Shot noise in the chaotic-to-regular crossover regime

We investigate the shot noise for phase-coherent quantum transport in the chaotic-to-regular crossover regime. Employing the Modular Recursive Green's Function Method for both ballistic and disordered two-dimensional cavities we find the Fano factor and the transmission eigenvalue distribution for regular systems to be surprisingly similar to those for chaotic systems. We argue that in the case of regular dynamics in the cavity, diffraction at the lead openings is the dominant source of shot noise. We also explore the onset of the crossover from quantum to classical transport and develop a quasi-classical transport model for shot noise suppression which agrees with the numerical quantum data.Comment: 4 pages, 3 figures, submitted to Phys.Rev.Let

PCDAmpl, a new antigen at the interface of the embryonic collecting duct epithelium and the nephrogenic mesenchyme

P CDAmpl, a new antigen at the interface of the embryonic collecting duct epithelium and the nephrogenic mesenchyme. In the neonatal rabbit kidney nephrogenesis is not yet terminated. The ampullar collecting duct epithelium acts as an inducer that generates the nephron anlagen, however, to date the morphogenic mechanisms involved are unknown. A presupposition for successful nephron induction is the close tissue interaction between the basal aspect of the ampullar collecting duct epithelium and the surrounding mesenchyme. To gain new insights in this area we raised monoclonal antibodies (mabs), to identify specific structures localized at the tissue interface. With the generated mab CDAmpl we found an intensive immunohistochemical reaction between the basal aspect of the ampullar collecting duct epithelium and the mesenchyme. The label was most concentrated at the ampullar tip and continuously decreased in the shaft region. In the maturing collecting duct of the neonatal kidney and in the adult renal collecting duct no immunohistochemical reaction was found. The binding pattern of mab CDAmpl is different from that of all known collecting duct cell markers and from antibodies against known basement membrane compounds such as laminin or collagen type IV. Under in vitro conditions immunoreactivity with mab CDAmpl was obtained using embryonic collecting duct epithelia and perfusion culture. The antigen was present in specimens treated with Iscove's modified Dulbecco's Medium (IMDM) containing 10% fetal bovine serum. Omittance of serum or hormonal treatment with aldosterone, insulin or vitamin D3 led to the disappearance of the newly detected antigen, while characteristics of the differentiated collecting duct cells were up-regulated. We conclude that the expression of P CDAmpl is a characteristic feature of the embryonic parts of the collecting duct epithelium. It may play a pivotal role during nephron induction

Repression of anti-proliferative factor Tob1 in osteoarthritic cartilage

Osteoarthritis is the most common degenerative disorder of the modern world. However, many basic cellular features and molecular processes of the disease are poorly understood. In the present study we used oligonucleotide-based microarray analysis of genes of known or assumed relevance to the cellular phenotype to screen for relevant differences in gene expression between normal and osteoarthritic chondrocytes. Custom made oligonucleotide DNA arrays were used to screen for differentially expressed genes in normal (n = 9) and osteoarthritic (n = 10) cartilage samples. Real-time polymerase chain reaction (PCR) with gene-specific primers was used for quantification. Primary human adult articular chondrocytes and chondrosarcoma cell line HCS-2/8 were used to study changes in gene expression levels after stimulation with interleukin-1β and bone morphogenetic protein, as well as the dependence on cell differentiation. In situ hybridization with a gene-specific probe was applied to detect mRNA expression levels in fetal growth plate cartilage. Overall, more than 200 significantly regulated genes were detected between normal and osteoarthritic cartilage (P < 0.01). One of the significantly repressed genes, Tob1, encodes a protein belonging to a family involved in silencing cells in terms of proliferation and functional activity. The repression of Tob1 was confirmed by quantitative PCR and correlated to markers of chondrocyte activity and proliferation in vivo. Tob1 expression was also detected at a decreased level in isolated chondrocytes and in the chondrosarcoma cell line HCS-2/8. Again, in these cells it was negatively correlated with proliferative activity and positively with cellular differentiation. Altogether, the downregulation of the expression of Tob1 in osteoarthritic chondrocytes might be an important aspect of the cellular processes taking place during osteoarthritic cartilage degeneration. Activation, the reinitiation of proliferative activity and the loss of a stable phenotype are three major changes in osteoarthritic chondrocytes that are highly significantly correlated with the repression of Tob1 expression

Suppression of Decoherence in Fast-Atom Diffraction at Surfaces

Scattering of fast neutral atoms with keV kinetic energies at alkali-halide surfaces under grazing angles displays intriguing diffraction patterns. The surprisingly strong persistence of quantum coherence despite the impulsive interaction with an environment at solid state density and elevated temperatures raises fundamental questions such as to the suppression of decoherence and of the quantum-to-classical crossover. We present an ab initio simulation of the quantum diffraction of fast helium beams at a LiF (100) surface in the direction and compare with recent experimental diffraction data. From the quantitative reconstruction of diffraction images the vertical LiF-surface reconstruction, or buckling, can be determined

Identification and assessment of opportunities and threats for the Circular Economy arising from E-commerce

The present study identifies, describes and assesses in detail opportunities and threats for the Circular Economy arising from E-commerce. A broad literature research and direct stakeholder input led to the identification of 18 opportunities and 23 threats for the Circular Economy, allocated to 7 different clusters. Most of the identified threats refer to “Logistics and transport”, while opportunities refer mainly to the topics “Accessibility of information” and “Digitalisation”. By means of a comparative assessment in the current situation and future optimistic and pessimistic potential developments, the direct and indirect effects of the opportunities and threats have been evaluated, with specific focus on 7 selected product categories. In total, 11 opportunities and 16 threats have been assessed as either medium or highly relevant. The assessment revealed that most of the threats classified as highly relevant belong to the cluster “Logistics and transport”, including induced parcel transport, parcel return and inefficient transport, while most of the highly relevant opportunities are to be found in the cluster “Accessibility of information”, as in the case of second-hand commerce or product portfolio.JRC.B.5-Circular Economy and Industrial Leadershi

Miljökonsekvenser av mediekonsumtion inbäddad i digitala ekosystem : En bottom up-analys av det återkommande fallet av papperslös läsning i Tyskland

Digitalization has been reshaping the media landscape in recent years, often conveying an implicit promise of becoming less dependent on physical resources. At the same time, the current understanding of digital reading goes beyond dedicated e-readers or definable digital media products such as magazines or newspapers. In fact, it must be perceived as a function or service obtained from existing and ever-expanding “digital ecosystems”. There is furthermore a clear and unambiguous trend that relatively small and mobile devices are on the rise for consuming all kinds of media. Next to potentially enabling environmental gains compared to traditional paper-based media consumption, there are agreeing indications of a shift from overall electricity consumption dominated by end-user devices towards an increasing importance of less tangible data transmission networks and data centers. Therefore, a bottom-up analysis is deemed to compliment more general top-down observations and assessments. To this end, an elaborated reference scenario is proposed as to bridge the mere analytical method of Life Cycle Assessment (LCA) with behavioral aspects based on German market observations and surveys. The prevailing aim of this study is to detect environmental hot-spots and absolute impacts linked to the service of accessing text-based content via connected electronic devices. In doing so, this study takes the position that both types of media consumption – digital and paper-based - are incommensurable due to the very evident differences in provided functions, markets, and industries. Therefore, an attributional and stand-alone LCA is considered appropriate. The perceived current situation (reference scenario) evolves around substantiated estimates and assumptions concerning production of devices, use of devices as well as operation of essential data transmission network components. Looking at potential hot-spots, electricity consumption linked to data transmission could be a decisive factor for the environmental performance of digital reading. However, the actual importance of data transmission infrastructures depends on both methodological choices and a range of parameters or trends. For instance, the relative importance is shifted when more recent estimates of electricity intensities are incorporated. Depending on actual and localized electricity intensity of data transmission, the amount of data required to provide an expected function may inhibit environmental potentials of digital media consumption. Postulating average annual consumption of digital contents and assuming actual substitution of equivalent printed media products, about 50 kg CO2-equivalents. could potentially be avoided. This theoretical potential is based on the calculated global warming potential (GWP) associated with digital reading according to the reference scenario which amounts to about 29 kg CO2-equivalents. Therefore, this study supports findings from previous studies that indicated environmental benefits of digital reading. Compared to other functions or services (e.g. video/music streaming, podcasts, audio books) embedded in the same “digital ecosystems”, reading requires little amount of data. If allocation of upstream effects is based on time, the relative importance of data transmission networks could be gauged and compared by adopting a “data-to-service time” ratio. Taking the reference scenario as a starting point, a perceivable ratio for digital reading is 0.015 GB/h, including systemic inefficiencies. In contrast, streaming of high-definition video contents can easily consume 3 GB/h, a 200-fold increase. The audience of this study comprises providers of digital reading services and/or other media services as well as end-users as integral element in “digital ecosystems”. Besides, the report proposes a conceptual assessment framework which can be applied to other contemporary digital services or functions.De senaste åren har digitalisering omformat medielandskapet, med ett implicit löfte om att minska beroendet av fysiska resurser. Dessutom finns det tydliga trender som pekar mot en ökad användning av små, mobila enheter för att konsumera alla sorters media. En uppdaterad bottom-up analys bedöms komplettera mer generella observationer och bedömningar. Om man antar årliga genomsnittliga konsumtionsmönster i Tyskland, så är tillverkningen av elektroniska slutanvändarenheter – oavsett om de är till för enskilda ändamål (e-läsare) eller om de är multifunktionella (smartphone, surfplatta) – onekligen en miljömässigt kritisk punkt för digitalt läsande. Elförbrukningen, som sker i samband med dataöverföringen, kan också vara en avgörande faktor för den övergripande miljöpåverkan av digital läsning. Dock beror den faktiska påverkan av dataöverförningsinfrastrukturer dels på metodologiska val men även på ett antal andra parametrar och trender. Genom att undersöka indikatorn för global uppvärmning kan denna studie konstatera att resultaten stödjer tidigare forskning, som redan pekar på de miljömässiga vinsterna av digitalt läsande. Målgruppen för denna studie innefattar både distributörer av digitala läs-tjänster och/eller andra media tjänster såväl som slutanvändare som ett integrerat element i ”digitala ekosystem”

Miljökonsekvenser av mediekonsumtion inbäddad i digitala ekosystem : En bottom up-analys av det återkommande fallet av papperslös läsning i Tyskland

Digitalization has been reshaping the media landscape in recent years, often conveying an implicit promise of becoming less dependent on physical resources. At the same time, the current understanding of digital reading goes beyond dedicated e-readers or definable digital media products such as magazines or newspapers. In fact, it must be perceived as a function or service obtained from existing and ever-expanding “digital ecosystems”. There is furthermore a clear and unambiguous trend that relatively small and mobile devices are on the rise for consuming all kinds of media. Next to potentially enabling environmental gains compared to traditional paper-based media consumption, there are agreeing indications of a shift from overall electricity consumption dominated by end-user devices towards an increasing importance of less tangible data transmission networks and data centers. Therefore, a bottom-up analysis is deemed to compliment more general top-down observations and assessments. To this end, an elaborated reference scenario is proposed as to bridge the mere analytical method of Life Cycle Assessment (LCA) with behavioral aspects based on German market observations and surveys. The prevailing aim of this study is to detect environmental hot-spots and absolute impacts linked to the service of accessing text-based content via connected electronic devices. In doing so, this study takes the position that both types of media consumption – digital and paper-based - are incommensurable due to the very evident differences in provided functions, markets, and industries. Therefore, an attributional and stand-alone LCA is considered appropriate. The perceived current situation (reference scenario) evolves around substantiated estimates and assumptions concerning production of devices, use of devices as well as operation of essential data transmission network components. Looking at potential hot-spots, electricity consumption linked to data transmission could be a decisive factor for the environmental performance of digital reading. However, the actual importance of data transmission infrastructures depends on both methodological choices and a range of parameters or trends. For instance, the relative importance is shifted when more recent estimates of electricity intensities are incorporated. Depending on actual and localized electricity intensity of data transmission, the amount of data required to provide an expected function may inhibit environmental potentials of digital media consumption. Postulating average annual consumption of digital contents and assuming actual substitution of equivalent printed media products, about 50 kg CO2-equivalents. could potentially be avoided. This theoretical potential is based on the calculated global warming potential (GWP) associated with digital reading according to the reference scenario which amounts to about 29 kg CO2-equivalents. Therefore, this study supports findings from previous studies that indicated environmental benefits of digital reading. Compared to other functions or services (e.g. video/music streaming, podcasts, audio books) embedded in the same “digital ecosystems”, reading requires little amount of data. If allocation of upstream effects is based on time, the relative importance of data transmission networks could be gauged and compared by adopting a “data-to-service time” ratio. Taking the reference scenario as a starting point, a perceivable ratio for digital reading is 0.015 GB/h, including systemic inefficiencies. In contrast, streaming of high-definition video contents can easily consume 3 GB/h, a 200-fold increase. The audience of this study comprises providers of digital reading services and/or other media services as well as end-users as integral element in “digital ecosystems”. Besides, the report proposes a conceptual assessment framework which can be applied to other contemporary digital services or functions.De senaste åren har digitalisering omformat medielandskapet, med ett implicit löfte om att minska beroendet av fysiska resurser. Dessutom finns det tydliga trender som pekar mot en ökad användning av små, mobila enheter för att konsumera alla sorters media. En uppdaterad bottom-up analys bedöms komplettera mer generella observationer och bedömningar. Om man antar årliga genomsnittliga konsumtionsmönster i Tyskland, så är tillverkningen av elektroniska slutanvändarenheter – oavsett om de är till för enskilda ändamål (e-läsare) eller om de är multifunktionella (smartphone, surfplatta) – onekligen en miljömässigt kritisk punkt för digitalt läsande. Elförbrukningen, som sker i samband med dataöverföringen, kan också vara en avgörande faktor för den övergripande miljöpåverkan av digital läsning. Dock beror den faktiska påverkan av dataöverförningsinfrastrukturer dels på metodologiska val men även på ett antal andra parametrar och trender. Genom att undersöka indikatorn för global uppvärmning kan denna studie konstatera att resultaten stödjer tidigare forskning, som redan pekar på de miljömässiga vinsterna av digitalt läsande. Målgruppen för denna studie innefattar både distributörer av digitala läs-tjänster och/eller andra media tjänster såväl som slutanvändare som ett integrerat element i ”digitala ekosystem”

Shot noise in transport through quantum dots: Clean versus disordered samples

Abstract We investigate the role of disorder and diffractive scattering in the shot noise power of quantum transport through a two-dimensional quantum dot. By tuning the strength of the disorder potential and the openings of the dot, we numerically explore the influence of quantum scattering mechanisms on the current shot noise. For small cavity openings we find the shot noise for disordered samples to be of almost equal magnitude as for clean samples where transport is ballistic. We explain this finding by diffractive scattering at the cavity openings which act as strong noise sources. Estimates for the shot noise induced by both the disorder potential and the diffractive openings are presented that agree with the numerical data