34,109 research outputs found

    Repeated Disasters and Chronic Environmental Changes Impede Generational Transmission of Indigenous Knowledge

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    Indigenous coastal communities are interdependent with the environment and families are vulnerable to the environmental changes that disrupt culture, continuity, and livelihood. The purpose of this study was to elucidate meaning from shared cultural perceptions of experiencing repeated disasters and other environmental changes among a United States Indigenous coastal community. This study is part of a larger community- engaged study and reports results from phenomological semi-structured in-depth qualitative interviews (n=19). Participants were enrolled tribal members with a strong ethnic identity and earned a majority of their income from subsistence activities. The results highlight that discrimination, which is part of the broader context of historical oppression, has set the stage for heightened vulnerability in Indigenous communities. Indigenous families are highly connected to their place and environment, yet environmental changes (e.g. repeated disasters, chronic land loss, and climate change) creates barriers for many elder participants pass on traditional knowledge and lifeways to their grandchildren and future generations. Indigenous peoples’ relationship with the land is spiritual, cultural, and place-specific. Interruption of Indigenous Peoples’ ability to interact with the land acculturation, lack of self-determination and discrimination are contemporary forms of trauma

    Origins of choice-related activity in mouse somatosensory cortex.

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    During perceptual decisions about faint or ambiguous sensory stimuli, even identical stimuli can produce different choices. Spike trains from sensory cortex neurons can predict trial-to-trial variability in choice. Choice-related spiking is widely studied as a way to link cortical activity to perception, but its origins remain unclear. Using imaging and electrophysiology, we found that mouse primary somatosensory cortex neurons showed robust choice-related activity during a tactile detection task. Spike trains from primary mechanoreceptive neurons did not predict choices about identical stimuli. Spike trains from thalamic relay neurons showed highly transient, weak choice-related activity. Intracellular recordings in cortex revealed a prolonged choice-related depolarization in most neurons that was not accounted for by feed-forward thalamic input. Top-down axons projecting from secondary to primary somatosensory cortex signaled choice. An intracellular measure of stimulus sensitivity determined which neurons converted choice-related depolarization into spiking. Our results reveal how choice-related spiking emerges across neural circuits and within single neurons

    Elimination of the light shift in rubidium gas cell frequency standards using pulsed optical pumping

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    Changes in the intensity of the light source in an optically pumped, rubidium, gas cell frequency standard can produce corresponding frequency shifts, with possible adverse effects on the long-term frequency stability. A pulsed optical pumping apparatus was constructed with the intent of investigating the frequency stability in the absence of light shifts. Contrary to original expectations, a small residual frequency shift due to changes in light intensity was experimentally observed. Evidence is given which indicates that this is not a true light-shift effect. Preliminary measurements of the frequency stability of this apparatus, with this small residual pseudo light shift present, are presented. It is shown that this pseudo light shift can be eliminated by using a more homogeneous C-field. This is consistent with the idea that the pseudo light shift is due to inhomogeneity in the physics package (position-shift effect)

    Competition of Multinationals from Different Cultural Backgrounds: Does Familiarity Breed Contempt?

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    This paper considers competition between two multinationals (U, J) who compete in a third market (K). The multinationals have similar cost structures, but differ in that J comes from a country that is "culturally similar" to K, and hence produces products that match more closely the preferences of K residents.  This similarity gives J an advantage in K’s market and, if only one firm may enter, J can earn higher profits.  However, we show: (i)K may benefit more from the entry of the dissimilar firm (U), and (ii)in a strategic competition between the two firms, the cultural similarity may be a strategic disadvantage.

    A critical review on sustainable biochar system through gasification: energy and environmental applications

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    This review lays great emphasis on production and characteristics of biochar through gasification. Specifically, the physicochemical properties and yield of biochar through the diverse gasification conditions associated with various types of biomass were extensively evaluated. In addition, potential application scenarios of biochar through gasification were explored and their environmental implications were discussed. To qualitatively evaluate biochar sustainability through the gasification process, all gasification products (i.e., syngas and biochar) were evaluated via life cycle assessment (LCA). A concept of balancing syngas and biochar production for an economically and environmentally feasible gasification system was proposed and relevant challenges and solutions were suggested in this review

    Metrological characterization of the pulsed Rb clock with optical detection

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    We report on the implementation and the metrological characterization of a vapor-cell Rb frequency standard working in pulsed regime. The three main parts that compose the clock, physics package, optics and electronics, are described in detail in the paper. The prototype is designed and optimized to detect the clock transition in the optical domain. Specifically, the reference atomic transition, excited with a Ramsey scheme, is detected by observing the interference pattern on a laser absorption signal. \ The metrological analysis includes the observation and characterization of the clock signal and the measurement of frequency stability and drift. In terms of Allan deviation, the measured frequency stability results as low as 1.7×1013 τ1/21.7\times 10^{-13} \ \tau^{-1/2}, τ\tau being the averaging time, and reaches the value of few units of 101510^{-15} for τ=104\tau=10^{4} s, an unprecedent achievement for a vapor cell clock. We discuss in the paper the physical effects leading to this result with particular care to laser and microwave noises transferred to the clock signal. The frequency drift, probably related to the temperature, stays below 101410^{-14} per day, and no evidence of flicker floor is observed. \ We also mention some possible improvements that in principle would lead to a clock stability below the 101310^{-13} level at 1 s and to a drift of few units of 101510^{-15} per day

    Area spectra versus entropy spectra in black holes in topologically massive gravity

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    We consider the area and entropy spectra of black holes in topologically massive gravity with gravitational Chern-Simons term. The examples we consider are the BTZ black hole and the warped AdS black hole. For the non-rotating BTZ black hole, the area and entropy spectra are equally spaced and independent of the coupling constant \v of the Chern-Simons term. For the rotating BTZ black hole case, the spectra of the inner and outer horizon areas are not equally spaced in general and dependent of the coupling constant \v. However the entropy spectrum is equally spaced and independent of the coupling constant \v. For the warped AdS black holes for >ˇ1\v >1 by using the quasinormal modes obtained without imposing the boundary condition at radial infinity we find again that the entropy spectrum is equally spaced and independent of the coupling constant \v, while the spectra of the inner and outer horizon areas are not equally spaced and dependent of the coupling constant \v. Our result implies that the entropy spectrum has a universal behavior regardless of the presence of the gravitational Chern-Simons term, and therefore it implies that the entropy is more `fundamental' than the horizon area.Comment: 16 page
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