used as a guideline to select appropriate input variables (band combination) for ANN models based on the principle of parsimony for water quality retrieval. The approach is illustrated through a case study of Beaver Reservoir in Arkansas, USA. The results of the case study are highly promising and validate the input selection procedure outlined in this paper. The results indicate that this approach could significantly reduce the effort and computational time required to develop an ANN water quality model.
Priming of intracellular calcium stores in rat CA1 pyramidal neurons
Authors: Hong Min , Ross William N.
Published: August 2007

Repetitive synaptic stimulation evokes large amplitude Ca2+ release waves from internal stores in many kinds of pyramidal neurons. The waves result from mGluR mobilization of IP3 leading to Ca2+‐induced Ca2+ release. In most experiments in slices, regenerative Ca2+ release can be evoked for only a few trials. We examined the conditions required for consistent release from the internal stores in hippocampal CA1 pyramidal neurons. We found that priming with action potentials evoked at 0.5–1 Hz for intervals as short as 15 s were sufficient to fill the stores, while sustained subthreshold depolarization or subthreshold synaptic stimulation lasting from 15 s to 2 min was less effective. A single episode of priming was effective for about 2–3 min. Ca2+ waves could also be evoked by uncaging IP3 with a UV flash in the dendrites. Priming was necessary to evoke these waves repetitively; 7–10 spikes in 15 s were again effective for this protocol, indicating that priming acts to refill the stores and not at a site upstream to the production of IP3. These results suggest that normal spiking activity of pyramidal neurons in vivo should be sufficient to maintain their internal stores in a primed state ready to release Ca2+ in response to an appropriate physiological stimulus. This may be a novel form of synaptic plasticity where a cell's capacity to release Ca2+ is modulated by its average firing frequency.
Comment on “On Mach’s critique of Newton and Copernicus,” by Herbert I. Hartman and Charles Nissim-Sabat [Am. J. Phys. 71 (11), 1163–1169 (2003)]
Authors: Bhadra A. , Das S. C.
Published: August 2007

Hartman and Nissim-Sabat have argued that Mach’s idea of the relativity of rotational motion suffers from internal inconsistencies and leads to a contradiction that there cannot be a stationary bucket in a rotating universe. They also claimed that non-inertial electromagnetic and stellar aberration observations can distinguish between a rotating and a stationary universe, whereas according to Mach there cannot be any observable way to distinguish these two cases. We contest these objections.
Velocity field measurements in a rectangular conduit with particle image velocimetry
Authors: Martino Román , Paterson Agnes , Piva Marcelo F.
Published: August 2007

We present a simple experimental setup to study the velocity profile in a rectangular closed conduit. Particle image velocimetry was applied to obtain the velocity profiles for several values of aspect ratios and for different flow rates. The velocity profile is obtained in the central longitudinal plane of the conduit and in the downstream region where the flow is fully developed. Close agreement between experimental results and theoretical predictions is found.
Real Time Relativity: Exploratory learning of special relativity
Authors: Savage C. M. , Searle A. , McCalman L.
Published: August 2007

“Real Time Relativity” is a computer program that lets users move at relativistic speeds through a simulated world populated with planets, clocks, and buildings. The counterintuitive and spectacular optical effects of relativity are prominent, while systematic exploration of the simulation allows the user to discover relativistic effects such as length contraction and the relativity of simultaneity. We report on the physics and technology underpinning the simulation, and our experience using it for teaching special relativity to first year students.
An electrochromic film device to teach polymer electrochemical physics
Authors: Huang Mei-Rong , Tao Tao , Li Xin-Gui , Gong Qian-Cheng
Published: August 2007

We discuss the background associated with an electrochromic device that can reversibly change its color and optical density at a specific potential. We discuss the underlying science needed to make a new polyaniline (PAN)/polyvinyl alcohol(PVA) electrochromic composite film on an indium-tin oxide (ITO) conducting glass by electropolymerization and describe a reversible redox transition of the PAN. The experiment gives students an opportunity to fabricate an electrochromic device containing PAN, one of the most important conducting polymers. The experimental conditions are flexible so that each group of students can construct their own electrochromic device with particular behavior. Two techniques for polymerizing the PAN and three methods of demonstrating the electrochromism are given, depending on the available apparatus. A sophisticated three-electrode potentiostat or a crude apparatus containing a battery, wire, a variable resistor, and a voltage meter is used to synthesize the PAN deposit. The electrochromic property is repetitively observed by reversibly changing the applied potentials on the device. A potentiostatic apparatus, a single flashlight battery, or a flashlight battery accompanied by a variable resistor allows students to observe multicolor electrochromism. The experiments significantly enhance students’ understanding of polymer chemicophysics principles and their appreciation of novel variable colorful films. The experiments are safe and easy to perform, provided that appropriate precautions are taken.
Irreversible transfer processes of thermoelectric generators
Authors: Chen Min , Rosendahl Lasse , Bach Inger , Condra Thomas , Pedersen John
Published: August 2007

We discuss a novel tool based on heat flow diagrams for analyzing irreversible processes associated with thermoelectric devices and discuss some ambiguous descriptions and errors in related investigations. We consider thermoelectric generators as a paradigm of a heat engine cycle and determine the heat flow distribution by treating the one-dimensional heat transfer differential equation. Representative heat flow diagrams are used to study the influence of internal and external irreversible processes of heat conduction and Joule heat generation.
Optical diffraction microscopy in a teaching laboratory
Authors: Thibault Pierre , Rankenburg Ivan C.
Published: August 2007

We discuss an optics experiment that reproduces all important aspects of diffraction microscopy or coherent diffractive imaging. This technique is used to reconstruct an object’s image from its diffraction pattern. The experimental setup is described in detail and only requires material readily available in a well-equipped optics teaching laboratory. The data analysis procedure is explained, in particular the reconstruction part, for which an iterative phase retrieval algorithm is used. The method is illustrated by showing the complex-valued reconstruction of an insect wing from a diffraction pattern measured with this setup.
Verification of the Rayleigh scattering cross section
Authors: Chakraborti Sayan
Published: August 2007

A simple experiment is described for the direct determination of the wavelength dependence of the Rayleigh scattering cross section using the classic example of the blue sky. Suggestions for inclusion into an undergraduate lab are discussed.
20th-Century Industrial Black Carbon Emissions Altered Arctic Climate Forcing
Authors: McConnell Joseph R. , Edwards Ross , Kok Gregory L. , Flanner Mark G. , Zender Charles S. , Saltzman Eric S. , Banta J. Ryan , Pasteris Daniel R. , Carter Megan M. , Kahl Jonathan D. W.
Published: August 2007

Black carbon (BC) from biomass and fossil fuel combustion alters chemical and physical properties of the atmosphere and snow albedo, yet little is known about its emission or deposition histories. Measurements of BC, vanillic acid, and non–sea-salt sulfur in ice cores indicate that sources and concentrations of BC in Greenland precipitation varied greatly since 1788 as a result of boreal forest fires and industrial activities. Beginning about 1850, industrial emissions resulted in a sevenfold increase in ice-core BC concentrations, with most change occurring in winter. BC concentrations after about 1951 were lower but increasing. At its maximum from 1906 to 1910, estimated surface climate forcing in early summer from BC in Arctic snow was about 3 watts per square meter, which is eight times the typical preindustrial forcing value.
LeuT-Desipramine Structure Reveals How Antidepressants Block Neurotransmitter Reuptake
Authors: Zhou Zheng , Zhen Juan , Karpowich Nathan K. , Goetz Regina M. , Law Christopher J. , Reith Maarten E. A. , Wang Da-Neng
Published: August 2007

Tricyclic antidepressants exert their pharmacological effect—inhibiting the reuptake of serotonin, norepinephrine, and dopamine—by directly blocking neurotransmitter transporters (SERT, NET, and DAT, respectively) in the presynaptic membrane. The drug-binding site and the mechanism of this inhibition are poorly understood. We determined the crystal structure at 2.9 angstroms of the bacterial leucine transporter (LeuT), a homolog of SERT, NET, and DAT, in complex with leucine and the antidepressant desipramine. Desipramine binds at the inner end of the extracellular cavity of the transporter and is held in place by a hairpin loop and by a salt bridge. This binding site is separated from the leucine-binding site by the extracellular gate of the transporter. By directly locking the gate, desipramine prevents conformational changes and blocks substrate transport. Mutagenesis experiments on human SERT and DAT indicate that both the desipramine-binding site and its inhibition mechanism are probably conserved in the human neurotransmitter transporters.
ON THE STANDARD APPROACH TO RENORMALIZATION GROUP IMPROVEMENT
Authors: CHISHTIE F. A. , ELIAS V. , MANN R. B. , MCKEON D. G. C. , STEELE T. G.
Published: August 2007

Two approaches to renormalization-group improvement are examined: the substitution of the solutions of running couplings, masses and fields into perturbatively computed quantities is compared with the systematic sum of all the leading log (LL), next-to-leading log (NLL) etc. contributions to radiatively corrected processes, with n-loop expressions for the running quantities being responsible for summing Nn-1LL contributions. A detailed comparison of these procedures is made in the context of the effective potential V in the 4-dimensional O(4) massless λϕ4 model, showing the distinction between these procedures at two-loop order when considering the NLL contributions to the effective potential V.
HOLOGRAPHIC SPHERICALLY SYMMETRIC METRICS
Authors: PETRI MICHAEL
Published: August 2007

The holographic principle (HP) conjectures, that the maximum number of degrees of freedom of any realistic physical system is proportional to the system's boundary area. The HP has its roots in the study of black holes. It has recently been applied to cosmological solutions. In this article we apply the HP to spherically symmetric static space-times.

We find that any regular spherically symmetric object saturating the HP is subject to tight constraints on the (interior) metric, energy-density, temperature and entropy-density. Whenever gravity can be described by a metric theory, gravity is macroscopically scale invariant and the laws of thermodynamics hold locally and globally, the (interior) metric of a regular holographic object is uniquely determined up to a constant factor and the interior matter-state must follow well defined scaling relations. When the metric theory of gravity is general relativity, the interior matter has an overall string equation of state (EOS) and a unique total energy-density. Thus the holographic metric derived in this article can serve as simple interior 4D realization of Mathur's string fuzzball proposal.

Some properties of the holographic metric and its possible experimental verification are discussed. The geodesics of the holographic metric describe an isotropically expanding (or contracting) universe with a nearly homogeneous matter-distribution within the local Hubble volume. Due to the overall string EOS the active gravitational mass-density is zero, resulting in a coasting expansion with Ht = 1, which is compatible with the recent GRB-data.
WHAT IS THE SIGNIFICANCE OF THE CONSERVATION OF ELECTRIC CHARGE Q?
Authors: UNG CHAN TSAN
Published: August 2007

The conservation of electric charge Q is a universal law in the sense that it should be conserved in any interaction, known or yet unknown. However, Q should not be considered as a simple number but as the half sum of two irreducible quantities, the baryon lepton asymmetric number BAL = A-L (where A is the baryonic number and L is the leptonic number) and total flavor TF. Conservation of electric charge implies obviously conservation of Q (considered as a simple number) but also BAL and TF. We verify that electromagnetism and strong interaction which conserve Q, A and L and all individual flavors conserve obviously BAL and TF; that weak interaction which conserves Q, A and L conserves also BAL and TF. However, conservation of BAL does not necessarily imply conservation of A and L. In effect Δ BAL = 0 has another solution ΔA = ΔL = ±1 which points to a possible solution to explain how a material and neutral universe could arise evolving from an A = 0, L = 0, Q = 0 state to an A > 0, Q = 0 state through a process which would conserve BAL and TF without conserving separately A and L.
FINAL-STATE INTERACTIONS IN DOUBLE POLARIZATION CROSS SECTIONS OF THE EXCLUSIVE REACTION $^2\vec H(\vec\gamma,\pi^0n)p$ IN THE Δ(1232)-RESONANCE REGION
Authors: AL-THOYAIB S. S.
Published: August 2007

The influence of the final-state NN- and πN-rescattering on double polarization cross sections for the exclusive reaction [Formula: see text], involving polarization of the photon beam and the deuteron target, is investigated in the Δ(1232)-resonance region. We found that the effect of NN-rescattering is quite important, whereas the contribution from πN-rescattering is found to be negligible. Sizeable effects, mainly from the NN-rescattering, are found leading to an appreciable reduction of the polarized cross sections. In addition, the effect of final state interactions on the beam-target double polarization E asymmetry is investigated. In contrast to the polarized cross sections, these effects are found to be very small in case of the E asymmetry.
RESEARCH ON PARAMETERIZED ALGORITHMS OF THE INDIVIDUAL HAPLOTYPING PROBLEM
Authors: XIE MINZHU , CHEN JIAN'ER , WANG JIANXIN
Published: August 2007

The individual haplotyping problem is a computing problem of reconstructing two haplotypes for an individual based on several optimal criteria from one's fragments sequencing data. This paper is based on the fact that the length of a fragment and the number of the fragments covering a SNP (single nucleotide polymorphism) site are both very small compared with the length of a sequenced region and the total number of the fragments and introduces the parameterized haplotyping problems. With m fragments whose maximum length is k1, n SNP sites and the number of the fragments covering a SNP site no more than k2, our algorithms can solve the gapless MSR (Minimum SNP Removal) and MFR (Minimum Fragment Removal) problems in the time complexity O(nk1k2 + m log m + nk2 + mk1) and [Formula: see text] respectively. Since, the value of k1 and k2 are both small (about 10) in practice, our algorithms are more efficient and applicable compared with the algorithms of V. Bafna et al. of time complexity O(mn2) and O(m2n + m3), respectively.
A HIDDEN MARKOV MODEL FOR PREDICTING PROTEIN INTERFACES
Authors: NGUYEN CAO , GARDINER KATHELEEN J. , CIOS KRZYSZTOF J.
Published: August 2007

Protein–protein interactions play a defining role in protein function. Identifying the sites of interaction in a protein is a critical problem for understanding its functional mechanisms, as well as for drug design. To predict sites within a protein chain that participate in protein complexes, we have developed a novel method based on the Hidden Markov Model, which combines several biological characteristics of the sequences neighboring a target residue: structural information, accessible surface area, and transition probability among amino acids. We have evaluated the method using 5-fold cross-validation on 139 unique proteins and demonstrated precision of 66% and recall of 61% in identifying interfaces. These results are better than those achieved by other methods used for identification of interfaces.
Seepage characteristics and landsliding of the A3 zone of the Barton Beds
Authors: Barton M.E. , Thomson R.I.
Published: August 2007

The most characteristic feature of the Barton Clay cliffs of Christchurch Bay is the presence of a number of preferred bedding plane surfaces of shearing. Most of these are contained within clay horizons and the reason for their preferential use by the coastal landslides is unknown. One surface, however, is at the base of the 2.7 m thick A3 Zone which consists of inter-bedded sand and clays. This surface is well exposed and forms a distinct feature in the cliffs throughout nearly the whole of the 1.5 mile coastal outcrop of the A3 Zone.

The paper discusses the reason why a shear surface is preferentially developed at this stratigraphic location. Three possible causes are discussed under the headings of (i) pore pressure fluctuation, (ii) seepage erosion and piping and (iii) equilibration response time. The first two are well established theories but the third is a new hypothesis derived from the original Bishop and Bjerrum theory of delayed equilibration. It is considered that the discussion is useful in the general context of landsliding at sand/clay junctions in overconsolidated soils.
Influence of water on engineering properties of weathered rocks
Authors: Turk N. , Dearman W.R.
Published: August 2007

The influence of groundwater on the engineering properties of rocks is well known. Because of its importance, rock mass classification methods include groundwater as one of the main classification parameters. Perhaps the best indication of the influence of groundwater on rock mass properties comes from the application of geophysical resistivity and seismic refraction techniques to investigate groundwater. When ground conditions change from an unsaturated to a saturated state, resistivity and velocity of the rock mass change markedly.

In nature, groundwater affects rock properties either by changes in pore water pressure or by chemical reaction. While increase in pore water pressure decreases the total normal stress in the rock mass, chemical reactions cause rocks to weather resulting in changes in physical and mechanical properties. Pore water pressure is best evaluated in the rock mass by
in situ
measurements. However, the properties of weathered rocks are very often best studied in the laboratory. Over the last decade the influence of weathering on the engineering properties of mainly igneous and sedimentary rocks, under dry and saturated conditions, has been investigated. A great deal of test data has been accumulated on the index and engineering properties of fresh and weathered rocks from the UK and abroad. Analysis of the available test data shows that while certain rock properties increase with weathering and saturation, others decrease.

In this paper changes with saturation in selected index and engineering properties of fresh and weathered porphyrites and andesites from the UK and Turkey are reported. Established relations between the dry to saturation index and engineering properties of weathered rocks will also be presented.
Hydrogeological investigation of a proposed waste disposal site at Nant Y Gwyddon, South Wales
Authors: Tonkin R.
Published: August 2007

The paper describes an investigation into the feasibility of siting a large landfill site on an extensive hilltop plateau, in an area receiving annual rainfall in excess of 2000 mm. The underlying rocks mainly comprise jointed sandstones. Water resources are located on and adjacent to the area and are fed by streams rising within it. The method of site operation required (i.e. containment or dispersal) could be determined only be means of detailed investigation capable of quantifying pollution risks. A groundwater tracing test was performed in conjunction with a surface water survey. These are described and the results and interpretation presented. The proposed method of site development is summarised.
Economical collection of reliable groundwater information
Authors: Sutton J.S. , Eldred C.D.
Published: August 2007

Many site investigations fail to provide reliable information on site groundwater levels and quality yet such information is frequently crucial for successful design and construction. In many cases instrumentation and long term monitoring are either unjustifiable or impracticable. However, adherence to a series of simple rules ensuring accurate recording of water levels and flush returns with reference to borehole and casing depth, throughout the drilling or boring programme, can ensure that reliable information is obtained. Similarly simple and cheap equipment can ensure that general parameters defining water quality (pH and EC) and unstable parameters such as dissolved gases, hardness and alkalinity can be reliably determined, although care is required to ensure that samples are representative particularly if no trial excavations are made.

The use of this type of information and the requirement for it where it has not been properly collected are illustrated with reference to investigations for road construction, an opencast coal mine and a major dewatering operation.