537 research outputs found
Factors influencing farmers' forestland-use changes over 15 years (2005–2020) in Thua Thien Hue province, Vietnam
Over the last decades, Vietnam has seen substantial shifts in forest landscape uses and associated livelihoods. We document the livelihood transformations in Nam Dong, a mountainous district of Central Vietnam, where land uses have changed from the utilisation of products from natural forests and shifting cultivation (swidden agriculture) to acacia tree-dominated plantation forestry. Forestry policies (forestland allocation, plantation development agendas), the increase in the economic value of acacia, and household livelihood assets are the primary factors driving these changes. We also found that there are differences in the access to and ownership of forestland with regard to households of different communities and between poor vs wealthy households. Therefore, careful attention needs to be paid to guide future land use policies in the area to foster social and ecological sustainability.
HIGHLIGHTS
• Major livelihood and forestland-use changes have taken place in central Vietnam over the last two decades.
• There has been widespread conversion of forestland (degraded natural forests, swidden land) and cropland to acacia plantations.
• Household-scale forestland use changes were primarily driven by forestry policies, the market for woodchips, and land resource access.
• There is inequality in access to and ownership of forestland between poor and wealthier households in the mountain district of Vietnam.
• Cases of illegal forestland conversions pose challenges to ensuring sustainable forest landscapes
Current Perspective and Advancements of Alginate-Based Transplantation Technologies
Versatile yet biocompatible bio-materials are in high demand in nearly every industry, with biological and biomedical engineering relying heavily on common biomaterials like alginate polymers. Alginate is a very common substance found in various marine plants which can easily be extracted and purified through cheap nonhazardous methods. A key characteristic of alginate polymers includes easily manipulatable physical properties due to its inert but functional chemical composition. Factors including its functional versatility, long-term polymer stability and biocompatibility have caused alginate-based technologies to draw major attention from both the scientific and industrial communities alike. While also used in food industry manufacturing and standard dental procedures, this chapter will focus on a discussion of the both clinical and nonclinical use of alginate-based technologies in transplantation for regenerative cell and drug delivery systems. In addition, we overview the immune system response prompted following implantation of alginate hydrogels. Consequences of immune cell reactivity to foreign materials, such as inflammation and the foreign body response (FBR), are also analyzed and current and future strategies for potential circumvention of severe immune responses toward alginate-based devices are reviewed and suggested
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Calculation and Validation of Thermomechanical Stresses in Flip Chip BGA Using the ATC4.2 Test Vehicle
We report the first in situ measurements of thermomechanical stresses in a 1000 I/O 250 {micro}m pitch piezoresistive flip chip test chip assembled to a 755 I/O 1.0 mm pitch 35 mm Ball Grid Array (BGA). The BGA substrates employed build-up dielectric layers containing micro-vias over conventional fiberglass laminate cores. Experimental data, which include in situ stress and die bending measurements, were correlated to closed form and Finite Element Method (FEM) calculations. Cracking and delamination were observed in some of the experimental groups undergoing temperature cycling. Through use of bounding conditions in the FEM simulations, these failures were associated with debonding of the underfill fillet from the die edge that caused stresses to shift to weaker areas of the package
Looking into the matter of light-quark hadrons
In tackling QCD, a constructive feedback between theory and extant and
forthcoming experiments is necessary in order to place constraints on the
infrared behaviour of QCD's \beta-function, a key nonperturbative quantity in
hadron physics. The Dyson-Schwinger equations provide a tool with which to work
toward this goal. They connect confinement with dynamical chiral symmetry
breaking, both with the observable properties of hadrons, and hence provide a
means of elucidating the material content of real-world QCD. This contribution
illustrates these points via comments on: in-hadron condensates; dressed-quark
anomalous chromo- and electro-magnetic moments; the spectra of mesons and
baryons, and the critical role played by hadron-hadron interactions in
producing these spectra.Comment: 11 pages, 7 figures. Contribution to the Proceedings of "Applications
of light-cone coordinates to highly relativistic systems - LIGHTCONE 2011,"
23-27 May, 2011, Dallas. The Proceedings will be published in Few Body
System
State sampling dependence of the Hopfield network inference
The fully connected Hopfield network is inferred based on observed
magnetizations and pairwise correlations. We present the system in the glassy
phase with low temperature and high memory load. We find that the inference
error is very sensitive to the form of state sampling. When a single state is
sampled to compute magnetizations and correlations, the inference error is
almost indistinguishable irrespective of the sampled state. However, the error
can be greatly reduced if the data is collected with state transitions. Our
result holds for different disorder samples and accounts for the previously
observed large fluctuations of inference error at low temperatures.Comment: 4 pages, 1 figure, further discussions added and relevant references
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Sharp Trace Hardy-Sobolev-Maz'ya Inequalities and the Fractional Laplacian
In this work we establish trace Hardy and trace Hardy-Sobolev-Maz'ya
inequalities with best Hardy constants, for domains satisfying suitable
geometric assumptions such as mean convexity or convexity. We then use them to
produce fractional Hardy-Sobolev-Maz'ya inequalities with best Hardy constants
for various fractional Laplacians. In the case where the domain is the half
space our results cover the full range of the exponent of the
fractional Laplacians. We answer in particular an open problem raised by Frank
and Seiringer \cite{FS}.Comment: 42 page
Stress corrosion cracking in Al-Zn-Mg-Cu aluminum alloys in saline environments
Copyright 2013 ASM International. This paper was published in Metallurgical and Materials Transactions A, 44A(3), 1230 - 1253, and is made
available as an electronic reprint with the permission of ASM International. One print or electronic copy may
be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via
electronic or other means, duplications of any material in this paper for a fee or for commercial purposes, or
modification of the content of this paper are prohibited.Stress corrosion cracking of Al-Zn-Mg-Cu (AA7xxx) aluminum alloys exposed to saline environments at temperatures ranging from 293 K to 353 K (20 °C to 80 °C) has been reviewed with particular attention to the influences of alloy composition and temper, and bulk and local environmental conditions. Stress corrosion crack (SCC) growth rates at room temperature for peak- and over-aged tempers in saline environments are minimized for Al-Zn-Mg-Cu alloys containing less than ~8 wt pct Zn when Zn/Mg ratios are ranging from 2 to 3, excess magnesium levels are less than 1 wt pct, and copper content is either less than ~0.2 wt pct or ranging from 1.3 to 2 wt pct. A minimum chloride ion concentration of ~0.01 M is required for crack growth rates to exceed those in distilled water, which insures that the local solution pH in crack-tip regions can be maintained at less than 4. Crack growth rates in saline solution without other additions gradually increase with bulk chloride ion concentrations up to around 0.6 M NaCl, whereas in solutions with sufficiently low dichromate (or chromate), inhibitor additions are insensitive to the bulk chloride concentration and are typically at least double those observed without the additions. DCB specimens, fatigue pre-cracked in air before immersion in a saline environment, show an initial period with no detectible crack growth, followed by crack growth at the distilled water rate, and then transition to a higher crack growth rate typical of region 2 crack growth in the saline environment. Time spent in each stage depends on the type of pre-crack (“pop-in” vs fatigue), applied stress intensity factor, alloy chemistry, bulk environment, and, if applied, the external polarization. Apparent activation energies (E a) for SCC growth in Al-Zn-Mg-Cu alloys exposed to 0.6 M NaCl over the temperatures ranging from 293 K to 353 K (20 °C to 80 °C) for under-, peak-, and over-aged low-copper-containing alloys (~0.8 wt pct), they are typically ranging from 20 to 40 kJ/mol for under- and peak-aged alloys, and based on limited data, around 85 kJ/mol for over-aged tempers. This means that crack propagation in saline environments is most likely to occur by a hydrogen-related process for low-copper-containing Al-Zn-Mg-Cu alloys in under-, peak- and over-aged tempers, and for high-copper alloys in under- and peak-aged tempers. For over-aged high-copper-containing alloys, cracking is most probably under anodic dissolution control. Future stress corrosion studies should focus on understanding the factors that control crack initiation, and insuring that the next generation of higher performance Al-Zn-Mg-Cu alloys has similar longer crack initiation times and crack propagation rates to those of the incumbent alloys in an over-aged condition where crack rates are less than 1 mm/month at a high stress intensity factor
Phase diagram of the one-dimensional extended attractive Hubbard model for large nearest-neighbor repulsion
We consider the extended Hubbard model with attractive on-site interaction U
and nearest-neighbor repulsions V. We construct an effective Hamiltonian
H_{eff} for hopping t<<V and arbitrary U<0. Retaining the most important terms,
H_{eff} can be mapped onto two XXZ models, solved by the Bethe ansatz. The
quantum phase diagram shows two Luttinger liquid phases and a region of phase
separation between them. For density n<0.422 and U<-4, singlet superconducting
correlations dominate at large distances. For some parameters, the results are
in qualitative agreement with experiments in BaKBiO.Comment: 6 pages, 3 figures, submitted to Phys. Rev.
Grain Surface Models and Data for Astrochemistry
AbstractThe cross-disciplinary field of astrochemistry exists to understand the formation, destruction, and survival of molecules in astrophysical environments. Molecules in space are synthesized via a large variety of gas-phase reactions, and reactions on dust-grain surfaces, where the surface acts as a catalyst. A broad consensus has been reached in the astrochemistry community on how to suitably treat gas-phase processes in models, and also on how to present the necessary reaction data in databases; however, no such consensus has yet been reached for grain-surface processes. A team of ∼25 experts covering observational, laboratory and theoretical (astro)chemistry met in summer of 2014 at the Lorentz Center in Leiden with the aim to provide solutions for this problem and to review the current state-of-the-art of grain surface models, both in terms of technical implementation into models as well as the most up-to-date information available from experiments and chemical computations. This review builds on the results of this workshop and gives an outlook for future directions
A Small Molecule that Induces Intrinsic Pathway Apoptosis with Unparalleled Speed
Apoptosis is generally believed to be a process thatrequires several hours, in contrast to non-programmed forms of cell death that can occur in minutes. Our findings challenge the time-consuming nature of apoptosis as we describe the discovery and characterization of a small molecule, named Raptinal, which initiates intrinsic pathway caspase-dependent apoptosis within minutes in multiple cell lines. Comparison to a mechanistically diverse panel of apoptotic stimuli reveals that Raptinal-induced apoptosis proceeds with unparalleled speed. The rapid phenotype enabled identification of the criticalroles of mitochondrial voltage-dependent anion channel function, mitochondrial membrane potential/coupled respiration, and mitochondrial complex I, III, and IV function for apoptosis induction. Use of Raptinal in whole organisms demonstrates its utility for studying apoptosis invivo for a variety of applications. Overall, rapid inducers of apoptosis are powerful tools that will be used in a variety of settings to generate further insight into the apoptotic machinery. Palchaudhuri etal. describe the discovery of a small molecule called "Raptinal" that induces unusually rapid apoptotic cell death via the intrinsic pathway. Their work describes the utility of Raptinal as a tool for apoptosis induction relative to other available small molecules
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