12,927 research outputs found
Remote sensing utilization of developing countries: An appropriate technology
The activities of the Agency for international development were discussed. Regional and national training centers were established to create an understanding of the role and impact of remote sensing on the developing process. Workshops, training seminars, and demonstration projects were conducted. Research on application was carried out and financial and technical assistance to build or strengthen a country's capability were granted
Exploring Deep Space: Learning Personalized Ranking in a Semantic Space
Recommender systems leverage both content and user interactions to generate
recommendations that fit users' preferences. The recent surge of interest in
deep learning presents new opportunities for exploiting these two sources of
information. To recommend items we propose to first learn a user-independent
high-dimensional semantic space in which items are positioned according to
their substitutability, and then learn a user-specific transformation function
to transform this space into a ranking according to the user's past
preferences. An advantage of the proposed architecture is that it can be used
to effectively recommend items using either content that describes the items or
user-item ratings. We show that this approach significantly outperforms
state-of-the-art recommender systems on the MovieLens 1M dataset.Comment: 6 pages, RecSys 2016 RSDL worksho
Quantum Coherence in Two Dimensions
The formation and evaporation of two dimensional black holes are discussed.
It is shown that if the radiation in minimal scalars has positive energy, there
must be a global event horizon or a naked singularity. The former would imply
loss of quantum coherence while the latter would lead to an even worse
breakdown of predictability. CPT invariance would suggest that there ought to
be past horizons as well. A way in which this could happen with wormholes is
described.Comment: 11 pages, DAMTP-R93/15, CALT-68-1861, Tex, 3 appended uuencoded
figure
Eating to exit: autophagy-enabled senescence revealed
Autophagy and senescence are two distinct cellular responses to stress that are also tumor suppression mechanisms. In this issue of Genes & Development, Young and colleagues ( pp. 798-803) discovered that autophagy is induced during and facilitates the process of senescence. Knowing now that these two pathways are functionally intertwined sets the stage for establishing how they function cooperatively in the cancer setting
Positron annihilation lifetime spectroscopy study of Kapton thin foils
Variable energy positron annihilation lifetime spectroscopy (VE-PALS) experiments on polyimide material Kapton are reported. Thin Kapton foils are widely used in a variety of mechanical, electronic applications. PALS provides a sensitive probe of vacancy-related defects in a wide range of materials, including open volume in polymers. Varying the positron implantation energy enables direct measurement of thin foils. Thin Kapton foils are also commonly used to enclose the positron source material in conventional PALS measurements performed with unmoderated radionuclide sources. The results of depth-profiled positron lifetime measurements on 7.6 μm and 25 μm Kapton foils are reported and determine a dominant 385(1) ps lifetime component. The absence of significant nanosecond lifetime component due to positronium formation is confirmed
On Recognizing Transparent Objects in Domestic Environments Using Fusion of Multiple Sensor Modalities
Current object recognition methods fail on object sets that include both
diffuse, reflective and transparent materials, although they are very common in
domestic scenarios. We show that a combination of cues from multiple sensor
modalities, including specular reflectance and unavailable depth information,
allows us to capture a larger subset of household objects by extending a state
of the art object recognition method. This leads to a significant increase in
robustness of recognition over a larger set of commonly used objects.Comment: 12 page
Comments on the black hole information problem
String theory provides numerous examples of duality between gravitational
theories and unitary gauge theories. To resolve the black hole information
paradox in this setting, it is necessary to better understand how unitarity is
implemented on the gravity side. We argue that unitarity is restored by
nonlocal effects whose initial magnitude is suppressed by the exponential of
the Bekenstein-Hawking entropy. Time-slicings for which effective field theory
is valid are obtained by demanding the mutual back-reaction of quanta be small.
The resulting bounds imply that nonlocal effects do not lead to observable
violations of causality or conflict with the equivalence principle for
infalling observers, yet implement information retrieval for observers who stay
outside the black hole.Comment: 18 pages, 2 figures, revtex, v2 figure added and some improvements to
presentatio
Probabilistic Search for Object Segmentation and Recognition
The problem of searching for a model-based scene interpretation is analyzed
within a probabilistic framework. Object models are formulated as generative
models for range data of the scene. A new statistical criterion, the truncated
object probability, is introduced to infer an optimal sequence of object
hypotheses to be evaluated for their match to the data. The truncated
probability is partly determined by prior knowledge of the objects and partly
learned from data. Some experiments on sequence quality and object segmentation
and recognition from stereo data are presented. The article recovers classic
concepts from object recognition (grouping, geometric hashing, alignment) from
the probabilistic perspective and adds insight into the optimal ordering of
object hypotheses for evaluation. Moreover, it introduces point-relation
densities, a key component of the truncated probability, as statistical models
of local surface shape.Comment: 18 pages, 5 figure
AdS/CFT and the Information Paradox
The information paradox in the quantum evolution of black holes is studied
within the framework of the AdS/CFT correspondence. The unitarity of the CFT
strongly suggests that all information about an initial state that forms a
black hole is returned in the Hawking radiation. The CFT dynamics implies an
information retention time of order the black hole lifetime. This fact
determines many qualitative properties of the non-local effects that must show
up in a semi-classical effective theory in the bulk. We argue that no
violations of causality are apparent to local observers, but the semi-classical
theory in the bulk duplicates degrees of freedom inside and outside the event
horizon. Non-local quantum effects are required to eliminate this redundancy.
This leads to a breakdown of the usual classical-quantum correspondence
principle in Lorentzian black hole spacetimes.Comment: 16 pages, harvmac, reference added, minor correction
Remote sensing in Michigan for land resource management
The application of NASA earth resource survey technology to resource management and environmental protection in Michigan was investigated. Remote sensing techniques to aid Michigan government agencies were applied in the following activities: (1) land use inventory and management, (2) great lakes shorelands protection and management, (3) wetlands protection and management, and (4) soil survey. In addition, information was disseminated on remote sensing technology, and advice and assistance was provided to a number of users
- …
