Mechanical Unfolding of a Simple Model Protein Goes Beyond the Reach of One-Dimensional Descriptions

We study the mechanical unfolding of a simple model protein. The Langevin dynamics results are analyzed using Markov-model methods which allow to describe completely the configurational space of the system. Using transition path theory we also provide a quantitative description of the unfolding pathways followed by the system. Our study shows a complex dynamical scenario. In particular, we see that the usual one-dimensional picture: free-energy vs end-to-end distance representation, gives a misleading description of the process. Unfolding can occur following different pathways and configurations which seem to play a central role in one-dimensional pictures are not the intermediate states of the unfolding dynamics.Comment: 10 pages, 6 figure

Understanding air release through air valves

[EN] Water transients with entrapped air can originate large pressure peaks that can severely damage distribution networks. Entrapped air can have a damping or amplifying effect on these undesirable pressure peaks. Unfortunately, the complexity of the phenomenon too often makes it difficult to obtain a fully reliable prediction about when air pockets will mitigate or accentuate water transients. Furthermore, the value of some of the parameters involved in the conventional numerical models cannot be calculated or measured and need to be determined through a calibration process. With the aim of overcoming most of the aforementioned uncertainties, this paper summarizes a complete set of tests conducted at WL | Delft Hydraulics. These tests were simulated by means of a tailored numerical model that includes a set of parameters whose values were determined by means of a calibration process. The experimental setup, a large-scale facility, consisted of a single steep pipeline with an air valve installed at its top end. Air release through different air valves was tested under different conditions. © 2011 American Society of Civil Engineers.This research has been possible thanks to the European Community Programme "Access to Major Research Infrastructure" under the Fifth Framework Growth Programme (Contract No. GIRT-CT-2002-05069).Carlos Alberola, MDM.; Arregui De La Cruz, F.; Cabrera Marcet, E.; Palau, C. (2011). Understanding air release through air valves. Journal of Urban Planning and Development. 137(4):461-469. doi:10.1061/(ASCE)HY.1943-7900.0000324S461469137

Follow-up of a new titanium-coated polyetheretherketone cage for the cervical spine

Poly-ether-ether-ketone (PEEK) cages have lower modulus of elasticity when compared with Titanium (TTN) cages. This suggests that PEEK-cages could show a lower rate of subsidence after anterior cervical discectomy-fusion (ACDF) and might lead to a lower loss of correction. We investigated the one to five year-results of standalone PEEK-TTN-porous coated cages in a patient cohort from 2014 to 2017. The patients underwent single-level ACDF for disc herniation and degenerative discopathy. Clinical and radiological outcome were assessed in 50 eligible patients after a mean of 27 months. Results: Solid arthrodesis was found in 84%. Neck disability index (NDI), and visual analogue scale (VAS) of neck and arm show comparable results to the literature. Conclusions: Clinical and radiological outcomes of ACDF with PEEK-body-cages with a porous coated surface show good bony integration. The modulus of elasticity, design, shape, size, cage surface architecture, as well as bone density, endplate preparation, radical microdiscectomy and distraction during surgery should be considered as important factors influencing the clinical results. One main advantage, over titanium cages, is the absence of MRI artifacts, allowing an excellent postoperative follow-up. inferior clinical outcome compared with bone grafts due to a higher elasticity modulus, which could result in cage subsidence.8 Nevertheless, due to structural properties, TTN implants are likely to provide a good osseo-integration9 and several clinical studies demonstrate successful results after implantation of TTN-cages.10-13 PEEKcages have a modulus of elasticity closely resembling that of cortical bone, which might lead to advantages in load sharing and stress distribution. This might reduce the subsidence rate with an improved segmental correction in the long term and a potentially higher fusion rate.14-16 A direct comparison of cervical TTNand PEEKcages in a clinical setting is very rarely found in the literature, 16, 17 and even less studies consequently compare the radiological results.16, 17 The latter studies showed the PEEK-implants being superior in maintaining cervical interspace height and achieving radiographic fusion, 16, 17 even suggesting to cease the application of TTN-cages in cervical spine surgery.16 A solution in-between are newer cages that combine the benefit of both materials: PEEK-body cages plasma-sprayed with a porous titanium surface which is tightly bonded to the PEEK surface.18, 19 On TTN alloy substrates, osteoblasts exhibit a more differentiated phenotype and increased bone morphogenetic protein production than on poly-ether-ether-ketone.20 A group of Japanese surgeons found that TTN-coated PEEK cages exhibit radiographic signs of bone on-growth, as represented by vertebral cancellous condensation around the cage, compared with that around the uncoated PEEK cage.21 Therefore, a TTN-coated PEEK cage may have the potential to promote solid fusion and to improve clinical outcomes in cervical interbody fusion surgery. This keeps the ideal elasticity modulus close to a bonelike elasticity modulus and offers a highly biocompatible surface that is well tolerated by bone and allows its ongrowth to the porous surface. The aim of the present study is to assess clinical and radiological results of CeSpace XP®, a titanium-coated PEEK cage

Burst detection in water networks using principal component anlysis

The following work presents a multivariate statistical technique applied to the control of water inflows into district metering areas (DMAs) of urban networks. This technique, called principal-component analysis (PCA), allows for a sensitive and quick analysis of the inflows into a DMA without hassling mathematical algorithms. The PCA technique simplifies the original set of flow rate data recorded by the supervisory control and data acquisition (SCADA) system, synthesizing the most significant information into a statistical model that is able to explain most of the behavior of the water distribution network. The PCA technique also allows for the establishment of control charts that help system operators in the identification of anomalous behaviors regarding water use, bursts, or illegal connections. The described technique has been proven to offer high detection sensitivity to bursts or other unexpected consumptions.Palau Estevan, CV.; Arregui De La Cruz, F.; Carlos Alberola, MDM. (2012). Burst detection in water networks using principal component anlysis. Journal of Water Resources Planning and Management. 138(1):47-54. doi:10.1061/(ASCE)WR.1943-5452.0000147S4754138

Comparative theoretical analysis between parallel and perpendicular geometries for 2D particle patterning in photovoltaic ferroelectric substrates

This paper describes the dielectrophoretic potential created by the evanescent electric field acting on a particle near a photovoltaic crystalsurface depending on the crystal cut. This electric field is obtained from the steady state solution of the Kukhtarev equations for thephotovoltaic effect, where the diffusion term has been disregarded. First, the space charge field generated by a small, square, light spotwhere d << l (being d a side of the square and l the crystal thickness) is studied. The surface charge density generated in both geometriesis calculated and compared as their relation determines the different properties of the dielectrophoretic potential for both cuts. The shapeof the dielectrophoretic potential is obtained and compared for several distances to the sample. Afterwards other light patterns are studiedby the superposition of square spots, and the resulting trapping profiles are analysed. Finally the surface charge densities and trappingprofiles for different d/l relations are studied

Metodología para la evaluación del error de medición de un parque de contadores

[ES] El rendimiento volumétrico de un abastecimiento es quizás uno de los parámetros más importantes a la hora de analizar la eficiencia de un sistema de distribución de agua. Sin embargo para realizar una estimación correcta del mismo se debe conocer una serie de factores como son: el volumen no medido, el no contabilizado debido al subcontaje de los contadores domiciliarios o el perdido en fugas. El presente artículo propone una metodología para estimar la porción de volumen no registrado que corresponde al subcontaje de contadores. Se estructura en dos partes. La primera se centra en la obtención de la forma de consumir de los abonados. En la segunda se lleva a cabo un análisis estadístico del parque de contadores para, en función de la forma de consumir de los abonados, calcular la precisión media del mismo y, en consecuencia, el volumen no registrado en los contadores domiciliarios.El presente trabajo ha sido parcialmente financiado por la CICYT, a través del proyecto de investigación "Monitorización de redes de distribución de agua y su aplicación a la detección de fugas" Ref. AMB95-0869.Arregui De La Cruz, F.; García-Serra García, J.; López Patiño, G.; Martínez Solano, J. (1998). Metodología para la evaluación del error de medición de un parque de contadores. Ingeniería del Agua. 5(4):55-66. https://doi.org/10.4995/ia.1998.2772SWORD556654Amirola Camps J. J. (1997) Control de pérdidas de agua. Análisis de pérdidas y fugas en redes de abastecimiento. Curso 4/1997. A.S.A.Andrés M. (1995) Mejora del Rendimiento y de la Fiabilidad en Sistemas de Distribución de Agua. Ed. Grupo Mecánica de Fluidos. U.P.V.Arregui F. (1998) Propuesta de una Metodología para el Análisis y Gestión del Parque de Contadores de Agua en un Abastecimiento. Tesis Doctoral. Universidad Politécnica de Valencia.AWWA (1986) Water Meters-Selection. Installation. Testing and Maintenance. AWWA 3rd Ed.; Denver, COAWWA (1966) Determination of Economic Period for Water meter Replacement. J. of AWWA. Junio 1966; pp 642-650.Bowen P.T., Harp J.F., Baxter J.W., Shull R.D. (1993) Residential Water Use Patterns. Ed American Water Works Association Research Foundation. Denver, COBrittain, R.L. (1974) Small Meter Periodic Test Limit Extension Study. Unpublished Report, Philadelphia Suburban Water Company.Daniel W.W., Terriel J.C. (1994) Business Statistics for Management and Economics. Houghton Mifflin Company. BostonGraeser, H.J. (1958) Detecting Lost Water at Dallas. L of AWWA. Juho 1958; pp 925-932Hudson, W.D. (1964) Reduction of Unaccounted-for Water. J. ofAWWA. Febrero 1964; pp 143-148Male J.W., Noss R.R., Moore I.C. (1985) Identifying and Reducing Losses in Water Distribution Systems. Noyes Publications.Nielsen, N. (1969) Determination of Proper Age for 5/8 Inch Meters in the Hacken sack and Spring Valley Systems. Report for the Hackensack Water Company, Harrington Park, NJ.Planells F., Antolí A., López V., Sanz F., García-Serra J. (1987) Diagnóstico de la gestión óptima de contadores en un sistema de distribución de agua. Tecnología del Agua N°38 1987.Siseo, R.J. (1967) The case for Meter Replacement Programs J. of AWWA ,Nov. 1967; pp 1149-1455.Skarda, B.C. (1987) The Swiss Experience with Performance Indicators and Special Viewpoints on Water Networks. IWSA Workshop on Performance Indicators and Distributions Systems. LNEC. Lisboa. Mayo 1997Yanov, D.A., Koch, R.N. (1987) A Modern Residential Flow Demand Study. Session 27 of AWWA Annual Conference. Kansas City, KS

Use of polyethylene glycol coatings for optical fibre humidity sensing

Humidity induced change in the refractive index and thickness of the polyethylene glycol (PEG) coatings are in situ investigated for a range from 10 to 95%, using an optical waveguide spectroscopic technique. It is experimentally demonstrated that, upon humidity change, the optical and swelling characteristics of the PEG coatings can be employed to build a plastic fibre optic humidity sensor. The sensing mechanism is based on the humidity induced change in the refractive index of the PEG film, which is directly coated onto a polished segment of a plastic optical fibre with dip-coating method. It is observed that PEG, which is a highly hydrophilic material, shows no monotonic linear response to humidity but gives different characteristics for various ranges of humidity levels both in index of refraction and in thickness. It undergoes a physical phase change from a semi-crystal line structure to a gel one at around 80% relative humidity. At this phase change point, a drastic decrease occurs in the index of refraction as well as a drastic increase in the swelling of the PEG film. In addition, PEG coatings are hydrogenated in a vacuum chamber. It is observed that the hydrogen has a preventing effect on the humidity induced phase change in PEG coatings. Finally, the possibility of using PEG coatings in construction of a real plastic fibre optic humidity sensor is discussed. (C) 2008 The Optical Society of Japan

Update of electronic tagging data and methodologies for Atlantic bluefin tuna in order to plan future tagging activities

This document presents the current electronic tagging information available for management strategy evaluation. This information also allows to identify gaps, in sizes and geographical areas, that should be taken into account to plan future tagging activities. It also describes the status of current electronic tag databases, advantages and disadvantages of electronic tags used on Atlantic bluefin tuna and outlines the technological advances that will allow the use of different types of tags (pop-up satellite archival, archival internal and acoustic tags) to improve the description of movements of this species. The conclusions section summarizes the progress needed to develop the use of electronic tagging on Atlantic bluefin tuna