7,508 research outputs found
Observer and Particle Transformations and Newton's Laws
A frequently confused point in studies of symmetry violation is the
distinction between observer and particle transformations. In this work, we
consider a model in which a coefficient in the Standard-Model Extension leads
to violations of rotation invariance in Newton's second law. The model
highlights the distinction between observer and particle transformations.Comment: Presented at the Sixth Meeting on CPT and Lorentz Symmetry,
Bloomington, Indiana, June 17-21, 201
The significance of organic carbon and nutrient export from peatland-dominated landscapes subject to disturbance, a stoichiometric perspective
The terrestrial-aquatic interface is a crucial environment in which to consider the fate of exported terrestrial carbon in the aquatic system. Here the fate of dissolved organic carbon (DOC) may be controlled by nutrient availability. However, peat-dominated headwater catchments are normally of low nutrient status and thus there is little data on how DOC and nutrient export co-varies. We present nutrient and DOC data for two UK catchments dominated by peat headwaters. One, Whitelee, is undergoing development for Europe's largest windfarm. Glen Dye by comparison is relatively undisturbed. At both sites there are significant linear relationships between DOC and soluble reactive phosphorus and nitrate concentrations in the drainage waters. However, inter-catchment differences exist. Changes in the pattern of nutrient and carbon export at Whitelee reveal that landscape disturbance associated with windfarm development impacts the receiving waters, and that nutrient export does not increase in a stoichiometric manner that will promote increase in microbial biomass but rather supports aquatic respiration. In turn greater CO2 efflux may prevail. Hence disturbance of terrestrial carbon stores may impact the both the aquatic and gaseous carbon cycle. We suggest estimates of aquatic carbon export should inform the decision-making process prior to development in ecosystems and catchments with high terrestrial carbon storage
Thirteen Years of Reflection on Auditory Graphing: Promises, Pitfalls, and Potential New Directions
While developments in sound production hardware now make the creation of auditory graphs possible for casual users of personal computers, some of the same pitfalls to effective auditory display development that arose in the early 1990âs continue to impede effective applications of this promising technology. Most of these pitfalls stem from lack of adequate understanding about key properties of auditory perception and attention and from inappropriate generalizations of existing data visualization practices. At the same time, however, we now know about some strategies that appear to work and offer promise for making sonification a useful and accepted tool for data exploration and decision making. The present paper summarizes several selected examples in each of these categories, along some suggestions for future research directions
Growth, Condition, and Trophic Relations of Stocked Trout in Southern Appalachian Mountain Streams
Stream trout fisheries are among the most popular and valuable in the United States, but many are dependent on hatcheries to sustain fishing and harvest. Thus, understanding the ecology of hatcheryâreared trout stocked in natural environments is fundamental to management. We evaluated the growth, condition, and trophic relations of Brook Trout Salvelinus fontinalis, Brown Trout Salmo trutta, and Rainbow Trout Oncorhynchus mykiss that were stocked in southern Appalachian Mountain streams in western North Carolina. Stocked and wild (naturalized) trout were sampled over time (monthly; September 2012âJune 2013) to compare condition and diet composition and to evaluate temporal dynamics of trophic position with stable isotope analysis. Relative weights (Wr) of stocked trout were inversely associated with their stream residence time but were consistently higher than those of wild trout. Weight loss of harvested stocked trout was similar among species and sizes, but fish stocked earlier lost more weight. Overall, 40% of 141 stomachs from stocked trout were empty compared to 15% of wild trout stomachs (N = 26). We identified a much higher rate of piscivory in wild trout (18 times that of stocked trout), and wild trout were 4.3 times more likely to consume gastropods relative to stocked trout. Hatcheryâreared trout were isotopically similar to coâoccurring wild fish for both ÎŽ13C and ÎŽ15N values but were less variable than wild trout. Differences in sulfur isotope ratios (ÎŽ34S) between wild and hatcheryâreared trout indicated that the diets of wild fish were enriched in ÎŽ34S relative to the diets of hatcheryâreared fish. Although hatcheryreared trout consumed prey items similar to those of wild fish, differences in consumption or behavior (e.g., reduced feeding) may have resulted in lower condition and negative growth. These findings provide critical insight on the trophic dynamics of stocked trout and may assist in developing and enhancing stream trout fisheries
An Investigation of the Cognitive and Perceptual Dynamics of a ColorâDigit Synesthete
L, a 47-year-old female of Choctaw descent, was first identified as a potential synesthete on the basis of self-report data regarding digitâcolor associations. Upon completion of the identification procedures typified in the literature, it was concluded that L met the classic memory-performance criteria used to identify synesthetic ability. A series of Stroop-type tasks were then performed to identify the dynamics of her synesthetic experiences. The results of these analyses provided three findings of note. First, the clear pattern of response-time differences between L and the control group suggests that tasks designed to produce involuntary divisions of attention can be an effective means by which to demonstrate that synesthetic experiences are involuntary but elicited. Second, the significantly slower performance by L on a negative-priming Stroop list shaped around her colorâdigit associations indicates the presence of a lexical component in her synesthetic experience. Third, the use of a manual color-classification task for which a verbal response was not employed served to confirm the presence of a lexical component in Lâs synesthetic experiences. The implications of these results for current synesthetic theories are then discussed. Finally, a clustering solution of a portion of Lâs colorâdigit experiences is presented, along with the ramifications of its results on the nature of Lâs perceptual experience
Dynamical symmetry of isobaric analog 0+ states in medium mass nuclei
An algebraic sp(4) shell model is introduced to achieve a deeper
understanding and interpretation of the properties of pairing-governed 0+
states in medium mass atomic nuclei. The theory, which embodies the simplicity
of a dynamical symmetry approach to nuclear structure, is shown to reproduce
the excitation spectra and fine structure effects driven by proton-neutron
interactions and isovector pairing correlations across a broad range of nuclei.Comment: 7 pages, 5 figure
New effective interaction for -shell nuclei and its implications for the stability of the ==28 closed core
The effective interaction GXPF1 for shell-model calculations in the full
shell is tested in detail from various viewpoints such as binding energies,
electro-magnetic moments and transitions, and excitation spectra. The
semi-magic structure is successfully described for or Z=28 nuclei,
Mn, Fe, Co and Ni, suggesting the
existence of significant core-excitations in low-lying non-yrast states as well
as in high-spin yrast states. The results of odd-odd nuclei, Co
and Cu, also confirm the reliability of GXPF1 interaction in the isospin
dependent properties. Studies of shape coexistence suggest an advantage of
Monte Carlo Shell Model over conventional calculations in cases where
full-space calculations still remain too large to be practical.Comment: 29pages, 26figures, to be published in Physical Review
Double Charge Exchange And Configuration Mixing
The energy dependence of forward pion double charge exchange reactions on
light nuclei is studied for both the Ground State transition and the
Double-Isobaric-Analog-State transitions. A common characteristic of these
double reactions is a resonance-like peak around 50 MeV pion lab energy. This
peak arises naturally in a two-step process in the conventional pion-nucleon
system with proper handling of nuclear structure and pion distortion. A
comparison among the results of different nuclear structure models demonstrates
the effects of configuration mixing. The angular distribution is used to fix
the single particle wave function.Comment: Added 1 figure (now 8) corrected references and various other change
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