Potential Weak Points Research Articles

Estudo da relação das famílias com o controle financeiro de recursos

This article reports the reality faced in personal and family control in the receipt and use, control and application of financial resources of the people who are part of a poor community on the outskirts of the metropolitan region of Sao Paulo. The research was conducted through a questionnaire answered by community members, and the results show the potential and possible weak points to be developed through talks on finances.

Particle–Fluid–Structure Interaction for Debris Flow Impact on Flexible Barriers

AbstractFlexible barriers are increasingly used for the protection from debris flow in mountainous terrain due to their low cost and environmental impact. However, the development of a numerical tool for the rational design of such structures is still a challenge. In this work, a hybrid computational framework is presented, using a total Lagrangian formulation of the finite element method to represent a flexible barrier. The actions exerted on the structure by a debris flow are obtained from simultaneous simulations of the flow of a fluid‐grain mixture, using two conveniently coupled solvers: the discrete element method governs the motion of the grains, while the free‐surface non‐Newtonian fluid phase is solved using the lattice Boltzmann method. Simulations on realistic geometries show the dependence of the momentum transfer on the barrier on the composition of the debris flow, challenging typical assumptions made during the design process today. In particular, we demonstrate that both grains and fluid contribute in a nonnegligible way to the momentum transfer. Moreover, we show how the flexibility of the barrier reduces its vulnerability to structural collapse, and how the stress is distributed on its fabric, highlighting potential weak points.

Eagle Ford Shale Well Control: Drilling and Tripping

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 163984, ’Eagle Ford Shale Well Control: Drilling and Tripping in Unconventional Oil and Gas Plays,’ by K. Ridley, SPE, M. Jurgens, SPE, R.J. Billa, SPE, and J.F. Mota, SPE, Shell, prepared for the 2013 SPE Middle East Unconventional Gas Conference and Exhibition, Muscat, Oman, 28-30 January. The paper has not been peer reviewed. In late 2010, Shell began an Eagle Ford appraisal program in the Piloncillo Ranch lease in south Texas. These wells are 8,500- to 9,500-ft-true-vertical-depth (TVD) horizontals, with an average total depth of 14,500-ft measured depth (MD). Initially, underbalanced-drilling techniques were used to drill the formation. As more wells were drilled, completion fracturing of offset wells began to cause well-control problems as induced fractures were encountered in horizontal sections during drilling. The authors describe the development of well-control techniques that allowed successful drilling operations. Well Design The original pore-pressure concept drove the field to a basic two-string casing design. The wells have 9?-in. surface casing and 5½-in. production casing. The surface-casing point was designed to be set between 3,000- and 3,500-ft TVD in the Midway shale below the base of the freshwater aquifer, which varies between 2,000- and 2,800-ft TVD. The fracture strength at this point was found to be 17 lbm/gal equivalent mud weight (EMW), which was considered to be sufficient for kick tolerance through the openhole interval to total depth (TD) in the Eagle Ford. The next hole section is then drilled out of the surface shoe to the kickoff point in the Austin chalk and landed in the upper Eagle Ford, where a 5,000-ft lateral section is drilled. The bottomhole assemblies (BHAs) were optimized until one run was possible from drilling out the surface shoe to TD of the well. The fracture strength of the surface shoe, along with the assumed pore pressure of 12.5 lbm/gal EMW in the Eagle Ford, allowed for a two-string design. This initial appraisal phase consisted of single-well pads with 5,000-ft laterals along a preferred azimuth. With further field development, the plan was set with multiwell pads in order to minimize the footprint and reduce undeveloped space in the reservoir (Fig. 1). Drilling—Phase 1: Initial Wells The first wells were drilled with a mud weight (MW) of 11.0 lbm/gal and exhibited few well-control challenges. No flow was observed while making connections or when performing flow checks at TD, and minimal background gas while drilling and at bottoms-up upon reaching TD was common. There was no flare during drilling, but the flare at bottoms-up at TD averaged between 10 and 20 ft. Previous experience in the Eagle Ford and other tight gas plays showed this level of gas to be manageable with a conventional rotating control device and a mud/gas separator. Some losses were encountered during the initial 5½-in.- production-casing cement jobs with a two-slurry design of top of cement at surface and a 12.7-lbm/gal lead and 16.4-lbm/gal tail. This was attributed to formation weakness in the Olmos sand, which occurred from 5,300- to 6,700-ft TVD. Equivalent-circulating- density simulations established this formation as a potential weak point, with an estimated fracture strength between 13- and 14-lbm/gal EMW across the field.

基于粒度反推法的景观生态安全格局优化——以海口市秀英区为例

PDF HTML阅读 XML下载 导出引用 引用提醒 基于粒度反推法的景观生态安全格局优化——以海口市秀英区为例 DOI: 10.5846/stxb201402170274 作者: 作者单位: 中南林业科技大学,中南林业科技大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家林业行业公益性项目(201004032);海南省林业厅重点科研项目(LK20118478);湖南省"十二五"重点学科——森林经理学科(034-0014) ; Landscape ecological security pattern optimization based on the granularity inverse method: a case study in Xiuying District, Haikou Author: Affiliation: Central South University of Forestry and Technology,Central South University of Forestry and Technology Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:景观生态安全格局优化是改善生态环境、促进人与自然和谐发展的有效途径。为给海口市秀英区生态环境建设提供科学依据和景观生态安全格局优化方法改进提供参考,提出了粒度反推法和生态阻力面综合构建法,结合GIS技术和最小耗费距离模型探讨了海口市秀英区景观生态安全格局优化途径。结果表明:(1)400m粒度生态景观组分是秀英区生态源地选取的合适参照,秀英区有生态源地18块、生态廊道17条、生态节点11个,新增生态源地建设的参考规模为38.5hm2,生态源地的生态服务极限距离为800m,需将现有的11块非生态景观类型斑块转换为生态景观类型,总面积20.26 hm2。(2)粒度反推法能为生态源地选取提供客观参考,在生态源地选择方面比传统方法具有更强的理论基础和客观性,解决了客观选取生态源地的问题。(3)综合生态阻力面能对生态阻力的实际情况进行较好地模拟。显、隐性生态阻力面之间存在显著差异,能反映生态系统中潜在的生态薄弱点,这些生态薄弱点往往是容易被忽略而又需要重点建设的区域。 Abstract:The Landscape Ecological Security Pattern Optimization Approach (LESPOA) is an effective way of promoting healthier ecosystems and harmonious relationships between people and their surrounding environment. Currently, there are shortcomings to this approach because it lacks objectivity in ecological site selection, and when simulating ecological resistances, it doesn't consider the interactions between these resistances. In order to address these issues, this paper uses the granularity inverse method and the comprehensive construction method of ecological surface resistance, which combines the technology of GIS with a least-cost distance model, to apply the LESPOA in Xiuying district. We aimed to provide a scientific basis for ecological environment construction and a method for improving the LESPOA. The results were: (1) When the granularity of ecological landscape component is 400 m, the ecological landscape component is an appropriate method for selecting ecological sources. According to the above appropriate method, there were 18 ecological sources (8 primary and 10 secondary), 17 ecological corridors, and 11 ecological nodes in Xiuying district. The reference scale of new ecological sources was 38.5 hm2. The maximum ecological service distance for whole ecological source structure was about 800 m. When the distance between different ecological patches is approximately 200 m, we should enhance the ecological connections between them. Currently, there are 11 non-ecological landscape patches (with a total area of 20.26 hm2) in Xiuying district that need to be converted to ecological landscape patch;(2) The granularity inverse method has a stronger theoretical basis and greater objectivity than traditional methods of ecological source selection, and it also can reflects the connective characteristics of landscape pattern. Therefore, the results from this method can supply more accurate references for ecological construction than traditional methods. (3) The comprehensive ecological resistance surface considers the interaction between resistances and thus can better simulate the physical characteristics of ecological resistances than the traditional ecological resistance surface that just considers land use type. There are significant differences between dominant ecological resistance and recessive ecological resistance, which can reflect potential ecological weak points. Most of the ecological weak points in Xiuying district are woodlands that are surrounded by farmland, unused land, and construction land. Although these ecological weak points can easily be neglected, it is important to focus on enhancing the connections between the weak points and ecological sources in order to restore natural ecologic processes. 参考文献 相似文献 引证文献

Partial preperitoneal mesh repair of inguinal hernia :A new approach

Context One of the commonly performed surgeries for inguinal hernias is tension free mesh repair Lichtenstein Mesh Repair. Recurrence after lichtenstein repair varies between 0-12 with a mean of 3-4. The common sites of recurrences include area just above and lateral to pubic tubercle area lateral to internal ring. The following study is conducted with the intension of evaluating the efficacy of the newer method of mesh fixationAim To study the factors of postoperative pain morbidity and recurrence following partial pre-peritoneal mesh repair of inguinal hernia and comparing the same with Lichtenstein repair of inguinal herniaMethods and Material Patients were divided into group A and group B who underwent Lichrenstein and partial pre-peritoneal mesh repair respectively. Postoperatively patients were followed up up to 1 year and various factors such as pain loss of sensation and recurrence were evaluated.Results During 8 day follow-up patients who underwent partial pre-peritoneal mesh repair complained less pain compared to other group. But they had higher chance of loss of sensation. During later follow-ups no significant difference was noted. No recurrence was noted in our study.Conclusion Partial pre-peritoneal mesh repair can be used as an effective alternative to Lichtenstein mesh repair with the advantage of covering the potential weak point of medial and lateral ends inguinal canal more widely.nbsp

Impact of Investments in Generating Units and Transmission and Distribution Power Grids by 2025 on Voltage Stability and Branches Load in ENERGA SA Operational Territory – Main Findings of Research Project

The article summarizes a research project which was conducted in order to ensure what will be the influence of future investments and changes in the Polish Power System on the stability and functionality of the ENERGA SA distribution grid system. Development of the ENERGA SA distribution grid system was also included. Only stable states were tested for various cases of system load and generation in power plants (the Nuclear Power Plant in Żarnowiec was taken into account) and also in wind farms. The system was also tested in N-1 and N-2 states. The result of this study is an overall evaluation of the ENERGA SA distribution grid condition, as well as the identification of potential weak points inside this structure. DOI: 10.12736/issn.2300-3022.2013101 1. Project objective and scope The objective of the project was to investigate how the investments made by 2025 will affect the operation of the 110 kV distribution grid owned by ENERGA SA. The study considered the transmission system’s extension by PSE according to [1, 2], the distribution system’s extension in accordance with ENERGAOPERATOR SA’s grid development plan for the next few years, and information about newly-built, planned and connected generation sources. The main focus is on the problem of power output from a large number of wind farms connected in northern Poland, and the planned location of a nuclear power plant in Żarnowiec area. The potentially weakest 110 kV nodes and lines owned by ENERGA SA were identified. The study focused on analysis of the system’s global stability and on analysis of N-1 and N-2 for different variants of the system operation (different system loads and different scenarios for power generation in the system). Additionally, the project continues the master’s thesis [3], which examined the impact of Żarnowiec nuclear power plant’s connection on the operation of the national power system. 2. Research methodology description Power flows were calculated using the PlansLAB software, in which a voltage stability analysing script developed by these authors was implemented. Voltage stability is construed here as the possibility to load down the NPS with an apparent power in a way that triggers neither sharp voltage drops nor a voltage collapse. This is related to the limited potential of reactive power generation in the NPS, which affects voltage levels in substations. The algorithm had enabled monitoring the node voltages and line currents while the power system was loaded down. The loading (here also called simulation) was done by gradually increasing the power supplied to all receivers in the system, and balancing power in the system by some power plants, mainly centrally dispatched generating units (JWCD). The study focused on the steady-states, and neglected dynamic states. The basic variants of the NPS operating states were the following models: summer day (LD), summer night (LN), winter day (ZD) and winter peak (ZS). For comparison of how the system operation conditions will change over the years, calculations were carried out for the years 2012 and 2025. For the line current carrying capacity analysis the ZS model was mainly used, which had the highest currents due to peak of power consumption. • The 2025 models were extended versions of the 2012 models. They include: The change in the electricity generation structure in line with the PSE assumptions [2] for 2025, including the connection in the OSD ENERGA-OPERATOR SA area of wind farms with aggregate output over 5 GW, and of nuclear power plant in Żarnowiec with one 1600 MW unit. Decommissioning of some generation units, according to the PSE plans, was also taken into account. D. Falkowski, M. Zarzycki | Acta Energetica 1/14 (2013) | 4–11

EFSA's contribution to the implementation of the EU legislation on pesticide residues in food

The active involvement of EFSA in the area of pesticide residues assessment started in 2006 following the adoption of new legislation on maximum residue levels (MRLs) of pesticides in food (Regulation (EC) No 396/2005). EFSA took on a new role as an independent risk assessment body in the process of MRL setting, providing important contributions in the EU-wide harmonisation of MRLs. With the development of a risk assessment model (EFSA PRIMo) the risk assessment process has become more transparent. EFSA is now involved in all routine MRL setting processes by giving advice to the risk managers and, so far, has given recommendations on ca. 1 200 MRLs. EFSA also provides other scientific assessments, in many cases where urgent advice is needed due to unexpected incidences which require immediate risk management action. Currently, high priority is given to the systematic MRL review, which involves making a comprehensive inventory of the scientific studies and performing risk assessments for the pesticides covered by this programme. Another major task for EFSA is the drafting of the Annual Report on Pesticide Residues, which gives an overview of the pesticide residues in food available to European consumers. EFSA has revised the data collection of monitoring results to allow more powerful data analysis to identify potential consumer risks and weak points in the food production system, and to develop strategies for improvements. EFSA places major emphasis on risk communication on topics related to pesticide residues, which is an integral part of EFSA's tasks as risk assessor. Building on the achievements of the last six years, future challenges for EFSA include the continued improvement of risk assessment methodologies (updating risk assessment models, developing new methodologies for cumulative risk assessment) and the timely provision of risk assessments for MRL applications and MRL reviews.

Structural analysis of the envelope gp120 V3 loop for some HIV-1 variants circulating in the countries of Eastern Europe

The V3 loop on gp120 from human immunodeficiency virus type 1 (HIV-1) is a focus of many research groups involved in anti-AIDS drug development because this region of the protein is a principal target for neutralizing antibodies and a major determinant for cell tropism and syncytium formation. In this study, the nucleotide sequences of the env gene region coding the V3 loop were determined by DNA sequencing methods for four novel HIV-1 strains that circulate in the countries of Eastern Europe, such as Russia, Belarus, Ukraine, etc. Based on the empirical data obtained, the 3D structures of the V3 loops associated with these viral modifications were generated by computer modeling and then compared to discover similarities in the spatial arrangement of this functionally important site of gp120. Despite the HIV-1 genetic variety, several regions of the V3 loop that contain residues critical for cell tropism were shown to be structurally invariant, which may explain its exceptional role in a co-receptor usage. These data together with those on the biological activity of the V3 individual residues clearly show that these conserved structural motifs of gp120 represent potential HIV-1 weak points most suitable for therapeutic intervention.

On the Parallelization of Vector Fitting Algorithms

The so-called vector fitting (VF) algorithm has gained much popularity over the last few years. This technique provides a very effective system identification tool that, starting from input-output responses of a linear and time-invariant system, computes a rational approximation of its transfer matrix. The latter is routinely used to synthesize compact broadband equivalent circuits or state-space models of possibly complex interconnects at the chip, package, board, or even system level. The VF algorithm is based on a combination of iterative linear least squares solutions and eigensolutions, and proves robust and reliable. A potential weak point of VF is its relatively poor scalability with the complexity of the structure under modeling. When the number of input-output ports is very large (one hundred or more, as in the case of power buses or packages), the excessive computational requirements may hinder VF performance and prevent its successful application. In this paper, we address these issues by first presenting a detailed analysis of the computational cost of all the algorithm parts. The results show a very good potential for VF parallelization for multicore hardware, and suggest a few alternative parallelization strategies. Each of these strategies is described in detail. Finally, numerical results and comparisons are provided on a large set of industrial benchmarks. These results demonstrate excellent scalability and speedup factors for the parallel sections of the algorithm, leading to a drastic reduction in overall runtime.

Environmental life cycle assessment as a tool for identification and assessment of environmental aspects in environmental management systems (EMS) part 1: methodology

The paper presents a discussion on the possibilities of using life cycle assessment (LCA) in identification and assessment of environmental aspects in environmental management systems based on the requirements of the international ISO14001 standard and the European Union EMAS regulation. Some modifications of LCA methodology are proposed in part 1, while the results of a review of environmental aspects for 36 organisations with implemented environmental management systems (EMS) are presented in part 2 of the article. The scope of the systems analysed in EMS and in LCA is different. This comes as the result of the fact that both ISO 14001 and EMAS are focused on an organisation contrary to ISO14040x, which are focused on a product life cycle. For the present work, this resulted in a need of adjusting the LCA methodology to EMS specificity, and vice versa. Some suggestions of such modifications are presented and discussed in the paper. A preliminary analysis was carried out on 36 organisations, which have EMS compliant with the ISO14001 or EMAS regulations. It has found a certain disproportion between input and output-related environmental aspects included in most of the analysed registers. The probable reasons for such disproportion could be the fact that the output-related environmental aspects are easier to manage by organisation and are often regulated by laws. Legal requirements are a significant criterion in the environmental aspects assessment. Based on the assessments carried out and the observations made, some conclusions have been drawn with regard to weaknesses and strengths and usefulness of LCA, as a result of a comparison to the traditional approaches used in EMS in the discussed area. LCA has evident advantages like: standardised methodology; possibility of inclusion of the quantitative information; presence of some methodological steps enabling the verification of the collected data; ability to generate of reproducible results. At the same time, the following potential weak points can be observed: a complexity of the procedure; higher time and cost requirements (especially related to an inventory phase); difficulties with assessing of environmental aspects with the qualitative character and these related to emergency situations; limitation related to the lack of relevant characterisation factors in the currently used LCIA methods. LCA ought to be considered as a tool used for identification and assessment of environmental aspects in EMS. The listed limitations do not disqualify its suitability to be used. After certain simplifications, LCA seems to be a valuable alternative to the methodologies currently in use.

Environmental life cycle assessment (LCA) as a tool for identification and assessment of environmental aspects in environmental management systems (EMS)

The paper presents a discussion on the possibilities of using LCA in identification and assessment of environmental aspects in environmental management systems based on the requirements of the international ISO14001 standard and the European Union EMAS regulation. Some modifications of LCA methodology are proposed in Part 1 while the results of a review of environmental aspects for 36 organisations with implemented EMS are presented in Part 2 of the article. The scope of the systems analysed in EMS and in LCA is different. This comes as the result of the fact that both ISO 14001 and EMAS are focused on an organisation on contrary to ISO14040x which are focused on a product life cycle. For the present work, this resulted in a need of adjusting the LCA methodology to EMS specificity and vice versa. Some suggestions of such modifications are presented and discussed in the paper. A preliminary analysis was carried out on 36 organisations which have environmental management systems compliant with the ISO14001 or EMAS regulations. A certain disproportion between input and output related environmental aspects included in most of the analysed registers was found. The probable reasons for such disproportion could be the fact that the output related environmental aspects are easier to manage by organisation and are often regulated by laws. Legal requirements are a significant criterion in the environmental aspects assessment. Based on the assessments carried out and the observations made, some conclusions have been drawn with regard to weaknesses and strengths and usefulness of LCA, as a result of a comparison to the traditional approaches used in EMS in the discussed area. LCA has evident advantages like: standardised methodology, possibility of inclusion of the quantitative information, presence of some methodological steps enabling the verification of the collected data, and ability to generate of reproducible results. At the same time, the following potential weak points can be observed: a complexity of the procedure, higher time, and cost requirements (especially related to an inventory phase); difficulties with assessing of environmental aspects with the qualitative character and these related to emergency situations; and limitation related to the lack of relevant characterisation factors in the currently used life cycle impact assessment methods. LCA ought to be considered as a tool used for identification and assessment of environmental aspects in environmental management systems. The listed limitations do not disqualify its suitability to be used. After certain simplifications, LCA seems to be a valuable alternative to the methodologies currently in use.

CAD/CAM Implant Suprastructures: Accuracy, Durability and Precision

Traditional methods for implant prosthetic frame fabrication have been complicated by the process utilized to construct the frameworks. The casting method has been shown to complicate passive fit to the implant fixtures due to shrinkage and expansion of the materials used to construct the prosthesis. Additionally, castings not providing homogeneous masses of metal and microbubbles in the cast metal are very common leading to potential weak points in the prosthesis. In recent years, technology has allowed CAD/CAM processes to virtually create these frames eliminating the expansion and contraction seen in castings. As these structures are milled from solid blocks of homogenous metal, bubbles are eliminated from the final prosthesis thus providing stronger frameworks. This article will discuss the pitfalls of traditional methods and the benefits of CAD/CAM implant fixed and bar-overdenture prosthetics.

Effect of transglutaminase 2 (TG2) deficiency on atherosclerotic plaque stability in the apolipoprotein E deficient mouse

BackgroundTransglutaminase 2 (TG2), a cross-linking enzyme that confers supra-molecular structures with extra rigidity and resistance against proteolytic degradation, is expressed in the shoulder regions of human atherosclerotic plaques. It has been proposed that TG2 prevents tearing and promotes plaque repair at these potential weak points, and also promotes ectopic calcification of arteries. TG2 is also expressed within plaques that develop within the brachiocephalic arteries of apolipoprotein E (apoE) deficient mice. ObjectivesTo determine the role that TG2 plays in plaque development and calcification, mice were bred that were doubly deficient in apoE and TG2, and were maintained on a high-fat diet for 6 months. ResultsLesion size and composition were not significantly altered in the apoE/TG2 double-knockout mice, with the exception of a 9.7% decrease in the proportion of the plaque occupied by lipid (p=0.032). The frequency of buried fibrous caps within brachiocephalic plaques was significantly higher in male than in female mice, but TG2 deficiency had no effect on either gender. The extent of lesion calcification varied markedly between individual mice, but it was not decreased in the apoE/TG2 double-knockout mice. ConclusionThese data indicate that, in the apoE knockout mouse model of atherosclerosis, TG2 does not influence plaque composition or calcification. The data further suggest that TG2 does not influence plaque stability or repair in these mice.

Belassene Fremdkörper aus Sicht der OP-Schwester

Patient safety in the operating room is of high priority for the surgical team and for all healthcare workers involved. Counting procedures contribute to minimizing potential risks for the patients, especially in preventing them from leaving the operating room with retained, unintended foreign bodies. A total of 64% of operating room nurses involved in a survey are reported as having been involved in a surgical procedure in which the correct count prevented foreign bodies from being left in the patient. In addition, the strengths and potential weak points of the counting procedures could be identified. The results of the survey and drafts for a standard counting control as well as procedural recommendations are presented for discussion. A recommendation can be provided for each surgical department in order to check their own counting methods for avoiding potential risks.

Modelling the Acoustical and Airflow Performance of Simple Lined Ventilation Apertures

The pressure differences that can be used to drive a natural ventilation system are very small and thus large apertures are required to allow sufficient air to enter and leave a building to ensure good air quality or thermal comfort. Large apertures are potential acoustic weak points on a façade and may require some form of acoustic treatment such as absorbent linings, in which case the ventilator is similar to a short section of lined duct. In ducts, the performance of absorbent linings increases with the length of lining and the ratio of the length of lined perimeter to the cross sectional area of the duct. Thus, for a duct of a given cross sectional area, a lining is more effective for a duct with a high aspect ratio than for a duct with a square cross section. However, the high aspect ratio cross section will result in greater flow resistance and impede the airflow performance. In this paper numerical methods are employed to investigate the effect of different configurations of a lined aperture on the acoustical and ventilation performance of the aperture in order to establish the optimum configurations.

Quantitative determination of the topological propensities of amyloidogenic peptides

One of the interesting puzzles of amyloid beta-peptide of Alzheimer's disease (Aβ) is that it appears to polymerize into amyloid fibrils in a parallel beta sheet topology, while smaller subsets of the peptide produce anti-parallel beta sheets. In order to target potential weak points of amyloid fibrils in a rational drug design effort, it would be helpful to understand the forces that drive this change. We have designed two peptides CHQKLVFFAEDYNGKDEAFFVLKQHW and CHQKLVFFAEDYNGKHQKLVFFAEDW that join the significant amyloidogenic Aβ (14–23) sequence HQKLVFFAED in parallel and anti-parallel topologies, respectively. (Here, the word “parallel” refers only to residue sequence and not backbone topology). The N-termini of the hairpins were labeled with the fluorescent dye 5-((((2-iodoacetyl)amino)ethyl)amino)naphthalene-1-sulfonic acid (IAEDANS), forming a fluorescence energy transfer donor–acceptor pair with the C-terminus tryptophan. Circular dichroism results show that the anti-parallel hairpin adopts a beta-sheet conformation, while the parallel hairpin is disordered. Fluorescent Resonance Energy Transfer (FRET) results show that the distance between the donor and the acceptor is significantly shorter in the anti-parallel topology than in the parallel topology. The fluorescence intensity of anti-parallel hairpin also displays a linear concentration dependence, indicating that the FRET observed in the anti-parallel hairpin is from intra-molecular interactions. The results thus provide a quantitative estimate of the relative topological propensities of amyloidogenic peptides. Our FRET and CD results show that beta sheets involving the essential Aβ (14–23) fragment, strongly prefer the anti-parallel topology. Moreover, we provide a quantitative estimate of the relative preference for these two topologies. Such analysis can be repeated for larger subsets of Aβ to determine quantitatively the relative degree of preference for parallel/anti-parallel topologies in given fragments of Aβ.

Spontaneous flexor tendon rupture in the palm: The role of a variation of tendon anatomy

Spontaneous flexor tendon rupture is rare. We report 2 cases that occurred in association with a common flexor digitorum profundus (FDP) tendon to the ring and small fingers. The tendon bifurcated at the midpalmar level and ruptured at the point of bifurcation. To our knowledge this tendon variation has not been reported previously and has not been associated with spontaneous tendon rupture. Both ruptures occurred in the dominant small finger of elderly men in the absence of trauma. We believe that this unusual tendon arrangement represents a potential weak point in the musculotendinous unit. We discuss the role of this anatomic variant in the pathomechanics of tendon rupture. (J Hand Surg 2003;28A:149-152. Copyright © 2003 by the American Society for Surgery of the Hand.)

Complementary use of ion trap/time-of-flight mass spectrometry in combination with capillary high-pressure liquid chromatography: early characterization of in vivo metabolites of the cathepsin K inhibitor NVP-AAV490 in rat

Cathepsin K is a cysteine proteinase, primarily expressed in osteoclasts, which has a strong collagenolytic activity and plays an essential role involved in bone matrix degradation. Its inhibition could provide a novel approach to the treatment and prevention of osteoporosis. One structural class of lead compounds in our cathepsin K inhibitors program is based on an arylaminoethyl amide scaffold, which has potential metabolic weak points that might be stabilized by appropriate chemical modification(s). For the identification of potential metabolic “soft spots” and the rational design of improved derivatives, early biotransformation of a potent arylaminoethyl amide cathepsin K inhibitor (NVP-AAV490-NX) was investigated in plasma, urine and liver homogenates of rats after intravenous bolus administration of 10 mg/kg. The detection and identification of metabolites was achieved by high-resolution mass spectrometry (time-of-flight MS) and multi-dimensional mass spectrometry (ion trap MS). Both mass spectrometers were combined with reversed-phase capillary high-performance liquid chromatography columns. It was demonstrated that both mass analyzers complement each other and that, even in the sub-nanogram range, the resulting set of MS data can be successfully used to elucidate most of the metabolic changes unambiguously, solely by mass spectrometric techniques. The proposed metabolite structures were additionally corroborated by exact mass measurement of the protonated molecular ions to confirm the predicted elemental composition, by determination of the number of the exchangeable hydrogen atoms replacing water against deuterium oxide as mobile phase and, in one case, by an MS 3 product ion experiment in order to elucidate the site of conjugation.

Sources and control of instrumental drift in the surface forces apparatus

Instrumental drift in the surface forces apparatus (SFA) has been carefully scrutinized. A diversity of different contributions with different characteristic time constants could be distinguished. The face seal of the functional attachment was identified as a potential weak point in the mechanical loop of the instrument. We compared drift in three different design variants and found that the drift rate may vary over four orders of magnitude. We believe that the presented results are applicable to a number of different SFA types.

Cost-efficiency and performance of individual and small-scale treatment plants

The problem of diffuse pollution by individual housing can be tackled by installation of individual wastewater treatment systems. At the moment there are initiatives towards standardisation and certification of these systems to ensure efficient installations. Treatment results of recently installed individual plants prove to be very good towards BOD, COD and SS removal. Factors such as frequency of maintenance, control and mechanical breakdown may however affect these promising results. Investment and operation costs per PE are discussed and compared with a more centralised approach, emphasising the highly variable nature of these costs for individual wastewater treatment. Additional long-term experience is needed to evaluate the potential weak points and achieve improved cost-benefit analysis.