How does exposure to violence affect civilian social networks during wartime? Social networks play critical roles in civil wars by enabling civilians to endure the destruction of conflict. However, ...little is known about how these networks change in response to violence. I employ original survey data from camps for the internally displaced in Kachin State, Myanmar, an area of active civil conflict, to determine how exposure to violence affects the social networks of internally displaced people (IDPs). I find that those exposed to violence have fewer initial, new, and close ties. However, those exposed to violence do not form ties with other exposed IDPs at a higher rate than with non-exposed IDPs.
•I investigate the relationship between exposure to violence and civilian social networks•I use original survey data from internally displaced people in Kachin State, Myanmar•I find that those exposed to violence have fewer initial, new, and close ties.•IDPs exposed to violence do not form ties with other exposed IDPs at higher rates
This paper presents a simple 2D method for rapid time resolved quantitative imaging of acoustic waves using refracto-vibrometry. We present the theoretical background, the experimental method and ...reconstructions of acoustic reflection and interference. We investigate the applicability of the method, in particular the effect of sound radiator geometry. Finite element and experimental reconstructions of the sound fields are analysed. The spatial limitations and accuracy of the method are presented and discussed.
This study introduces optical feedback interferometry as a simple and effective technique for the two-dimensional visualisation of acoustic fields. We present imaging results for several pressure ...distributions including those for progressive waves, standing waves, as well as the diffraction and interference patterns of the acoustic waves. The proposed solution has the distinct advantage of extreme optical simplicity and robustness thus opening the way to a low cost acoustic field imaging system based on mass produced laser diodes.
Closed circulatory systems (CCS) underlie the function of vertebrate organs, but in long bones their structure is unclear, although they constitute the exit route for bone marrow (BM) leukocytes. To ...understand neutrophil emigration from BM, we studied the vascular system of murine long bones. Here we show that hundreds of capillaries originate in BM, cross murine cortical bone perpendicularly along the shaft and connect to the periosteal circulation. Structures similar to these trans-cortical-vessels (TCVs) also exist in human limb bones. TCVs express arterial or venous markers and transport neutrophils. Furthermore, over 80% arterial and 59% venous blood passes through TCVs. Genetic and drug-mediated modulation of osteoclast count and activity leads to substantial changes in TCV numbers. In a murine model of chronic arthritic bone inflammation, new TCVs develop within weeks. Our data indicate that TCVs are a central component of the CCS in long bones and may represent an important route for immune cell export from the BM.
How can demand for electricity be estimated without fine-grained usage data? Employing an original and large dataset, we develop a novel method for determining drivers of demand without electricity ...meter data. We first segment Indian consumers by their willingness to pay for electricity service, their level of usage, and their satisfaction with lighting, and then use cluster membership as a dependent variable in order to determine which household-level factors predict electricity usage. Our approach employs machine-learning and more traditional regression techniques to determine the optimal number of segments, generate the segments, and determine the predictors of segment membership. The dataset consists of more than 10,000 households in more than 200 villages in the states of Bihar, Odisha, Rajasthan, and Uttar Pradesh. We find that the rural Indian electricity market can be segmented into three clusters based on households' willingness to pay, satisfaction with lighting, and appliance wattage. The clusters consist of potential customers, low-demand customers, and high-use customers. We then determine the predictors of membership in these clusters. We show that different types of consumers can be identified along easily observable measures. Moreover, we show that there are clear groups of consumers that vary along their satisfaction, willingness to pay, and existing appliance usage.
•Employing an original and large dataset of more than 10,000 households in more than 200 villages in India, we develop a method for determining drivers of demand without electricity meter data.•We segment Indian consumers by their willingness to pay for electricity service, their level of usage, and their satisfaction with lighting.•We use cluster membership as a dependent variable in order to determine which household-level factors predict electricity usage.•We show that different types of consumers can be identified along easily observable measures.
How does removing the leadership of online hate organizations from online platforms change behavior in their target audience? We study the effects of six network disruptions of designated and banned ...hate-based organizations on Facebook, in which known members of the organizations were removed from the platform, by examining the online engagements of the audience of the organization. Using a differences-in-differences approach, we show that on average the network disruptions reduced the consumption and production of hateful content, along with engagement within the network among periphery members. Members of the audience closest to the core members exhibit signs of backlash in the short term, but reduce their engagement within the network and with hateful content over time. The results suggest that strategies of targeted removals, such as leadership removal and network degradation efforts, can reduce the ability of hate organizations to successfully operate online.
Rural electrification has progressed unevenly across the world since 1945, with some rural communities gaining access to power decades earlier than others. We examine the association between early ...electrification and the quality of electricity service to households, testing the hypothesis that aging infrastructure compromises the quality of electricity service. Using the 2014–2015 ACCESS survey from rural India, we find that early electrification is associated with improvements in the quality of electricity service, even controlling for village size and distance to nearest town. A possible explanation for the finding is that early electrification generates economic gains that allow the rural community to invest in maintenance and upgrades.
•Early electrification predicts better quality of electricity service in rural India.•Rural electrification policy should emphasize quality of infrastructure and electricity service.•Evidence from 669 villages across six states of India.
Moth wings are acoustic metamaterials Neil, Thomas R.; Shen, Zhiyuan; Robert, Daniel ...
Proceedings of the National Academy of Sciences - PNAS,
12/2020, Letnik:
117, Številka:
49
Journal Article
Recenzirano
Odprti dostop
Metamaterials assemble multiple subwavelength elements to create structures with extraordinary physical properties (1–4). Optical metamaterials are rare in nature and no natural acoustic ...metamaterials are known. Here, we reveal that the intricate scale layer on moth wings forms a metamaterial ultrasound absorber (peak absorption = 72% of sound intensity at 78 kHz) that is 111 times thinner than the longest absorbed wavelength. Individual scales act as resonant (5) unit cells that are linked via a shared wing membrane to form this metamaterial, and collectively they generate hard-to-attain broadband deep-subwavelength absorption. Their collective absorption exceeds the sum of their individual contributions. This sound absorber provides moth wings with acoustic camouflage (6) against echolocating bats. It combines broadband absorption of all frequencies used by bats with light and ultrathin structures that meet aerodynamic constraints on wing weight and thickness. The morphological implementation seen in this evolved acoustic metamaterial reveals enticing ways to design high-performance noise mitigation devices.
This paper presents a method for time resolved quantitative imaging of acoustic waves. We present the theoretical background, the experimental method and the comparison between experimental and ...numerical reconstructions of acoustic reflection and interference. Laser Doppler vibrometry is used to detect the modulation of the propagation velocity of light, c, due to pressure-dependant changes in the refractive index of air. Variation in c is known to be proportional to variation in acoustic pressure and thus can be used to quantify sound pressure fluctuations. The method requires the laser beam to travel through the sound field, in effect integrating pressure along a transect line. We investigate the applicability of the method, in particular the effect of the geometry of the sound radiator on line integration. Both experimental and finite element reconstructions of the sound field are in good agreement, corroborating punctual pressure measurements from a precision microphone. Spatial limitations and accuracy of the method are presented and discussed.
After War Times Fortune, T. Thomas; Weinfeld, Daniel R; Herd-Clark, Dawn J ...
2014, 2014-09-30
eBook
T. Thomas Fortune was a leading African American publisher, editor, and journalist of the late nineteenth and early twentieth centuries, who was born a slave in antebellum Florida lived through ...emancipation, and rose to become a literary lion of his generation. In T. Thomas Fortune's “ After War Times,” Daniel R. Weinfeld brings together a series of twenty-three autobiographical articles Fortune wrote about his formative childhood during Reconstruction and subsequent move to Washington, DC.
 
By 1890 Fortune had founded a predecessor organization to the National Association for the Advancement of Colored People, known as the National Afro-American League, but his voice found its most powerful expression and influence in poetry, prose, and journalism. It was as a journalist that Fortune stirred national controversy by issuing a passionate appeal to African American southerners: “ I propose to start a crusade,” he proclaimed in June 1900, “ to have the negroes of the South leave that section and to come north or go elsewhere. It is useless to remain in the South and cry Peace! Peace! When there is no peace.” The movement he helped propel became known as “ the Great Migration.”
 
By focusing on Thomas’ s ruminations about his disillusion with post– Civil War Florida, Weinfeld highlights the sources of Fortune’ s deep disenchantment with the South, which intensified when the Reconstruction order gave way to Jim Crow– era racial discrimination and violence. Even decades after he left the South, Fortune’ s vivid memories of incidents and personalities in his past informed his political opinions and writings. Scholars and readers interested in Southern history in the aftermath of the Civil War, especially the experiences of African Americans, will find much of interest in this vital collection of primary writings.
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