1,314 research outputs found
On the theory of diamagnetism in granular superconductors
We study a highly disordered network of superconducting granules linked by
weak Josephson junctions in magnetic field and develop a mean field theory for
this problem. The diamagnetic response to a slow {\it variations} of magnetic
field is found to be analogous to the response of a type-II superconductor with
extremely strong pinning. We calculate an effective penetration depth
and critical current and find that both and
are non-zero but are strongly suppressed by frustration.Comment: REVTEX, 12 pages, two Postscript figure
Towards a Learning-Aware Application Guided by Hierarchical Classification of Learner Profiles
Learner profiling is a methodology that draws a parallel from user profiling. Implicit feedback is often used in recommender systems to create and adapt user profiles. In this work the implicit feedback is based on the learner's answering behaviour in the Android application UnlockYourBrain, which poses different basic mathematical questions to the learners. We introduce an analytical approach to model the learners' profile according to the learner's answering behaviour. Furthermore, similar learner's profiles are grouped together to construct a learning behaviour cluster. The choice of hierarchical clustering as a means of classification of learners' profiles derives from the observations of learners behaviour. This in turn reflects the similarities and subtle differences of learner behaviour, which are further analysed in more detail. Building awareness about the learner's behaviour is the first and necessary step for future learning-aware applications
Anisotropy in the helicity modulus of a 3D XY-model: application to YBCO
We present a Monte Carlo study of the helicity moduli of an anisotropic
classical three-dimensional (3D) XY-model of YBCO in superconducting state. It
is found that both the ab-plane and the c-axis helicity moduli, which are
proportional to the inverse square of the corresponding magnetic field
penetration depth, vary linearly with temperature at low temperatures. The
result for the c-axis helicity modulus is in disagreement with the experiments
on high quality samples of YBCO. Thus we conclude that purely classical phase
fluctuations of the superconducting order parameter cannot account for the
observed c-axis electrodynamics of YBCO.Comment: 7 pages, 1 figur
Nonlinear Seebeck Effect in a Model Granular Superconductor
The change of the Josephson supercurrent density of a weakly-connected
granular superconductor in response to externally applied arbitrary thermal
gradient dT/dx (nonlinear Seebeck effect) is considered within a model of 3D
Josephson junction arrays. For dT/dx>(dT/dx)_c, where (dT/dx)_c is estimated to
be of the order of 10^4 K/m for YBCO ceramics with an average grain's size of
10 microns, the weak-links-dominated thermopower S (Seebeck coefficient) is
predicted to become strongly dT/dx-dependent.Comment: REVTEX, no figure
Evaluation of small mammal pet supplies offered in German retail under animal welfare aspects
German retailers offer a large variety of accessories for pets. However, not all products are suitable for pet husbandry. Several articles can negatively influence the wellbeing of pets or cause injuries, but empirical studies that evaluate accessories for small pets under animal welfare aspects are rare. In the present study, we assessed articles manufactured or sold in Germany in the product categories pet cages, hay racks, running wheels, exercise balls, harnesses and leashes, tube systems, and hamster bedding. To do so, we searched 28 German websites, visited 50 pet shops and 13 home improvement and garden centers on site and afterwards examined the animal welfare compliance of the products according to various evaluation criteria. Most of the examined products were rated not suitable for pet husbandry and were animal-welfare-adverse. This result applies to 86.1% (n = 87) of the 101 assessed running wheel models, 82.7% (n = 172) of the 208 assessed pet cage models and 55.6% (n = 40) of the 72 assessed hay rack models. The articles in the product categories exercise balls, harnesses and leashes, tube systems, and hamster bedding were also found unsuitable due to animal welfare concerns. Furthermore, we found clear shortcomings regarding article declarations. In some cases, relevant product information (e.g., dimensions) were missing, or the presented information was too general (e.g., rodent cage). Improperly declared pet accessories make it difficult for pet owners to decide whether a product is suitable or unsuitable for the species they keep. A declaration duty for manufacturers of pet products could ensure that German retailers only offer properly declared pet accessories and facilitate the decision for pet owners to purchase products appropriate for the pets they keep. Furthermore, a voluntary product certification for manufacturers would allow retailers to check the animal welfare compliance of articles before including them in their assortment. If a product is unsuitable for pet husbandry because it does not meet the set requirements, it must be considered animal-welfare-adverse and removed from the assortment. As done for the Austrian āanimal welfare label,ā an independent, qualified third party could do the certification
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C/EBP Transcription Factors in Human Squamous Cell Carcinoma: Selective Changes in Expression of Isoforms Correlate with the Neoplastic State
The CCAAT/Enhancer Binding Proteins (C/EBPs) are a family of leucine-zipper transcription factors that regulate physiological processes such as energy metabolism, inflammation, cell cycle, and the development and differentiation of several tissues including skin. Recently, a role for C/EBPs in tumor cell proliferation and differentiation has been proposed, but the incomplete characterization in the literature of multiple translational isoforms of these proteins has made interpretation of these roles difficult. Therefore, we have carefully reexamined C/EBP isoform expression in human non-melanoma skin cancers. C/EBPĪ±, C/EBPĪ², and C/EBPĪ“ were analyzed histologically in squamous cell carcinomas (SCC). The individual isoforms of C/EBPĪ± and C/EBPĪ² were examined by immunofluorescent digital imaging, western blotting and DNA binding activity (electrophoretic mobility shift analysis). Expression of all C/EBP family proteins was decreased in SCC tumors. Suppression was greatest for C/EBPĪ±, less for C/EBPĪ², and least for C/EBPĪ“. Western analyses confirmed that C/EBPĪ± p42 and p30 isoforms were decreased. For C/EBPĪ², only the abundant full-length isoform (C/EBPĪ²ā1, LAP*, 55 kD) was reduced, whereas the smaller isoforms, C/EBPĪ²ā2 (LAP, 48 kD) and C/EBPĪ²ā3 (LIP, 20 kD), which are predominantly nuclear, were significantly increased in well- and moderately-differentiated SCC (up to 14-fold for C/EBPĪ²ā3). These elevations correlated with increases in PCNA, a marker of proliferation. Although C/EBPĪ² displayed increased post-translational modifications in SCC, phosphorylation of C/EBPĪ²ā1 (Thr 235) was not altered. C/EBP-specific DNA binding activity in nuclear and whole-cell extracts of cultured cells and tumors was predominantly attributable to C/EBPĪ². In summary, two short C/EBPĪ² isoforms, C/EBPĪ²ā2 and C/EBPĪ²ā3, represent strong candidate markers for epithelial skin malignancy, due to their preferential expression in carcinoma versus normal skin, and their strong correlation with tumor proliferation
Equivalency of four research-grade movement sensors to assess movement behaviors and its implications for population surveillance
Novel ānano-phageā interfaces for wireless biosensors
The prevention of food-borne illness has become a very important factor in public health.
Meantime, the conventional microbiological detection techniques are time consuming, require
proficiency and appropriate laboratory conditions. Recently, there has been an extensive work
undertaken towards the development of diagnostic biosensor devices for on-site detection of
biological threats that explore a diversity of transduction mechanisms and bio-recognition
elements. In particular, the environmentally robust filamentous phages have been successfully
used as an alternative to fragile antibodies in wireless biosensor system for real-time pathogen
detection. However, when phages are used as interface, they can aggregate forming bundles of
fibers that cannot cover completely the sensorās interface leading to the decrease in sensorās
performance. In this work we developed novel wireless magnetoelastic biosensors with interface
formed by biorecognition nanoparticles called ānano-phageā. āNano-phageā comprises
nanoparticles with diameter ~11 nm composed of self-assembled fusion major coat protein of
landscape phages selected against the target analyte. For proof-of-concept, we investigated
interfaces formed by three model phages selected from landscape libraries: streptavidin binders 7b1
and SAE10 and clone E2 highly specific and selective for S. typhimurium. Beside food borne
pathogens, this new approach can be used to develop biosensors with increased performance for
early detection of cancer diseases and other pathologies
Studies on dental erosion: An in vitro model of root surface erosion
The document attached has been archived with permission from the Australian Dental Association (8th Jan 2008). An external link to the publisherās copy is included.Most research on dental erosion has focused on erosion in enamel. However, the increasing retention of teeth into old age has increased the potential for root surface erosion. The nature and kinetics of root surface erosion have not yet been adequately explored. The objective of this project was to develop an in vitro model of root surface erosion in order to investigate the polarised light microscopy of controlled erosion and the histology and rate of demineralisation of this process in root cementum/dentine. The results demonstrate a process quite different in outcome from that in enamel erosion. Erosion results in loss of volume of enamel. However, it leaves a root surface softened though with little volume loss so long as the demineralised collagen remains hydrated. The polarised light histology was similar to that seen in root surface caries. The rate of erosive demineralisation of tooth roots by selected acids was investigated, with differing rates of demineralisation similar to that seen in enamel erosion observed. The process of erosion showed evidence of significant diffusion control.I. White, J. McIntyre and R. Loga
Indication of Superconductivity at 35 K in Graphite-Sulfur Composites
We report magnetization measurements performed on graphite--sulfur composites
which demonstrate a clear superconducting behavior below the critical
temperature T = 35 K. The Meissner-Ochsenfeld effect, screening
supercurrents, and magnetization hysteresis loops characteristic of type-II
superconductors were measured. The results indicate that the superconductivity
occurs in a small sample fraction, possibly related to the sample surface.Comment: published versio
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