Spherical means with centers on a hyperplane in even dimensions

Given a real-valued function on R-n we study the problem of recovering the function from its spherical means over spheres centered on a hyperplane. An old paper of Bukhgeim and Kardakov derived an inversion formula for the odd n case with great simplicity and economy. We apply their method to derive an inversion formula for the even n case. A feature of our inversion formula, for the even n case, is that it does not require the Fourier transform of the mean values or the use of the Hilbert transform, unlike the previously known inversion formulas for the even n case. Along the way, we extend the isometry identity of Bukhgeim and Kardakov for odd n, for solutions of the wave equation, to the even n case.

Workers are doing it for themselves? Local labor solidarity in precarious times

Historically, organized labor has played a fundamental role in guaranteeing basic rights and privileges for screen media workers and defending union and guild members (however unevenly) from egregious abuses of power. Yet, despite the recent turn to labor in media and cultural studies, organized labor today has received only scant attention, even less so in locations outside Hollywood. This presentation thus intervenes in two significant ways: first, it acknowledges the ongoing global ‘undoing’ of organized labor as a consequence of footloose production and conglomeration within the screen industries, and second, it examines a case example of worker solidarity and political praxis taking shape outside formal labor institutions in response to those structural shifts. Accordingly, it links an empirical study of individual agency to broader debates associated with the spatial dynamics of screen media production, including local capacity, regional competition, and precariousness. Drawing from ethnographic interviews with local film and television workers in Glasgow, Scotland, I consider the political alliance among three nascent labor organizations in the city: one for below-the-line crew, one for facility operators, and (oddly enough) one for producers. Collectively, the groups share a desire to transform Glasgow into a global production hub, following the infrastructure developments in nearby cities like Belfast, Prague, and Budapest. They furthermore frame their objectives in political terms: establishing global scale is considered a necessary maneuver to improve local working conditions like workplace safety, income disparity, skills training, and job access. Ultimately, I argue these groups are a product of an inadequate union structure and outdated policy vision for the screen sector , once-supportive institutions currently out of sync with the global realities of media production. Furthermore, the groups’ advocacy efforts reveal the extent to which workers themselves (in additional to capital) can seek “spatial fixes” to suture their prospects to specific political and economic goals. Of course, such activities manifest under conditions outside of the workers’ control but nevertheless point to an important tension within capitalist social relations, namely that the agency to reshape the spatial relationships in their own lives recasts the geography of labor in terms that aren’t inherent or exclusive to the interests of global capital.

Long-term Accelerated Multistress Aging of Composite Outdoor Polymeric Insulators

Polymeric outdoor insulators are being increasingly used for electrical power transmission and distribution in the recent years. One of the current topics of interest for the power transmission community is the aging of such outdoor polymeric insulators. A few research groups are carrying out aging studies at room temperature with wet period as an integral part of multistress aging cycle as specified by IEC standards. However, aging effect due to dry conditions alone at elevated temperatures and electric stress in the presence of radiation environment has probably not been explored. It is interesting to study and understand the insulator performance under dry conditions where wet periods are either rare or absent and to estimate the extent of aging caused by multiple stresses. This paper deals with the long-term accelerated multistress aging on full-scale 11 kV distribution class composite silicone rubber insulators. In order to assess the long-term synergistic effect of electric stress, temperature and UV radiation on insulators, they are subjected to accelerated aging in a specially designed multistress-aging chamber for 3800 hours. All the stresses are applied at an accelerated level. Using a data acquisition system developed for the work, leakage current has been monitored in LabVIEW environment. Chemical changes due to degradations have been studied using Energy Dispersive X-Ray analysis, Scanning Electron Microscope and Fourier transform Infrared Spectroscopy. Periodically different parameters like low molecular weight (LMW) molecular content, hydrophobicity, leakage current and surface morphology were monitored. The aging study is under progress and only intermediate results are presented in this paper.

Quality assessment of CdZnTe (Zn similar to 4 %) crystals

We have studied the as grown and annealed CdZnTe (Zn similar to 4 %) crystals for the assessment of their crystalline quality. As grown crystals suffer from tellurium precipitates and cadmium vacancies, which are inherent, due to retrograde solid solubility curve in the phase diagram. This is reflected in the Fourier transform infrared (FTIR) spectra over the 400 - 4500 cm(-1) range by a strong absorption around 2661 cm(-1) which corresponds to the band gap of tellurium confirming their presence, where-as a monotonic decrease in the transmission with the decrease in wave number indicates the presence of cadmium vacancies. Obviously the presence of Cd vacancies lead to the formation of tellurium precipitates confirming their presence. Annealed samples under cadmium + zinc ambient at 650 degrees C for 6 hours show an improvement in the transmission over the same range. This can be attributed to thermo-migration of tellurium precipitates and hence bonding with Cd or Zn to form CdZnTe. This is further supported by the reduced full width at half maximum in the X-ray diffraction rocking curve of these CdZnTe crystals. Cadmium annealing although can passivate Cd vacancy related defects and reduce the Te precipitates, as is observed in our low temperature Photoluminescence (PL) spectra, alone may not be sufficient possibly due to the loss of Zn. Vacuum annealing at 650 degrees C for 6 hours further deteriorated the material quality as is reflected in the low temperature PL spectra by the introduction of a new defect band around 0.85 eV and reduced IR transmission.

Synthesis of BaSO4 nanoparticles by precipitation method using sodium hexa metaphosphate as a stabilizer

We describe the synthesis and structure of Barium sulfate nanoparticles by precipitation method in the presence of water soluble inorganic stabilizing agent, sodium hexametaphosphate, (NaPO3)(6). The structural parameters were refined by the Rietveld refinement method using powder X-ray diffraction data. Barium sulfate nanoparticles were crystallized in the orthorhombic structure with space group Pbnm (No. 62) having the lattice parameters a = 7.215(1) (angstrom), b = 8.949(1) (angstrom) and c = 5.501 (1) (angstrom) respectively. Transmission electron microscopy study reveals that the nanoparticles are size range, 30-50 nm. Fourier transform infrared spectra showed distinct absorption due to the SO42- moiety at 1115 and 1084 cm(-1) indicating formation of barium sulfate nanoparticles free from the phosphate group from the stabilizer used in the synthesis. (C) 2009 Elsevier Ltd. All rights reserved.

Automated Discovery of Structured Process Models: Discover Structured vs. Discover and Structure

This paper addresses the problem of discovering business process models from event logs. Existing approaches to this problem strike various tradeoffs between accuracy and understandability of the discovered models. With respect to the second criterion, empirical studies have shown that block-structured process models are generally more understandable and less error-prone than unstructured ones. Accordingly, several automated process discovery methods generate block-structured models by construction. These approaches however intertwine the concern of producing accurate models with that of ensuring their structuredness, sometimes sacrificing the former to ensure the latter. In this paper we propose an alternative approach that separates these two concerns. Instead of directly discovering a structured process model, we first apply a well-known heuristic technique that discovers more accurate but sometimes unstructured (and even unsound) process models, and then transform the resulting model into a structured one. An experimental evaluation shows that our “discover and structure” approach outperforms traditional “discover structured” approaches with respect to a range of accuracy and complexity measures.

Photocatalytic degradation of methyl methacrylate copolymers

The photolytic and photocatalytic degradation of the copolymers poly(methyl methacrylate-co-butyl methacrylate) (MMA–BMA), poly(methyl methacrylate-co-ethyl acrylate) (MMA–EA) and poly(methyl methacrylate-co-methacrylic acid) (MMA–MAA) have been carried out in solution in the presence of solution combustion synthesized TiO2 (CS TiO2) and commercial Degussa P-25 TiO2 (DP 25). The degradation rates of the copolymers were compared with the respective homopolymers. The copolymers and the homopolymers degraded randomly along the chain. The degradation rate was determined using continuous distribution kinetics. For all the polymers, CS TiO2 exhibited superior photo-activity compared to the uncatalysed and DP 25 systems, owing to its high surface hydroxyl content and high specific surface area. The time evolution of the hydroxyl and hydroperoxide stretching vibration in the Fourier transform-infrared (FT-IR) spectra of the copolymers indicated that the degradation rate follows the order MMA–MAA > MMA–EA > MMA–BMA. The same order is observed for the rate coefficients of photocatalytic degradation. The photodegradation rate coefficients were compared with the activation energy of pyrolytic degradation. In degradation by pyrolysis, it was observed that MMA–BMA was the least stable followed by MMA–EA and MMA–MAA. The observed contrast in the order of thermal stability compared to the photo-stability of these copolymers was attributed to the two different mechanisms governing the scission of the polymer and the evolution of the products.

Irradiation-mediated tailoring of carbon nanotubes

The ever-increasing demand for faster computers in various areas, ranging from entertaining electronics to computational science, is pushing the semiconductor industry towards its limits on decreasing the sizes of electronic devices based on conventional materials. According to the famous law by Gordon E. Moore, a co-founder of the world s largest semiconductor company Intel, the transistor sizes should decrease to the atomic level during the next few decades to maintain the present rate of increase in the computational power. As leakage currents become a problem for traditional silicon-based devices already at sizes in the nanometer scale, an approach other than further miniaturization is needed to accomplish the needs of the future electronics. A relatively recently proposed possibility for further progress in electronics is to replace silicon with carbon, another element from the same group in the periodic table. Carbon is an especially interesting material for nanometer-sized devices because it forms naturally different nanostructures. Furthermore, some of these structures have unique properties. The most widely suggested allotrope of carbon to be used for electronics is a tubular molecule having an atomic structure resembling that of graphite. These carbon nanotubes are popular both among scientists and in industry because of a wide list of exciting properties. For example, carbon nanotubes are electronically unique and have uncommonly high strength versus mass ratio, which have resulted in a multitude of proposed applications in several fields. In fact, due to some remaining difficulties regarding large-scale production of nanotube-based electronic devices, fields other than electronics have been faster to develop profitable nanotube applications. In this thesis, the possibility of using low-energy ion irradiation to ease the route towards nanotube applications is studied through atomistic simulations on different levels of theory. Specifically, molecular dynamic simulations with analytical interaction models are used to follow the irradiation process of nanotubes to introduce different impurity atoms into these structures, in order to gain control on their electronic character. Ion irradiation is shown to be a very efficient method to replace carbon atoms with boron or nitrogen impurities in single-walled nanotubes. Furthermore, potassium irradiation of multi-walled and fullerene-filled nanotubes is demonstrated to result in small potassium clusters in the hollow parts of these structures. Molecular dynamic simulations are further used to give an example on using irradiation to improve contacts between a nanotube and a silicon substrate. Methods based on the density-functional theory are used to gain insight on the defect structures inevitably created during the irradiation. Finally, a new simulation code utilizing the kinetic Monte Carlo method is introduced to follow the time evolution of irradiation-induced defects on carbon nanotubes on macroscopic time scales. Overall, the molecular dynamic simulations presented in this thesis show that ion irradiation is a promisingmethod for tailoring the nanotube properties in a controlled manner. The calculations made with density-functional-theory based methods indicate that it is energetically favorable for even relatively large defects to transform to keep the atomic configuration as close to the pristine nanotube as possible. The kinetic Monte Carlo studies reveal that elevated temperatures during the processing enhance the self-healing of nanotubes significantly, ensuring low defect concentrations after the treatment with energetic ions. Thereby, nanotubes can retain their desired properties also after the irradiation. Throughout the thesis, atomistic simulations combining different levels of theory are demonstrated to be an important tool for determining the optimal conditions for irradiation experiments, because the atomic-scale processes at short time scales are extremely difficult to study by any other means.

Fusion of Multisensor Data:Review and Comparative Analysis

Image fusion is a formal framework which is expressed as means and tools for the alliance of multisensor, multitemporal, and multiresolution data. Multisource data vary in spectral, spatial and temporal resolutions necessitating advanced analytical or numerical techniques for enhanced interpretation capabilities. This paper reviews seven pixel based image fusion techniques - intensity-hue-saturation, brovey, high pass filter (HPF), high pass modulation (HPM), principal component analysis, fourier transform and correspondence analysis.Validation of these techniques on IKONOS data (Panchromatic band at I m spatial resolution and Multispectral 4 bands at 4 in spatial resolution) reveal that HPF and HPM methods synthesises the images closest to those the corresponding multisensors would observe at the high resolution level.

New Strategies for the Enrichment of Metallic Single-Walled Carbon Nanotubes

Enrichment of metallic single-walled carbon nanotubes (SWNTs) has been accomplished by several means, including new extraction and synthetic procedures and by interaction with metal nanoparticles as well as electron donor molecules. In the presence of Fe(CO)(5) the arc discharge method yields nearly pure metallic nanotubes. Fluorous chemistry involving the preferential diazotization of metallic SWNTs offers a good procedure of obtaining the pure metallic species. Interaction of gold or platinum nanoparticles as well as of electron-donor molecules such as aniline and tetrathiafulvalene (TTF) transform semiconducting SWNTs into metallic ones. Raman and electroni spectroscopies provide ideal means to monitor enrichment of metallic SWNTs.

A semi-analytical solution for multilayer diffusion in a composite medium consisting of a large number of layers

Diffusion in a composite slab consisting of a large number of layers provides an ideal prototype problem for developing and analysing two-scale modelling approaches for heterogeneous media. Numerous analytical techniques have been proposed for solving the transient diffusion equation in a one-dimensional composite slab consisting of an arbitrary number of layers. Most of these approaches, however, require the solution of a complex transcendental equation arising from a matrix determinant for the eigenvalues that is difficult to solve numerically for a large number of layers. To overcome this issue, in this paper, we present a semi-analytical method based on the Laplace transform and an orthogonal eigenfunction expansion. The proposed approach uses eigenvalues local to each layer that can be obtained either explicitly, or by solving simple transcendental equations. The semi-analytical solution is applicable to both perfect and imperfect contact at the interfaces between adjacent layers and either Dirichlet, Neumann or Robin boundary conditions at the ends of the slab. The solution approach is verified for several test cases and is shown to work well for a large number of layers. The work is concluded with an application to macroscopic modelling where the solution of a fine-scale multilayered medium consisting of two hundred layers is compared against an “up-scaled” variant of the same problem involving only ten layers.

Hydrothermal synthesis and characterization of CaSO4 pseudomicrorods

Calcium sulphate (CaSO4) pseudomicrorods have been synthesized by alow-temperature hydrothermal method using CaSO4 powder as a precursor and hexadecylamine as a surfactant at 180 degrees C for at different intervals of time. The powder X-ray diffraction pattern indicates that the as-formed pseudomicrorods are of orthorhombic phase with lattice parameters a = 7.0023(4) angstrom, b = 6.9939(5) angstrom and c = 6.2434(4) angstrom. Scanning electron microscopy images show that the pseudomicrorods have diameters of about 0.2-2.5 mm and lengths of about 2-10 mm. Fourier transform infrared spectroscopy shows a strong doublet near 609 and 681 cm(-1) arising from nu(4) (SO42) bending vibrations. The strongest band observed at 1132 cm(-1) is associated with nu(3) (SO42-) stretching vibrations. The band near 420-450 cm(-1) is attributed to nu(2) (SO42-) bending vibrations. The Raman spectrum exhibits an intense peak at 1008 cm(-1) associated with the SO42- mode. The photoluminescence spectrum exhibits UV bands (330, 350 nm), strong green bands (402, 436 nm) and weak blue bands (503 nm). A widening of the optical band gap was observed as the particle size decreased.

How do construction firms learn on collaborative infrastructure projects?

Construction firms that employ collaborative procurement approaches develop operating routines through joint learning so as to improve infrastructure project performance. This paper reports a study based on a survey sample of 320 construction practitioners which were involved in collaborative infrastructure delivery in Australia. The study developed valid and reliable scales for measuring collaborative learning capability (CLC), and used the scales to evaluate the CLC of contractor and consultant firms within the sample. The evaluation suggests that whilst these firms explore knowledge from both internal and external sources, transform both explicit and tacit knowledge, and apply and internalise new knowledge, they can improve the extent to which these routines are applied to optimise project performance.

Ruumis ja rauta : esseitä esineiden sosiaalisuudesta

"Body and Iron: Essays on the Socialness of Objects" focuses on the bodily-material interaction of human subjects and technical objects. It poses a question, how is it possible that objects have an impact on their human users and examines the preconditions of active efficacy of objects. In this theoretical task the work relies on various discussions drawing from realistic ontology, phenomenology of body, neurophysiology of Antonio Damasio and psychoanalysis to establish both objects and bodies as material entities related in a causal interaction with each other. Out of material interaction emerge a symbolic field, psyche and culture that produce representations of interactions with material world they remain dependent on and conditioned by. Interaction with objects informs the human body via its somatosensory systems: interoseptive and proprioseptive (or kinesthetic) systems provide information to central nervous system of the internal state of the body and muscle tensions and motor activity of the limbs. Capability to control the movements of one's body by the internal "feel" of being a body turns out to be a precondition to the ability to control artificial extensions of the body. Motor activity of the body is involved in every perception of environment as the feel of one's own body is constitutive of any perception of external objects. Perception of an object cause changes in the internal milieu of the body and these changes in the organism form a bodily representation of an external object. Via these "muscle images" the subject can develop a feel for an instrument. Bodily feel for an object is pre-conceptual, practical knowledge that resists articulation but allows sensing the world through the object. This is what I would call sensual knowledge. Technical objects intervene between body and environment, transforming the relation of perception and motor activity. Once connected to a vehicle, human subject has to calibrate visual information of his or her position and movement in space to the bodily actions controlling the machine. It is the machine that mediates the relation of human actions to the relation of her body to its environment. Learning to use the machine necessarily means adjusting his or her bodily actions to the responses of the machine in relation to environmental changes it causes. Responsiveness of the machine to human touch "teaches" its subject by providing feedback of the "correctitude" of his or her bodily actions. Correct actions form a body technique of handling the object. This is the way of socialness of objects. While responding to human actions they generate their subjects. Learning to handle a machine means accepting the position of the user in the program of action materialized in the construction of the object. Objects mediate, channel and transform the relation of the body to its environment and via environment to the body itself according to their material and technical construction. Objects are sensory media: they channel signals and information from the environment thus constituting a representation of environment, a virtual or artificial reality. They also feed the body directly with their powers equipping their user with means of regulating somatic and psychic states of her self. For these reasons humans look for the company of objects. Keywords: material objects, material culture, sociology of technology, sociology of body, mobility, driving

Agoralla : avauksia ympäristöasiantuntijoiden vuorovaikutusprosesseista

Ympäristöasiantuntijoiden vuorovaikutusta on tutkittu agoralla (antiikin tori). Se on julkinen tila, jossa markkinat, politiikka, tiede ja yhteiskunta kohtaavat. Tutkimus kuuluu yhteiskuntatieteellisen ympäristötutkimuksen alaan, mutta siinä hyödynnetään myös tulevaisuudentutkimusta. Työn motivaationa on ollut tekijän monitieteinen koulutustausta: yhteiskuntatieteilijä ja luonnontieteilijä. Miten ja miksi vuorovaikutus eri asiantuntijoiden välillä on haasteellista ja merkityksellistä esimerkiksi metsän biodiversiteetin vähenemisen ehkäisemiseksi. Keskeisiä käsitteitä ovat asiantuntijuus, vuorovaikutus, tiedon luotettavuusja kontekstisidonnaisuus, Väitöskirja koostuu neljästä eri asiantuntijuustarinasta. Ensimmäinen (luku 2) perustuu haastatteluihin suomalaisten ja saksalaisten bio- ja yhteiskuntatietelijöiden käsityksistä luonnosta ja ympäristöstä. Tutkimusongelmana on luonnontieteilijöiden ja yhteiskuntatieteilijöiden Suomessa ja Saksassa ”kulttuurierot” luonnon ja ympäristön käsitteellistämisessä. Johtopäätöksenä on, että aistittu luonto, ympäröivä ympäristö sekä ihmisen muokkaama elinympäristö eivät tunne selkeitä tiede- eikä maanrajoja. Tämä luku toimii ponnahduslautana konstruktioiden taakse vuorovaikutuksen haasteisiin. Kirjan toinen tarina (luku 3) perustuu haastatteluihin suomalaisten metsän biodiversiteettiasiantuntijoiden vuorovaikutuksesta. Tutkimusongelman lähtökohtana on metsän biodiversiteetin väheneminen ja tästä seuraavat polittisetkin vuorovaikutustilanteet. Miten konteksti vaikuttaa eri asiantuntijoiden vuorovaikutukseen ja mitä tästä seuraa? Analyysin päätulos on implisiittisen, vahvasti kontekstisidonnaisen asiantuntijatiedon hyödyntämisen tarve ja voimavara metsän biodiversiteetin vähenemisen ennaltaehkäisemiksi. Kolmas tarina asiantuntijuudesta (luku 4) perustuu Etelä-Suomen metsien suojelutoimikunnassa (Metso) tehtyihin havainnointeihin. Tutkija on näin ollut itse eräänlaisella torilla havainnoijana. Tutkimusongelmana on ”ohipuhuminen”, tiedon luotettavuus ja implisiittien tiedon hyväksyttävyys. Johtopäätöksenä on asiantuntijuuden vahva kontekstisidonnaisuus hetkeen ja paikkaan ja yhteisen kielen (vrt. transdisiplinaarisuus) löytyminen yhteisen tavoitteen saavuttamiseksi. Merkittäviä välineitä vuorovaikutuksen onnistumiseen ovat esimerkiksi yhteinen vahva tavoitetila, interkatio, joka koskee läsnä olevia ihmisiä ei instituutioita sekä fasilitaattorin vahva rooli tulkkina ja välittäjänä. Neljäs tarina (luku 5) vie agoran konkretiaan. Tässä luvussa on kehitetty eläytymiskävely- menetelmää, jossa fasilitaattori (tutkija) johdattaa Espoon keskuksessa hallinnon, politiikan, asukkaiden ja konsultin edustajat aistimaan ja tulkitsemaan alueen sosiaalista tilaa, toiminnallisuutta ja elämyksellisyyttä. Ongelmana on aistimaailman asiantuntemuksen hyödyntämättömyys yhdyskuntasuunnittelun välineenä mm. asiantuntijoiden vuorovaikutuksen välineenä. Menetelmäkehitys on aluillaan, mutta jo tässä tapauksessa käy ilmi, että jaettu tila, jaetut aistikokemukset konkreettisella kävelyllä avaavaat vuorovaikutuksen uusiin ulottuvuuksiin, jossa implisiittiselle asiantuntemukselle annetaan sijansa vuorovaikutuksessa ja tätä kautta voidaan vaikuttaa myös tehtäviin päätöksiin, toimenpiteisiin. Johtopäätöksissä (luku 6) korostuu implisiittisen asiantuntijuuden merkitys. Onnistunut vuorovaikutteinen toiminta eri asiantuntijoiden kesken esimerkiksi erilaisia ympäristöongelmia –ja ilmiöitä ratkottaessa ja pohdittaessa vaatii vuorovaikutusosaamista. Tutkimuksen lopuksi suositellaan esimerkiksi ennakkoluulottomia avauksia agoralla. Asiantuntijuus ei ole yksi ja vain asiaatuntevuus on mahdollista. Agora on jatkuvassa liikkeessä ja juuri siinä piilee voimavara tulevaisuuden haasteisiin erilaisilla rajapinnoilla. Avainsanat: asiantuntijuus, vuorovaikutus, tieto, konteksti, agora