bluuebunny/crossref_metadata_2025 huggingface dataset:
Thin discs, thick dwarfs and the effects of stellar feedback
Authors: Sánchez-Janssen R. , Méndez-Abreu J. , Aguerri J. A. L.
Published: June 2010

We investigate the role of stellar mass in shaping the intrinsic thickness of galaxy discs by determining the probability distribution of apparent axial ratios (b/a) for two different samples that probe the faint end of the galaxy luminosity function. We find that the b/a distribution has a characteristic ‘U-shape’ and identify a limiting mass M*≈ 2 × 109M⊙ below which low-mass galaxies start to be systematically thicker. This tendency holds for very faint (MB∼−8) dwarfs in the local volume, which are essentially spheroidal systems. We argue that galaxy shape is the result of the complex interplay between mass, specific angular momentum and stellar feedback effects. Thus, the increasing importance of turbulent motions in lower mass galaxies leads to the formation of thicker systems, a result supported by the latest hydrodynamical simulations of dwarf galaxy formation and other theoretical expectations. We discuss several implications of this finding, including the formation of bars in faint galaxies, the deprojection of Hi line profiles and simulations of environmental effects on the dwarf galaxy population.
Malin 1: interacting galaxy pair?
Authors: Reshetnikov V. P. , Moiseev A. V. , Ya. Sotnikova N.
Published: June 2010

Malin1 is a unique, extraordinarily large low-surface brightness galaxy. The structure and the origins of the galaxy are poorly understood. The reason for this is the absence of detailed observational data, especially of high-resolution kinematics. In this Letter, we study the stellar kinematics of the inner part (r≤ 15 kpc) of Malin1.

We present spectroscopic arguments in favour of a small galaxy – Malin1B – being a companion probably interacting with the main galaxy – Malin1. This object is clearly seen in many published images of Malin1 but is not mentioned in any astronomical data bases. Malin1B is located at a projected distance of 14kpc from Malin1's nucleus and has small – 65 ± 16km s−1– relative velocity, which we determined for the first time. We suggest that the ongoing interaction with Malin1B can explain the main morphological features of Malin1's central region – two-armed spiral structure, a bar and an external one-armed spiral pattern.

We also investigated the large-scale environment of Malin1 and postulated that the galaxy SDSSJ123708.91 + 142253.2 might be responsible for the formation of an extended low-surface brightness envelope by means of head-on collision with Malin1 (in the framework of the collision scenario proposed by Mapelli et al.). To test the collisional origins of Malin1's global structure, more observational data and new numerical models are needed.
TUBULAR CONCRETIONS IN NEW ZEALAND PETROLIFEROUS BASINS: LIPID BIOMARKER EVIDENCE FOR MINERALISATION AROUND PROPOSED MIOCENE HYDROCARBON SEEP CONDUITS
Authors: Pearson M.J. , Grosjean E. , Nelson C.S. , Nyman S.L. , Logan G.A.
Published: June 2010

Trapped organic compounds (lipids) have been analysed in tubular carbonate concretions and their host sediments in Miocene deep water mudrocks from coastal outcrops in East Coast Basin and Taranaki Basin of North Island, New Zealand. The concretions, including calcitic, dolomitic and mixed mineralogies, have varied morphologies in many cases suggestive of conduits or pipes that channelled the escape of subsurface fluids and/or hydrocarbon gases. The extracted lipids include water column and/or diagenetically‐derived alkanes, fatty acids and alcohols as well as specific marker compounds (including archaeal pentamethylicosane (PMI) and archaeol) associated with subsurface anaerobic oxidation of upwardly seeping methane gas (AOM). Strong carbon‐13 isotopic depletions (δ13C –75 to –120‰) measured for PMI, archaeol and other AOM‐specific marker compounds on three concretion samples support involvement of AOM in generating bicarbonate‐rich fluid that was at least partly responsible for cementing the pipe‐like concretions and central conduits. Other morphological types appear not to be AOM‐related. Sterane and n‐alkane parameters indicate low thermal maturity of the extracted organic matter. The molecular and compound specific isotopic organic geochemical evidence that some tubular concretions functioned as methane conduits thus supports an assertion that the tubular concretions represent ‘fossilised’ parts of the subsurface plumbing of biogenic or thermogenic hydrocarbon‐fed cold seep systems.
STRONTIUM ISOTOPE DATING OF SPICULITIC PERMIAN STRATA FROM SPITSBERGEN OUTCROPS AND BARENTS SEA WELL‐CORES
Authors: Ehrenberg S.N. , McArthur J.M. , Thirlwall M.F.
Published: June 2010

Eight samples of brachiopod shell material have been analyzed for their strontium isotope composition in order to more accurately date Lower to Upper Permian siliceous biogenic strata of Spitsbergen (Kapp Starostin Formation) and the southern Barents Sea (Røye Formation). The results are interpreted as showing a mid‐Artinskian age for the basal Vøringen Member of the Kapp Starostin Formation and a range of late Artinskian to Roadian for the overlying part of this unit. The upper part of the Røye Formation yields ages in the range Roadian to Wuchiapingian. These results are consistent with available biostratigraphic data and confirm the potential of strontium isotope stratigraphy for developing a more accurate chronology of the widespread spiculite deposits that characterize the northern margin of Pangea in late‐Early Permian to Late Permian time and which constitute a potential target for petroleum exploration.
DISTRIBUTION OF PETROPHYSICAL PARAMETERS IN THE CAMBRO‐ORDOVICIAN DIBSIYAH MEMBER OF THE WAJID SANDSTONE, SW SAUDI ARABIA
Authors: Abdulkadir I. T. , Sahin A. , Abdullatif O. M.
Published: June 2010

The Cambrian‐Ordovician Dibsiyah Member is the lowermost unit of the Wajid Sandstone, a major aquifer in SW Saudi Arabia. The Dibsiyah is present throughout most of south‐central Arabia including the Rub'Al‐Khali Basin where it is a potential exploration target and a reservoir for gas. The Member can be divided into Upper and Lower Units based on depositional facies. The Lower Unit is interpreted to have been deposited in a fluvial setting, whereas the Upper Unit, which displays abundant bioturbation, was deposited in shallow‐marine conditions.

Patterns of porosity and permeability distribution in the Dibsiyah Member were analysed statistically. In general, the Member exhibits a limited range of porosity values and a wide range of permeability values. Histograms show that the porosity distribution of both Lower and Upper Units are approximately normal, and that their corresponding vertical and horizontal permeability distributions are positively skewed.

The coefficient of variation for porosity in both the Lower and Upper Units is less than 0.5 indicating that the porosity range is small. However, the horizontal and vertical permeability values are more variable due to the spatial distribution of architectural elements and sedimentary structures within both units. The dissolution of unstable minerals, together with inhomogenous grain packing and poor connectivity, has resulted in a variable permeability distribution.
On functional motor adaptations: from the quantification of motor strategies to the prevention of musculoskeletal disorders in the neck–shoulder region
Authors: Madeleine P.
Published: June 2010

Background: Occupations characterized by a static low load and by repetitive actions show a high prevalence of work‐related musculoskeletal disorders (WMSD) in the neck–shoulder region. Moreover, muscle fatigue and discomfort are reported to play a relevant initiating role in WMSD. Aims: To investigate relationships between altered sensory information, i.e. localized muscle fatigue, discomfort and pain and their associations to changes in motor control patterns.

Materials & Methods: In total 101 subjects participated. Questionnaires, subjective assessments of perceived exertion and pain intensity as well as surface electromyography (SEMG), mechanomyography (MMG), force and kinematics recordings were performed.

Results: Multi‐channel SEMG and MMG revealed that the degree of heterogeneity of the trapezius muscle activation increased with fatigue. Further, the spatial organization of trapezius muscle activity changed in a dynamic manner during sustained contraction with acute experimental pain. A graduation of the motor changes in relation to the pain stage (acute, subchronic and chronic) and work experience were also found. The duration of the work task was shorter in presence of acute and chronic pain. Acute pain resulted in decreased activity of the painful muscle while in subchronic and chronic pain, a more static muscle activation was found. Posture and movement changed in the presence of neck–shoulder pain. Larger and smaller sizes of arm and trunk movement variability were respectively found in acute pain and subchronic/chronic pain. The size and structure of kinematics variability decreased also in the region of discomfort. Motor variability was higher in workers with high experience. Moreover, the pattern of activation of the upper trapezius muscle changed when receiving SEMG/MMG biofeedback during computer work.

Discussion: SEMG and MMG changes underlie functional mechanisms for the maintenance of force during fatiguing contraction and acute pain that may lead to the widespread pain seen in WMSD. A lack of harmonious muscle recruitment/derecruitment may play a role in pain transition. Motor behavior changed in shoulder pain conditions underlining that motor variability may play a role in the WMSD development as corroborated by the changes in kinematics variability seen with discomfort. This prognostic hypothesis was further, supported by the increased motor variability among workers with high experience.

Conclusion: Quantitative assessments of the functional motor adaptations can be a way to benchmark the pain status and help to indentify signs indicating WMSD development. Motor variability is an important characteristic in ergonomic situations. Future studies will investigate the potential benefit of inducing motor variability in occupational settings.
Epiphora: an evidence based approach to the 12 minute consultation
Authors: Blackmore K.J. , Ainsworth G. , Robson A.K.
Published: June 2010

Clin. Otolaryngol. 2010, 35, 210–214

Background:  Epiphora is the presence of a watering eye which may be due to reflex tearing or defective drainage of tears. Whilst most cases present to the ophthalmologist the otolaryngologist has a key role to play in both assessment and management of these patients.

Methods:  This review was based on a literature search last performed on 21st October 2009. MEDLINE and Cochrane databases were searched using the subject headings ‘epiphora’ or ‘functional epiphora’ in combination with diagnosis, investigation, management, treatment, intervention and surgery. Results were limited to English language articles. The personal biographies of the senior authors were also used.

Conclusion:  An accurate assessment of the site and degree of obstruction is important to ensure the correct management is undertaken. Medical treatment with nasal steroid spray may be effective but the majority of obstructed cases will require surgical intervention in the form of dacryocystorhinostomy (DCR). There is increasing evidence that powered endoscopic DCR has outcomes comparable with the ‘gold standard’ procedure of external DCR.
Oral health disparities and the workforce: a framework to guide innovation
Authors: Hilton Irene V. , Lester Arlene M.
Published: June 2010

Introduction: Oral health disparities currently exist in the United States, and workforce innovations have been proposed as one strategy to address these disparities. A framework is needed to logically assess the possible role of workforce as a contributor to and to analyze workforce strategies addressing the issue of oral health disparities.

Methods: Using an existing framework, A Strategic Framework for Improving Racial/Ethnic Minority Health and Eliminating Racial/Ethnic Health Disparities, workforce was sequentially applied across individual, environmental/community, and system levels to identify long‐term problems, contributing factors, strategies/innovation, measurable outcomes/impacts, and long‐term goals. Examples of current workforce innovations were applied to the framework.

Results: Contributing factors to oral health disparities included lack of racial/ethnic diversity of the workforce, lack of appropriate training, provider distribution, and a nonuser‐centered system. The framework was applied to selected workforce innovation models delineating the potential impact on contributing factors across the individual, environmental/community, and system levels. The framework helps to define expected outcomes from workforce models that would contribute to the goal of reducing oral health disparities and examine impacts across multiple levels. However, the contributing factors to oral health disparities cannot be addressed by workforce innovation alone.

Conclusion: The Strategic Framework is a logical approach to guide workforce innovation, solutions, and identification of other aspects of the oral healthcare delivery system that need innovation in order to reduce oral health disparities.
Private sector approaches to workforce enhancement
Authors: Wendling Wayne R.
Published: June 2010

Objectives: This paper addresses the private practice model of dental care delivery in the US. The great majority of dental care services are delivered through this model and thus changes in the model represent a means to substantially change the supply and availability of dental services. The two main forces that change how private practices function are broad economic factors, which alter the demand for dental care and innovations in practice structure and function which alter the supply and cost of services.

Methods: Economics has long recognized that although there are private market solutions for many issues, not all problems can be addressed through this model. The private practice of dentistry is a private market solution that works for a substantial share of the market. However, the private market may not work to resolve all issues associated with access and utilization. Solutions for some problems call for creative private – public arrangements – another form of innovation; and market‐based solutions may not be feasible for each and every problem. This paper discusses these economic factors and innovation as they relate to the private practice of dentistry, with special emphasis on those elements that have increased the capacity of the dental practice to offer services to those with limited means to access fee‐based care.

Results: Innovations are frequently described as new care delivery models or new workforce models. However, innovation can occur on an ongoing and regular basis as dental practices examine new ways to combine capital and human resources and to leverage the education and skill of the dentists to a greater number of patients. Innovation occurs within a market context as the current and projected economic returns reward the innovation. Innovation can also occur through private–public arrangements.

Conclusions: There are indications of available capacity within the existing delivery system to expand service delivery. The Michigan Medicaid Healthy Kids Dental program is discussed as one example of how dental services to Medicaid insured children were effectively expanded using the private practice model.
The challenge to delivering oral health services in rural America
Authors: Skillman Susan M. , Doescher Mark P. , Mouradian Wendy E. , Brunson Diane K.
Published: June 2010

Objectives: This review identifies the challenges to oral health in rural America and describes areas of innovation in prevention, delivery of dental services, and workforce development that may improve oral health for rural populations.

Methods: This descriptive article is based on literature reviews and personal communications.

Results: Rural populations have lower dental care utilization, higher rates of dental caries, lower rates of insurance, higher rates of poverty, less water fluoridation, fewer dentists per population, and greater distances to travel to access care than urban populations. Improving the oral health of rural populations requires practical and flexible approaches to expand and better distribute the rural oral health workforce, including approaches tailored to remote areas. Solutions that involve mass prevention/public health interventions include increasing water fluoridation, providing timely oral health education, caries risk assessment and referral, preventive services, and offering behavioral interventions such as smoking and tobacco cessation programs. Solutions that train more providers prepared to work in rural areas include recruiting students from rural areas, training students in rural locations, and providing loan repayment and scholarships. Increasing the flexibility and capacity of the oral health workforce for rural areas could be achieved by creating new roles for and new types of providers. Solutions that overcome distance barriers include mobile clinics and telehealth technology.

Conclusions: Rural areas need flexibility and resources to develop innovative solutions that meet their specific needs. Prevention needs to be at the front line of rural oral health care, with systematic approaches that cross health professions and health sectors.
Dendritic cell vaccination in human melanoma: relationships between clinical effects and vaccine parameters
Authors: Nakai Noriaki , Hartmann Gunther , Kishimoto Saburo , Katoh Norito
Published: June 2010

Eleven years have passed since the start of the first trial of dendritic cell (DC) vaccination for melanoma. A review of 54 trials was performed to evaluate the relationship between clinical effects and vaccine parameters. Significant differences were found between use of immature and mature DCs with regard to progressive disease (PD), between stage III and IV for clinical response, between use and non‐use of adjuvants with regard to stable disease (SD) in treatment with tumor/tumor lysate‐pulsed DCs, between positive and negative delayed‐type hypersensitivity (DTH) for PD, and between increased and unchanged interferon (IFN)‐γ‐secreting T cells for clinical response. These results are consistent with the partial efficacy of vaccination with mature DCs in early stage melanoma and the partial correlation of efficacy with positive DTH and increased IFN‐γ‐secreting T cells. DC vaccination alone had a limited clinical effect and a modified regimen is needed to enhance antigen‐specific cytotoxic T cells and decrease immunosuppression.
Combination treatment of db/db mice with exendin‐4 and gastrin preserves β‐cell mass by stimulating β‐cell growth and differentiation
Authors: Tamaki Motoyuki , Fujitani Yoshio , Uchida Toyoyoshi , Hirose Takahisa , Kawamori Ryuzo , Watada Hirotaka
Published: June 2010

Aim/Introduction:  Preservation of β‐cell mass is crucial for maintaining long‐term glucose homeostasis. Therapies based on incretin and its mimetics are expected to achieve this goal through various biological functions, particularly the restoration of β‐cell mass. Here we tested the effects of gastrin and exendin‐4 in type 2 diabetic animals.

Materials and Methods:  The effects of exendin‐4 and gastrin on β‐cell function and mass were examined in 8‐week‐old db/db mice. INS‐1 beta cells and AR42J cells were used to determine the molecular mechanism underlying the effects of the two agents. Immunohistochemistry, western blotting and RT‐PCR assays were used to assess the biological effects of the two agents.

Results:  Two weeks of combination administration of exendin‐4 plus gastrin resulted in a significant improvement of glucose tolerance associated with a marked preservation of β‐cell mass in db/db mice. Immunohistochemical analysis showed that such treatment resulted in the appearance of numerous irregularly‐shaped small islets and single insulin‐positive cells. While gastrin had little biological effect on INS‐1 β‐cells consistent with low expression of its intrinsic receptor on these cells, it caused differentiation of AR42J cells into insulin‐producing cells. Co‐stimulation with exendin‐4 significantly enhanced gastrin‐induced endocrine differentiation of AR42J precursor cells. These findings were further supported by enhanced expression of key genes involved in β‐cell differentiation and maturation, such as neurogenin3 (Ngn3) and MafA.

Conclusions:  These results suggest that combination treatment of db/db mice with exendin‐4 and gastrin preserves β‐cell mass by stimulating β‐cell growth and differentiation. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.00044.x, 2010)
A Comparison of Phase Doppler Analyzer (Dual-PDA) and Optical Patternator Data for Twin-Fluid and Pressure-Swirl Atomizer Sprays
Authors: Muliadi Ariel R. , Sojka Paul E. , Sivathanu Yudaya R. , Lim Jongmook
Published: June 2010

The goal of this study was to determine when patternation information derived from Phase Doppler Analyzer (Dantec Dynamics, Skovlunde, Denmark, dual-PDA) measurements of volume flux, drop velocity, and mean size agreed with corresponding values measured using an optical patternator (Enurga, Inc., West Lafayette, IN, SetScan OP-600). To achieve this, data from each instrument were transformed into spatially resolved absorptances (equivalent to drop surface area per unit spray volume) and compared. Key conclusion is absorptance agreement to within 20% in many cases. However, discrepancies between phase Doppler analyzer (PDA)-calculated and optical patternator-measured absorptances become larger as the drop arrival rate increases, as the mean drop size decreases, and when a significant drop size-velocity correlation is present. These discrepancies are attributed to an underestimation of the volume flux (which becomes more important with increasing droplet arrival rate), an over-reporting of the mean drop diameter (which is the result of the restrictive data acquisition scheme applied when ensuring mass closure for the PDA measurements), the limited PDA dynamic range (which can preclude simultaneously accounting for both the largest and smallest drops in the spray), and by the optical patternator’s number-density based measurement scheme (which will not yield the same results as the flux-based PDA when a drop size-velocity correlation is present).
An Analytical Modeling of the Central Core Flow in a Rotor-Stator System With Several Preswirl Conditions
Authors: Debuchy Roger , Abdel Nour Fadi , Bois Gérard
Published: June 2010

In the most part of an enclosed rotor-stator system with separated boundary layers, the flow structure is characterized by a central core rotating as a solid body with a constant core-swirl ratio. This behavior is not always observed in an isolated rotor-stator cavity, i.e., without any centripetal or centrifugal throughflow, opened to the atmosphere at the periphery: Recent works have brought to evidence an increasing level of the core-swirl ratio from the periphery to the axis, as in the case of a rotor-stator with superposed centripetal flow. The present work is based on an asymptotical approach in order to provide a better understanding of this process. Assuming that the boundary layers behave as on a single rotating disk in a stationary fluid on the rotor side, and on a stationary disk in a rotating fluid on the stator side, new analytical relations are obtained for the core-swirl ratio, the static pressure on the stator, and also the total pressure at midheight of the cavity. An experimental study is performed: Detailed measurements provide data for several values of the significant dimensionless parameters: 1.14≤10−6×Re≤1.96, 0.05≤G≤0.10, and 0.07≤104×Ek≤2.65. The analysis of the results shows a good agreement between the theoretical solution and the experimental results. The analytical model can be used to provide a better understanding of the flow features. In addition, radial distributions of both core-swirl ratio, dimensionless static pressure on the stator, as well as dimensionless total pressure at midheight of the cavity, which are of interest to the designers, can be computed with an acceptable accuracy knowing the levels of the preswirl coefficient Kp and the solid body rotation swirl coefficient KB.
Flowfield Investigation at Propeller Thrust Reverse
Authors: Roosenboom Eric W. M. , Schröder Andreas
Published: June 2010

The flow phenomena in the slipstream around an eight-bladed propeller at thrust reverse conditions are analyzed using double stereoscopic particle image velocimetry in the Airbus Low-Speed Wind Tunnel Facility in Bremen, Germany. Several planes are scanned using a traversing system, as well as measurements at several phase angles. In the present paper only properties in the propeller symmetry plane will be compared. The fluid mechanical properties for two different propeller blade pitch angle settings are investigated and compared for their ability to deliver a negative thrust. The first setting has identical blade pitch angles for all propeller blades; the second setting has alternating blade pitch angles. It is concluded that the latter setting provides better aerodynamic flow properties.
Development-Length Requirements for Fully Developed Laminar Flow in Concentric Annuli
Authors: Poole R. J.
Published: June 2010

In this technical brief we report the results of a systematic numerical investigation of developing laminar flow in axisymmetric concentric annuli over a wide range of radius ratio (0.01<Ri/Ro<0.8) and Reynolds number (0.001<Re<1000). When the annular gap is used as the characteristic length scale we find that for radius ratios greater than 0.5 the development length collapses to the channel-flow correlation. For lower values of radius ratio the wall curvature plays an increasingly important role and the development length remains a function of both radius ratio and Reynolds number. Finally we show that the use of an empirical modified length scale to normalize both the development length and the characteristic length scale in the Reynolds number collapses all of the data onto the channel-flow correlation regardless of the radius ratio.
Factors of Safety for Richardson Extrapolation
Authors: Xing Tao , Stern Frederick
Published: June 2010

A factor of safety method for quantitative estimates of grid-spacing and time-step uncertainties for solution verification is developed. It removes the two deficiencies of the grid convergence index and correction factor methods, namely, unreasonably small uncertainty when the estimated order of accuracy using the Richardson extrapolation method is greater than the theoretical order of accuracy and lack of statistical evidence that the interval of uncertainty at the 95% confidence level bounds the comparison error. Different error estimates are evaluated using the effectivity index. The uncertainty estimate builds on the correction factor method, but with significant improvements. The ratio of the estimated order of accuracy and theoretical order of accuracy P instead of the correction factor is used as the distance metric to the asymptotic range. The best error estimate is used to construct the uncertainty estimate. The assumption that the factor of safety is symmetric with respect to the asymptotic range was removed through the use of three instead of two factor of safety coefficients. The factor of safety method is validated using statistical analysis of 25 samples with different sizes based on 17 studies covering fluids, thermal, and structure disciplines. Only the factor of safety method, compared with the grid convergence index and correction factor methods, provides a reliability larger than 95% and a lower confidence limit greater than or equal to 1.2 at the 95% confidence level for the true mean of the parent population of the actual factor of safety. This conclusion is true for different studies, variables, ranges of P values, and single P values where multiple actual factors of safety are available. The number of samples is large and the range of P values is wide such that the factor of safety method is also valid for other applications including results not in the asymptotic range, which is typical in industrial and fluid engineering applications. An example for ship hydrodynamics is provided.
Multidimensional Results Reporting to Participants in Genomic Studies: Getting It Right
Authors: Kohane Isaac S. , Taylor Patrick L.
Published: June 2010

Research study participants desire personal study results, creating questions about whether and how such results should be communicated.
Nuclear Role of WASp in the Pathogenesis of Dysregulated T
H
1 Immunity in Human Wiskott-Aldrich Syndrome
Authors: Taylor Matthew D. , Sadhukhan Sanjoy , Kottangada Ponnappa , Ramgopal Archana , Sarkar Koustav , D’Silva Sheryl , Selvakumar Annamalai , Candotti Fabio , Vyas Yatin M.
Published: June 2010

Nuclear role for WASp in
T-BET
transcription.
Alternative Control: What’s WASp Doing in the Nucleus?
Authors: Teitell Michael A.
Published: June 2010

A new paper suggests a role for epigenetic modifiers in the management of defective T helper type 1 immunity in Wiskott-Aldrich syndrome.
Improved Analysis
Authors: Carlson Nichole
Published: June 2010

Studies of conditions in which participants experience recurring disease episodes require specialized statistical analysis.
Three dimensional CT angiography versus digital subtraction angiography in the detection of intracranial aneurysms in subarachnoid hemorrhage
Authors: Prestigiacomo Charles J , Sabit Aria , He Wenzhuan , Jethwa Pinakin , Gandhi Chirag , Russin Jonathan
Published: June 2010

Introduction

Ruptured intracranial aneurysms are responsible for over 90% of cases of spontaneous subarachnoid hemorrhage (SAH). Conventional digital subtraction angiography (DSA) remains the gold standard for diagnosing the source of SAH. A prospective study is presented wherein SAH patients underwent three dimensional CT angiography (CTA) prior to DSA in order to assess the specificity and sensitivity of this non-invasive modality to detect aneurysms.

Methods

179 consecutive patients with spontaneous SAH presented over 36 months, as identified by screening CT and CTA. Patients with negative CTA findings underwent DSA within 24 h of presentation. All patients who were determined to have angiographically negative SAH underwent follow-up DSA 2 weeks later.

Results

Of the 179 patients screened by CTA, 13 (7%) were negative for aneurysms or other vascular lesions (arteriovenous malformation or dural fistula) on CTA and underwent DSA. No new lesions were identified on six vessel angiography, resulting in a 0% false negative rate (sensitivity 100%, predictive value 100%). MRI to rule out thrombosed aneurysms and repeat angiography at the 2 week follow-up were negative.

Conclusions

Sensitivity and specificity were higher than previously reported, suggesting that CTA may be used as an initial screening tool in lieu of DSA. Further studies are necessary to determine if CTA can supplant DSA in ruling out all forms of vascular disease in idiopathic SAH.
How do gravel-bed rivers braid?
Authors: Ashmore Peter E.
Published: June 2010

Sedimentary processes and bed forms leading to the onset of braiding were observed in small-scale hydraulic models of gravel-bed streams. The laboratory streams had a variety of combinations of (constant) discharge and slope but identical bed-material particle-size distributions. From initially straight channels, braiding occurred by four different processes: deposition and accumulation of a central bar, chute cutoff of point bars, conversion of single transverse unit bars to mid-channel braid bars, and dissection of multiple bars. In these experiments the chute cutoff mechanism was the most common, but the predominant braiding mechanism depends upon sediment mobility (excess bed shear stress) and the bed-form regime. At very low excess bed shear stress the central bar process dominates, but at higher excess bed shear stress slip-face unit bars are more common, bed scour at confluences is more pronounced, and propogation of alternate convergence (scour) and divergence (deposition) is more likely; thus chute cutoffs and bar conversion dominate. The multiple bar mechanism is restricted to channels with very high width/depth ratio. All of these processes, along with avulsion, are significant for maintenance of an established braided channel.The direct physical sedimentary cause of primary braiding is essentially the same in all these processes: local aggradation (often by stalling of bed-load sheets) and loss of competence in a lateral flow expansion. The chute cutoff process occurs in a morphologically distinctive setting and may be aided by other factors, but it is usually triggered by the local thalweg shoaling that is the fundamental physical mechanism causing the onset of braiding by the other processes. Local short-term pulses in bed-load supply are often the trigger for the initiation and maintenance of braiding, regardless of the exact braiding process.
Elimination of membrane compliance in undrained triaxial testing. I. Measurement and evaluation
Authors: Nicholson P.G. , Seed R.B. , Anwar H.A.
Published: June 2010

Several alternative approaches have been suggested for evaluation and correction of the testing errors caused by membrane compliance. The degree to which membrane compliance may affect the results of an undrained test is a function of the soil grain size and overall geometry of the test specimen, as well as specimen density and range of effective confining stresses during a given test. Membrane-compliance effects may be negligible for fine sands and silts tested in conventional 71 mm diameter samples, since even very thin membranes cannot penetrate significantly into the small surficial voids. For medium to coarse sands and gravels, however, membrane-compliance effects may have a significant influence on test results. The scope of this paper is threefold: firstly, to review, examine, and evaluate the variety of methods to measure and characterize membrane compliance; secondly, to develop an improved understanding of the factors affecting membrane compliance; and thirdly, to provide an enhanced, updated, and expanded correlation for estimating membrane compliance characteristics as a function of material grain size for a range of soil types, including a wide range of gradation types and representative grain sizes from silts through gravels. Key words : membrane, penetration, compliance, undrained testing, triaxial, measurement, evaluation.
Dynamic deformation characteristics of sands and rockfill materials
Authors: Yasuda Nario , Matsumoto Norihisa
Published: June 2010

Cyclic torsional simple shear (CTSS) tests and cyclic triaxial (CTX) tests were carried out to investigate the dynamic deformation characteristics of sands and rockfill materials. It was found that the shear modulus and damping ratio can be expressed as a function of shear strain, void ratio, and confining stress. Also the shear modulus in CTSS tests is larger than in CTX tests because of the influence of the intermediate principal stress. When the shear strain is increased, the shear modulus (G) and damping ratio (h) of the rockfill materials were altered at smaller strains than in sands. Key words : sands, rockfill materials, torsional simple shear, shear modulus, damping ratio.
Characteristics of ground surface settlement during excavation
Authors: Ou Chang-Yu , Hsieh Pio-Go , Chiou Dar-Chang
Published: June 2010

The objective of this paper is to study the characteristics of ground surface settlement during excavation. Ten excavation cases in Taipei with good-quality construction and field observation data are selected to study the characteristics of excavation behavior. The location of maximum lateral wall deflection, magnitude of maximum lateral wall deflection, relationship of maximum lateral wall deflection and maximum ground surface settlement, location of maximum ground surface settlement, and apparent influence range are thus established based on the actual excavation cases. Finally, an empirical formula is proposed to predict the ground surface settlement profile at the center section of an excavation, where the behavior may be characterized by plane-strain conditions. Key words : excavation, surfac settlement, wall deflection, plane strain, empirical formula.
pH influence on selectivity and retention of heavy metals in some clay soils
Authors: Yong Raymond N. , Phadungchewit Yuwaree
Published: June 2010

The problem of varying species of heavy metals existing as individual species or in combination with each other in simulated contaminant leachates (solutions) is studied in relation to selectivity and retention in four different kinds of soil. The influence of pH on the retention characteristics is also examined. The results obtained from the heavy metals single-species and composite-species adsorption tests indicate that in evaluating the attenuation potential of the soil substrate (i.e., contaminant attenuation), account needs to be given to the sensitivity of the soil – heavy metals contaminant system to the pH of the leachate and the competitive effect between the heavy metals present in the leachate. A change in the soil solution pH results in a corresponding change of the dominant retention mechanism of heavy metals in the soils. At high pH values, precipitation mechanisms (e.g., precipitating as hydroxides and (or) as carbonates) dominate. As pH decreases, precipitation becomes less important, and cation exchange becomes dominant. High amounts of heavy metals are retained in the soils if the soil buffer capacity remains high enough to resist a change in pH. The selectivity order of heavy-metal retention in soils depends on the pH of soil solution. At soil solution pH values above 4 or 5, when precipitation prevails, the selectivity order obtained is given as Pb > Cu > Zn ≥ Cd, as demonstrated for the illite, montmorillonite, and natural clay soils. At lower soil solution pH values, the selectivity order obtained is given as Pb > Cd > Zn > Cu, as can be seen in the case of kaolinite and montmorillonite. Key words : heavy metals, retention, selectivity, preferential adsorption, precipitation.
Selective sequential extraction analysis of heavy-metal retention in soil
Authors: Yong Raymond N. , Galvez-Cloutier Rosa , Phadungchewit Yuwaree
Published: June 2010

The selective sequential extraction method of analysis is used in this study to determine the distribution of heavy metals in some clay soils, to assist in evaluation of the role of the various clay soil solids (clay minerals, organics, amorphous materials, and carbonates) in heavy-metal retention capability as a function of acidity of the leachate. The chemical speciation model MINTEQ (metal speciation equilibrium model for surface and groundwater) is used to calculate the probable percent distribution of different species of heavy metals present in the leachate used. The selective sequential extraction method is based on the fact that different forms of heavy metals that are retained in soil (e.g., as oxides, hydroxides, carbonates, bound with organic matter) can be extracted selectively by using appropriate reagents. The results show that heavy metals can be retained in the four clay soils studied by several soil phases or mechanisms such as exchangeable, carbonate, hydroxide, and organic phases. The retention of heavy metals in any phase depends on soil solution pH, soil constituents, and the type of heavy metal. At high soil solution pH values, retention of heavy metal by precipitation mechanisms prevails, whereas at low soil solution pH, retention by cation exchange mechanisms becomes dominant. The results from the selective sequential extraction analysis support the conclusion of the significance of soil buffer capacity with regard to heavy-metal retention. The capacity of the soils to retain high amounts of heavy metals as they receive increasing amounts of acid (i.e., as the pH is reduced) depends directly on the soil initial pH values and on their buffer capacities. Key words : selective sequential analysis, exchangeable cations, heavy metals, equilibrium models, oxides.
Anisotropic three-dimensional behavior of a normally consolidated clay
Authors: Kirkgard M.M. , Lade P.V.
Published: June 2010

An experimental study is presented of the influence of the intermediate principal stress on the stress–strain, pore-pressure, and strength characteristics of a normally consolidated, natural anisotropic clay, San Francisco Bay Mud, under undrained conditions. Consolidated undrained triaxial compression tests and triaxial tests with independent control of all three principal stresses on cubical specimens were performed. The stress–strain behavior and the pore-pressure characteristics as well as the effective stress failure surface can be described as being cross-anisotropic. Key words : anisotropic soils, clays, deformation, shear strength, triaxial tests.
CARDINALITY OF RATIONAL HOMOTOPY TYPES OF SIMPLY CONNECTED CW COMPLEXES
Authors: BENKHALIFA MAHMOUD
Published: June 2010

The aim of this paper is to consider the following problem: given a simply connected CW complex X of finite type, find the cardinal of the set of rational homotopy types of CW complexes Y such that H*(Y, ℚ) is isomorphic, as a commutative graded algebra, to H*(X, ℚ). For this purpose we introduce a long exact sequence, called the Whitehead exact sequence, which we associated with the minimal Sullivan model of X and which allows us to define the notion of the adapted couple associated with X. Thus we show that the rational homotopy type of X is completely determined by the equivalence class of its adapted couple.
ON THE EXTENSION OF THE MEAN CURVATURE FLOW IN ARBITRARY CODIMENSION
Authors: HAN XIAOLI , SUN JUN
Published: June 2010

In this paper we first give an integral condition under which the mean curvature flow can be extended in arbitrary codimension. Then we investigate some properties of Type I singularity.
SEMISTABILITY OF SYZYGY BUNDLES ON PROJECTIVE SPACES IN POSITIVE CHARACTERISTICS
Authors: TRIVEDI V.
Published: June 2010

We generalize a result of Flenner, proved in characteristic zero, to positive characteristics. We prove that the first syzygy bundle, [Formula: see text], of the line bundle [Formula: see text] over [Formula: see text] is semistable, for a certain infinite set of integers d ≥ 0. Moreover, for arbitrary d, there is a "good enough estimate" on [Formula: see text] in terms of d and n; thus a strong restriction theorem of Langer, proved earlier for characteristic k > d, is valid in arbitrary characteristics.
ON FINITE NONCOMMUTATIVITY IN QUANTUM FIELD THEORY
Authors: LÅNGVIK MIKLOS , ZAHABI ALI
Published: June 2010

We consider various modifications of the Weyl–Moyal star-product, in order to obtain a finite range of nonlocality. The basic requirements are to preserve the commutation relations of the coordinates as well as the associativity of the new product. We show that a modification of the differential representation of the Weyl–Moyal star-product by an exponential function of derivatives will not lead to a finite range of nonlocality. We also modify the integral kernel of the star-product introducing a Gaussian damping, but find a nonassociative product which remains infinitely nonlocal. We are therefore led to propose that the Weyl–Moyal product should be modified by a cutoff-like function, in order to remove the infinite nonlocality of the product. We provide such a product, but it appears that one has to abandon the possibility of analytic calculation with the new product.
PREDICTING THE SYNCHRONIZATION OF A NETWORK OF ELECTRONIC REPRESSILATORS
Authors: TOKUDA ISAO T. , WAGEMAKERS ALEXANDRE , SANJUÁN MIGUEL A. F.
Published: June 2010

Synchronization of coupled oscillators is by now a very well studied subject. A large number of analytical and computational tools are available for the treatment of experimental results. This article focuses on a method recently proposed to construct a phase model from experimental data. The advantage of this method is that it extracts a phase model in a noninvasive manner without any prior knowledge of the experimental system. The aim of the present research is to apply this methodology to a network of electronic genetic oscillators. These electronic circuits mimic the dynamics of a synthetic genetic oscillator, called "repressilator", which is capable of synthesizing autonomous biological rhythms. The obtained phase model is shown to be capable of recovering the route leading to synchronization of genetic oscillators. The predicted onset point of synchronization agrees quite well with the experiment. This encourages further application of the present method to synthetic biological systems.
A METRIC APPROACH TO PLASTICITY VIA HAMILTON–JACOBI EQUATION
Authors: AURICCHIO FERDINANDO , BONETTI ELENA , MARIGONDA ANTONIO
Published: June 2010

Thermodynamical consistency of plasticity models is usually written in terms of the so-called "maximum dissipation principle". In this paper, we discuss constitutive relations for dissipative materials written through suitable generalized gradients of a (possibly non-convex) metric. This new framework allows us to generalize the classical results providing an interpretation of the yield function in terms of Hamilton–Jacobi equations theory.
Fly Motion Vision
Authors: Borst Alexander , Haag Juergen , Reiff Dierk F.
Published: June 2010

Fly motion vision and resultant compensatory optomotor responses are a classic example for neural computation. Here we review our current understanding of processing of optic flow as generated by an animal's self-motion. Optic flow processing is accomplished in a series of steps: First, the time-varying photoreceptor signals are fed into a two-dimensional array of Reichardt-type elementary motion detectors (EMDs). EMDs compute, in parallel, local motion vectors at each sampling point in space. Second, the output signals of many EMDs are spatially integrated on the dendrites of large-field tangential cells in the lobula plate. In the third step, tangential cells form extensive interactions with each other, giving rise to their large and complex receptive fields. Thus, tangential cells can act as matched filters tuned to optic flow during particular flight maneuvers. They finally distribute their information onto postsynaptic descending neurons, which either instruct the motor centers of the thoracic ganglion for flight and locomotion control or act themselves as motor neurons that control neck muscles for head movements.
The Genomic, Biochemical, and Cellular Responses of the Retina in Inherited Photoreceptor Degenerations and Prospects for the Treatment of These Disorders
Authors: Bramall Alexa N. , Wright Alan F. , Jacobson Samuel G. , McInnes Roderick R.
Published: June 2010

The association of more than 140 genes with human photoreceptor degenerations, together with studies of animal models of these monogenic diseases, has provided great insight into their pathogenesis. Here we review the responses of the retina to photoreceptor mutations, including mechanisms of photoreceptor death. We discuss the roles of oxidative metabolism, mitochondrial reactive oxygen species, metabolic stress, protein misfolding, and defects in ciliary proteins, as well as the responses of Müller glia, microglia, and the retinal vasculature. Finally, we report on potential pharmacologic and biologic therapies, the critical role of histopathology as a prerequisite to treatment, and the exciting promise of gene therapy in animal models and in phase 1 trials in humans.