1,110 research outputs found
Transnational Actors and the Governance of Urban Climate Adaptation in India
In cities that are pursuing climate change adaptation actions, transnational
actors are critical catalysts for financing programs, generating public
awareness, and legitimizing the agenda. However, scholars of urban climate
adaptation have yet to understand whether such external interventions have
long-lasting effects on the sustainability and equity of urban governance
processes, particularly when placed in context with competing development
priorities across the global South. In this paper, I draw on experiences from
three cities in India – Surat, Indore, and Bhubaneswar – to analyze the
multilevel dynamics that link local adaptation actions with their supporting
transnational networks and funders. Drawing on a comparative multi-scale case
study methodology, I find that current capacity deficits in Indian cities
indeed allow external actors to catalyze adaptation, but this relationship
becomes more dialectical farther into the planning and implementation stages.
The governance of climate adaptation in fact involves embedding adaptation
into bureaucratic practices, financial processes, spatial plans, and
institutional cultures. The interaction between these four pathways results in
the coproduction of knowledge, co-creation of options, and inter-
institutionalization of standards, practices, and behaviors. A particular
actor’s ability to exert authority over how interventions are framed,
financed, bureaucratized, and built across the urban landscape then yields
different patterns of adaptation. This finding therefore reasserts the role of
urban political actors operating within the global climate governance regime
and the marketplace for climate finance
Urban climate adaptation and the reshaping of state–society relations:the politics of community knowledge and mobilisation in Indore, India
Current research on climate change adaptation in cities highlights the role of local governments in facilitating adaptation actions, but rarely assesses whether (and if so, how) local communities organise around emerging climate priorities to affect political change. This paper explores changing state–society relationships through the reconstitution of community collectives and advocacy organisations for advancing climate change adaptation in the Indian city of Indore. The paper shows that communities are indeed recognising the need for adaptation but are, at the same time, integrating adaptation actions with existing strategies for advocating development rights. Communities are also rebuilding alliances between municipal and local institutions for public service and infrastructure provision, which point to the centrality of community politics in urban climate adaptation processes. However, such mobilisations are often dependent on existing political networks and a legacy of advocacy around poverty alleviation needs, which sideline more transformative agendas around inclusiveness, equity, and resilient urban futures
Human Atlas: A Tool for Mapping Social Networks
Most social network analyses focus on online social networks. While these networks encode important aspects of our lives they fail to capture many real-world connections. Most of these connections are, in fact, public and known to the members of the community. Mapping them is a task very suitable for crowdsourcing: it is easily broken down in many simple and independent subtasks. Due to the nature of social networks|presence of highly connected nodes and tightly knit groups|if we allow users to map their immediate connections and the connections between them, we will need few participants to map most connections within a community. To this end, we built the Human Atlas, a web-based tool for mapping social networks. To test it, we partially mapped the social network of the MIT Media Lab. We ran a user study and invited members of the community to use the tool. In 4.6 man-hours, 22 participants mapped 984 connections within the lab, demonstrating the potential of the tool
Resorufin analogs preferentially bind cerebrovascular amyloid: potential use as imaging ligands for cerebral amyloid angiopathy
<p>Abstract</p> <p>Background</p> <p>Cerebral amyloid angiopathy (CAA) is characterized by deposition of fibrillar amyloid β (Aβ) within cerebral vessels. It is commonly seen in the elderly and almost universally present in patients with Alzheimer's Disease (AD). In both patient populations, CAA is an independent risk factor for lobar hemorrhage, ischemic stroke, and dementia. To date, definitive diagnosis of CAA requires obtaining pathological tissues via brain biopsy (which is rarely clinically indicated) or at autopsy. Though amyloid tracers labeled with positron-emitting radioligands such as [<sup>11</sup>C]PIB have shown promise for non-invasive amyloid imaging in AD patients, to date they have been unable to clarify whether the observed amyloid load represents neuritic plaques versus CAA due in large part to the low resolution of PET imaging and the almost equal affinity of these tracers for both vascular and parenchymal amyloid. Therefore, the development of a precise and specific non-invasive technique for diagnosing CAA in live patients is desired.</p> <p>Results</p> <p>We found that the phenoxazine derivative resorufin preferentially bound cerebrovascular amyloid deposits over neuritic plaques in the aged Tg2576 transgenic mouse model of AD/CAA, whereas the congophilic amyloid dye methoxy-X34 bound both cerebrovascular amyloid deposits and neuritic plaques. Similarly, resorufin-positive staining was predominantly noted in fibrillar Aβ-laden vessels in postmortem AD brain tissues. Fluorescent labeling and multi-photon microscopy further revealed that both resorufin- and methoxy-X34-positive staining is colocalized to the vascular smooth muscle (VSMC) layer of vessel segments that have severe disruption of VSMC arrangement, a characteristic feature of CAA. Resorufin also selectively visualized vascular amyloid deposits in live Tg2576 mice when administered topically, though not systemically. Resorufin derivatives with chemical modification at the 7-OH position of resorufin also displayed a marked preferential binding affinity for CAA, but with enhanced lipid solubility that indicates their use as a non-invasive imaging tracer for CAA is feasible.</p> <p>Conclusions</p> <p>To our knowledge, resorufin analogs are the fist class of amyloid dye that can discriminate between cerebrovascular and neuritic forms of amyloid. This unique binding selectivity suggests that this class of dye has great potential as a CAA-specific amyloid tracer that will permit non-invasive detection and quantification of CAA in live patients.</p
PET imaging of in vivo caspase-3/7 activity following myocardial ischemia-reperfusion injury with the radiolabeled isatin sulfonamide analogue [(18)F]WC-4-116
The utility of [(18)F]WC-4-116, a PET tracer for imaging caspase-3 activation, was evaluated in an animal model of myocardial apoptosis. [(18)F]WC-4-116 was injected into rats at 3 hours after a 30 min period of ischemia induced by temporary occlusion of the left anterior descending coronary artery in Sprague-Dawley rats. [(18)F]WC-4-116 uptake was quantified by 1) autoradiography, 2) microPET imaging studies, and 3) post-PET biodistribution studies. MicroPET imaging also assessed uptake of the non-caspase-3-targeted tracer [(18)F]ICMT-18 at 3 hours postischemia. Enzyme assays and Western blotting assessed caspase-3 activation in both at-risk and not-at-risk regions. Caspase-3 enzyme activity increased in the at-risk but not in the not-at-risk myocardium. Quantitative autoradiographic analysis of [(18)F]WC-4-116 demonstrated nearly 2-fold higher uptake in the ischemia-reperfusion (IR) versus sham animals. [(18)F]WC-4-116 microPET imaging studies demonstrated that the IR animals was similarly elevated in relation to sham. [(18)F]ICMT-18 uptake did not increase in at-risk myocardium despite evidence of caspase-3 activation. Biodistribution studies with [(18)F]WC-4-116 confirmed the microPET findings. These data indicate that the caspase-3-PET tracer [(18)F]WC-4-116 can noninvasively image in vivo caspase activity during myocardial apoptosis and may be useful for clinical imaging in humans
Elucidation of Relaxation Dynamics Beyond Equilibrium Through AI-informed X-ray Photon Correlation Spectroscopy
Understanding and interpreting dynamics of functional materials \textit{in
situ} is a grand challenge in physics and materials science due to the
difficulty of experimentally probing materials at varied length and time
scales. X-ray photon correlation spectroscopy (XPCS) is uniquely well-suited
for characterizing materials dynamics over wide-ranging time scales, however
spatial and temporal heterogeneity in material behavior can make interpretation
of experimental XPCS data difficult. In this work we have developed an
unsupervised deep learning (DL) framework for automated classification and
interpretation of relaxation dynamics from experimental data without requiring
any prior physical knowledge of the system behavior. We demonstrate how this
method can be used to rapidly explore large datasets to identify samples of
interest, and we apply this approach to directly correlate bulk properties of a
model system to microscopic dynamics. Importantly, this DL framework is
material and process agnostic, marking a concrete step towards autonomous
materials discovery
Observing Dynamical Phases of a Bardeen-Cooper-Schrieffer Superconductor in a Cavity QED Simulator
In conventional Bardeen-Cooper-Schrieffer (BCS) superconductors, electrons
with opposite momenta bind into Cooper pairs due to an attractive interaction
mediated by phonons in the material. While superconductivity naturally emerges
at thermal equilibrium, it can also emerge out of equilibrium when the system's
parameters are abruptly changed. The resulting out-of-equilibrium phases are
predicted to occur in real materials and ultracold fermionic atoms but have not
yet been directly observed. This work realizes an alternate way to generate the
proposed dynamical phases using cavity quantum electrodynamics (cavity QED).
Our system encodes the presence or absence of a Cooper pair in a long-lived
electronic transition in Sr atoms coupled to an optical cavity and
represents interactions between electrons as photon-mediated interactions
through the cavity. To fully explore the phase diagram, we manipulate the ratio
between the single-particle dispersion and the interactions after a quench and
perform real-time tracking of subsequent dynamics of the superconducting order
parameter using non-destructive measurements. We observe regimes where the
order parameter decays to zero ("phase I"), assumes a non-equilibrium
steady-state value ("phase II"), or exhibits persistent oscillations ("phase
III") in the form of a self-generated Floquet phase. The capability to emulate
these dynamical phases in optical cavities without real Cooper pairs
demonstrates that programmable simulators can overcome many challenges faced by
traditional approaches. This opens up exciting prospects for quantum
simulation, including the potential to engineer unconventional superconductors
and to probe beyond mean-field effects like the spectral form factor, and for
increasing coherence time for quantum sensing.Comment: Main Text with Supporting Material, 18 pages, 10 figure
Recommended from our members
AI-NERD: Elucidation of relaxation dynamics beyond equilibrium through AI-informed X-ray photon correlation spectroscopy
Understanding and interpreting dynamics of functional materials in situ is a grand challenge in physics and materials science due to the difficulty of experimentally probing materials at varied length and time scales. X-ray photon correlation spectroscopy (XPCS) is uniquely well-suited for characterizing materials dynamics over wide-ranging time scales. However, spatial and temporal heterogeneity in material behavior can make interpretation of experimental XPCS data difficult. In this work, we have developed an unsupervised deep learning (DL) framework for automated classification of relaxation dynamics from experimental data without requiring any prior physical knowledge of the system. We demonstrate how this method can be used to accelerate exploration of large datasets to identify samples of interest, and we apply this approach to directly correlate microscopic dynamics with macroscopic properties of a model system. Importantly, this DL framework is material and process agnostic, marking a concrete step towards autonomous materials discovery
Ten Million Degree Gas in M 17 and the Rosette Nebula: X-ray Flows in Galactic H II Regions
We present the first high-spatial-resolution X-ray images of two high-mass
star forming regions, the Omega Nebula (M 17) and the Rosette Nebula (NGC
2237--2246), obtained with the Chandra X-ray Observatory Advanced CCD Imaging
Spectrometer (ACIS) instrument. The massive clusters powering these H II
regions are resolved at the arcsecond level into >900 (M 17) and >300 (Rosette)
stellar sources similar to those seen in closer young stellar clusters.
However, we also detect soft diffuse X-ray emission on parsec scales that is
spatially and spectrally distinct from the point source population. The diffuse
emission has luminosity L_x ~ 3.4e33 ergs/s in M~17 with plasma energy
components at kT ~0.13 and ~0.6 keV (1.5 and 7 MK), while in Rosette it has L_x
\~6e32 ergs/s with plasma energy components at kT ~0.06 and ~0.8 keV (0.7 and 9
MK). This extended emission most likely arises from the fast O-star winds
thermalized either by wind-wind collisions or by a termination shock against
the surrounding media. We establish that only a small portion of the wind
energy and mass appears in the observed diffuse X-ray plasma; in these blister
H II regions, we suspect that most of it flows without cooling into the
low-density interstellar medium. These data provide compelling observational
evidence that strong wind shocks are present in H II regions.Comment: 35 pages, including 11 figures; to appear in ApJ, August 20, 2003. A
version with high-resolution figures is available at
ftp://ftp.astro.psu.edu/pub/townsley/diffuse.ps.g
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