3,378 research outputs found
Light Hadron Spectroscopy: Theory and Experiment
Rapporteur talk at the Lepton-Photon Conference, Rome, July 2001: reviewing
the evidence and strategies for understanding scalar mesons, glueballs and
hybrids, the gluonic Pomeron and the interplay of heavy flavours and light
hadron dynamics. Dedicated to the memory of Nathan Isgur, long-time
collaborator and friend, whose original ideas in hadron spectroscopy formed the
basis for much of the talk.Comment: to be published in "Lepton Photon 2001 Conference Proceedings" (World
Scientific Publishing), 19 pages with 6 figure
Central production of mesons: Exotic states versus Pomeron structure
We demonstrate that the azimuthal dependence of central meson production in
hadronic collisions, when suitably binned, provides unambiguous tests of
whether the Pomeron couples like a conserved vector-current to protons. We
discuss the possibility of discriminating between q-qbar and glueball
production in such processes. Our predictions apply also to meson production in
tagged two-photon events at electron--positron colliders and to vector-meson
production in ep collisions at HERA.Comment: 15 pages, latex, no figur
Production of , , and in hadronic decays
A coherent study of the production of (, 2, 3 corresponding to
, , and ) in is
reported based on a previously proposed glueball and nonet mixing
scheme, and a factorization for the decay of , where
denotes the isoscalar vector mesons and , and denotes
pseudoscalar mesons. The results show that the decays are very
sensitive to the structure of those scalar mesons, and suggest a glueball in
the GeV region, in line with Lattice QCD. The presence of significant
glueball mixings in the scalar wavefunctions produces peculiar patterns in the
branching ratios for , which are in good agreement
with the recently published experimental data from the BES collaboration.Comment: Version accepted by PRD; Numerical results in Tab IV and VI changed
due to correction of an error in quoting an experimental datum; Conclusion is
not change
Radiative decays: a new flavour filter
Radiative decays of the orbital excitations of the ,
and to the scalars , and are shown to
provide a flavour filter, clarifying the extent of glueball mixing in the
scalar states. A complementary approach to the latter is provided by the
radiative decays of the scalar mesons to the ground-state vectors ,
and . Discrimination among different mixing scenarios is strong.Comment: 12 pages, 1 table, 0 figure
Taphonomic and Sedimentologic Study of the Cretaceous Tepee Buttes Limestone
The Tepee Buttes methane seep deposits exist today as topographically defined limestone features in the surrounding Pierre Shale of the Campanian Western Interior Seaway. The present sloping surface has previously been assumed to be indicative of original seep structure, and biofacies were interpreted as roughly ringing a central vent core. Contradictory field observations in this study have prompted a more detailed taphonomic approach to the Tepee Buttes limestone, and certain depositional features such as reworked horizontal shell beds were noted and examined in detail for the first time. The results of a taphonomic and sedimentologic analysis reveal a complex history of reworking that likely involved current action and bioturbation by burrowing seep fauna. We found no clear evidence for deposition along a sloping surface as inclined as today, and buttes are interpreted as having low/uneven original relief
The First Direct Distance and Luminosity Determination for a Self-Luminous Giant Exoplanet: The Trigonometric Parallax to 2MASS1207334-393254Ab
We present the first trigonometric parallax and distance for a young
planetary mass object. A likely TW Hya cluster member, 2MASSW J1207334-393254Ab
(hereafter 2M1207Ab) is an M8 brown dwarf with a mid to late L type planetary
mass companion. Recent observations of spectral variability have uncovered
clear signs of disk accretion and outflow, constraining the age of the system
to <10 Myr. Because of its late spectral type and the clearly youthful nature
of the system, 2M1207b is very likely a planetary mass object. We have measured
the first accurate distance and luminosity for a self-luminous planetary mass
object. Our parallax measurements are accurate to <2 mas (1sigma) for 2M1207Ab.
With 11 total epochs of data taken from January 2006 through April 2 007 (475
images for 2M1207Ab), we determine a distance of 58.8+-7.0 pc (17.0{+2.3}{-1.8}
mas, 1.28sigma) to 2M1207Ab and a calculated luminosity of 0.68-2.2x10^-5 Lsun
for 2M1207b. Hence 2M1207Ab is a clear member of the TW Hya cluster in terms of
its distance, proper motions, and youthful nature. However, as previously noted
by Mohanty and co-workers, 2M1207b's luminosity appears low compared to its
temperature according to evolutionary models.Comment: 12 pages, 3 figures, accepted to ApJ Letter
Developing digital interventions: a methodological guide.
Digital interventions are becoming an increasingly popular method of delivering healthcare as they enable and promote patient self-management. This paper provides a methodological guide to the processes involved in developing effective digital interventions, detailing how to plan and develop such interventions to avoid common pitfalls. It demonstrates the need for mixed qualitative and quantitative methods in order to develop digital interventions which are effective, feasible, and acceptable to users and stakeholders
Analysis of the X(1576) as a tetraquark state with the QCD sum rules
In this letter, we take the point of view that the X(1576) be tetraquark
state which consists of a scalar-diquark and an anti-scalar-diquark in relative
-wave, and calculate its mass in the framework of the QCD sum rules
approach. The numerical value of the mass is
consistent with the experimental data, there may be some tetraquark component
in the vector meson X(1576).Comment: 6 pages, 1 figure, second version, typos correcte
The effects of eccentric exercise on delayed onset muscle soreness, muscle function and free radical production
Delayed onset muscle soreness (DOMS) is a muscle strain injury that presents as tender or aching muscles, often felt during palpation or movement. DOMS is associated with unaccustomed, high-force muscular work and is most pronounced if the work involves a significant eccentric component. Despite substantial research into DOMS its aetiology is still unresolved. There have been recent suggestions that reactive oxygen species (ROS) may be involved in the aetiology of DOMS, however the evidence for this association is equivocal. Therefore, the aims of this thesis were to investigate the effects of unaccustomed exercise (downhill running) on DOMS, specifically investigating the role of ROS in its aetiology. Once this had been established, the effects of dietary intervention and antioxidant supplementation on DOMS and ROS were also investigated.
Study 1 demonstrated that downhill running, which resulted in DOMS, also induced the production of ROS, detected by ESR spectroscopy as well as an increases in serum malondialdehyde (MDA) concentration. It was noted that this increase in ROS occurred -72 h post exercise and was therefore likely to be a result of increased phagocyte activity. Furthermore, the increase in ROS occurred after peak DOMS and when muscle function (as determined by losses of muscle torque assessed by isokinetic dynamometry) was returning to pre-exercise levels, suggesting a temporal dissociation between ROS production and DOMS following downhill running. Circulating levels of ROS were still increasing 72 h post exercise so this study was unable to map the full time-course of ROS production following downhill running.
Study 2 investigated the effects of dietary CHO intake on DOMS, ROS and muscle function. It was found that pre-exercise CHO status had no effect on ROS production, DOMS or losses of muscle function following downhill running. The study demonstrated a bi-phasic increase in creatine kinase (CK), with the second increase corresponding with the post-exercise ROS production. The study extended the postexercise sampling period to 96 h, however, ROS were still increasing at this time and therefore this study was also unable to conclude a definitive tune course of ROS production following downhill running.
Study 3 demonstrated that prolonged ascorbic acid supplementation attenuated the post-exercise increase in ROS production compared to placebo. This attenuation in ROS prevented the secondary peak in CK activity, however it had no effect on DOMS. Interestingly, supplementation with ascorbic acid resulted in more prolonged losses of muscle function. ROS peaked at 96 h post exercise and therefore the time course ofROS production following downhill running was established.
From these studies it was concluded that downhill running did result in post-exercise ROS production. This post-exercise ROS production was associated with secondary muscle damage as measured by plasma CK activity although it had no effect on DOMS. Since supplementation with ascorbic acid attenuated ROS production and prolonged the losses of muscle function, it was suggested that ROS produced by phagocytes m the days following muscle-damaging exercise have a positive role in assisting in the recovery from the traum
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