144 research outputs found
Propagator with Positive Cosmological Constant in the 3D Euclidian Quantum Gravity Toy Model
We study the propagator on a single tetrahedron in a three dimensional toy
model of quantum gravity with positive cosmological constant. The cosmological
constant is included in the model via q-deformation of the spatial symmetry
algebra, that is, we use the Tuarev-Viro amplitude. The expected repulsive
effect of dark energy is recovered in numerical and analytic calculations of
the propagator at large scales comparable to the infrared cutoff. However, due
to the simplicity of the model we do not obtain the exact Newton limit of the
propagator. This is a first step toward the similar calculation in the full 3+1
dimensional theory with larger numbers of simplicies.Comment: 7 pages, 2 figure
A coarse-grained generalized second law for holographic conformal field theories
We consider the universal sector of a -dimensional large-
strongly-interacting holographic CFT on a black hole spacetime background .
When our CFT is coupled to dynamical Einstein-Hilbert gravity with Newton
constant , the combined system can be shown to satisfy a version of the
thermodynamic Generalized Second Law (GSL) at leading order in . The
quantity is
non-decreasing, where is the (time-dependent) area
of the new event horizon in the coupled theory. Our is the notion of
(coarse-grained) CFT entropy outside the black hole given by causal holographic
information -- a quantity in turn defined in the AdS dual by the
renormalized area of a corresponding bulk causal
horizon. A corollary is that the fine-grained GSL must hold for finite
processes taken as a whole, though local decreases of the fine-grained
generalized entropy are not obviously forbidden. Another corollary, given by
setting , states that no finite process taken as a whole can
increase the renormalized free energy , with constants set by . This latter corollary
constitutes a 2nd law for appropriate non-compact AdS event horizons.Comment: minor corrections, 18 page
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A role for palaeoecology in anticipating future change in mountain regions?
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Steady-state and Dynamic Probe Characteristics in a Low-density Plasma
The problem with which this investigation is concerned is that of determining the steady-state and dynamic characteristics of the admittance of a metallic probe immersed in a laboratory plasma which has the low electron densities and low electron temperatures characteristic of the ionospheric plasma. The problem is separated into three related topics: the design and production of the laboratory plasma, the measurement of the steady-state properties of dc and very low frequency probe admittance, and the study of transient ion sheath effects on radio frequency probe admittance
Gab2 Promotes Hematopoietic Stem Cell Maintenance and Self-Renewal Synergistically with STAT5
Grb2-associated binding (Gab) adapter proteins play major roles in coordinating signaling downstream of hematopoietic cytokine receptors. In hematopoietic cells, Gab2 can modulate phosphatidylinositol–3 kinase and mitogen associated protein kinase activities and regulate the long-term multilineage competitive repopulating activity of hematopoietic stem cells (HSCs). Gab2 may also act in a linear pathway upstream or downstream of signal transducer and activator of transcription-5 (STAT5), a major positive regulator of HSC function. Therefore, we aimed to determine whether Gab2 and STAT5 function in hematopoiesis in a redundant or non-redundant manner.), reduced HSC survival, and dramatic loss of self-renewal potential as measured by serial transplantation.These data demonstrate new functions for Gab2 in hematopoiesis in a manner that is non-redundant with STAT5. Furthermore, important synergy between STAT5 and Gab2 was observed in HSC self-renewal, which might be exploited to optimize stem cell-based therapeutics
Evaluating the potential of innovations across aquaculture product value chains for poverty alleviation in Bangladesh and India
Evidence is presented that innovation across aquaculture value chains can contribute to poverty reduction through income generation and increased consumption of nutritious aquatic foods. Innovation is defined and contextualized in relation to aquaculture development. Opportunities for aquaculture innovation across value chains for poverty reduction and sustainable production are described. Contemporary trends in aquaculture development in Bangladesh and India, with a focus on 2011-2020, are reviewed, as understanding transformative change to aquatic food systems during this period could benefit millions of poor and marginal consumers. Market-led commercial production, instigated by private sector entrepreneurs for domestic markets, has underpinned the surge in freshwater fish culture in key geographical locations. In contrast booms in shrimp production have been associated with export opportunities and related cycles of boom-and-bust have been described, with busts attributed to falling market prices and disease outbreaks. Innovation could safeguard supplies of affordable fish to poorer groups (especially young children and pregnant and breastfeeding women) and enable better health management of aquatic animals including coordination of surveillance and disease control measures. Innovation to effectively promote better management practices and integrated services provision to large numbers of small- and medium-scale producers could contribute to poverty reduction. Opportunities for future innovation to ensure that aquaculture development is sustainable are critically reviewed. Innovative strategies to add value to byproducts and utilize waste resources could avoid negative environmental impacts, recycle nutrients and create income generating opportunities. A new paradigm for development assistance that identifies and supports promising innovation trajectories across jurisdictions, product value chains, institutional regimes and food systems is needed. Government agencies must be responsive to the needs of businesses throughout aquatic food systems and devise policies and regulatory regimes that support transformative and sustained growth of the aquaculture sector. Investment in capacity-building, education, research and training and action to promote an enabling institutional environment must be regarded as essential elements to maximize and share equitably the benefits arising and avoid potential negative impacts of inappropriate innovations
Toward full integration of quantitative and qualitative methods in case study research: insights from investigating child welfare inequalities
Delineation of the full integration of quantitative and qualitative methods throughout all stages of multisite mixed methods case study projects remains a gap in the methodological literature. This article offers advances to the field of mixed methods by detailing the application and integration of mixed methods throughout all stages of one such project; a study of child welfare inequalities. By offering a critical discussion of site selection and the management of confirmatory, expansionary and discordant data, this article contributes to the limited body of mixed methods exemplars specific to this field. We propose that our mixed methods approach provided distinctive insights into a complex social problem, offering expanded understandings of the relationship between poverty, child abuse, and neglect
So you think you can track?
This work introduces a multi-camera tracking dataset consisting of 234 hours
of video data recorded concurrently from 234 overlapping HD cameras covering a
4.2 mile stretch of 8-10 lane interstate highway near Nashville, TN. The video
is recorded during a period of high traffic density with 500+ objects typically
visible within the scene and typical object longevities of 3-15 minutes. GPS
trajectories from 270 vehicle passes through the scene are manually corrected
in the video data to provide a set of ground-truth trajectories for
recall-oriented tracking metrics, and object detections are provided for each
camera in the scene (159 million total before cross-camera fusion). Initial
benchmarking of tracking-by-detection algorithms is performed against the GPS
trajectories, and a best HOTA of only 9.5% is obtained (best recall 75.9% at
IOU 0.1, 47.9 average IDs per ground truth object), indicating the benchmarked
trackers do not perform sufficiently well at the long temporal and spatial
durations required for traffic scene understanding
A global biophysical typology of mangroves and its relevance for ecosystem structure and deforestation
Mangrove forests provide many ecosystem services but are among the world's most threatened ecosystems. Mangroves vary substantially according to their geomorphic and sedimentary setting; while several conceptual frameworks describe these settings, their spatial distribution has not been quantified. Here, we present a new global mangrove biophysical typology and show that, based on their 2016 extent, 40.5% (54,972 km2) of mangrove systems were deltaic, 27.5% (37,411 km2) were estuarine and 21.0% (28,493 km2) were open coast, with lagoonal mangroves the least abundant (11.0%, 14,993 km2). Mangroves were also classified based on their sedimentary setting, with carbonate mangroves being less abundant than terrigenous, representing just 9.6% of global coverage. Our typology provides a basis for future research to incorporate geomorphic and sedimentary setting in analyses. We present two examples of such applications. Firstly, based on change in extent between 1996 and 2016, we show while all types exhibited considerable declines in area, losses of lagoonal mangroves (- 6.9%) were nearly twice that of other types. Secondly, we quantify differences in aboveground biomass between mangroves of different types, with it being significantly lower in lagoonal mangroves. Overall, our biophysical typology provides a baseline for assessing restoration potential and for quantifying mangrove ecosystem service provision
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