Multiple ecosystem services in the uplands of vietnam: rice or forests VS. rice and forests

Uplands of Vietnam provide important ecosystem services (ES): food production for the mainly poor and marginalized populations, biodiversity reservoir, and watershed-regulating functions. However, as population increases, finding land uses that alleviate poverty, increase food production, and maintain other ES over time poses real challenges. In the early 2000's, agricultural and forest conservation policies were introduced that triggered the development of irrigated rice. But most bottom valleys will not be large enough to sustain food needs, and the competition between food production and other ES will remain problematic. Besides, requiring farmers to limit their agricultural production in favor of other ES is unlikely to occur unless alternative remunerating activities are proposed to sustain their livelihoods. New varieties and natural resource management technologies have the potential to produce high rice yields even in rainfed conditions, allowing the production one additional rice crop per year. Once food production goals are met on a smaller area, farmers may develop other activities on the sloping areas such as forest re-growth or cultivating permanent crops. As such, the new technologies could contribute indirectly to the success of forest protection/rehabilitation projects. We developed a framework that accounted for agriculture-forestry-environment interactions and analyzed the trade-offs faced by typical farmers. Basic simulation runs with realistic expert data allowed us to discuss the effects of new technologies on these trade-offs. We argued that focusing on forestry alone for preserving watershed ES is likely to be less efficient and equitable than a double-pronged approach of promoting food production intensification and forestry projects. (Résumé d'auteur

The Changing Narratives of Death, Dying, and HIV in the United Kingdom

Death and infection were closely linked from the start of the HIV epidemic, until successful treatments became available. The initial impact of mostly young, gay men dying from HIV was powerful in shaping UK responses. Neoliberal discourses developed at the same time, particularly focusing on how citizens (rather than the state) should take responsibility to improve health. Subsequently “successful ageing” became an allied discourse, further marginalising death discussions. Our study reflected on a broad range of meanings around death within the historical UK epidemic, to examine how dying narratives shape contemporary HIV experiences. Fifty-one participants including people living with HIV, professionals, and activists were recruited for semistructured interviews. Assuming a symbolic interactionist framework, analysis highlighted how HIV deaths were initially experienced as not only traumatic but also energizing, leading to creativity. With effective antiretrovirals, dying changed shape (e.g., loss of death literacy), and better integration of palliative care was recommended

Overcoming device unreliability with continuous learning in a population coding based computing system

The brain, which uses redundancy and continuous learning to overcome the unreliability of its components, provides a promising path to building computing systems that are robust to the unreliability of their constituent nanodevices. In this work, we illustrate this path by a computing system based on population coding with magnetic tunnel junctions that implement both neurons and synaptic weights. We show that equipping such a system with continuous learning enables it to recover from the loss of neurons and makes it possible to use unreliable synaptic weights (i.e. low energy barrier magnetic memories). There is a tradeoff between power consumption and precision because low energy barrier memories consume less energy than high barrier ones. For a given precision, there is an optimal number of neurons and an optimal energy barrier for the weights that leads to minimum power consumption

Ultra-high-frequency piecewise-linear chaos using delayed feedback loops

We report on an ultra-high-frequency (> 1 GHz), piecewise-linear chaotic system designed from low-cost, commercially available electronic components. The system is composed of two electronic time-delayed feedback loops: A primary analog loop with a variable gain that produces multi-mode oscillations centered around 2 GHz and a secondary loop that switches the variable gain between two different values by means of a digital-like signal. We demonstrate experimentally and numerically that such an approach allows for the simultaneous generation of analog and digital chaos, where the digital chaos can be used to partition the system's attractor, forming the foundation for a symbolic dynamics with potential applications in noise-resilient communications and radar

Ageing with HIV

Applying Fraser’s inequalities framework to our UK-based HIV and Later Life (HALL) study, we show that, for the growing population of older people living with HIV (PLWH), HIV intersects with ethnicity, sex, sexuality, stigma, and ageism to produce bivalent identities. These shape their experience of ageing with HIV and intersect with economic factors, the social status order, and statutory policy to subject them to socioeconomic and cultural injustices only roughly captured by Fraser’s three domains of inequality. Under recognition, the stigmatization of HIV and its exacerbation by normative ageist expectations threaten social relationships. Under resources, older PLWH’s disproportionate financial disadvantage, linked to interrupted work histories, uncertain migration status, and recent changes to benefits on which PLWH are disproportionately reliant and whose new criteria disadvantage them, make access to support from others living with HIV and from HIV organizations even more essential for mental health and wellbeing. Finally, under representation, stigma and homophobia in care settings may undermine the quality of long-term care, and defunding of HIV organizations and welfare benefit changes via neo-liberal policies and austerity measures create political disenfranchisement and barriers to social participation. Thus, Fraser’s clear-cut domains imperfectly capture factors undermining underlying causes of older PLWH’s disadvantage: HIV-specific supports (resources) established to compensate for difficulties emanating from Fraser’s recognition and resources domains are increasingly threatened by agents operating within Fraser’s representation domain. Our conclusion considers other sources of older PLWH’s underrepresentation: their waning participation in activism and advocacy on their own behalf, and inadequate attention by non-HIV organizations

Cosmological constraints from CMB distortion

We examine bounds on adiabatic and isocurvature density fluctuations from $\mu$-type spectral distortions of the cosmic microwave background (CMB). Studies of such distortion are complementary to CMB measurements of the spectral index and its running, and will help to constrain these parameters on significantly smaller scales. We show that a detection on the order of $\mu \sim 10^{-7}$ would strongly be at odds with the standard cosmological model of a nearly scale-invariant spectrum of adiabatic perturbations. Further, we find that given the current CMB constraints on the isocurvature mode amplitude, a nearly scale-invariant isocurvature mode (common in many curvaton models) cannot produce significant $\mu$-distortion. Finally, we show that future experiments will strongly constrain the amplitude of the isocurvature modes with a highly blue spectrum as predicted by certain axion models.Comment: 6 pages, 4 figures, version 3 contains a new figure showing the contribution to \mu_k as a function of k, and a clarification regarding the acoustic wave energy, accompanied by a related acknowledgement and referenc

Cyclic AMP Signaling: A Molecular Determinant of Peripheral Nerve Regeneration

Disruption of axonal integrity during injury to the peripheral nerve system (PNS) sets into motion a cascade of responses that includes inflammation, Schwann cell mobilization, and the degeneration of the nerve fibers distal to the injury site. Yet, the injured PNS differentiates itself from the injured central nervous system (CNS) in its remarkable capacity for self-recovery, which, depending upon the length and type of nerve injury, involves a series of molecular events in both the injured neuron and associated Schwann cells that leads to axon regeneration, remyelination repair, and functional restitution. Herein we discuss the essential function of the second messenger, cyclic adenosine monophosphate (cyclic AMP), in the PNS repair process, highlighting the important role the conditioning lesion paradigm has played in understanding the mechanism(s) by which cyclic AMP exerts its proregenerative action. Furthermore, we review the studies that have therapeutically targeted cyclic AMP to enhance endogenous nerve repair

Antiferromagnetism and singlet formation in underdoped high-Tc cuprates: Implications for superconducting pairing

The extended $t-J$ model is theoretically studied, in the context of hole underdoped cuprates. Based on results obtained by recent numerical studies, we identify the mean field state having both the antiferromagnetic and staggered flux resonating valence bond orders. The random-phase approximation is employed to analyze all the possible collective modes in this mean field state. In the static (Bardeen Cooper Schrieffer) limit justified in the weak coupling regime, we obtain the effective superconducting interaction between the doped holes at the small pockets located around $\bm{k}= (\pm \pi/2, \pm \pi/2)$. In contrast to the spin-bag theory, which takes into acccount only the antiferromagnetic order, this effective force is pair breaking for the pairing without the nodes in each of the small hole pocket, and is canceled out to be very small for the $d_{x^2-y^2}$ pairing with nodes which is realized in the real cuprates. Therefore we conclude that no superconducting instability can occur when only the magnetic mechanism is considered. The relations of our work with other approaches are also discussed.Comment: 20 pages, 7 figures, REVTeX; final version accepted for publicatio