Probing the microenvironmental conditions for induction of superficial zone protein expression

SummaryObjectiveTo determine the in vitro conditions which promote expression of superficial zone protein (SZP).MethodsChondrocytes from 6-month-old calves were expanded in monolayer culture and the expression of SZP in alginate bead and monolayer culture was quantified with quantitative real time-polymerase chain reaction (qRT-PCR) and immunostaining. The effect of oxygen tension on SZP expression was determined by qRT-PRC analysis of cells cultured in two dimension (2D) and three dimension (3D) under hypoxic (1% pO2) or normoxic (21% pO2) conditions. Finally, to examine the effect of cyclic tensile strain on expression of SZP in 2D and 3D cultures, chondrocytes encapsulated in alginate beams or seeded on type I collagen coated polydimethylsiloxane (PDMS) chambers were subjected to 5% strain at 1 Hz, 2 h/day for 4 days or 2 h at the fourth day of culture and mRNA levels were quantified.ResultsBovine chondrocytes in monolayer showed a drastic decrease in SZP expression, similar in trend to the commonly reported downregulation of type II collagen (Col2). Chondrocytes embedded in alginate beads for 4 days re-expressed SZP but not Col2. SZP expression was higher under normoxic conditions whereas Col2 was upregulated only in alginate beads under hypoxic conditions. Cyclic mechanical strain showed a tendency to upregulate mRNA levels of SZP.ConclusionsA microenvironment encompassing a soft encapsulation material and 21% oxygen is sufficient for fibroblastic chondrocytes to re-express SZP. These results serve as a guideline for the design of stratified engineered articular cartilage and suggest that microenvironmental cues (oxygen tension level) strongly influence the pattern of SZP expression in vivo

Trajectories of charged particles trapped in Earth's magnetic field

I outline the theory of relativistic charged-particle motion in the magnetosphere in a way suitable for undergraduate courses. I discuss particle and guiding center motion, derive the three adiabatic invariants associated with them, and present particle trajectories in a dipolar field. I provide twelve computational exercises that can be used as classroom assignments or for self-study. Two of the exercises, drift-shell bifurcation and Speiser orbits, are adapted from active magnetospheric research. The Python code provided in the supplement can be used to replicate the trajectories and can be easily extended for different field geometries.Comment: 10 pages, 7 figures. Submitted to American Journal of Physic

Modelling manufacturing deformations in corner sections made of composite materials

A three-step finite element model has been implemented to predict the spring-in of L-shaped parts. The material property development during the cure has been modelled as step changes during transitions between viscous, rubbery and glassy states of the resin. The tool-part interaction is modelled as a sliding interface with a constant sliding shear stress. The effect of various material and geometric variables on the deformation of L-Section parts are investigated by a parameter sensitivity analysis. The spring-in predictions obtained by the finite element method are compared to experimental measurements for unidirectional and cross-ply parts of various thicknesses and radii. Results indicate that although a 2D plane strain model can predict the spring-in measured at the symmetry plane fairly well, it is not sufficient to capture the complex deformation patterns observed. © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav

Greater Expectations?

Physically Unclonable Functions (PUFs) are key tools in the construction of lightweight authentication and key exchange protocols. So far, all existing PUF-based authentication protocols follow the same paradigm: A resource-constrained prover, holding a PUF, wants to authenticate to a resource-rich verifier, who has access to a database of pre-measured PUF challenge-response pairs (CRPs). In this paper we consider application scenarios where all previous PUF-based authentication schemes fail to work: The verifier is resource-constrained (and holds a PUF), while the prover is resource-rich (and holds a CRP-database). We construct the first and efficient PUF-based authentication protocol for this setting, which we call converse PUF-based authentication. We provide an extensive security analysis against passive adversaries, show that a minor modification also allows for authenticated key exchange and propose a concrete instantiation using controlled Arbiter PUFs

2-Chloro-7,8,9,10-tetra­hydro­cyclo­hepta­[b]indol-6(5H)-one

In the title mol­ecule, C13H12ClNO, the dihedral angle between the benzene and pyrrole rings is 1.38 (9)°. The cyclo­heptene ring adopts a distorted twist chair and sofa conformation. Inter­molecular N—H⋯O hydrogen bonds form an R 2 2(10) loop in the crystal packing. Further, weak C—H⋯O and C—H⋯π (involving the benzene ring) inter­actions are found in the crystal structure

Freedom walk of the Turks in Bulgaria: Events of May in 1989 and their reflections

Bu çalışma, 02-05 Haziran 2010 tarihleri arasında Antalya[Türkiye]’da düzenlenen 2. International Geography Symposium-Mediterranean Environment’da bildiri olarak sunulmuştur.The Events of May having a distinctive place in the history of Bulgaria of Socialist Era in 1989 lead the major ethnical issues which are avoided to be discussed. These social events indicate that the processes of returning to origin which has the essence of assimilation and Bulgarization are not accepted and internalized by the Turkish Minority. The Events of May left its traces of shame as a bloody stain in the history of the Bulgaria. In the conflicts between innocent and civil mass of Turkish peoples and armed security forces, many people were injured, beaten, arrested and disabled. What is more to the point, during these events, the innocent Turks were killed who had not got any offence. In this study, reasons, progress, properties, reflections and results of the Events of May are discussed. In this study for which the Bulgarian scientific resources are frequently referred, those social events which are not known well in Turkey are enlightened and the struggle of the Turks in Bulgaria for their rights and freedom in 20th century is semtinized. (C) 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of The 2nd International Geography Symposium-Mediterranean Environmen