3,834 research outputs found
Improved high voltage insulator for use in vacuum
High voltage insulator for electron bombardment ion thruster has electric field directed through dielectric material and electrons emitted by field emission are constrained in negative junction region. Surface flashover and unstable operation are eliminated, and maximum voltage is limited only by dielectric strength of material, aluminum oxide in this case
Changes in Imja Tsho in the Mount Everest Region of Nepal
Imja Tsho, located in the Sagarmatha ( Everest) National Park of Nepal, is one of the most studied and rapidly growing lakes in the Himalayan range. Compared with previous studies, the results of our sonar bathymetric survey conducted in September of 2012 suggest that its maximum depth has increased from 90.5 to 116.3 +/- 5.2 m since 2002, and that its estimated volume has grown from 35.8 +/- 0.7 to 61.7 +/- 3.7 million m(3). Most of the expansion of the lake in recent years has taken place in the glacier terminus-lake interface on the eastern end of the lake, with the glacier receding at about 52 m yr(-1) and the lake expanding in area by 0.04 km(2) yr(-1). A ground penetrating radar survey of the Imja-Lhotse Shar glacier just behind the glacier terminus shows that the ice is over 200 m thick in the center of the glacier. The volume of water that could be released from the lake in the event of a breach in the damming moraine on the western end of the lake has increased to 34.1 +/- 1.08 million m(3) from the 21 million m(3) estimated in 2002.USAID Climate Change Resilient Development (CCRD) projectFulbright FoundationNational Geographic SocietyCenter for Research in Water Resource
Visualisation Tools for Multi-Perspective, Cross-Sector, Long-Term Infrastructure Performance Evaluation
Across different infrastructure sectors there are systems that help to monitor the current and near-future operation
and performance of a particular system. Whilst Supervisory Control and Data Acquisition (SCADA) systems are critical
to maintaining acceptable levels of functionality, they do not provide insights over the longer timescales across which
strategic investment decisions play out. To understand how individual or multiple, interdependent, infrastructure
sectors perform over longer timescales, capacity/demand modelling is required. However, the outputs of such
models are often a complex high-dimensionality result-set, and this complexity is further compounded when crosssector
evaluation is required. To maximise utility of such models, tools are required that can process and present
key outputs. In this paper we describe the development of prototype tools for infrastructure performance evaluation
in relation to different strategic decisions and the complex outputs generated from capacity and demand models of
five infrastructure sectors (energy, water, waste water, solid waste, transport) investigated within the UK Infrastructure
Transitions Research Consortium (ITRC). By constructing tools that expose various dimensions of the model outputs,
a user is able to take greater control over the knowledge discovery process
Noether symmetries, energy-momentum tensors and conformal invariance in classical field theory
In the framework of classical field theory, we first review the Noether
theory of symmetries, with simple rederivations of its essential results, with
special emphasis given to the Noether identities for gauge theories. Will this
baggage on board, we next discuss in detail, for Poincar\'e invariant theories
in flat spacetime, the differences between the Belinfante energy-momentum
tensor and a family of Hilbert energy-momentum tensors. All these tensors
coincide on shell but they split their duties in the following sense:
Belinfante's tensor is the one to use in order to obtain the generators of
Poincar\'e symmetries and it is a basic ingredient of the generators of other
eventual spacetime symmetries which may happen to exist. Instead, Hilbert
tensors are the means to test whether a theory contains other spacetime
symmetries beyond Poincar\'e. We discuss at length the case of scale and
conformal symmetry, of which we give some examples. We show, for Poincar\'e
invariant Lagrangians, that the realization of scale invariance selects a
unique Hilbert tensor which allows for an easy test as to whether conformal
invariance is also realized. Finally we make some basic remarks on metric
generally covariant theories and classical field theory in a fixed curved
bakground.Comment: 31 pa
What About the “T’s”?: Addressing the Needs of a Transgender Student at a CCCU Member Institution
As the discussion of the LGBT community continues to evolve and inform decisions at higher education institutions, evidence suggests the “T”–transgender–discussion at CCCU institutions has remained stagnant and largely unrecognized. In June 2011 ACSD’s New Professionals Collaborative asked professionals to present a case study on how a CCCU institution would house a transgender student who had already been admitted into the institution. The authors found the literature on the subject to be sparse, and within the Christian context it is nearly nonexistent. The few precedents and best practices on housing a transgender student do not appear to align with the values of a CCCU institution. There are, however, a few viable housing options to explore, and while an exhaustive list was not created, several of the most likely are examined and discussed. Understanding that a transgender student’s situation is unique and recognizing a lack of knowledge, precedent, and expertise on the subject, the recommendation is to have a conversation with the student about institutional fit. If an agreement to live by the institution’s values is reached, the authors assert housing the student with his/her biological sex most aligns with the institution’s values. Ultimately, the most compelling conclusion and discussion is that CCCU institutions must urgently lay a philosophical and theological foundation on the transgender issue
Evidence for a superfluid density in t--J ladders
Applying three independent techniques, we give numerical evidence for a
finite superfluid density in isotropic hole-doped t--J ladders: We show the
existence of anomalous flux quantization, emphasising the contrasting behaviour
to that found in the `Luttinger liquid' regime stabilised at low electron
densities; We consider the nature of the low-lying excitation modes, finding
the 1-D analog of the superconducting state; And using a density matrix
renormalization group approach, we find long range pairing correlations and
exponentially decaying spin-spin correlations.Comment: 4 pages, revtex, postscript figs included, submitted to PR
NTR plume modeling
Viewgraphs on nuclear thermal propulsion are presented. Topics covered include computational fluid dynamics (CFD) for plume analysis; molecular fluid dynamics; molecular CFD characteristics; direct-simulation Monte-Carlo (DSMC) method; integration of DSMC and Navier-Stokes computations; and density profiles
A First Step Towards Automatically Building Network Representations
To fully harness Grids, users or middlewares must have some knowledge on the
topology of the platform interconnection network. As such knowledge is usually
not available, one must uses tools which automatically build a topological
network model through some measurements. In this article, we define a
methodology to assess the quality of these network model building tools, and we
apply this methodology to representatives of the main classes of model builders
and to two new algorithms. We show that none of the main existing techniques
build models that enable to accurately predict the running time of simple
application kernels for actual platforms. However some of the new algorithms we
propose give excellent results in a wide range of situations
Fully Dried Two-Dimensional Paper Network for Enzymatically Enhanced Detection of Nucleic Acid Amplicons
Two-dimensional paper networks (2DPNs) have enabled the use of paper-based platforms to perform multistep immunoassays for detection of pathogenic diseases at the point-of-care. To date, however, detection has required the user to provide multiple signal enhancement solutions and been limited to protein targets. We solve these challenges by using mathematical equations to guide the device design of a novel 2DPN, which leverages multiple fluidic inputs to apply fully dried solutions of hydrogen peroxide, diaminobenzidine, and horseradish peroxidase signal enhancement reagents to enhance the limit-ofdetection of numerous nucleic acid products. Upon rehydration in our unique 2DPN design, the dried signal enhancement solution reduces the limit-of-detection (LOD) of the device to 5 Ă— 1011 nucleic acid copies/mL without increasing false positive detection. Our easy-to-use device retains activity after 28 days of dry storage and produces reliable signal enhancement 40 min after sample application. The fully integrated device demonstrated versatility in its ability to detect double-stranded and single-stranded DNA samples, as well as peptide nucleic acids
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