Fingerlike aggregates in thin-layer electrodeposition

Electrodeposition experiments conducted in a thin-layer horizontal cell containing a nonbinary aqueous electrolyte prepared with cupric sulfate and sodium sulfate gave rise to fingerlike deposits, a novel and unexpected growth mode in this context. Both the leading instability from which fingers emerge and some distinctive features of their steady evolution are interpreted in terms of a simple model based on the existing theory of fingering in fluids.

Dense Concrete Layer as Top Course of Bridge Deck Construction, HR-502, 1990

The use of deicing salts in this part of the country is a necessity to remove ice from our bridges. The use of these salts has always been a problem since the chloride-ions penetrate the concrete and reach the steel and cause corrosion which eventually cause deterioration of both the steel and concrete. One method used to try to prevent this from happening was to apply a waterproof membrane to the concrete after it was placed. This method did help, but was not cost effective as the longevity of the membrane system was of relatively short duration. For this reason, this research project was initiated. After the original deck was placed a second layer of concrete about 1 1/2" thick was placed on top. Biennial evaluation of the decks included testing for delaminations and steel corrosion. Cores were also obtained for a chloride analysis. Testing and observations showed the two-layer bridge deck to be effective in preventing corrosion. Since the time this project was initiated, epoxy steel has been introduced and is a cost effective way to protect the steel from corrosion.

JXTAnonym: An anonymity layer for JXTA services messaging

With the evolution of the P2P research eld, new problems, such as those related with information security, have arisen. It is important to provide security mechanisms to P2P systems, since it has already become one of the key issues when evaluating them. However, even though many P2P systems have been adapted to provide a security baseline to their underlying applications, more advanced capabilities are becoming necessary. Speci cally, privacy preservation and anonymity are deemed essential to make the information society sustainable. Unfortunately, sometimes, it may be di cult to attain anonymity unless it is included into the system's initial design. The JXTA open protocols speci cation is a good example of this kind of scenario. This work studies how to provide anonymity to JXTA's architecture in a feasible manner and proposes an extension which allows deployed services to process two-way messaging without disclosing the endpoints'identities to third parties.

A robust audio watermarking scheme based on MPEG 1 Layer 3 Compression

This paper describes an audio watermarking scheme based on lossy compression. The main idea is taken from an image watermarking approach where the JPEG compression algorithm is used to determine where and how the mark should be placed. Similarly, in the audio scheme suggested in this paper, an MPEG 1 Layer 3 algorithm is chosen for compression to determine the position of the mark bits and, thus, the psychoacoustic masking of the MPEG 1 Layer 3compression is implicitly used. This methodology provides with a high robustness degree against compression attacks. The suggested scheme is also shown to succeed against most of the StirMark benchmark attacks for audio.

A security layer for JXTA core protocols

JXTA define un conjunto de seis protocolos básicos especialmente adecuados para una computación ad hoc, permanente, multi-hop, peer-to-peer (P2P). Estos protocolos permiten que los iguales cooperen y formen grupos autónomos de pares. Este artículo presenta un método que proporciona servicios de seguridad en los protocolos básicos: protección de datos, autenticidad, integridad y no repudio. Los mecanismos que se presentan son totalmente distribuidos y basados ¿¿en un modelo puro peer-to-peer, que no requieren el arbitraje de un tercero de confianza o una relación de confianza establecida previamente entre pares, que es uno de los principales retos en este tipo de entornos.

Joint physical-MAC layer design of the broadcast channel protocol in adhoc networks

Broadcast transmission mode in ad hoc networks is critical to manage multihop routing or providing medium accesscontrol (MAC)-layer fairness. In this paper, it is shown that ahigher capacity to exchange information among neighbors may beobtained through a physical-MAC cross-layer design of the broadcastprotocol exploiting signal separation principles. Coherentdetection and separation of contending nodes is possible throughtraining sequences which are selected at random from a reducedset. Guidelines for the design of this set are derived for a lowimpact on the network performance and the receiver complexity.

IP Telephony in Third Generation Mobile Systems: Transport Layer Dimensioning

Tämä diplomityö käsittelee kolmannen sukupolven matkaviestinjärjestelmien kuljetuskerroksen mitoitusta. Nykyisten matkapuhelinverkkojen korvaajiksi suunnitellut kolmannen sukupolven matkaviestinjärjestelmät tulevat yhdistämään perinteisen puhelinviestinnän ja uudenlaiset datapalvelut. Uudet verkot tulevat perustumaan pakettivälitteiseen tiedonsiirtoon joka mahdollistaa molempien liikennetyyppien, puheen sekä datan, siirtämisen samassa verkossa. Tämän ratkaisun uskotaan tarjoavan paremmat mahdollisuudet uusien palvelujen luomiseen ja parantavan tiedonsiirtokapasiteettia. Siirtyminen pakettivälitteiseen tiedonsiirtoon aiheuttaa kuitenkin suuria muutoksia verkkoarkkitehtuurissa. Tässä diplomityössä tarkastellaan tulevien runkoverkkojen mitoitukseen liittyviä näkökohtia sekä muodostetaan alustavia kuljetuskerroksen mitoitusohjeita. Diplomityö on tehty osaksi diplomi-insinöörin tutkintoa Lappeenrannan teknillisessä korkeakoulussa. Työ on tehty Nokia Networksin palveluksessa Helsingissä, vuoden 2000 toisella puoliskolla.

Homonymous Ganglion Cell Layer Thinning After Isolated Occipital Lesion: Macular OCT Demonstrates Transsynaptic Retrograde Retinal Degeneration.

A 48-year-old man was examined 24 months after medial and surgical treatment of an isolated well-circumscribed right occipital lobe abscess. An asymptomatic residual left homonymous inferior scotoma was present. Fundus examination revealed temporal pallor of both optic discs, and optical coherence tomography (OCT) revealed mild temporal loss of retinal nerve fiber layer in both eyes. No relative afferent pupillary defect was present. Assessment of the retinal ganglion cell layer demonstrated homonymous thinning in a pattern corresponding to the homonymous visual field loss. There were no abnormalities of the lateral geniculate nuclei or optic tracts on review of the initial brain computed tomography and follow-up magnetic resonance imaging. We believe our patient showed evidence of transsynaptic retrograde degeneration after an isolated right occipital lobe lesion, and the homonymous neuronal loss was detected on OCT by assessing the retinal ganglion cell layer.

Physical layer development in third generation protocol software architecture

Diplomityön tavoitteena oli kehittää kolmannen sukupolven fyysistä protokollakerrosta matkapuhelimen ohjelmistoarkkitehtuurille. Kolmannen sukupolven matkapuhelinjärjestelmät ovat aikaisempia järjestelmiä monimutkaisempia. Ohjelmiston koon ja monimutkaisuuden sekä aikataulujen kiireellisyyden vuoksi on tullut tarve ottaa käyttöön formaaleja menetelmiä ohjelmiston kehitystyöhön. Formaalit kuvauskielet mahdollistavat tarkan, yksiselitteisen ja simuloitavissa olevan järjestelmäkuvauksen muodostamisen. Fyysinen protokollakerros tarjoaa tiedon siirtoa ylemmille protokollakerroksille. Tämän tiedonsiirron hallinta vaatii protokollakerrosten välistä viestinvälitystä. Formaaleja kuvauskieliä käyttämällä voidaan viestinvälityksen toteutusta automatisoida ja siinä tarvittavaa logiikkaa havainnollistaa. Työssä suunniteltiin, toteutettiin ja testattiin ylempien protokollakerrosten kanssa kommunikoivaa osaa fyysisestä protokollakerroksesta. Tuloksena saatiin solunvalintatoiminnallisuuden vaatiman kommunikoinnin ja tilakoneen toteutus ohjelmistoarkkitehtuurissa. Ohjelmistonkehityksen alkuvaiheiden havaittiin olevan fyysisen kerroksen suorituskyvyn kannalta merkittävässä asemassa, koska tällöin viestinvälityksen optimointi on helpointa. Formaalit kuvauskielet eivät ole sellaisenaan täysin soveltuvia tarkoin määritellyn ohjelmistoarkkitehtuurin osien kehitykseen.

Evaluation of GPRS Radio Link Control Layer in Weak RF Field

General Packet Radio Service (GPRS) mahdollistaa pakettimuotoisen tiedonsiirron GSM-verkossa. Se tarjoaa yhteyden pakettidataverkkoihin, nostaen samalla tiedonsiirtonopeutta radiorajapinnassa. Radioresurssit ovat varattuna vain silloin kun on jotain lähetettävää, tehden täten radioresurssien käytön paljon tehokkaammaksi. Tämä diplomityö keskittyy GPRS protokollaan ja erityisesti sen datapinossa olevaan Radio Link Control (RLC) kerrokseen. RLC-kerros huolehtii GPRS- puhelimen ja tukiaseman välisen yhteyden luotettavuudesta. Työn tavoitteena on tutkia RLC-kerroksen toiminnallisuutta ja sen luotettavuutta heikossa kentässä, sekä selvittää heikon kentän vaikutusta uudelleenlähetyksiin. Työn tuloksena saadaan arvio signaalin voimakkuuden sekä uudelleen lähetysten vaikutuksesta GPRS:n datansiirtonopeuteen. Tämä työ käsittelee myös lyhyesti GSM-järjestelmää, koska lukijan on näin helpompaa ymmärtää myös GPRS-järjestelmän vaatimia teknisiä muutoksia. Tämä diplomityö on tehty osana Nokia Matkapuhelimet Oyj:ssä käynnissä olevaa GPRS tuotekehitysprojektia. Työn tuloksia käytetään testauksen tukena ja niitä on käytetty apuna RLC-kerroksen luotettavuustestauksen suunnittelussa.

Proximity of excitatory synapses and astroglial gap junctions in layer IV of the mouse barrel cortex.

Neurons and astrocytes, the two major cell populations in the adult brain, are characterized by their own mode of intercellular communication--the synapses and the gap junctions (GJ), respectively. In addition, there is increasing evidence for dynamic and metabolic neuroglial interactions resulting in the modulation of synaptic transmission at the so-called "tripartite synapse". Based on this, we have investigated at the ultrastructural level how excitatory synapses (ES) and astroglial GJ are spatially distributed in layer IV of the barrel cortex of the adult mouse. We used specific antibodies for connexin (Cx) 30 and 43 to identify astroglial GJ, these two proteins are known to be present in the majority of astroglial GJ in the cerebral cortex. In electron-microscopic images, we measured the distance between two ES, between two GJ and between a GJ and its nearest ES. We found a ratio of two GJ per three ES in the hollow and septal areas. Taking into account the size of an astrocyte domain, the high density of GJ suggests the occurrence of reflexive type, i.e. GJ between processes of the same astrocyte. Interestingly, the distance between an ES and an astroglial GJ was found to be significantly lower than that between either two synapses or between two GJ. These observations indicate that the two modes of cell-to-cell communication are not randomly distributed in layer IV of the barrel cortex. Consequently, this feature may provide the morphological support for the recently reported functional interactions between neuronal circuits and astroglial networks.

Molecular dynamics simulation of the spherical electrical double layer of a soft nanoparticle. Effect of the surface and counterion valence

Molecular dynamics simulations were performed to study the ion and water distribution around a spherical charged nanoparticle. A soft nanoparticle model was designed using a set of hydrophobic interaction sites distributed in six concentric spherical layers. In order to simulate the effect of charged functionalyzed groups on the nanoparticle surface, a set of charged sites were distributed in the outer layer. Four charged nanoparticle models, from a surface charge value of −0.035 Cm−2 to − 0.28 Cm−2, were studied in NaCl and CaCl2 salt solutions at 1 M and 0.1 M concentrations to evaluate the effect of the surface charge, counterion valence, and concentration of added salt. We obtain that Na + and Ca2 + ions enter inside the soft nanoparticle. Monovalent ions are more accumulated inside the nanoparticle surface, whereas divalent ions are more accumulated just in the plane of the nanoparticle surface sites. The increasing of the the salt concentration has little effect on the internalization of counterions, but significantly reduces the number of water molecules that enter inside the nanoparticle. The manner of distributing the surface charge in the nanoparticle (uniformly over all surface sites or discretely over a limited set of randomly selected sites) considerably affects the distribution of counterions in the proximities of the nanoparticle surface.