135 research outputs found
A survey of exploratory search systems based on LOD resources
The fact that the existing Web allows people to effortlessly share data over the Internet has resulted in the accumulation of vast amounts
of information available on the Web.Therefore, a powerful search technology that will allow retrieval of relevant information is one of the main requirements for the success of the Web which is complicated further due to use of many different formats for storing information. Semantic Web technology plays a major role in resolving this problem by permitting the search
engines to retrieve meaningful information. Exploratory search system, a special information seeking and exploration approach, supports users who are unfamiliar with a topic or whose search goals are vague and unfocused to learn and investigate a topic through a set of activities. In order to achieve exploratory search goals Linked Open Data (LOD) can be used to help search systems in retrieving related data, so the investigation task runs smoothly.This paper provides an overview of the Semantic Web Technology, Linked Data and search strategies, followed by a survey of the state of the art Exploratory Search Systems based on LOD.Finally the systems are compared in various aspects such as algorithms, result rankings and explanations
Precision control of thermal transport in cryogenic single-crystal silicon devices
We report on the diffusive-ballistic thermal conductance of multi-moded
single-crystal silicon beams measured below 1 K. It is shown that the phonon
mean-free-path is a strong function of the surface roughness
characteristics of the beams. This effect is enhanced in diffuse beams with
lengths much larger than , even when the surface is fairly smooth, 5-10
nm rms, and the peak thermal wavelength is 0.6 m. Resonant phonon
scattering has been observed in beams with a pitted surface morphology and
characteristic pit depth of 30 nm. Hence, if the surface roughness is not
adequately controlled, the thermal conductance can vary significantly for
diffuse beams fabricated across a wafer. In contrast, when the beam length is
of order , the conductance is dominated by ballistic transport and is
effectively set by the beam area. We have demonstrated a uniformity of 8%
in fractional deviation for ballistic beams, and this deviation is largely set
by the thermal conductance of diffuse beams that support the
micro-electro-mechanical device and electrical leads. In addition, we have
found no evidence for excess specific heat in single-crystal silicon membranes.
This allows for the precise control of the device heat capacity with normal
metal films. We discuss the results in the context of the design and
fabrication of large-format arrays of far-infrared and millimeter wavelength
cryogenic detectors
A comparison between the fourth order linear differential equation with its boundary value problem
In this paper, we study a fourth order linear differential equation. We found an upper bound for the solutions of this differential equation and also, we prove that all the solutions are in L4(0, ∞). By comparing these results we obtain that all the eigenfunction of the boundary value problem generated by this differential equation are bounded and in L4(0, ∞)
Scalable background-limited polarization-sensitive detectors for mm-wave applications
We report on the status and development of polarization-sensitive detectors
for millimeter-wave applications. The detectors are fabricated on
single-crystal silicon, which functions as a low-loss dielectric substrate for
the microwave circuitry as well as the supporting membrane for the
Transition-Edge Sensor (TES) bolometers. The orthomode transducer (OMT) is
realized as a symmetric structure and on-chip filters are employed to define
the detection bandwidth. A hybridized integrated enclosure reduces the
high-frequency THz mode set that can couple to the TES bolometers. An
implementation of the detector architecture at Q-band achieves 90% efficiency
in each polarization. The design is scalable in both frequency coverage, 30-300
GHz, and in number of detectors with uniform characteristics. Hence, the
detectors are desirable for ground-based or space-borne instruments that
require large arrays of efficient background-limited cryogenic detectors.Comment: 7 pages, 3 figures, Presented at SPIE Astronomical Telescopes and
Instrumentation 2014: Millimeter, Submillimeter, and Far-Infrared Detectors
and Instrumentation for Astronomy VII. To be published in Proceedings of SPIE
Volume 915
Silicon-Based Antenna-Coupled Polarization-Sensitive Millimeter-Wave Bolometer Arrays for Cosmic Microwave Background Instruments
We describe feedhorn-coupled polarization-sensitive detector arrays that
utilize monocrystalline silicon as the dielectric substrate material.
Monocrystalline silicon has a low-loss tangent and repeatable dielectric
constant, characteristics that are critical for realizing efficient and uniform
superconducting microwave circuits. An additional advantage of this material is
its low specific heat. In a detector pixel, two Transition-Edge Sensor (TES)
bolometers are antenna-coupled to in-band radiation via a symmetric planar
orthomode transducer (OMT). Each orthogonal linear polarization is coupled to a
separate superconducting microstrip transmission line circuit. On-chip
filtering is employed to both reject out-of-band radiation from the upper band
edge to the gap frequency of the niobium superconductor, and to flexibly define
the bandwidth for each TES to meet the requirements of the application. The
microwave circuit is compatible with multi-chroic operation. Metalized silicon
platelets are used to define the backshort for the waveguide probes. This
micro-machined structure is also used to mitigate the coupling of out-of-band
radiation to the microwave circuit. At 40 GHz, the detectors have a measured
efficiency of 90%. In this paper, we describe the development of the 90 GHz
detector arrays that will be demonstrated using the Cosmology Large Angular
Scale Surveyor (CLASS) ground-based telescope
Spatial Ricci scalar dark energy model
Inspired by holographic principle, we suggest that the density of dark energy
is proportional to the spatial Ricci scalar curvature (SRDE). Such model is
phenomenologically viable. The best fit values of its parameters at 68%
confidence level are found to be: and
, constrained from the Union+CFA3 sample of 397 SNIa and
the BAO measurement. We find the equation of state of SRDE crosses -1 at
. The present values of the deceleration parameter for
SRDE is found to be . The phase transition from deceleration
to acceleration of the Universe for SRDE occurs at the redshift . After studying on the perturbation of each component of the Universe, we
show that the matter power spectra and cosmic microwave background temperature
anisotropy is slightly affected by SRDE, compared with CDM.Comment: 9 pages, 7 figure
CELL DEATH AND AUTOPHAGY: CYTOKINES, DRUGS, AND NUTRITIONAL FACTORS
Cellsmay use multiple pathways to commit suicide. In certain contexts, dying cells generate large amounts
of autophagic vacuoles and clear large proportions of their cytoplasm, before they finally die, as exemplified
by the treatment of human mammary carcinoma cells with the anti-estrogen tamoxifen (TAM,
≤1 M). Protein analysis during autophagic cell death revealed distinct proteins of the nuclear fraction
including GST- and some proteasomal subunit constituents to be affected during autophagic cell death.
Depending on the functional status of caspase-3, MCF-7 cells may switch between autophagic and apoptotic
features of cell death [Fazi, B., Bursch,W., Fimia, G.M., Nardacci R., Piacentini, M., Di Sano, F., Piredda,
L., 2008. Fenretinide induces autophagic cell death in caspase-defective breast cancer cells. Autophagy
4(4), 435–441]. Furthermore, the self-destruction of MCF-7 cells was found to be completed by phagocytosis
of cell residues [Petrovski, G., Zahuczky, G., Katona, K., Vereb, G., Martinet,W., Nemes, Z., Bursch,W.,
Fésüs, L., 2007. Clearance of dying autophagic cells of different origin by professional and non-professional
phagocytes. Cell Death Diff. 14 (6), 1117–1128].
Autophagy also constitutes a cell’s strategy of defense upon cell damage by eliminating damaged bulk
proteins/organelles. This biological condition may be exemplified by the treatment of MCF-7 cells with
a necrogenic TAM-dose (10 M), resulting in the lysis of almost all cells within 24 h. However, a transient
(1 h) challenge of MCF-7 cells with the same dose allowed the recovery of cells involving autophagy.
Enrichment of chaperones in the insoluble cytoplasmic protein fraction indicated the formation of aggresomes,
a potential trigger for autophagy. In a further experimental model HL60 cells were treated with
TAM, causing dose-dependent distinct responses: 1–5 MTAM, autophagy predominant; 7–9 M, apoptosis
predominant; 15 M, necrosis. These phenomena might be attributed to the degree of cell damage
caused by tamoxifen, either by generating ROS, increasing membrane fluidity or forming DNA-adducts.
Finally, autophagy constitutes a cell’s major adaptive (survival) strategy in response to metabolic challenges
such as glucose or amino acid deprivation, or starvation in general. Notably, the role of autophagy
appears not to be restricted to nutrient recycling in order to maintain energy supply of cells and to adapt
cell(organ) size to given physiological needs. For instance, using a newly established hepatoma cell line
HCC-1.2, amino acid and glucose deprivation revealed a pro-apoptotic activity, additive to TGF- 1. The proapoptotic
action of glucose deprivation was antagonized by 2-deoxyglucose, possibly by stabilizing the
mitochondrial membrane involving the action of hexokinase II. These observations suggest that signaling
cascades steering autophagy appear to provide links to those regulating cell number.
Taken together, our data exemplify that a given cell may flexibly respond to type and degree of
(micro)environmental changes or cell death stimuli; a cell’s response may shift gradually from the elimination
of damaged proteins by autophagy and the recovery to autophagic or apoptotic pathways of cell
death, the failure of which eventually may result in necrosis
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