bluuebunny/crossref_metadata_2025 huggingface dataset:
Recovery from disturbance requires resynchronization of ecosystem nutrient cycles
Authors: Rastetter E. B. , Yanai R. D. , Thomas R. Q. , Vadeboncoeur M. A. , Fahey T. J. , Fisk M. C. , Kwiatkowski B. L. , Hamburg S. P.
Published: November 2012

Nitrogen (N) and phosphorus (P) are tightly cycled in most terrestrial ecosystems, with plant uptake more than 10 times higher than the rate of supply from deposition and weathering. This near‐total dependence on recycled nutrients and the stoichiometric constraints on resource use by plants and microbes mean that the two cycles have to be synchronized such that the ratio of N:P in plant uptake, litterfall, and net mineralization are nearly the same. Disturbance can disrupt this synchronization if there is a disproportionate loss of one nutrient relative to the other. We model the resynchronization of N and P cycles following harvest of a northern hardwood forest. In our simulations, nutrient loss in the harvest is small relative to postharvest losses. The low N:P ratio of harvest residue results in a preferential release of P and retention of N. The P release is in excess of plant requirements and P is lost from the active ecosystem cycle through secondary mineral formation and leaching early in succession. Because external P inputs are small, the resynchronization of the N and P cycles later in succession is achieved by a commensurate loss of N. Through succession, the ecosystem undergoes alternating periods of N limitation, then P limitation, and eventually co‐limitation as the two cycles resynchronize. However, our simulations indicate that the overall rate and extent of recovery is limited by P unless a mechanism exists either to prevent the P loss early in succession (e.g., P sequestration not stoichiometrically constrained by N) or to increase the P supply to the ecosystem later in succession (e.g., biologically enhanced weathering). Our model provides a heuristic perspective from which to assess the resynchronization among tightly cycled nutrients and the effect of that resynchronization on recovery of ecosystems from disturbance.
A Stochastic Analysis of Cross‐Hole Ground‐Penetrating Radar Zero‐Offset Profiles for Subsurface Characterization
Authors: Rossi Matteo , Cassiani Giorgio , Binley Andrew
Published: November 2012

Cross‐hole ground‐penetrating radar (GPR) zero‐offset profiling (ZOP) is a well‐established technique for the measurement of the one‐dimensional (1‐D) vertical distribution of soil dielectric permittivity and has often been used in time‐lapse mode for the monitoring of natural or man‐made infiltration and soil moisture redistribution processes in the vadose zone. However, in spite of its widespread use, the quantitative interpretation of ZOPs in terms of dielectric permittivity profiles is known to be fraught with difficulties. Often a simplified approach is adopted that translates directly ZOP travel times into electromagnetic (EM) velocities and these, in turn, into dielectric permittivities and soil volumetric moisture content. This approach is known to lead to over‐smoothed moisture content profiles, which are a consequence of the ZOP measurement scale, controlled by critical refractions along fast layers and averaging effects within the first Fresnel zone. Such smooth profiles are not necessarily compatible with the true soil moisture content that should be reproduced by water flow models. In this paper we present a stochastic inversion approach that aims at solving these issues. The approach is based on a forward stochastic simulation that generates the expected travel times by means of a two‐dimensional (2‐D) full waveform modeling, thus reproducing all physical processes that contribute to profile smoothing. We first assess the robustness of this approach on synthetic data, where the true dielectric permittivity profile is known. Then we apply the technique to two different case studies, where the results of the proposed technique show supporting evidence from independent information on the sites' stratigraphy. The proposed approach proves to be capable of reconstructing sharp dielectric profiles, in addition to assigning relevant uncertainty bounds derived from the expected errors in travel time picking. These results may prove very useful in a correct assessment of the hydrological implications of the measured dielectric permittivity, and thus moisture content, profile.
Bayesian Markov‐Chain‐Monte‐Carlo Inversion of Time‐Lapse Crosshole GPR Data to Characterize the Vadose Zone at the Arrenaes Site, Denmark
Authors: Scholer Marie , Irving James , Looms Majken C. , Nielsen Lars , Holliger Klaus
Published: November 2012

The ground‐penetrating radar (GPR) geophysical method has the potential to provide valuable information on the hydraulic properties of the vadose zone because of its strong sensitivity to soil water content. In particular, recent evidence has suggested that the stochastic inversion of crosshole GPR traveltime data can allow for a significant reduction in uncertainty regarding subsurface van Genuchten–Mualem (VGM) parameters. Much of the previous work on the stochastic estimation of VGM parameters from crosshole GPR data has considered the case of steady‐state infiltration conditions, which represent only a small fraction of practically relevant scenarios. We explored in detail the dynamic infiltration case, specifically examining to what extent time‐lapse crosshole GPR traveltimes, measured during a forced infiltration experiment at the Arreneas field site in Denmark, could help to quantify VGM parameters and their uncertainties in a layered medium, as well as the corresponding soil hydraulic properties. We used a Bayesian Markov‐chain‐Monte‐Carlo inversion approach. We first explored the advantages and limitations of this approach with regard to a realistic synthetic example before applying it to field measurements. In our analysis, we also considered different degrees of prior information. Our findings indicate that the stochastic inversion of the time‐lapse GPR data does indeed allow for a substantial refinement in the inferred posterior VGM parameter distributions compared with the corresponding priors, which in turn significantly improves knowledge of soil hydraulic properties. Overall, the results obtained clearly demonstrate the value of the information contained in time‐lapse GPR data for characterizing vadose zone dynamics.
LNAPL Removal from Unsaturated Porous Media Using Surfactant Infiltration
Authors: Zhong Lirong , Oostrom Mart
Published: November 2012

A series of unsaturated column experiments was conducted to evaluate light nonaqueous phase liquid (LNAPL) removal during surfactant solution infiltration. Surfactant‐LNAPL phase behavior tests were conducted to optimize the remedial solutions. Packed sand and site sediment columns were first processed to establish representative LNAPL smear zones under unsaturated conditions. Infiltration of low‐concentration surfactant was then applied in a stepwise flush mode, with 0.33 column pore volume (PV) of solution in each flush. The influence of infiltrated surfactant solution volume and pH on LNAPL removal was assessed. A LNAPL bank was observed at the front of the first surfactant infiltration in each column, indicating that a very low surfactant concentration is needed to reduce the LNAPL‐water interfacial tension sufficiently to mobilize trapped LNAPL under unsaturated conditions. More LNAPL was recovered as additional steps of surfactant infiltration were applied. Up to 99% LNAPL was removed after six infiltration steps, with approximately 2.0 PV of total surfactant solution application, suggesting surfactant infiltration may be an effective method for vadose zone LNAPL remediation. The influence of pH tested in this study (3.99∼10.85) was insignificant because the buffering capacity of the sediment kept the pH in the column higher than the zero point charge (pHzp) of the sediment and therefore surfactant sorption was negligible.
An Automated Suction Lysimeter for Improved Soil Water Sampling
Authors: Farsad A. , Herbert S.J. , Hashemi M. , Sadeghpour A.
Published: November 2012

Leaching of chemicals (e.g., fertilizers, manure, pesticides, and petroleum products) from urban regions and areas impacted by human development is one of the main sources of underground nonpoint‐source pollution. Most methods of soil water sampling are not capable of extracting representative soil water samples to determine leaching volume and solute concentrations since they fail to create normal leaching conditions in the soil. Thus the volume of soil‐water collected, as well as its solute concentration, may not be accurately estimated. Sixteen units of cost effective and accurate automated lysimeters were designed and installed to measure post‐harvest nitrate leaching from a rye (Secale cereale L.) cover crop field during the falls and winters of 2007 to 2009. Major parts of the electronic system were electronic controller, data logger memory, digital clock and its battery backup circuit, relays, LCD display and electronic signal conditioning interfaces for amplifying, off‐setting, and digitizing the signals from vacuum sensors. The electronic system was designed to monitor soil tension every second with accuracy of 1 cm and apply the proper amount of suction to the sampling media (ceramic plate). Hourly data from soil tension and vacuum applied to the system were collected and stored by each unit. A safety system was designed for protecting the vacuum pump against unexpected major vacuum leakage events. The controller can be easily reprogrammed for different performance strategies. The automated lysimeter showed an accurate and reliable performance in both lab and field conditions. Ambient soil matric pressure and matric pressure above the samplers indicated a strong linear correlation which confirms that the lysimeter was successful in maintaining the sampler vacuum in equilibrium with soil.
Contaminants in Vadose Zone Environments
Authors: Wellman Dawn M. , Freshley Mark D. , Johnson Tim C. , Miracle Ann L.
Published: November 2012

Contaminants in vadose zone environments pose a long‐term source and threat to groundwater resources, human health, and the environment. A number of technical, regulatory, and policy challenges and opportunities are associated with contamination in vadose zone environments, particularly in remediation. In this special section, 12 papers present novel approaches to characterize, monitor, remediate, and predict the transport and fate of contaminants in vadose zone environments.
Unsealed tubewells lead to increased fecal contamination of drinking water
Authors: Knappett Peter S. K. , McKay Larry D. , Layton Alice , Williams Daniel E. , Alam Md. J. , Mailloux Brian J. , Ferguson Andrew S. , Culligan Patricia J. , Serre Marc L. , Emch Michael , Ahmed Kazi M. , Sayler Gary S. , van Geen Alexander
Published: November 2012

Bangladesh is underlain by shallow aquifers in which millions of drinking water wells are emplaced without annular seals. Fecal contamination has been widely detected in private tubewells. To evaluate the impact of well construction on microbial water quality 35 private tubewells (11 with intact cement platforms, 19 without) and 17 monitoring wells (11 with the annulus sealed with cement, six unsealed) were monitored for culturable Escherichia coli over 18 months. Additionally, two ‘snapshot’ sampling events were performed on a subset of wells during late-dry and early-wet seasons, wherein the fecal indicator bacteria (FIB) E. coli, Bacteroidales and the pathogenicity genes eltA (enterotoxigenic E. coli; ETEC), ipaH (Shigella) and 40/41 hexon (adenovirus) were detected using quantitative polymerase chain reaction (qPCR). No difference in E. coli detection frequency was found between tubewells with and without platforms. Unsealed private wells, however, contained culturable E. coli more frequently and higher concentrations of FIB than sealed monitoring wells (p < 0.05), suggestive of rapid downward flow along unsealed annuli. As a group the pathogens ETEC, Shigella and adenovirus were detected more frequently (10/22) during the wet season than the dry season (2/20). This suggests proper sealing of private tubewell annuli may lead to substantial improvements in microbial drinking water quality.
Seismic Assessment of St James Church by Means of Pushover Analysis – Before and After the New Zealand Earthquake
Authors: S. Araujo Ana , B. Lourenco Paulo , V. Oliveira Daniel , Leite Joao
Published: November 2012

The paper presents a numerical study for the seismic assessment of the St James Church in Christchurch, New Zealand affected by the recent 2011 earthquake and subsequent aftershocks. The structural behavior of the Church has been evaluated using the finite element modelling technique, in which the nonlinear behavior of masonry has been taken into account by proper constitutive assumptions. Two numerical models were constructed, one incorporating the existing structural damage and the other considering the intact structure. The validation of the numerical models was achieved by the calibration of the damaged model according to dynamic identification tests carried out in situ after the earthquake. Non-linear pushover analyses were carried out on both principal directions demonstrating that, as a result of the seismic action, the Church can no longer be considered safe. Pushover analysis results of the undamaged model show reasonable agreement with the visual inspection performed in situ, which further validates the model used. Finally, limit analysis us-ing macro-block analysis was also carried out to validate the main local collapse mechanisms of the Church.
Note on a question of Reinhold Baer on pregroups II
Authors: Gaglione Anthony , Lipschutz Seymour , Spellman Dennis
Published: November 2012

Reinhold Baer asked the relationship between certain properties in a nonempty
set P with a partial operation (called an ?add" by Baer [1]). The first
paper in our sequence [Paper I] answered his question for a special type of
an add called a pregroup by Stallings [12]. This paper [Paper II] answers an
analogous question for a wider class of adds.
Warped product CR-submanifolds of Lorentzian β-Kenmotsu manifolds
Authors: Uddin Siraj , Ozel Cenap , Khan Azam
Published: November 2012

We study the geometry of warped product submanifolds of Lorentzian ?-Kenmotsu
manifolds. We obtain a characterization result for CR-warped products.
Some further results on a question of Yi
Authors: Banerjee Abhijit
Published: November 2012

Concerning a question of Yi [18], we study the problem of uniqueness of
meromorphic functions sharing two sets with the notion of weighted sharing of
sets and obtain four results which will not only improve the results of
Lahiri [12], Lin-Yi [20] but also improve a recent result of the present
author [3] and thus provide an answer to the question of Gross [6] in a more
compact and convenient way. We exhibit two examples to show that a condition
in one of our results is sharp. Till now our result is the best in this
regard.
The status of teeth in relation to socio-demographic characteristics, oral hygiene habits and oral health behavior among adolescents in the eastern region of Republika Srpska
Authors: Stojanovic Nikola , Krunic Jelena , Cicmil Smiljka , Davidovic Lado
Published: November 2012

Introduction. The aim of this study was to determine the prevalence of dental
caries and analyze the status of teeth in relation to sociodemographic
factors and habits and behavior related to oral health among adolescents in
the eastern region of Republika Srpska. Material and Methods. The study
included 212 adolescents (71 males and 141 females) age 16-18 years.
Information about sociodemographic characteristics, oral hygiene habits and
behaviors related to oral health were collected using a questionnaire. The
prevalence of dental caries was determined by applying the DMFT index and its
components (D - decayed, M - extracted, F - filled teeth). The status of
teeth was analyzed in relation to socio-demographic variables, oral hygiene
habits and behavior related to oral health. Results. The mean DMFT value of
examined population was approximately 8.6. A significant difference in the
status of teeth of adolescents was reported in relation to the place of
residence and oral hygiene habits - brushing frequency and the use of dental
floss. A significant difference in the caries prevalence was recorded
depending on the elapsed time from last visit and reasons for visiting
dentist. Conclusion. The results suggested that the place of residence, oral
hygiene habits and behavior related to oral health influenced the status of
teeth of adolescents in the eastern region of Republika Srpska.
Exact Algorithms for Maximum Clique: A Computational Study
Authors: Prosser Patrick
Published: November 2012

We investigate a number of recently reported exact algorithms for the maximum clique problem. The program code is presented and analyzed to show how small changes in implementation can have a drastic effect on performance. The computational study demonstrates how problem features and hardware platforms influence algorithm behaviour. The effect of vertex ordering is investigated. One of the algorithms (MCS) is broken into its constituent parts and we discover that one of these parts frequently degrades performance. It is shown that the standard procedure used for rescaling published results (i.e., adjusting run times based on the calibration of a standard program over a set of benchmarks) is unsafe and can lead to incorrect conclusions being drawn from empirical data.
Prenatal Diagnosis of Chromosome Abnormalities: A 13-Year Institution Experience
Authors: Comas Carmen , Echevarria Mónica , Rodríguez María Ángeles , Rodríguez Ignacio , Serra Bernat , Cirigliano Vincenzo
Published: November 2012

Objective: To analyze trends in screening and invasive prenatal diagnosis of chromosome abnormalities (CA) over a 13-year period and correlate them to changes in the national prenatal screening policy. Methods: We retrospectively reviewed Down syndrome (DS) screening tests and fetal karyotypes obtained by prenatal invasive testing (IT) in our fetal medicine unit between January 1999 and December 2011. Results: A total of 24,226 prenatal screening tests for DS and 11,045 invasive procedures have been analyzed. Over a 13-year period, utilization of non-invasive screening methods has significantly increased from 57% to 89%. The percentage of invasive procedures has declined from 49% to 12%, although the percentage of IT performed for maternal anxiety has increased from 22% to 55%. The percentage of detected CA increased from 2.5% to 5.9%. Overall, 31 invasive procedures are needed to diagnose 1 abnormal case, being 23 procedures in medical indications and 241 procedures in non-medical indications. Conclusions: Our experience on screening and invasive prenatal diagnostic practice shows a decrease of the number of IT, with a parallel decline in medical indications. There is an increasing efficiency of prenatal screening program to detect CA. Despite the increasing screening policies, our population shows a growing request for prenatal IT. The a priori low risk population shows a not negligible residual risk for relevant CA. This observation challenges the current prenatal screening strategy focused on DS; showing that the residual risk is higher than the current cut-off used to indicate an invasive technique.
Proportional-Resonant Control of Doubly-Fed Induction Generator Wind Turbines for Low-Voltage Ride-Through Enhancement
Authors: Yan Yan , Wang Meng , Song Zhan-Feng , Xia Chang-Liang
Published: November 2012

A novel control strategy is proposed in this paper for the rotor side converter (RSC) of doubly-fed induction generator (DFIG)-based wind power generation systems. It is supposed to enhance the low-voltage ride-through (LVRT) capability of DFIGs during great-level grid voltage dips. The strategy consists of a proportional-resonant (PR) controller and auxiliary PR controllers. The auxiliary controllers compensate the output voltage of the RSC in case of grid faults, thus limiting the rotor inrush current of DFIG and meeting the requirements of LVRT. Sequential-component decompositions of current are not required in the control system to improve the response of system. Since the resonant compensator is a double-side integrator, the auxiliary controllers can be simplified through coordinate transformation. The feasibility of the control strategy is validated by simulation on a 1.5 MW wind-turbine driven DFIG system. The impact of the RSC converter voltage rating on the LVRT capability of DFIG is investigated. Meanwhile, the influence of angular frequency detection and control parameters are also discussed. Compared with traditional vector control schemes based on PI current controllers, the presented control strategy effectively suppress rotor current and reduce oscillations of DFIG power and torque under grid faults.
Synthesis Method for Thiosulfonate and Report of Its Insecticidal Activity in Anagasta kuehniella (Lepidoptera: Pyralidae)
Authors: Dos Santos Edson dos A. , Gonçalves Fernando M. , Prado Paulo César , Sasaki Daniele Y. , De Lima Dênis P. , Macedo Maria Lígia Rodrigues
Published: November 2012

Insect pests have caused economic losses valued at billions of dollars in agricultural production. Anagasta kuehniella (Zeller), the Mediterranean flour moth, is of major economic importance as a flour and grain feeder and is often a severe pest in flourmills. This study provides a suitable route for the direct preparation of thiosulfonates 2 and 3 from thiols, under mild conditions, with good yields; these thiosulfonates were tested for their regulatory effect on insect growth. The chronic ingestion of thiosulfonates resulted in a significant reduction in larval survival and weight. In addition, the tryptic activity of larvae was sensitive to these thiosulfonates. Results suggest that thiosulfonates 2 and 3 have a potential antimetabolic effect when ingested by A. kuehniella. The use of AgNO3/BF3·OEt2 and Al(H2PO4)3/HNO3 provides a suitable route for the direct preparation of thiosulfonates from thiols under mild conditions with good yields. These thiosulfonates were toxic for A. kuehniella larvae, suggesting their potential as biotechnological tools.
Simple Estimation of Förster Resonance Energy Transfer (FRET) Orientation Factor Distribution in Membranes
Authors: Loura Luís
Published: November 2012

Because of its acute sensitivity to distance in the nanometer scale, Förster resonance energy transfer (FRET) has found a large variety of applications in many fields of chemistry, physics, and biology. One important issue regarding the correct usage of FRET is its dependence on the donor-acceptor relative orientation, expressed as the orientation factor κ2. Different donor/acceptor conformations can lead to κ2 values in the 0 ≤ κ2 ≤ 4 range. Because the characteristic distance for FRET, R0, is proportional to (κ2)1/6, uncertainties in the orientation factor are reflected in the quality of information that can be retrieved from a FRET experiment. In most cases, the average value of κ2 corresponding to the dynamic isotropic limit (<κ2> = 2/3) is used for computation of R0 and hence donor-acceptor distances and acceptor concentrations. However, this can lead to significant error in unfavorable cases. This issue is more critical in membrane systems, because of their intrinsically anisotropic nature and their reduced fluidity in comparison to most common solvents. Here, a simple numerical simulation method for estimation of the probability density function of κ2 for membrane-embedded donor and acceptor fluorophores in the dynamic regime is presented. In the simplest form, the proposed procedure uses as input the most probable orientations of the donor and acceptor transition dipoles, obtained by experimental (including linear dichroism) or theoretical (such as molecular dynamics simulation) techniques. Optionally, information about the widths of the donor and/or acceptor angular distributions may be incorporated. The methodology is illustrated for special limiting cases and common membrane FRET pairs.
Role of Oxidative Stress in Hepatocarcinogenesis Induced by Hepatitis C Virus
Authors: Tsukiyama-Kohara Kyoko
Published: November 2012

Hepatitis C virus (HCV) easily establishes chronic hepatitis, cirrhosis, and hepatocellular carcinoma (HCC). During the progression of HCV infections, reactive oxygen species (ROS) are generated, and these ROS then induce significant DNA damage. The role of ROS in the pathogenesis of HCV infection is still not fully understood. Recently, we found that HCV induced the expression of 3β-hydroxysterol ∆24-reductase (DHCR24). We also found that a HCV responsive region is present in the 5'-flanking genomic promoter region of DHCR24 and the HCV responsive region was characterized as (−167/−140). Moreover, the transcription factor Sp1 was found to bind to this region in response to oxidative stress under the regulation of ataxia telangiectasia mutated (ATM) kinase. Overexpression of DHCR24 impaired p53 activity by suppression of acetylation and increased interaction with MDM2. This impairment of p53 suppressed the hydrogen peroxide-induced apoptotic response in hepatocytes. Thus, a target of oxidative stress in HCV infection is DHCR24 through Sp1, which suppresses apoptotic responses and increases tumorigenicity.
Molecular Mechanisms of RADA16-1 Peptide on Fast Stop Bleeding in Rat Models
Authors: Wang Ting , Zhong Xiaozhong , Wang Songtao , Lv Fei , Zhao Xiaojun
Published: November 2012

Ionic self-assembly of the peptide RADARADARADARADA (RADA16-1) may form a well-defined nanofiber and eventually a hydrogel scaffold, with a water content of over 99.5%. This leads to the establishment of a nanofiber barrier that can be used to achieve complete hemostasis in less than 20 s in multiple tissues and in a variety of different wounds. In the present study, the nanofiber scaffolds of RADA16-1 peptide were sonicated into smaller fragments to identify possible molecular mechanisms underlying the rapid cessation of bleeding associated with these materials. Atomic force microscopy (AFM), circular dichroism (CD), and rheometry were also used to evaluate the re-assembly kinetics of this peptide. A bleeding control experiment was performed in animal models to uncover the molecular mechanisms underlying this fast hemostasis. In this way, these sonicated fragments not only quickly reassembled into nanofibers indistinguishable from the original material, but the degree of reassembly was also correlated with an increase in the rigidity of the scaffold and increased as the time required for hemostasis increased.
Clerodendranoic Acid, a New Phenolic Acid from Clerodendranthus spicatus
Authors: Zheng Qingxia , Sun Zhaocui , Zhang Xiaopo , Yuan Jinquan , Wu Haifeng , Yang Junshan , Xu Xudong
Published: November 2012

Phenolic acid derivatives are typical constituents of Clerodendranthus spicatus which were considered to the active principles of this medicinal plant. These chemical constituents with their interesting frameworks and biological significance attracted our attention. As part of our ongoing chemical investigation of C. spicatus using various column chromatography techniques, a new phenolic compound, named clerodendranoic acid (1), was isolated from the aerial parts of C. spicatus together with five known ones, including rosmarinic acid (2), methyl rosmarinate (3), caffeic acid (4), methyl caffeate (5), ethyl caffeate (6). Their structures, including stereochemical configurations, were completely established by extensive spectroscopic methods, mainly inclvolving 1D, 2D NMR, as well as HRESIMS.
Overview of Micro- and Nano-Technology Tools for Stem Cell Applications: Micropatterned and Microelectronic Devices
Authors: Cagnin Stefano , Cimetta Elisa , Guiducci Carlotta , Martini Paolo , Lanfranchi Gerolamo
Published: November 2012

In the past few decades the scientific community has been recognizing the paramount role of the cell microenvironment in determining cell behavior. In parallel, the study of human stem cells for their potential therapeutic applications has been progressing constantly. The use of advanced technologies, enabling one to mimic the in vivo stem cell microenviroment and to study stem cell physiology and physio-pathology, in settings that better predict human cell biology, is becoming the object of much research effort. In this review we will detail the most relevant and recent advances in the field of biosensors and micro- and nano-technologies in general, highlighting advantages and disadvantages. Particular attention will be devoted to those applications employing stem cells as a sensing element.
« Tel est pris qui croyait prendre »
Authors: Edrei Béatrice , Rolo Duarte
Published: November 2012

Résumé La clinique individuelle des décompensations psychiques et somatiques en lien avec le travail soulève de nombreuses questions pour le praticien, sur les plans théorique, praxique et éthique. Cet article souhaite mettre en avant l’importance de se référer à un modèle théorique qui prenne en compte la dimension du travailler dans les cas cliniques relevant du domaine de la psychopathologie du travail. Pour l’illustrer, nous chercherons à rendre visibles, à partir d’une étude de cas, les dilemmes praxiques et les conflits d’interprétation qui constituent le quotidien des professionnels intervenant dans le champ de la clinique individuelle du travail. Cette réflexion sera alimentée par une confrontation entre psychosomatique et psychodynamique du travail. Elle nous permettra de mesurer l’importance de la psychodynamique de la reconnaissance dans l’étiologie des décompensations psychiques et somatiques.
Surgical Results of Patients With Unilateral Superior Oblique Palsy Presenting With Large Hypertropias
Authors: Nejad Mitra , Thacker Neepa , Velez Federico G. , Rosenbaum Arthur L. , Pineles Stacy L.
Published: November 2012

Purpose:

Surgical management of superior oblique palsy (SOP) is challenging because of combined vertical, horizontal, and torsional misalignment. The authors report the surgical results of patients with large primary position hypertropias (> 20 prism diopters [PD]) due to unilateral SOP.

Methods:

Criteria for success included correction of the anomalous head posture, primary position alignment between orthotropia and 6 PD of undercorrection, and no reoperation required for residual deviations in any direction of gaze.

Results:

Forty-five patients met inclusion criteria. Mean preoperative alignment in primary gaze was 26.5 ± 6.5 PD compared to 3.0 ± 4.4 PD postoperatively (
P
< .001). Twenty-three (51%) cases met the criteria for success with one operation. Of the patients who had single muscle surgery, 14% had a successful outcome, with a mean 67% (17.3 PD) reduction in hypertropia. Of patients who underwent simultaneous multiple muscle surgery, 58% met the criteria for a successful result, with a mean 92% (24.6 PD) reduction in primary gaze hypertropia. Success was the highest in patients who underwent ipsilateral inferior oblique combined with contralateral inferior rectus recessions with (60% success) or without (65% success) a Harada–Ito procedure.

Conclusion:

Undercorrections are frequent following surgery for unilateral SOP with preoperative deviations greater than 20 PD in primary position, especially after single-muscle surgery. Simultaneous multiple muscle surgery rarely results in overcorrection and is recommended in patients with SOP and more than 20 PD of hypertropia in primary position.
E-learning use patterns in the workplace – Web logs from interaction with a web based lecture
Authors: Ostlund Christian
Published: November 2012

When designing for e-learning the objective is to design for learning i.e. the technology supporting the learning activity should aid and support the learning process and be an arena where learning is likely to occur. To obtain this when designing e-learning for the workplace the author argue that it is important to have knowledge on how users actually access and use e-learning systems. In order to gain this knowledge web logs from a web lecture developed for a Scandinavian public body has been analyzed. During a period of two and a half months 15 learners visited the web lecture 74 times. The web lecture consisted of streaming video with exercises and additional links to resources on the WWW to provide an opportunity to investigate the topic from multiple perspectives. The web lecture took approximately one hour to finish. Using web usage mining for the analysis seven groups or interaction patterns emerged: peaking, one go, partial order, partial unordered, single module, mixed modules, non-video modules. Furthermore the web logs paint a picture of the learning activities being interrupted. This suggests that modules needs to be fine-grained (e.g. less than 8 minutes per video clip) so learnersâ?? do not need to waste time having to watch parts of a video clip while waiting for the part of interest to appear or having to fast forward. A clear and logical structure is also important to help the learner find their way back accurately and fast.
User Perceptions of Security Technologies
Authors: Kline Douglas M. , He Ling , Yaylacicegi Ulku
Published: November 2012

In this paper, user perceptions of information systems security are explored through a study of university students. Server authentication, which is often ignored by users, clouded by system administrators, and exploited by hackers, is explored in detail, as it significantly affects usability and requires user knowledge and participation. The study also investigates the respondents’ consistency, gender differences, and assessment of their own knowledge. Although users appear knowledgeable about security technologies, they rely more on peer opinion and reputation of web sites when making security decisions.
On Cognitive Models of Causal Inferences and Causation Networks
Authors: Wang Yingxu
Published: November 2012

Human thought, perception, reasoning, and problem solving are highly dependent on causal inferences. This paper presents a set of cognitive models for causation analyses and causal inferences. The taxonomy and mathematical models of causations are created. The framework and properties of causal inferences are elaborated. Methodologies for uncertain causal inferences are discussed. The theoretical foundation of humor and jokes as false causality is revealed. The formalization of causal inference methodologies enables machines to mimic complex human reasoning mechanisms in cognitive informatics, cognitive computing, and computational intelligence.
The Formal Design Models of Tree Architectures and Behaviors
Authors: Wang Yingxu , Tan Xinming
Published: November 2012

Trees are one of the most fundamental and widely used non-linear hierarchical structures of linked nodes. A binary tree (B-Tree) is a typical balanced tree where the fan-out of each node is at most two known as the left and right children. This paper develops a comprehensive design pattern of formal trees using the B-Tree architecture. A rigorous denotational mathematics, Real-Time Process Algebra (RTPA), is adopted, which allows both architectural and behavioral models of B-Trees to be rigorously designed and implemented in a top-down approach. The architectural models of B-Trees are created using RTPA architectural modeling methodologies known as the Unified Data Models (UDMs). The physical model of B-Trees is implemented using the left and right child nodes dynamically created in memory. The behavioral models of B-Trees are specified and refined by a set of Unified Process Models (UPMs) in three categories namely the management operations, traversal operations, and node I/O operations. This work has been applied in a number of real-time and nonreal-time system designs such as a real-time operating system (RTOS+), a general system organization model, and the ADT library for an RTPA-based automatic code generator.
Distributed Multi-Robot Localization
Authors: Panzieri Stefano , Pascucci Federica , Sciavicco Lorenzo , Setola Roberto
Published: November 2012

In this chapter, the design of a completely decentralized and distributed multi-robot localization algorithm is presented. The issue is approached using an Interlaced Extended Kalman Filter (IEKF) algorithm. The proposed solution allows the dynamic correction of the position computed by any single robot through information shared during the random rendezvous of robots. The agents are supposed to carry short-range antennas to enable data communication when they have a “visual” contact. The information exchange is limited to the pose variables and the associated covariance matrix. The algorithm combines the robustness of a full-state EKF with the effortlessness of its interlaced implementation. The proposed unsupervised method provides great flexibility by using exteroceptive sensors, even if it does not guarantee the same position estimate accuracy for each agent. However, it can be effective in case of connectivity loss among team robots. Moreover, it does not need synchronization between agents.
Local Path-Tracking Strategies for Mobile Robots Using PID Controllers
Authors: Pacheco Lluis , Luo Ningsu
Published: November 2012

Accurate path following is an important mobile robot research topic. In many cases, radio controlled robots are not able to work properly due to the lack of a good communication system. This problem can cause many difficulties when robot positioning is regarded. In this context, gaining automatic abilities becomes essential to achieving a major number of mission successes. This chapter presents a suitable control methodology used to achieve accurate path following and positioning of nonholonomic robots by using PID controllers. An important goal is to present the obtained experimental results by using the available mobile robot platform that consists of a differential driven one.
Mobile/Wireless Robot Navigation
Authors: Waqar Amina
Published: November 2012

Sensor-based localization has been found to be one of the most preliminary issues in the world of Mobile/Wireless Robotics. One can easily track a mobile robot using a Kalman Filter, which uses a Phase Locked Loop for tracing via averaging the values. Tracking has now become very easy, but one wants to proceed to navigation. The reason behind this is that tracking does not help one determine where one is going. One would like to use a more precise “Navigation” like Monte Carlo Localization. It is a more efficient and precise way than a feedback loop because the feedback loops are more sensitive to noise, making one modify the external loop filter according to the variation in the processing. In this case, the robot updates its belief in the form of a probability density function (pdf). The supposition is considered to be one meter square. This probability density function expands over the entire supposition. A door in a wall can be identified as peak/rise in the probability function or the belief of the robot. The mobile updates a window of 1 meter square (area depends on the sensors) as its belief. One starts with a uniform probability density function, and then the sensors update it. The authors use Monte Carlo Localization for updating the belief, which is an efficient method and requires less space. It is an efficient method because it can be applied to continuous data input, unlike the feedback loop. It requires less space. The robot does not need to store the map and, hence, can delete the previous belief without any hesitation.
Design of a Mobile Robot to Clean the External Walls of Oil Tanks
Authors: Acuña Hernán Gonzalez , Lara Alfonso René Quintero , Guerrero Ricardo Ortiz , Alvarez Jairo de Jesús Montes , Acevedo Hernando González , Diaz Elkin Yesid Veslin
Published: November 2012

This chapter describes a Mechatronics Design methodology applied to the design of a mobile robot to climb vertical surfaces. The first part of this chapter reviews different ways to adhere to vertical surfaces and shows some examples developed by different research groups. The second part presents the stages of Mechatronics design methodology used in the design, including mechanical design, electronics design, and control design. These stages describe the most important topics for optimally successful design. The final part provides results that were obtained in the design process and construction of the robot. Finally, the conclusions of this research work are presented.
Ad Hoc Communications for Wireless Robots in Indoor Environments
Authors: Del Río Laura Victoria Escamilla , Díaz Juan Michel García
Published: November 2012

This chapter presents a theoretical and experimental comparison of electromagnetic propagation models for indoor robot communication using mobile ad-hoc IEEE802.11 and IEEE802.15.4. The analysis includes the behavior of the electromagnetic signal using the abovementioned standards in two scenarios, both located inside the building of the College of Telematics of the University of Colima. The results of the propagation of the electromagnetic signals in the two scenarios were then compared with the mathematical model.
Preparing Student Sojourners for Cultural Immersion in Multiple User Virtual Environments
Authors: Galante Peter , Tharp Kevin W.
Published: November 2012

This paper examines the results of student reflections of their interactions in Second Life (SL) which were prompted by required class related activities. The research methodology used was qualitative meta-analysis based on a grounded theory approach. A theoretical framework based in a constructivist epistemology was used to examine cultural and pedagogical implications of introducing students to a virtual environment as part of a classroom experience. Data was gathered from two different populations, one consisting of undergraduate students utilizing SL as a pedagogical tool for learning visual literacy elements in an introductory photo class, the other consisting of graduate students in a Learning Technology course exploring SL to understand its potential for teaching and training. Examination of student reflections revealed remarkably similar results between groups with respect to their immersion into the SL environment and related culture. Analysis of the student reflections provide insight into pedagogical preparations that should be considered before introducing students into a Multiple User Virtual Environment (MUVE).
Tapping the Wisdom of Crowd Phenomenon in Healthcare Social Networks
Authors: Al-Kadi Alaa , Chatterjee Samir
Published: November 2012

Online social networks are increasing in popularity. Among teens, they are fast becoming synonymous with being online, i.e., using the Internet (Lenhart et al., 2011). As online social networks became widespread, it is found that people are using it for various purposes including work, leisure, entertainment, as well as healthcare. In this paper, the authors share their viewpoint and insights on the use of online social networks for healthcare related purposes which are sometimes also referred to as Health 2.0, or as Health Social Networks (HSNs). The authors examine the potential of HSNs in empowering patients and health information seekers towards wellbeing and healthy living. They also discuss the various potential uses of HSNs by healthcare providers and healthcare organizations. A three-dimensional framework is developed by analyzing 37 best-known commercial HSN sites to help categorize HSNs that can aide in their design process. More importantly, we provide an in-depth discussion on the future role of social networks within Healthcare.
Inter-Organizational IT Capability in China
Authors: Wu Jinnan , Liu Lin , Wang Nianxin , Wang Zhining
Published: November 2012

Prior studies of information technology (IT) capability mostly focused on dimensions and effects of IT capability at intra-organizational level in western context. This paper extends intra-organizational IT capability to inter-organizational IT capability, specifically examining process-oriented inter-organizational IT capability from a process-oriented perspective in an emerging market context. The authors use survey data from Chinese firms to identify dimensions of inter-organizational IT capability and validate its scale, compare the differences of inter-organizational IT capability in firms with three types of ownership structure, and test the relationship between these inter-organizational IT capability dimensions and firm performance. A comparative analysis reveals that seven inter-organizational IT capability measures identified in Chinese context are extended or more important than in the Western context. Empirical results show that inter-organizational IT capability varies between state-owned enterprises and non-state-owned enterprises. It is also found that four dimensions of inter-organizational IT capability have different impacts on firm performance.
The Application of DNA Self-Assembly Model for Bin Packing Problem
Authors: Wang Yanfeng , Bai Xuewen , Wei Donghui , Lu Weili , Cui Guangzhao
Published: November 2012

Bin Packing Problem (BPP) is a classical combinatorial optimization problem of graph theory, which has been proved to be NP-complete, and has high computational complexity. DNA self-assembly, a formal model of crystal growth, has been proposed as a mechanism for the bottom-up fabrication of autonomous DNA computing. In this paper, the authors propose a DNA self-assembly model for solving the BPP, this model consists of two units: grouping based on binary method and subtraction system. The great advantage of the model is that the number of DNA tile types used in the model is constant and it can solve any BPP within linear time. This work demonstrates the ability of DNA tiles to solve other NP-complete problems in the future.
Segmentation of Peripheral Blood Smear Images Using Tissue-Like P Systems
Authors: Sheeba Feminna , Nagar Atulya K. , Thamburaj Robinson , Mammen Joy John
Published: November 2012

The tissue-like P Systems, which are based on the methodology of cell and tissue behavior in a human body, are used in various areas of computation. Segmentation of medical images is one such area where these systems can be used to identify various details and objects in those images. It is a highly challenging process, especially when dealing with blood smear images, which have a very complex cell structure. In order to analyze each object individually and to avoid the cumbersome and error-prone existing manual methods, images can be segmented using appropriate automated segmentation techniques. The proposed work aims at segmenting the nuclei of the White Blood Cells (WBCs) of the peripheral blood smear images, using tissue-like P Systems, which can help to identify various pathological conditions. In the first approach, segmentation is color based. The second approach is intensity based. In the third approach, morphology is used to strengthen the findings from the results.
Cognitive Computational Models of Emotions and Affective Behaviors
Authors: Rodríguez Luis-Felipe , Ramos Félix , Wang Yingxu
Published: November 2012

Emotions are one of the important subconscious mechanisms that influence human behaviors, attentions, and decision making. The emotion process helps to determine how humans perceive their internal status and needs in order to form consciousness of an individual. Emotions have been studied from multidisciplinary perspectives and covered a wide range of empirical and psychological topics, such as understanding the emotional processes, creating cognitive and computational models of emotions, and applications in computational intelligence. This paper presents a comprehensive survey of cognitive and computational models of emotions resulted from multidisciplinary studies. It explores how cognitive models serve as the theoretical basis of computational models of emotions. The mechanisms underlying affective behaviors are examined as important elements in the design of these computational models. A comparative analysis of current approaches is elaborated based on recent advances towards a coherent cognitive computational model of emotions, which leads to the machine simulated emotions for cognitive robots and autonomous agent systems in cognitive informatics and cognitive computing.