Nanoscale electrical conductivity imaging using a nitrogen-vacancy center in diamond

The electrical conductivity of a material can feature subtle, nontrivial, and spatially-varying signatures with critical insight into the material's underlying physics. Here we demonstrate a conductivity imaging technique based on the atom-sized nitrogen-vacancy (NV) defect in diamond that offers local, quantitative, and noninvasive conductivity imaging with nanoscale spatial resolution. We monitor the spin relaxation rate of a single NV center in a scanning probe geometry to quantitatively image the magnetic fluctuations produced by thermal electron motion in nanopatterned metallic conductors. We achieve 40-nm scale spatial resolution of the conductivity and realize a 25-fold increase in imaging speed by implementing spin-to-charge conversion readout of a shallow NV center. NV-based conductivity imaging can probe condensed-matter systems in a new regime, and as a model example, we project readily achievable imaging of nanoscale phase separation in complex oxides.Comment: Supplementary information at en

Lukutaito ja kestävä kehitys

The author deals with the topic of sustainable development and literacy from the viewpoint of a poor developing country. The president of the Sarvodaya Movement, which represents a new literacy and development strategy, presents us with a new literacy of enlightenment as an alternative to the traditional! and functional concept of literacy. The author considers it to be considerably more appropriate for the needs of the exploited and discriminated against sectors of society as they strive to improve their lot.Kirjoittajan aiheena on kestävän kehityksen käsite ja lukutaito köyhän kehitysmaan näkökulmasta. Uudenlaista lukutaito- ja kehitysstrategiaa edustavan Sarvodaya-liikkeen presidentti tuo traditionaalisen ja funktionaalisen lukutaitokäsitteen rinnalle uuden, enlightenment literacyn, jonka kirjoittaja katsoo sopivan verrattomasti paremmin sorrettujen ja syrjittyjen kansankerrosten pyrkimyksiin parantaa asemaansa

Institutions, impact synergies and food security: a methodology with results from the Kala Oya Basin, Sri Lanka

Institutional development / Development plans / Development policy / Impact assessment / River basins / Food security / Models

Applicability of frozen-viscosity models of unsteady wall shear stress

The validity of assumed frozen-viscosity conditions underpinning an important class of theoretical models of unsteady wall shear stress in transient flows in pipes and channels is assessed using detailed computational fluid dynamics (CFD) simulations. The need for approximate one-dimensional ð1DÞfx; tg models of the wall stress is unavoidable in analyses of transient flows in extensive pipe networks because it would be economically impracticable to use higher order methods of analysis. However, the bases of the various models have never been established rigorously. It is shown herein that a commonly used approach developed by the first authors is flawed in the case of smoothwall flows although it is more plausible for rough-wall flows. The assessment process is undertaken for a particular, but important, unsteady flow case, namely, a uniform acceleration from an initially steady turbulent flow. First, detailed predictions from a validated CFD method are used to derive baseline solutions with which predictions based on approximate models can be compared. Then, alternative solutions are obtained using various prescribed frozen-viscosity distributions. Differences between these solutions and the baseline solutions are used to determine which frozen-viscosity distributions are the most promising starting points for developing 1Dfx; tg models of unsteady components of wall shear stress. It is shown that no frozen-viscosity distribution performs well for large times after the commencement of an acceleration. However, even the simplest approximation (laminar) performs well for short durations—which is when the greatest amplitudes of the unsteady components occu

Unsteady skin friction experimentation in a large diameter pipe

Experimental data for the validation of theoretical models of unsteady skin friction are limited and are available only for a few low Reynolds number flow cases. There is a strong need for detailed measurements in flows at high Reynolds numbers. In addition, there is a need for a wider range of well-controlled acceleration/deceleration rates and detailed visualization of flow structure and profiles. To address these needs, a large-scale pipeline apparatus at Deltares, Delft, The Netherlands, has been used for unsteady skin friction experiments including acceleration, deceleration and acoustic resonance tests. The apparatus consists of a constant head tank, a horizontal 200 mm diameter pipe of changeable length (44 to 49 metres) and a control valve at the downstream end. In addition to standard instrumentation, two distinctive instruments have been used: hot-film wall shear stress sensors ("direct" measurement of wall shear stress) and a PIV set-up for measurement of unsteady flow profiles. This paper describes the test rig, the instrumentation layout and the test programme. Finally, some initial test results are presented and discussed

Rural Development and Self-Support of the Villagers in the Third World

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Impact assessment and adaptation to climate change of plantations in Sri Lanka

This report documents the work undertaken by the IRI, FECT, NRMS and University of Peradeniya as part of the overall project. Separate reports were prepared by the Tea Research Institute, Coconut Research Institute and the Department of Meteorology in Sri Lanka. The work at IRI, FECT and NRMS has proceeded satisfactorily. The work was in the domain of climate and climate change, crop-climate impact analysis and contributions to synthesis. We have contributed significantly in terms of research output and in capacity building, which were the goals of the AIACC project

Frequency of natural out-crossing in partially cleistogamous pigeonpea lines in diverse environments

Natural out-crossing is the major cause of loss of varietal purity in pegeonpea [Cajanus cajan (L.) Millsp.]. The frequency of natural out-crossing of partially cleistogamous mutant lines, characterized by a modified keel and filamentous anthers, was studied at two locations in Sri Lanka and three locations in India. Indeterminate growth habit and normal floral morphology were used as dominant markers and the frequency of anural out-crossing was estimated as percentage of the observed hybrid plants. Natural out-crossing in the mutant lines in Sri Lanka ranged from 0.14 to 1.33% in comparison to 6.34 to 19.64% in the controls. In the Indian environments, natural outcrossing ranged from 0.16 to 2.67%. The mutant was higly stable over diverse environments, and may be of considerable economic importance in pigeonpea improvement and seed-production programs

Dynamics of notch pathway expression during mouse testis post-natal development and along the spermatogenic cycle

Articles in International JournalsThe transcription and expression patterns of Notch pathway components (Notch 1–3, Delta1 and 4, Jagged1) and effectors (Hes1, Hes2, Hes5 and Nrarp) were evaluated (through RT-PCR and IHC) in the mouse testis at key moments of post-natal development, and along the adult spermatogenic cycle. Notch pathway components and effectors are transcribed in the testis and expressed in germ, Sertoli and Leydig cells, and each Notch component shows a specific cell-type and timewindow expression pattern. This expression at key testis developmental events prompt for a role of Notch signaling in prepubertal spermatogonia quiescence, onset of spermatogenesis, and regulation of the spermatogenic cycle