3,604 research outputs found
Importance of Tests for the Complete Lorentz Structure of the t --> W+ b vertex at Hadron Colliders
The most general Lorentz-invariant decay-density-matrix for , or for , is expressed in terms
of eight helicity parameters. The parameters are physically defined in terms of
partial-width-intensities for polarized-final-states in decay.
The parameters are the partial width, the quark's chirality parameter
, the polarimetry parameter , a "pre-SSB" test parameter
, and four - interference parameters , ,
, which test for violation. They can be
used to test for non-CKM-type CP violation, anomalous 's, top
weak magnetism, weak electricity, and second-class currents. By stage-two
spin-correlation techniques, percent level statistical uncertainites are
typical for measurements at the Tevatron, and several mill level uncertainites
are typical at the LHC.Comment: Minor clarifications. Expression for r_{+-} corrected. 19 pages LaTex
+ Tables + 1 Figur
Contrasting responses of lizard occurrences to burrowing by a critically endangered seabird
Abstract
Seabirds are considered ecosystem engineers, because they facilitate ecosystem functioning (e.g., nutrient cycling), crucial for other marine and terrestrial species, including reptiles. However, studies of seabird-reptile interactions are limited. Here, we assessed the influence of the âCritically Endangeredâ Whenua Hou Diving Petrel (Pelecanoides whenuahouensis) on the occurrence of two threatened skinks, Stewart Island green skink (Oligosoma aff. chloronoton) and southern grass skink (O. aff. polychroma). We surveyed skinks for 26 consecutive days at 51 sites with and 48 sites without Diving Petrel burrows in the dunes on Codfish Island (Whenua Hou), New Zealand. We used occupancy modelling to assess the influence of burrows on the occurrence of skinks, while accounting for other factors affecting occupancy (Ψ) and detection probabilities (p). Diving Petrel burrows had a contrasting effect on the occurrence of skinks. On average, Î¨Ě of Stewart Island green skinks was 114% higher at sites with burrows compared to sites without, while Î¨Ě of southern grass skinks was only 2% higher. Occurrence of both skinks was negatively influenced by the presence of the other skink species. On average pĚ were low: 0.013 and 0.038 for Stewart Island green and southern grass skinks, respectively. Stewart Island green skinks appear attracted to burrows, which might facilitate thermoregulation (i.e., shelter from temperature extremes). The larger Stewart Island green skinks may subsequently exclude the smaller southern grass skinks at burrows, causing the contrasting relationships. We suggest that these interspecific interactions should be considered when implementing conservation management, e.g., through the order of species reintroductions
Kansas environmental and resource study: A Great Plains model
The author has identified the following significant results. Improvement in the land use classification accuracy of ERTS-1 MSS multi-images over Kansas can be made using two distances between neighboring grey tone N-tuples instead of one distance. Much more information is contained texturally than spectrally on the Kansas image. Ground truth measurements indicate that reflectance ratios of the 545 and 655 nm wavebands provide an index of plant development and possibly physiological stress. Preliminary analysis of MSS 4 and 5 channels substantiate the ground truth interpretation. Results of the land use mapping experiment indicate that ERTS-1 imagery has major potential in regionalization. The ways in which land is utilized within these regions may then be studied more effectively than if no adequate regionalization is available. A model for estimating wheat yield per acre has been applied to acreage estimates derived from ERTS-1 imagery to project the 1973 wheat yields for a ten county area in southwest Kansas. The results are within 3% of the preharvest estimates for the same area prepared by the USDA. Visual identification of winter wheat is readily achieved by using a temporal sequence of images. Identification can be improve by stratifying the project area into subregions having more or less homogeneous agricultural practices and crop mixes
Multifractal Scaling, Geometrical Diversity, and Hierarchical Structure in the Cool Interstellar Medium
Multifractal scaling (MFS) refers to structures that can be described as a
collection of interwoven fractal subsets which exhibit power-law spatial
scaling behavior with a range of scaling exponents (concentration, or
singularity, strengths) and dimensions. The existence of MFS implies an
underlying multiplicative (or hierarchical, or cascade) process. Panoramic
column density images of several nearby star- forming cloud complexes,
constructed from IRAS data and justified in an appendix, are shown to exhibit
such multifractal scaling, which we interpret as indirect but quantitative
evidence for nested hierarchical structure. The relation between the dimensions
of the subsets and their concentration strengths (the "multifractal spectrum'')
appears to satisfactorily order the observed regions in terms of the mixture of
geometries present: strong point-like concentrations, line- like filaments or
fronts, and space-filling diffuse structures. This multifractal spectrum is a
global property of the regions studied, and does not rely on any operational
definition of "clouds.'' The range of forms of the multifractal spectrum among
the regions studied implies that the column density structures do not form a
universality class, in contrast to indications for velocity and passive scalar
fields in incompressible turbulence, providing another indication that the
physics of highly compressible interstellar gas dynamics differs fundamentally
from incompressible turbulence. (Abstract truncated)Comment: 27 pages, (LaTeX), 13 figures, 1 table, submitted to Astrophysical
Journa
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The working alliance in stuttering treatment: a neglected variable?
Background
Multiple factors can influence the working alliance and treatment outcome in speech and language therapy. The âworking allianceâ is an important concept in treatment and can be described as the degree to which a treatment dyad is engaged in collaborative, purposive work. To date, relatively little attention has been paid to this concept within speech and language treatment in general, and within stuttering treatment research in particular.
Aims
To investigate the role of the working alliance within stuttering treatment, and to evaluate whether the quality of the working alliance correlated with clientsâ concept of motivation and treatment outcomes 6 months postâtherapy.
Methods & Procedures
Eighteen adults (21â61 years) participated in this multiple singleâcase treatment study, with treatment facilitated by an experienced speech and language therapist. The working alliance was investigated using the Working Alliance InventoryâShort Version Revised (WAIâSR), an Extended version of the Client Preferences for Stuttering Treatment (CPSTâE), the Overall Assessment of Speakersâ Experience of StutteringâAdult version (OASESâA), the Wright & Ayre Stuttering SelfâRating Profile (WASSP) and the Hospital Anxiety and Depression Scale (HADS).
Outcomes & Results
Analyses demonstrated significant associations between the working alliance and client motivation (r = 0.781) and treatment outcomes (r = 0.644) 6 months postâtreatment. The association between clientâled goals and therapy tasks appeared particularly important.
Conclusions & Implications
The working alliance between speech and language therapists and persons who stutter matters. Within the alliance, the level of clientâclinician agreement on treatment goals and therapy tasks may be of greater importance than the bond between client and clinician. Further research with greater numbers of participants is warranted
Artificial Intelligence in Swedish Policies::Values, benefits, considerations and risks
Part 4: AI, Data Analytics and Automated Decision MakingInternational audienceArtificial intelligence (AI) is said to be the next big phase in digitalization. There is a global ongoing race to develop, implement and make use of AI in both the private and public sector. The many responsibilities of governments in this race are complicated and cut across a number of areas. Therefore, it is important that the use of AI supports these diverse aspects of governmental commitments and values. The aim of this paper is to analyze how AI is portrayed in Swedish policy documents and what values are attributed to the use of AI. We analyze Swedish policy documents and map benefits, considerations and risks with AI into different value ideals, based on an established e-government value framework. We conclude that there is a discrepancy in the policy level discourse on the use of AI between different value ideals. Our findings show that AI is strongly associated with improving efficiency and service quality in line with previous e-government policy studies. Interestingly, few benefits are highlighted concerning engagement of citizens in policy making. A more nuanced view on AI is needed for creating realistic expectations on how this technology can benefit society
Diffusion controlled initial recombination
This work addresses nucleation rates in systems with strong initial
recombination. Initial (or `geminate') recombination is a process where a
dissociated structure (anion, vortex, kink etc.) recombines with its twin
brother (cation, anti-vortex, anti-kink) generated in the same nucleation
event. Initial recombination is important if there is an asymptotically
vanishing interaction force instead of a generic saddle-type activation
barrier. At low temperatures, initial recombination strongly dominates
homogeneous recombination. In a first part, we discuss the effect in one-,
two-, and three-dimensional diffusion controlled systems with spherical
symmetry. Since there is no well-defined saddle, we introduce a threshold which
is to some extent arbitrary but which is restricted by physically reasonable
conditions. We show that the dependence of the nucleation rate on the specific
choice of this threshold is strongest for one-dimensional systems and decreases
in higher dimensions. We discuss also the influence of a weak driving force and
show that the transport current is directly determined by the imbalance of the
activation rate in the direction of the field and the rate against this
direction. In a second part, we apply the results to the overdamped sine-Gordon
system at equilibrium. It turns out that diffusive initial recombination is the
essential mechanism which governs the equilibrium kink nucleation rate. We
emphasize analogies between the single particle problem with initial
recombination and the multi-dimensional kink-antikink nucleation problem.Comment: LaTeX, 11 pages, 1 ps-figures Extended versio
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