3,449 research outputs found
and in the nuclear medium
Recent studies of the resonance within chiral unitary theory
with coupled channels find the resonance as a dynamically generated state from
the interaction of the decuplet of baryons and the octet of mesons, essentially
a quasibound state of in this case, although the coupling
of the to the and makes this picture
only approximate. The decay channel of the
is forbidden in free space for the nominal mass of the , but
the coupling of the to components in the nuclear medium opens new
decay channels of the in the nucleus and produces a much larger
width. Together with medium modifications of the and
decay channels, the final width of the at nuclear matter
density is more than five times bigger than the free one. We perform the
calculations by dressing simultaneously the and the
resonances, finding moderate changes in the mass but
substantial ones in the width of both resonances.Comment: 20 pages, 6 figures; comparison made to data, new references and new
(small) decay channel include
Finite element structural model of a large, thin, completely free, flat plate
A finite element structural model of a 30.48 m x 30.48 m x 2.54 mm completely free aluminum plate is described and modal frequencies and mode shape data for the first 44 modes are presented. An explanation of the procedure for using the data is also presented. The model should prove useful for the investigation of controller design approaches for large flexible space structures
B_c meson spectrum and hyperfine splittings in theshifted large-N-expansion technique
In the framework of potential models for heavy quarkonium, we compute the
mass spectrum of the bottom-charmed meson system and spin-dependent
splittings from the Schr\"{o}dinger equation using the shifted-large-N
expansion technique. The masses of the lightest vector and
pseudoscalar states as well as the higher states below the threshold
are estimated. Our predicted result for the ground state energy is and are generally in exact agreement with earlier
calculations. Calculations of the Schr\"{o}dinger energy eigenvalues are
carried out up to third order of the energy series. The parameters of each
potential are adjusted to obtain best agreement with the experimental
spin-averaged data (SAD). Our findings are compared with the observed data and
with the numerical results obtained by other numerical methods.Comment: 28 pages, Late
Electromagnetic mirror drive system
Oscillatory electromagnetic mirror drive system for horizon scanner
Analysis of Environmental Influences on Dressed Stone Decay: a Case Study of Tafoni Development on a Hewn Djinn Block in Petra, Jordan
Petra, Jordan captivates tourists and researchers with its dramatic sandstone cliffs, Nabatean, Roman, Byzantine and Roman architecture, and rich cultural heritage. However, increasing tourism in the valley is exacerbating stone degradation and complicating heritage management. This research analyzed environmental influences on dressed stone decay via tafoni development and evaluating cell evolution on an isolated hewn feature, known as Djinn Block X. Resembling other sandstone blocks found in the area, this irregular sandstone monument exhibits faces ranging in size from 2.5m by 3.5m to 3.9m to 4.2m (29m perimeter). Protruding features, incisions along the top, and a large platform attached to the northern face suggests this monument was ritualistic or unfinished.
Over twenty morphometric and micrometeorologic variables were measured for the ten largest and smallest tafoni cells per face. Data were examined and analyzed statistically, photographically, and cartographically. A mirrored-value-aspect matrix was created to reveal statistical relationships between aspect and detailed measurements including cell depth, average diameter, estimated volume, surface temperatures, ambient temperature, and humidity. Results supported field observations displaying greatest decay on the southern and northern faces with r2 values as high as 0.157 at 144˚N for cell volume (total material lost). Moreover, morphometric data exhibited episodic spikes in cell growth, both by depth and diameter, supporting a possible threshold response explanation. These findings challenge steady-rate decay models and represent major implications for rock decay and tafoni research, as well as cultural stone assessment. Furthermore, Geomorphologic research such as this provides policy-makers information necessary to improve conservation efficacy for crucially sensitive heritage sites
Rock Art Management and Landscape Change: Mixed Field Assessment Techniques for Cultural Stone Decay
As tourism continues to grow as one of the world’s most ubiquitous markets, the development and promotion of non-invasive techniques for cultural stone decay analysis and landscape change are vital to establishing conditional base-lines to best aid cultural heritage management (CRM) efficacy. Using rock art as a medium, this dissertation presents three independent case studies employing the Rock Art Stability Index (RASI) and repeat photography to explore the merits of mixed rapid field assessment techniques in relation to CRM and heritage tourism. While rock art is only one example of irreplaceable world heritage resources, examining how they decay and what methods can effectively quantify their change provides valuable data leading to a better understanding of human/environment interaction within the context of tourism and cultural resource management. The first case study examines the applicability of combining the two methods on rock art in the Arkansan Ozark region, showing considerable promise. The second addresses the temporal flexibility of the mixed methods on rapidly changing, and highly impacted, rock art sites on Grenada, West Indies, demonstrating the method pairing’s tremendous monitoring and emergency response potential. The third case study explores adapting RASI to analyze other forms of cultural stone by employing the mixed methods on selected hewn monuments in Petra, Jordan, aptly identifying a critical disparity between appearance and stability. Ultimately, each case study exemplifies different aspects of cultural stone decay and modern challenges: from initial preliminary evaluations to assessing the impact of uninformed conservation efforts, and examining the influences of mass tourism and human interaction at heritage sites. Mixed field techniques effectively highlighted both the need for and benefits of employing such methods for rock art management, cultural stone stability, and global heritage management
Predictions for the unitarity triangle angles in a new parametrization
A new approach to the parametrization of the CKM matrix, , is considered
in which is written as a linear combination of the unit matrix and a
non-diagonal matrix which causes intergenerational-mixing, that is
. Such a depends on 3 real parameters
including the parameter . It is interesting that a value of
is required to fit the available data on the CKM-matrix
including CP-violation. Predictions of this fit for the angles ,
and for the unitarity triangle corresponding to
, are given. For
=, we obtain , and
. These values are just about in agreement, within errors,
with the present data. It is very interesting that the unitarity triangle is
expected to be approximately a right-angled, isosceles triangle. Our prediction
is in excellent agreement with the value reported by the Belle collaboration at the Lepton-Photon 2001 meeting.Comment: 11 pages, latex, no figure
Flavor independent systematics of excited baryons and intra-band transition
Transitions among excited nucleons are studied within a non-relativistic
quark model with a deformed harmonic oscillator potential. The transition
amplitudes are factorized into the -th moment and a geometrical factor. This
fact leads to an analogous result to the ``Alaga-rule'' for baryons.Comment: 4 Pages, 2 figures, Talk given at XVI International Conference on
Particles and Nuclei (PaNic02), Osaka, Japan, Sep.30 - Oct.4, 200
Analysis and simulation of a magnetic bearing suspension system for a laboratory model annular momentum control device
A linear analysis and the results of a nonlinear simulation of a magnetic bearing suspension system which uses permanent magnet flux biasing are presented. The magnetic bearing suspension is part of a 4068 N-m-s (3000 lb-ft-sec) laboratory model annular momentum control device (AMCD). The simulation includes rigid body rim dynamics, linear and nonlinear axial actuators, linear radial actuators, axial and radial rim warp, and power supply and power driver current limits
Using psychoeducation and role induction to improve completion rates in cognitive behavioural therapy
Background: Pre-treatment role induction interventions have been suggested to potentially enhance attendance and clinical outcomes in psychotherapy. Aims: This study aimed to evaluate the effects of a programme of 3 transdiagnostic seminars (TDS) for patients with common mental disorders accessing CBT in primary care. TDS included CBT psychoeducation and role induction. Methods: A random sample of patients (N = 49) participated in TDS followed by CBT (TDS+CBT) and they were compared to matched controls (N = 49) accessing usual CBT. TDS participants rated the relevance and quality of this intervention using an acceptability questionnaire (AQ). Treatment completion (vs. dropout) rates were compared across groups using chi-square tests. Post-treatment changes in depression (PHQ-9) and anxiety (GAD-7) symptoms were compared between groups using analysis of covariance controlling for potential confounders. Analyses were based on intention-to-treat principles. Results: Mean AQ ratings of the TDS intervention were comparable across diagnostic groups (p = .05). Treatment completion rates were significantly higher (p = .02) in the TDS+CBT group (87.8%) by comparison to usual CBT (68.8%). However, no significant differences in post-treatment symptom changes were found for depression (p = .34) or anxiety measures (p = .71). Conclusions: Incorporating a psychoeducational role induction prior to CBT significantly improved treatment retention, but not overall symptom reductions
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