46 research outputs found
Vector Bosons in the Randall-Sundrum 2 and Lykken-Randall models and unparticles
Unparticle behavior is shown to be realized in the Randall-Sundrum 2 (RS 2)
and the Lykken-Randall (LR) brane scenarios when brane-localized Standard Model
currents are coupled to a massive vector field living in the five-dimensional
warped background of the RS 2 model. By the AdS/CFT dictionary these
backgrounds exhibit certain properties of the unparticle CFT at large N_c and
strong 't Hooft coupling. Within the RS 2 model we also examine and contrast in
detail the scalar and vector position-space correlators at intermediate and
large distances. Unitarity of brane-to-brane scattering amplitudes is seen to
imply a necessary and sufficient condition on the positivity of the bulk mass,
which leads to the well-known unitarity bound on vector operators in a CFT.Comment: 60 pages, 8 figure
The AdS/QCD Correspondence: Still Undelivered
We consider the particle spectrum and event shapes in large N gauge theories
in different regimes of the short-distance 't Hooft coupling, lambda. The
mesons in the small lambda limit should have a Regge spectrum in order to agree
with perturbation theory, while generically the large lambda theories with
gravity duals produce spectra reminiscent of KK modes. We argue that these
KK-like states are qualitatively different from QCD modes: they are deeply
bound states which are sensitive to short distance interactions rather than the
flux tube-like states expected in asymptotically free, confining gauge
theories. In addition, we also find that the characteristic event shapes for
the large lambda theories with gravity duals are close to spherical, very
different from QCD-like (small lambda, small N) and Nambu-Goto-like (small
lambda, large N) theories which have jets. This observation is in agreement
with the conjecture of Strassler on event shapes in large 't Hooft coupling
theories, which was recently proved by Hofman and Maldacena for the conformal
case. This conclusion does not change even when considering soft-wall
backgrounds in the gravity dual. The picture that emerges is the following:
theories with small and large lambda are qualitatively different, while
theories with small and large N are qualitatively similar. Thus it seems that
it is the relative smallness of the 't Hooft coupling in QCD that prevents a
reliable AdS/QCD correspondence from emerging, and that reproducing
characteristic QCD-like behavior will require genuine stringy dynamics to be
incorporated into any putative dual theory.Comment: 32 pages, 15 figures; references added, minor changes, history
clarifie
A Brane World Perspective on the Cosmological Constant and the Hierarchy Problems
We elaborate on the recently proposed static brane world scenario, where the
effective 4-D cosmological constant is exponentially small when parallel
3-branes are far apart. We extend this result to a compactified model with two
positive tension branes. Besides an exponentially small effective 4-D
cosmological constant, this model incorporates a Randall-Sundrum-like solution
to the hierarchy problem. Furthermore, the exponential factors for the
hierarchy problem and the cosmological constant problem obey an inequality that
is satisfied in nature. This inequality implies that the cosmological constant
problem can be explained if the hierarchy problem is understood. The basic idea
generalizes to the multibrane world scenario. We discuss models with piecewise
adjustable bulk cosmological constants (to be determined by the 5-dimensional
Einstein equation), a key element of the scenario. We also discuss the global
structure of this scenario and clarify the physical properties of the particle
(Rindler) horizons that are present. Finally, we derive a 4-D effective theory
in which all observers on all branes not separated by particle horizons measure
the same Newton's constant and 4-D cosmological constant.Comment: revtex, 63 pages, 8 figures, one table, revised version, more
discussions on the global structure, references adde
Size Doesn't Matter: Towards a More Inclusive Philosophy of Biology
notes: As the primary author, OâMalley drafted the paper, and gathered and analysed data (scientific papers and talks). Conceptual analysis was conducted by both authors.publication-status: Publishedtypes: ArticlePhilosophers of biology, along with everyone else, generally perceive life to fall into two broad categories, the microbes and macrobes, and then pay most of their attention to the latter. âMacrobeâ is the word we propose for larger life forms, and we use it as part of an argument for microbial equality. We suggest that taking more notice of microbes â the dominant life form on the planet, both now and throughout evolutionary history â will transform some of the philosophy of biologyâs standard ideas on ontology, evolution, taxonomy and biodiversity. We set out a number of recent developments in microbiology â including biofilm formation, chemotaxis, quorum sensing and gene transfer â that highlight microbial capacities for cooperation and communication and break down conventional thinking that microbes are solely or primarily single-celled organisms. These insights also bring new perspectives to the levels of selection debate, as well as to discussions of the evolution and nature of multicellularity, and to neo-Darwinian understandings of evolutionary mechanisms. We show how these revisions lead to further complications for microbial classification and the philosophies of systematics and biodiversity. Incorporating microbial insights into the philosophy of biology will challenge many of its assumptions, but also give greater scope and depth to its investigations
Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.
BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362
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CEAP Quantifies Conservation Outcomes for Wildlife and People on Western Grazing Lands
Maximizing efficiency and effectiveness of limited resources to conserve America's vast western grazing lands requires a science-based approach. Working Lands for Wildlife, USDA's approach for conserving America's working lands, co-produces scientific tools and quantifies outcomes that help guide future implementation and improve delivery. Quantifying outcomes in conservation provides accountability for investments, and illustrates to readers the role of science in working lands conservation. Together, diverse partners continue expanding into new technologies to further enhance the productivity, profitability, and sustainability of valuable grazing lands.The Rangelands archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information
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Mapping tree canopy cover in support of proactive prairie grouse conservation in western North America
Invasive woody plant expansion is a primary threat driving fragmentation and loss of sagebrush (Artemisia spp.) and prairie habitats across the central andwestern United States. Expansion of native woody plants, including conifer (primarily Juniperus spp.) and mesquite (Prosopis spp.), over the past century is primarily attributable to wildfire suppression, historic periods of intensive livestock grazing, and changes in climate. To guide successful conservation programs aimed at reducing top-down stressors, we mapped invasive woody plants at regional scales to evaluate landscape level impacts, target restoration actions, and monitor restoration outcomes. Our overarching goal was to produce seamless regional products across sociopolitical boundaries with resolution fine enough to depict the spatial extent and degree of woody plant invasion relevant to greater sage-grouse (Centrocercus urophasianus) and lesser prairie-chicken (Tympanuchus pallidicinctus) conservation efforts. We mapped tree canopy cover at 1-m spatial resolution across an 11-state region (508 265 km2). Greater than 90% of occupied lesser prairie-chicken habitat was largely treeless for conifers (<1% canopy cover), whereas > 67% was treeless for mesquite. Conifers in the higher canopy cover classes (16-50% and >50% canopy cover) were scarce (<2% and 1% canopy cover), as was mesquite (<5% and 1% canopy cover). Occupied habitat by sagegrouse was more variable but also had a relatively large proportion of treeless areas (=71, SE=5%). Lowto moderate levels of conifer cover (1-20%) were fewer (= 23, SE = 5%) as were areas in the highest cover class (>50%; = 6, SE = 2%). Mapping indicated that a high proportion of invading woody plants are at a low to intermediate level. Canopy cover maps for conifer and mesquite resulting from this study provide the first and most geographically complete, high-resolution assessment of woody plant cover as a top-down threat to western sage-steppe and prairie ecosystems.The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information
Imputation of individual Longleaf Pine (Pinus palustris Mill.) Tree attributes from field and LiDAR data
Light Detection and Ranging (LiDAR) has demonstrated potential for forest inventory at the individual-tree level. The aim in this study was to predict individual-tree height (Ht; m), basal area (BA; m2), and stem volume (V; m3) attributes, imputing Random Forest k-nearest neighbor (RF k-NN) and individual-tree-level-based metrics extracted from a LiDAR-derived canopy height model (CHM) in a longleaf pine (Pinus palustris Mill.) forest in southwestern Georgia, United States. We developed a new framework for modeling tree-level forest attributes that comprise 3 steps: (i) individual tree detection, crown delineation, and tree-level-based metrics computation from LiDAR-derived CHM; (ii) automatic matching of LiDAR-derived trees and field-based trees for a regression modeling step using a novel algorithm; and (iii) RF k-NN imputation modeling for estimating tree-level Ht, BA, and V and subsequent summarization of these metrics at the plot and stand levels. RMSDs for tree-level Ht, BA, and V were 2.96%, 58.62%, and 8.19%, respectively. Although BA estimation accuracy was poor because of the longleaf pine growth habitat, individual-tree locations, Ht, and V were estimated with high accuracy, especially in low-canopy-cover conditions. Future efforts based on the findings could help improve the estimation accuracy of individual-tree-level attributes such as BA