2,925 research outputs found
Bears Prefer Trees in the Spring
As they emerge from their winter den, bears need an energy source and food is relatively scarce. Concurrently, trees are breaking dormancy and starting to generate carbohydrates. Consequently, bears commonly girdle Douglas-fir trees during the spring to feed on the available carbohydrates. Bears strip bark from a tree with their claws, then feed on the sapwood by scraping it from the heartwood with their teeth. Scattered remnants of bark strewn at the base of a tree and vertical tooth marks are characteristic indicators of bear activity. Most frequently bears forage on the lower bole of trees, girdling the bottom three to five feet. However, some bears may climb and feed on the upper boles while sitting on lateral branches. Occasionally, a bear will strip an entire tree
Pioneer Venus probe design
The summary provides descriptions for a set of probes designed to explore an inner rather than an outer planet, and designed to survive to 100 bars rather than 10 bars. The probes carry a variety of scientific instruments and their supporting integrated subsystems are adjusted to Venus environmental conditions
The observation of possible reconnection events in the boundary changes of solar coronal holes
Coronal holes are large scale regions of magnetically open fields which are easily observed in solar soft X-ray images. The boundaries of coronal holes are separatrices between large scale regions of open and closed magnetic fields where one might expect to observe evidence of solar magnetic reconnection. Previous studies by Nolte and colleagues using Skylab X-ray images established that large scale (greater than or equal to 9 x 10(4) km) changes in coronal hole boundaries were due to coronal processes, i.e., magnetic reconnection, rather than to photospheric motions. Those studies were limited to time scales of about one day, and no conclusion could be drawn about the size and time scales of the reconnection process at hole boundaries. Sequences of appropriate Skylab X-ray images were used with a time resolution of about 90 min during times of the central meridian passages of the coronal hole labelled Coronal Hole 1 to search for hole boundary changes which can yield the spatial and temporal scales of coronal magnetic reconnection. It was found that 29 of 32 observed boundary changes could be associated with bright points. The appearance of the bright point may be the signature of reconnection between small scale and large scale magnetic fields. The observed boundary changes contributed to the quasi-rigid rotation of Coronal Hole 1
Cherenkov and Scintillation Light Separation in Organic Liquid Scintillators
The CHErenkov / Scintillation Separation experiment (CHESS) has been used to
demonstrate the separation of Cherenkov and scintillation light in both linear
alkylbenzene (LAB) and LAB with 2g/L of PPO as a fluor (LAB/PPO). This is the
first such demonstration for the more challenging LAB/PPO cocktail and improves
on previous results for LAB. A time resolution of 338 +/- 12 ps FWHM results in
an efficiency for identifying Cherenkov photons in LAB/PPO of 70 +/- 3% and 63
+/- 8% for time- and charge-based separation, respectively, with scintillation
contamination of 36 +/- 5% and 38 +/- 4%. LAB/PPO data is consistent with a
rise time of 0.75 +/- 0.25 ns
Specifying Graph Languages with Type Graphs
We investigate three formalisms to specify graph languages, i.e. sets of
graphs, based on type graphs. First, we are interested in (pure) type graphs,
where the corresponding language consists of all graphs that can be mapped
homomorphically to a given type graph. In this context, we also study languages
specified by restriction graphs and their relation to type graphs. Second, we
extend this basic approach to a type graph logic and, third, to type graphs
with annotations. We present decidability results and closure properties for
each of the formalisms.Comment: (v2): -Fixed some typos -Added more reference
C++ Templates as Partial Evaluation
This paper explores the relationship between C++ templates and partial
evaluation. Templates were designed to support generic programming, but
unintentionally provided the ability to perform compile-time computations and
code generation. These features are completely accidental, and as a result
their syntax is awkward. By recasting these features in terms of partial
evaluation, a much simpler syntax can be achieved. C++ may be regarded as a
two-level language in which types are first-class values. Template
instantiation resembles an offline partial evaluator. This paper describes
preliminary work toward a single mechanism based on Partial Evaluation which
unifies generic programming, compile-time computation and code generation. The
language Catat is introduced to illustrate these ideas.Comment: 13 page
Cosmogenesis Backgrounds, Experiment Depth and the Solar Neutrino TPC
A Time Projection Chamber (TPC) is one of the promising candidates to perform
unique measurements in solar neutrino physics. Its features will enable it to
work at depths of the order of 2000 mwe. This paper describes an estimation of
the expected cosmogenic background at different depths including also the
background due to fission activation of the TPC material above ground.Comment: 15 pages, 3 figure
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