bluuebunny/crossref_metadata_2025 huggingface dataset:
Multidimensional Upwinding for Multiphase Transport in Porous Media
Authors: Kozdon J.. , Mallison B.. , Gerritsen M.. , Chen W..
Published: February 2011

Multidimensional transport for reservoir simulation is typically solved by applying 1D numerical methods in each spatial-coordinate direction. This approach is simple, but the disadvantage is that numerical errors become highly correlated with the underlying computational grid. In many real-field applications, this can result in strong sensitivity to grid design not only for the computed saturation/composition fields but also for critical integrated data such as breakthrough times. Therefore, to increase robustness of simulators, especially for adverse-mobility-ratio flows that arise in a variety of enhanced-oil-recovery (EOR) processes, it is of much interest to design truly multidimensional schemes for transport that remove, or at least strongly reduce, the sensitivity to grid design.

We present a new upstream-biased truly multidimensional family of schemes for multiphase transport capable of handling countercurrent flow arising from gravity. The proposed family of schemes has four attractive properties: applicability within a variety of simulation formulations with varying levels of implicitness, extensibility to general grid topologies, compatibility with any finite-volume flow discretization, and provable stability (monotonicity) for multiphase transport. The family is sufficiently expressive to include several previously developed multidimensional schemes, such as the narrow scheme, in a manner appropriate for general-purpose reservoir simulation.

A number of waterflooding problems in homogeneous and heterogeneous media demonstrate the robustness of the method as well as reduced transverse (cross-wind) diffusion and grid-orientation effects.
A Theoretical Study of Acid-Fracture Conductivity Under Closure Stress
Authors: Deng J.. , Hill A.D.. D. , Zhu D..
Published: February 2011

The conductivity of acid-etched fractures depends on spaces along the fracture created by uneven etching of the fracture walls remaining open after fracture closure. In this study, we have modeled the deformation of the irregular fracture surfaces created by acid etching and the resulting fracture conductivity as closure stress is applied to the fracture.

In our previous work, we modeled the dissolution of the fracture surfaces in a formation having small-scale heterogeneities in both permeability and mineralogy. This model yielded the geometry of the etched fracture at zero closure stress. Beginning with this profile of fracture width, we have modeled the deformation of the fracture surfaces as closure stress is applied to the fracture. At any cross section along the fracture, we approximate the fracture shape as being a series of elliptical openings. Assuming elastic behavior of the rock, we calculate how many elliptical gaps remain open and their sizes as a function of the applied stress. The sections of the fracture that are closed are assigned a conductivity because of small-scale roughness features using a correlation obtained from laboratory measurements of acid-fracture conductivity as a function of closure stress. The overall conductivity of the fracture is then obtained by numerically modeling the flow through this heterogeneous system.

Our previous work shows that high fracture conductivity can be created in acid fracturing if heterogeneity of the rock leads to the formation of channels along the fracture surfaces. In this study, we have determined how the channels in acid fracturing remain open as closure stress is applied. This model predicts the rock characteristics that are necessary for acid-fracture conductivity to be sustainable under high closure stress.
Modeling a Series of Nonaqueous Field-Scale Inhibitor Squeeze Treatments in the Heidrun Field
Authors: Vazquez Oscar , Ommen Theo van , Chen Ping , Martin Olav Selle , Juliussen Bjørn , Kolstø Erlend Holand , Gustavsen Øyvind
Published: February 2011

When a conventional aqueous squeeze treatment is not suitable for preventing scale formation, a nonaqueous treatment may be applied. Generally, these types of treatments include a nonaqueous phase and can be divided into different types on the basis of the delivery system. Despite the name, most nonaqueous treatments still contain some water because of the scale-inhibitor (SI) hydrophilic nature; it only truly dissolves in water.

The main purposes of this paper are (1) to model a series of polymer nonaqueous SI squeeze treatments deployed in the Heidrun field in the Norwegian sector of the North Sea, (2) to investigate alternatives to optimize the squeeze design by studying the effect of the overflush, and (3) to show the workflow to build the input-data model from the available field data. All the field-treatment designs under study included the injection of an amphiphilic-solvent phase as the SI carrier phase and injection of a diesel overflush.

The simulation and optimization calculations were conducted using a specialized near-wellbore model for scale treatments. The simulation study matched the well water cut for the time of the treatment, followed deriving a pseudoadsorption isotherm that was used to describe the SI retention in the formation. Heidrun coreflooding data and SI-returns data were used to build the input model. Finally, a sensitivity study on the effect of the overflush on the squeeze lifetime was carried out on the basis of the created input models.
Temperature-Induced Fracture Reconsolidation of Diatomaceous Rock During Forced Water Imbibition
Authors: Peng J.. , Kovscek A.R.. R.
Published: February 2011

We conducted a series of forced water-imbibition experiments to study the role of solution pH, temperature, salinity, and various divalent metal ions on silica dissolution and fracture reconsolidation of outcrop diatomite core. The experimental results suggest that temperature and pH are two of the most important factors that have an impact on silica dissolution of diatomite, in agreement with the literature. The presence of steam hinders silica dissolution because less aqueous phase is available to carry ions. Fracture healing and rock reconsolidation were observed when fluid was injected at elevated temperature. Tests suggest that both silica dissolution and confining stress are necessary for fracture reconsolidation. Fractures that are not closed by the confining stress do not tend to heal. The proposed mechanism for this process has three steps: (i) aqueous silicate production by silica dissolution, (ii) silicate gelation within the pore space and fracture, and (iii) stress closure of fractures to ensure that deposited silica cements the fracture closed. Given sufficient heating and liquid, fracture reconsolidation occurs.
Effective Perforating and Gravel Placement: Key to Low-Skin, Sand-Free Production in Gravel Packs
Authors: Jain Samyak , Tibbles Raymond , Munro Jock , Suppiah Rajeswary , Safin Norhisham
Published: February 2011

Cased-hole gravel packing is commonly used to control sand production from oil and gas wells. The success of a cased-hole gravel-pack job depends on the ability to effectively pack perforation tunnels, which act as conduits between the reservoir and the wellbore for hydrocarbon production.

This project presents a systematic approach for removal of perforation damage, effective gravel placement, and packing of the perforation tunnels. It was found that dynamic underbalanced perforating (DUP) greatly increased the ability to pack the perforation tunnels and improved the connectivity to the reservoir. Guidelines to DUP and executing the perforation-packing job are presented. This study also discusses the current practices commonly employed in cased-hole gravel packing to pack perforation tunnels and the potential limitations of these practices.

Incomplete packing of perforation tunnels is mostly encountered in gravel-pack jobs completed with brine as the carrier fluid (water packs). The proposed technique involves DUP before the gravel-pack operation, followed by pumping the gravel slugs in a nondamaging carrier fluid in concentrations ranging from 1 to 3 lbm of proppant added per gallon of fluid (ppa). These slugs range from 5 to 7 bbl and are pumped intermittently between stages of the completion fluid to minimize cost. The carrier fluid, by virtue of its viscosity and mechanical suspension capability, ensures that the gravel enters the perforations.

This technique was implemented successfully at the Abu Cluster field in west Malaysia. This reservoir had extremely high permeability (1.5 to 3 darcies), with sand production a major concern. Several jobs were completed with the previously mentioned technique, and perforation-packing factors improved from 8 to 38 lbm of gravel per foot of perforations. Discussion of the placement and production data is presented. Sand-free production has been achieved with reduced drawdown across the sandface. The results show a linear relationship between pack factor and normalized productivity index (PI), indicating that gravel-packed perforations improve well productivity.
A Method To Implement Permeability Anisotropy Associated With Fault Damage Zones in Reservoir Simulation
Authors: Paul Pijush , Zoback Mark , Hennings Peter
Published: February 2011

In this study, we present a method to incorporate the effects of fault damage zones (DZs) in a reservoir-simulation model. Permeability anisotropy associated with fault DZs depends on many factors, including the geometry of the faults in the reservoir and the associated dimension and density of fractures in the DZs. To model permeability anisotropy caused by fault DZs, we start by using geomechanically constrained discrete fracture models of DZs. Then, we use the orientation and size of the faults with reference to the grid axes to incorporate the effect of permeability anisotropy in the simulation grid. In this case study, in which faults are formed in an extensional regime, DZs show increased permeability along the strike of the fault and in the vertical direction, but there is no significant change in the permeability perpendicular to the faults. Inclusion of DZs in the simulation model shows significant improvement in the history matching in comparison to a base reservoir-simulation model with no DZs. Further, we analyze the uncertainty of the DZ modeling in the reservoir simulation by simulating multiple equiprobable models.
The octanol-air partition coefficient KOA as a predictor of gas-particle partitioning of polycyclic aromatic hydrocarbons and polychlorinated biphenyls at industrial and urban sites
Authors: Radonic Jelena , Vojinovic-Miloradov Mirjana , Turk-Sekulic Maja , Kiurski Jelena , Djogo Maja , Milovanovic Dusan
Published: February 2011

The main objectives of the research were to estimate the relationship between
the gas-particle partition coefficient, Kp, and the octanol-air partition
coefficient, KOA, of polycyclic aromatic hydrocarbons, PAHs, and
polychlorinated biphenyls, PCBs, at industrial and urban sites in the
Vojvodina region, to compare the obtained slopes and intercepts of the log
vs. log KOA relations with the results of regression analyses reported in
previous studies and to assess the consistency between the particle-bound
fractions predicted by the KOA absorption model and the results obtained
within field measurements. Fairly good log KP - log KOA correlations, with an
average value of the correlation coefficients of 0.70, indicate that the
partition coefficient KOA can be used as a prediction parameter of the
gas-particle partitioning processes for both classes of compounds. The
results of modelling the atmospheric distribution of PAHs using the KOA
absorption model showed inconsistencies between the measured and predicted
values of the particle-bound fraction, ?, of 1-2 orders of magnitude, while
significantly higher discrepancies for PAHs in the Nap-Ace range were found.
A similar variability of the measured/modelled ? values was obtained using
the Junge-Pankow adsorption model, indicating the presence of particles
enriched with PAHs. The conducted research showed that the KOA-based approach
was less suitable for predicting the gas-particle partitioning of PCBs in
urban and industrial sites, compared to the Junge-Pankow model.
Evidence That Nasal Insulin Induces Immune Tolerance to Insulin in Adults With Autoimmune Diabetes
Authors: Fourlanos Spiros , Perry Christine , Gellert Shane A. , Martinuzzi Emanuela , Mallone Roberto , Butler Jeanne , Colman Peter G. , Harrison Leonard C.
Published: February 2011

OBJECTIVE

Insulin in pancreatic β-cells is a target of autoimmunity in type 1 diabetes. In the NOD mouse model of type 1 diabetes, oral or nasal administration of insulin induces immune tolerance to insulin and protects against autoimmune diabetes. Evidence for tolerance to mucosally administered insulin or other autoantigens is poorly documented in humans. Adults with recent-onset type 1 diabetes in whom the disease process is subacute afford an opportunity to determine whether mucosal insulin induces tolerance to insulin subsequently injected for treatment.

RESEARCH DESIGN AND METHODS

We randomized 52 adults with recent-onset, noninsulin-requiring type 1 diabetes to nasal insulin or placebo for 12 months. Fasting blood glucose and serum C-peptide, glucagon-stimulated serum C-peptide, and serum antibodies to islet antigens were monitored three times monthly for 24 months. An enhanced ELISpot assay was used to measure the T-cell response to human proinsulin.

RESULTS

β-Cell function declined by 35% overall, and 23 of 52 participants (44%) progressed to insulin treatment. Metabolic parameters remained similar between nasal insulin and placebo groups, but the insulin antibody response to injected insulin was significantly blunted in a sustained manner in those who had received nasal insulin. In a small cohort, the interferon-γ response of blood T-cells to proinsulin was suppressed after nasal insulin.

CONCLUSIONS

Although nasal insulin did not retard loss of residual β-cell function in adults with established type 1 diabetes, evidence that it induced immune tolerance to insulin provides a rationale for its application to prevent diabetes in at-risk individuals.
Skin Intrinsic Fluorescence Correlates With Autonomic and Distal Symmetrical Polyneuropathy in Individuals With Type 1 Diabetes
Authors: Conway Baqiyyah N. , Aroda Vanita R. , Maynard John D. , Matter Nathaniel , Fernandez Stephen , Ratner Robert E. , Orchard Trevor J.
Published: February 2011

OBJECTIVE

To determine whether skin intrinsic fluorescence (SIF) was associated with autonomic neuropathy and confirmed distal symmetrical polyneuropathy (CDSP) in 111 individuals with type 1 diabetes (mean age 49 years, mean diabetes duration 40 years).

RESEARCH DESIGN AND METHODS

SIF was measured using the SCOUT DM device. Autonomic neuropathy was defined as an electrocardiographic abnormal heart rate response to deep breathing (expiration-to-inspiration ratio <1.1). CDSP was defined using the Diabetes Control and Complications Trial clinical exam protocol (the presence of two or more of the following: symptoms, sensory and/or motor signs, and/or reduced/absent tendon reflexes consistent with DSP) confirmed by the presence of an abnormal age-specific vibratory threshold (using a Vibratron II tester).

RESULTS

The prevalence of autonomic neuropathy and CDSP were 61 and 66%, respectively. SIF was higher in those with autonomic neuropathy (P < 0.0001). In multivariable analyses controlling for age and updated mean (18-year average) HbA1c, and allowing for other univariately and clinically significant correlates of autonomic neuropathy, each SD change in SIF was associated with a 2.6-greater likelihood of autonomic neuropathy (P = 0.006). Receiver operating characteristic (ROC) analyses revealed that SIF and updated mean HbA1c accounted for 80 and 57%, respectively, of the area under the curve (AUC) for autonomic neuropathy. SIF also was higher in those with CDSP (P < 0.0001) and remained so in multivariable analyses (odds ratio 2.70; P = 0.005). ROC analyses revealed that SIF and updated mean HbA1c accounted for 78 and 59%, respectively, of the AUC for CDSP.

CONCLUSIONS

SIF, a marker of dermal advanced glycation end products, appears to be more strongly associated with the presence of both CDSP and autonomic neuropathy than mean HbA1c.
Diagnostic Accuracy of Point-of-Care Testing for Diabetic Ketoacidosis at Emergency-Department Triage
Authors: Arora Sanjay , Henderson Sean O. , Long Theodore , Menchine Michael
Published: February 2011

OBJECTIVE

In the emergency department, hyperglycemic patients are screened for diabetic ketoacidosis (DKA) via a urine dipstick. In this prospective study, we compared the test characteristics of point-of-care β-hydroxybutyrate (β-OHB) analysis with the urine dipstick.

RESEARCH DESIGN AND METHODS

Emergency-department patients with blood glucose ≥250 mg/dL had urine dipstick, chemistry panel, venous blood gas, and capillary β-OHB measurements. DKA was diagnosed according to American Diabetes Association criteria.

RESULTS

Of 516 hyperglycemic subjects, 54 had DKA. The urine dipstick had a sensitivity of 98.1% (95% CI 90.1–100), a specificity of 35.1% (30.7–39.6), a positive predictive value of 15% (11.5–19.2), and a negative predictive value of 99.4% (96.6–100) for DKA. Using the manufacturer-suggested cutoff of >1.5 mmol/L, β-OHB had a sensitivity of 98.1% (90.1–100), a specificity of 78.6% (74.5–82.2), a positive predictive value of 34.9% (27.3–43), and a negative predictive value of 99.7% (98.5–100) for DKA.

CONCLUSIONS

Point-of-care β-OHB and the urine dipstick are equally sensitive for detecting DKA (98.1%). However, β-OHB is more specific (78.6 vs. 35.1%), offering the potential to significantly reduce unnecessary DKA work-ups among hyperglycemic patients in the emergency department.
Evaluation and verification of the WetSpa model based on selected rural catchments in Poland
Authors: Porretta-Brandyk Laura , Chormański Jarosław , Ignar Stefan , Okruszko Tomasz , Brandyk Andrzej , Szymczak Tomasz , Krężałek Katarzyna
Published: February 2011

Evaluation and verification of the WetSpa model based on selected rural catchments in Poland

The paper presents results of calibration and verification of the WetSpa model, which enables the modelling of rainfall-runoff process based on mass and energy balance in the soil-plantatmosphere system in the catchment. It is a model with distributed parameters, using the structure of raster GIS model to determine the spatial diversity of the catchment environment. This enables simulation of runoff from the catchment, including: precipitation, evapotranspiration, interception of plant surface and soil cover, infiltration and capillary rise in soil and groundwater runoff. Simulated processes depend on the required non-distributed parameters, which were calibrated based on hydrometeorological data from the three rural catchments with different physical and geographical characteristics: Mławka, located in the Wkra basin in Central Poland and the rivers Kamienna and Sidra, which are tributaries of the upper Biebrza in north-eastern part of the country. Distributed catchment parameters were specified on the basis of digital soil maps, land use maps and digital elevation model using GIS techniques. Non-distributed model parameters were calibrated for the three catchments using automatic techniques based on the PEST algorithm. The obtained values of these parameters were scrutinized in order to analyse differences resulting from various characteristics of the study areas. The quality of the model was verified upon dependent and independent data. Appropriate quality measures, including Nash-Sutcliffe efficiency measure, were used to assess model quality. For two catchments (the Sidra and Kamienna) the model showed a satisfactory quality for modelling high flows, it was, however, not satisfactory for low flows. The values for the Mławka catchment justified the assessment of the model quality measurements as very good and good. The factors most affecting the process of river outflow formation were determined using the analysis of model sensitivity to relative changes in parameter values. It was found that the evaluation of the model quality depended largely on the quality of meteorological data and proper parameterization of the soil cover.
Effect of Oxygen Incorporation into Cyclohexanone Ring on Antifeedant Activity
Authors: Dancewicz Katarzyna , Ratuś Barbara , Boratyński Filip , Kordan Bożena , Gabryś Beata , Wawrzeńczyk Czesław
Published: February 2011

Effect of Oxygen Incorporation into Cyclohexanone Ring on Antifeedant Activity

The behaviour of the peach potato aphidMyzus persicae(Sulz.) was studied during settling on plants. The experiment involved observing peach potato aphid activity after the application of some natural and synthetic cyclohexanones and the, respective ε-lactones and epoxy-ε-lactones which were obtained from the cyclohexanones. Stereochemistry, and the number and position of methyl substituents were important for the biological activity of the starting compounds: only trimethyl-substituted cyclohexanones were active,i.e.3.3.5-trimethylcyclohexanone (deterrent) and 2.2.6-trimethylcyclohexanone (attractant). The effect of oxygen incorporation into the cyclohexanone ring on deterrent activity varied depending on the starting compound. The ε-lactones that derived from saturated cyclohexanones were either weak attractants or were inactive, except the deterrent ε-lactone with three methyl groups at positions 3.7.7. None of the products of unsaturated ketone isophorone (weak deterrent) oxidation,i.e.epoxy isophorone, epoxy lactone, or unsaturated lactone, affected aphid settling. Of the two epoxy ketones obtained from (+)-dihydrocarvone that was inactive, only (2S, 5S)-2-methyl-5-((S)-1-methyloxiranyl)-cyclohexanone was a strong deterrent. Both epoxy-ε-lactones that derived from (+)-dihydrocarvone were strong deterrents.
The Effect of Plant Oils for Reducing Contamination of Stored Packaged-Foodstuffs
Authors: Allahvaisi Somaye , Maroufpoor Mostafa , Abdolmaleki Arman , Hoseini Saied-Ali , Ghasemzadeh Somaye
Published: February 2011

The Effect of Plant Oils for Reducing Contamination of Stored Packaged-Foodstuffs

A study to determine the effect of essential oils, used together with mixed packaging, on controlling stored-grain insects, was conducted in the laboratory. Plant essential oils are one of the materials that act like a contact-fumigant, offering the prospect for use in stored product protection. Plant essential oils must have the ability to repel the insects in order to prevent penetration to foodstuffs. The objective of the present study was to test the properties ofCinnamomum camphoraandSyzygium aromaticumfor preventing the penetration of pest insects, including:Sitotroga cerealellaandEphestia kuehniella5th instar larvae to packaged cereals. Ten grams of wheat and flour as foodstuffs were placed inside Cellophane packages and hung vertically in the top of a container. The repellent essential oils were used in the interior surface of containers. Each container had punctures at different parts and the insects were released around the container to determine insect penetration and the effect of the repellents. The experiments were conducted at 26±1°C, 60±5% RH in dark conditions. The highest concentration was 1.5 μl of essential oil per 0.5 ml acetone. Four days after the initiation of the experiment the results showedS. aromaticumhad more of a repellency effect thanC. camphoraon both pests that caused contamination deduction inside the packaged foodstuffs compared with the control. However, both the essential oils were effective as protectants of cereals butS. aromaticumwas more effective.S. aromaticumcaused the most repellency onE. kuehniella.The mean of repellency of all the concentrations was 81.4%. The results demonstrated the efficacy of these essential oils for use in organic food protection.C. camphoraandS. aromaticumcan prevent warehouse infestation of stored-product pests.
Innovation Management and an Innovative Ideas System
Authors: Brcar Franc , Lah Silvo
Published: February 2011

Innovation Management and an Innovative Ideas System

Innovation management is one of the most important tasks for managers in order to make their organizations successful and efficient. A part of this ranges from innovative employee ideas for small everyday improvements up to innovations that bring enormous savings. The survey tries to determine which factors influence the number of innovative ideas and to propose methods for improvements in this area. The basic research method used was a questionnaire, which helped us gather data and the basic method used for data processing was statistical analysis. First, we established that there is a progressive correlation between the number of innovative ideas submitted in the past and the number of anticipated innovative ideas in the future. Second, we established that the following three factors have an impact on innovation and creativity: (1) work and education; (2) working and living conditions; and (3) rewards and payment. Finally, we have established that there is a correlation between satisfaction with the rewards and payment factor and the current life-cycle stage of organization. To summarize, the level of innovation and creativity of employees is influenced by their overall satisfaction in an organization.
Modelling of the effects of land use changes on flood hydrograph in a small catchment of the Płaskowicka, southern part of Warsaw, Poland
Authors: Banasik Kazimierz , Pham Ngoc
Published: February 2011

Modelling of the effects of land use changes on flood hydrograph in a small catchment of the Płaskowicka, southern part of Warsaw, Poland

This study concerns the influence of urbanized trend affected on the flood hydrograph in a small catchment in Warsaw. Based on recorded events a selected procedure for simulation rainfall-runoff process has been accepted for flood estimation. The Soil Conservation Services Curve Number method (SCS-CN) and empirical formulae for Nash model parameters, developed by Rao at al. were used to analyze the nine selected events from 2007 to 2009. The analysis confirmed usefulness of the selected procedure, implicated in a home developed computer program, for estimating flood hydrographs as responses of the small urban catchment to heavy rainfall events. Flood hydrographs were estimated for three various stages of land use. The results demonstrate that the peak flood flow would increase over eight times due to urbanisation of the catchment.
Effects of age, gender and physical activity on plasma lipid profile
Authors: Okęcka-Szymańska Joanna , Hübner-Woźniak Elżbieta , Piątkowska Iwona , Malara Marzena
Published: February 2011

Effects of age, gender and physical activity on plasma lipid profile

Study aim: To assess the effects of gender, age and engagement in physical activities of elderly subjects on their plasma lipid profiles.

Material and methods: Four groups of subjects, n = 11 each, participated in the study: young men (YM) and women (YW), aged 25 - 32 years, and sedentary, elderly men (EM) and women (EW), aged 58 - 66 years; additionally, a group of 7 women (AW), aged 60 - 65 years, who trained twice weekly (45-min sessions) for 8 months, was studied. The following concentrations of lipids in plasma were recorded: triacylglycerols (TG), total cholesterol (TC) and its fractions: HDLC and LDLC (computed), as well as the TC/HDLC ratio.

Results: Lipid profiles were, generally, less favourable in elderly than in younger subjects, high HDLC values noted in active, elderly women being an exception. In elderly subjects, men's profiles were closer to those of younger subjects than in elderly women and differed significantly (p<0.001) lower for TC and LDLC compared with EW group. Triacylglycerols were within normal limits in all groups except EW; LDLC values were mostly abnormally high, the percentages of subjects having normal values ranging from 0 (YM and EW) to 27% (YW).

Conclusions: The age-dependent worsening of lipid profiles increased the risk of cardiovascular diseases in sedentary elderly subjects. On the other hand, the beneficial effects of motor activities on lipid profile observed in elderly women evidence the indispensability recommending of physical exercises to the elderly.
Primitive Membrane Formation, Characteristics and Roles in the Emergent Properties of a Protocell
Authors: Maurer Sarah Elizabeth , Monnard Pierre-Alain
Published: February 2011

All contemporary living cells are composed of a collection of self-assembled molecular elements that by themselves are non-living but through the creation of a network exhibit the emergent properties of self-maintenance, self-reproduction, and evolution. This short review deals with the on-going research that aims at either understanding how life emerged on the early Earth or creating artificial cells assembled from a collection of small chemicals. In particular, this article focuses on the work carried out to investigate how self-assembled compartments, such as amphiphile and lipid vesicles, contribute to the emergent properties as part of a greater system.
Estimating Neuronal Information: Logarithmic Binning of Neuronal Inter-Spike Intervals
Authors: Dorval Alan  D.
Published: February 2011

Neurons communicate via the relative timing of all-or-none biophysical signals called spikes. For statistical analysis, the time between spikes can be accumulated into inter-spike interval histograms. Information theoretic measures have been estimated from these histograms to assess how information varies across organisms, neural systems, and disease conditions. Because neurons are computational units that, to the extent they process time, work not by discrete clock ticks but by the exponential decays of numerous intrinsic variables, we propose that neuronal information measures scale more naturally with the logarithm of time. For the types of inter-spike interval distributions that best describe neuronal activity, the logarithm of time enables fewer bins to capture the salient features of the distributions. Thus, discretizing the logarithm of inter-spike intervals, as compared to the inter-spike intervals themselves, yields histograms that enable more accurate entropy and information estimates for fewer bins and less data. Additionally, as distribution parameters vary, the entropy and information calculated from the logarithm of the inter-spike intervals are substantially better behaved, e.g., entropy is independent of mean rate, and information is equally affected by rate gains and divisions. Thus, when compiling neuronal data for subsequent information analysis, the logarithm of the inter-spike intervals is preferred, over the untransformed inter-spike intervals, because it yields better information estimates and is likely more similar to the construction used by nature herself.
Energy Saving Effects of Wireless Sensor Networks: A Case Study of Convenience Stores in Taiwan
Authors: Chen Chih-Sheng , Lee Da-Sheng
Published: February 2011

Wireless sensor network (WSN) technology has been successfully applied to energy saving applications in many places, and plays a significant role in achieving power conservation. However, previous studies do not discuss WSN costs and cost-recovery. The application of WSNs is currently limited to research and laboratory experiments, and not mass industrial production, largely because business owners are unfamiliar with the possible favorable return and cost-recovery on WSN investments. Therefore, this paper focuses on the cost-recovery of WSNs and how to reduce air conditioning energy consumption in convenience stores. The WSN used in this study provides feedback to the gateway and adopts the predicted mean vote (PMV) and computational fluid dynamics (CFD) methods to allow customers to shop in a comfortable yet energy-saving environment. Four convenience stores in Taipei have used the proposed WSN since 2008. In 2008, the experiment was initially designed to optimize air-conditioning for energy saving, but additions to the set-up continued beyond 2008, adding the thermal comfort and crowds peak, off-peak features in 2009 to achieve human-friendly energy savings. Comparison with 2007 data, under the same comfort conditions, shows that the power savings increased by 40% (2008) and 53% (2009), respectively. The cost of the WSN equipment was 500 US dollars. Experimental results, including three years of analysis and calculations, show that the marginal energy conservation benefit of the four convenience stores achieved energy savings of up to 53%, recovering all costs in approximately 5 months. The convenience store group participating in this study was satisfied with the efficiency of energy conservation because of the short cost-recovery period.
Shallow-water craft from medieval Denmark
Authors: Bill Jan
Published: February 2011

En raison de sa superficie et de ses particularités naturelles, le Danemark ne jouit pas de grands réseaux fluviaux ou de lacs pouvant être utilisés pour le transport à l'intérieur des terres. Il présente, cependant, de nombreux fjords et bras de mer qui pénètrent loin dans les terres et forment des situations très comparables à celles des régions de fleuves et de lacs. À l'époque médiévale, les eaux intérieures ont une importance cruciale pour le transport et les communications, comme le prouve le nombre croissant de villes fondées sur leurs rives à cette époque.

De récentes fouilles ont permis de connaître un type spécial de navire conçu pour le cabotage en eaux peu profondes dans le sud-est du pays. Ces découvertes nous éclairent sur la manière dont les eaux intérieures étaient utilisées, sur le type de transport et nous permettent de mieux comprendre quelles forces régissaient l'économie et la société du Moyen Âge.

Cet exposé rappelle brièvement les évolutions du paysage urbain danois en 1000-1500 en termes d'accessibilité par navire. Il démontre la présence dans le sud-est du Danemark, d'un type de navire adapté à des eaux peu profondes et précise en quoi cela modifie notre compréhension de l'économie médiévale. Enfin, il tend à déterminer pour cette même période, l'existence dans l'ensemble du pays d'autres navires d'un type comparable.
Histoire de cordes et de rames
Authors: Lonchambon Catherine
Published: February 2011

The Durance river flows along 300 km from its source in the upper Alps to the Rhône where they meet south of Avignon. The most interesting part of its course for us is between Embrun and Avignon, where until the 19th century, ferries were used to cross. Its torrential character and its floods made the building of bridges before that tinte useless. In addition to this spirit, the Durance had the inconsistency of frequently opening up new courses. The way of operating, the structures and berth for the boats had to adapt to the constraints imposed by the river.

There were more than twenty ferries -for forty «communes» - on the lower and upper Durance, twenty boats described in the relative documents as covering the medieval and modern periods. The archives concerning the 14th, 15th and 16th centuries are scarce (10 %) but not negligeable. However it was not until the 18th century that a consistent mass of information became available. These texts enable us to reconstitute the general structures implemented for the ferries to operate smoothly:

- The flat-bottomed boat with raised sides measured 14 to 24 m, was equipped with an imposing rudder and a «arbre» or mast placed at two-thirds ofthe boat's length to the front. It travelled through water by means of a «grosse corde» or trail stretched across the river and against which the « arbre » slid while keeping the boat against the current; embarkation and disembarkation took place on wooden boarding decks which were moved according to the water level.

Other arrangements were made in addition to this simple diagram, aiming to reinforce the trail bridge and facilitate access to the ferry. During ordinary periods, the passage across was made by means ofthe trail bridge, but this ceased when the waters rose beyond a certain point. During shallow water periods, the ferry man used a small boat with oars. The lightness ο f thèse structures met the requirement to be able to move the port every time the waters changea bed and thus rendered the passage across rather difficult. The ideal berth was characterised by the existence of a sole branch of water to cross, without a ford nearby and with an easy access.

Despite ail this, the crossing was not devoid of ail danger and depended, to a large extent, on the skill and willingness of the ferrymen. For the preceding centuries, the présence of a trail is confirmed up until the 14th century. The other infrastructures are difficult to understand but it seems logical that they be restored as the crossing conditions remained unchanged between the Middle Ages and the 19th century. The development of such a complex System became, very early on, necessary due to the importance of trade relations between Provence and the Comté Venaissin as well as between lower and upper Provence.
Inland water boats and shipping in Sweden. The great lakes
Authors: Westerdahl Christer
Published: February 2011

Les bateaux des lacs et rivières de Suède n'ont pas été encore à ce jour, présentés de manière concluante, dans le cadre d'un colloque international. Le matériel archéologique est riche, et en partie bien conservé, principalement sur les trois sites de Vànern, Vâttern et M'alar en (dans cet ordre de grandeur, cf. fig. 1). D'une manière générale, l'intérêt de cette étude est de démontrer que des « zones de transport traditionnel» peuvent se rencontrer dans des environnements naturels diversifiés; chaque zone correspondant à un certain type de bateau adapté aux systèmes de communication, en fonction des chargements ou des abris portuaires (fig. 3).

En second lieu, ce travail met l'accent sur le fait que « des enclaves », en matière de transport, se rencontrent fréquemment dans chaque lac ou secteur de voies navigables. Ces « enclaves » géographiques et sociales ont sans doute déterminé la plupart des aspects du transport interne, depuis la construction des navires jusqu'à la navigation elle-même.
The Ma'agan Mikhael ship (Israël)
Authors: Kahanov Yaacov
Published: February 2011

Le navire a été découvert sous une couche de sable de 1 m d'épaisseur à une profondeur de 1,5 m, à 70 m au large du kibboutz Ma'agan Mikhael, à 35 km au sud de Haifa. Il mesure environ 13 m de long et son déplacement est de 25 tonnes. Il a été daté d'environ 400av.J.-C.

À bord se trouvaient 13 tonnes de pierres (de provenance non locale), quelque soixante-dix récipients en terre venant de Chypre et de l'est de la Grèce, des restes de nourriture, des cordages, des outils de charpenterie navale et une ancre en bois à une seule patte. Une grande quantité du bois de la coque a été retrouvée en excellent état. Aucune indication de présence de tarets ou de bernacles n'a été relevée. Le navire a été construit selon la méthode « bordé premier ». La quille, composée d'une seule pièce de bois, a été retrouvée entière, toujours solidaire de l'étrave et de l'étambot dont les courbures supérieures sont bien définies. À tribord, le bordé est resté en place jusqu'à la virure n° 11. Parmi les éléments internes, quatorze membrures complètes et l'emplanture du mât ont été retrouvées. Les pièces constitutives de l'étrave et de l'étambot étaient ligaturées. Le navire était probablement neuf lorsqu'il a coulé.

Technologiquement et chronologiquement, le bateau de Ma'agan Mikhael peut être situé entre les navires du VIe s. - Giglio, Bon-Porté et Gela - de la Méditerranée orientale et occidentale, et le navire de Kyrenia du IVe s. av. J.-C. de la Méditerranée orientale.
Seldom discussed features of ancient and medieval ship construction
Authors: Steffy J. Richard
Published: February 2011

Cet exposé met l'accent sur certaines caractéristiques structurales des navires marchands de l'Antiquité et du début du Haut Moyen Âge n'attirant habituellement que peu ou pas l'attention. Il montre également l'importance du rapport entre la taille des divers éléments de la coque et leur espacement. De tels détails peuvent en effet, faciliter l'identification des épaves, compte tenu de leur origine et de l'époque considérée. Dans tous les cas, ils nous permettent de mieux comprendre les méthodes de conception et de construction employées.
Romano-Celtic boatbuilding and the romanisation of landscape and boatbuilding practice
Authors: Goodburn Damian M.
Published: February 2011

Cet exposé aborde différents aspects de la construction navale dite « romano-celtique » (gallo-romaine), selon deux perspectives n'ayant pas encore reçu à ce jour une grande attention scientifique. L'accent est mis sur le caractère révolutionnaire de la façon de travailler le bois et sur l'analyse de la nature des matières premières utilisées afin de tenter une reconstitution des paysages boisés exploités à l'époque. Les exemples cités ont été enrichis par les nouvelles connaissances acquises sur le travail du bois chez les Romains, et par la reconstruction partielle en taille réelle d'une section de la coque du navire de Blackfriars 1. Ce travail apporte des informations sur le nord- ouest de l'Europe qui peuvent être comparées avec le travail de M. Rival sur les navires romains de style classique en Méditerranée1. Il a pour but en outre, de définir dans quelle mesure les découvertes nautiques peuvent éclairer certains aspects de l'histoire du paysage culturel que l'archéologie terrestre ne permet pas de cerner.
Bayonne and beyond
Authors: Hutchinson Gillian
Published: February 2011

Différentes traditions de construction navale se sont développées dans les diverses parties de l'Europe depuis les origines. Au Moyen Âge, et plus particulièrement à partir des Croisades, l'interaction entre les traditions et le partage de la technologie s'est accrue, ce qui explique qu'en 1500, le trois-mâts à coque à franc-bord était construit à travers toute l'Europe.

Cet exposé s'interrogera sur les moyens par lesquels la technologie peut s'être répandue d'une région à une autre, que ce soit par l'introduction de nouvelles méthodes, de nouvelles caractéristiques ou de nouveaux types de navires, et sur l'intégration ou la non-intégration des innovations dans les méthodes de construction déjà existantes. Certains avancent que la transmission ne s' est pas faite par une osmose progressive entre les ports européens, mais qu'elle résulte des efforts des constructeurs d'un nombre limité de régions côtières.
The Genoese cocha
Authors: Ciciliot Furio
Published: February 2011

Au XIIIe s., un nouveau type de gros navire, appelé cocha, apparaît dans la flotte génoise. Il disparaîtra au début du XVe s. Les spécialistes de la typologie nautique ont associé ce type de navire aux «cogs» du nord de l'Europe.

D'après les documents génois, la cocha comporte parfois plusieurs mâts, des voiles latines, trois gouvernails, plusieurs ponts, et est semblable à la navis, le navire génois type, déjà très courant au Xlf s.

Quelles sont les principales caractéristiques de la cocha ? Comment distingue-t-on la cocha de la navis ? Pourquoi la cocha génoise disparaît-elle au XVe s. sans laisser de témoignages linguistiques ?

Nous η 'avons pas de réponses précises à ces questions. Les documents que nous examinerons peuvent nous aider à émettre des hypothèses sur ces sujets qui comptent parmi les plus importants pour l'étude des relations entre les flottes de l'Atlantique et de la Méditerranée à l'époque médiévale.
L'épave du caboteur de Culip VI (Catalogne, Espagne)
Authors: Rieth Eric
Published: February 2011

The Culip VI wreck, lying at less than 10 m. deep in the creek of Culip located close to the Creus cap (Catatonia, Spain) was excavated in 1990 under Javier Nieto generai responsability. The excavation ofthe remains ofthe hull and their study was our responsability.

The Culip VI wreck, of which only 11m of the bottom of the hull is preserved, is dated (ceramics) at the beginning of the XlVh century. This wreck is that of a coaster (restored measurements : 16,35 m long from end to end, 4,11 m wide at the midship frante, 1,94 m of depth of hold; estimated tonnage at around 40 tons) whose structure has the architectural characteristics of Mediterranean skeleton tradition. The analysis of the surmarks and numerals engraved in the wood of the floor-timbers show that these «signs» reveal a controlied modification of the floor-timber moulds by reducing the length of the flat and increasing of the rising of the floor-timbers in relation to the so-called master mould and rising square method.

The most ancient wntten sources on this method ο f design enabling a large part of the frames to be predetermined date back to the XVth century and refer only to the aera of Venice and its arsenal. The wreck ofthe Culip VI coaster, probably of Catalan origin, dated at the beginning of the XIVh century, enables a new historical reading ο f this design method of the bottom of ships in the Mediterranean region.
The morticed frames of XVIth century Atlantic ships and the «madeiras da conta» of Renaissance texts
Authors: Loewen Brad
Published: February 2011

Une particularité des épaves de provenance ibérique au XVIe s. est la présence d'une série de varangues et de genoux autour du maître-couple qui sont liés par des mortaises à queue d'aronde. Dans le cas du navire de Red Bay, les couples mortaises s'opposent à la plupart des couples dont les membres ne sont pas attachés l'un à l'autre et qui sont ainsi appelés «membres flottants». Les couples mortaises ont souvent été comparés aux membres gabariés figurant sous le nom de « maderos de cuenta » ou « madeiras da conta » dans les manuscrits ibériques de l'époque.

Dans le cadre de l'analyse du navire de Red Bay, la correspondance entre les couples mortaises et les «maderas de cuenta» a été remise en question. Les manuscrits nous fournissent le nombre, la distribution et la forme des membres gabariés avec une variabilité parfois surprenante mais dont la distribution est toujours équilibrée vers l'avant et vers l'arrière du maître-couple. Ce qui est clair, c'est que parmi les six manuscrits principaux, il n'y en a qu'un seul qui mentionne les mortaises en tant que particularité des membres gabariés. Cependant la confrontation de données de Red Bay avec les manuscrits révèle les correspondances entre les couples mortaises et les « maderas de cuenta ».

Les résultats des fouilles archéologiques contredisent pourtant les documents écrits en suggérant une distribution inégale des couples mortaises devant et derrière le maître. Nous avons étudié cinq épaves et constaté que les couples mortaises sont nettement plus nombreux vers l'arrière que vers l'avant. Le fait que les constructeurs aient choisi un couple précis pour ne plus joindre rigidement varangue et genoux pourrait-il indiquer le point de départ d'une modification plus sophistiquée de la forme des couples, tel que le trébuchet, le «cancomo» ou encore l'« astilla muerta » ?